Lecture 2: Chemistry of Life Practice Questions

1. A linear monosaccharide has its carbonyl group located at carbon 1. How should it be classified?

1. An aldose
2. A polysaccharide
3. A ketose
4. A disaccharide

2. What best explains why sodium and chloride ions can dissolve in water?

1. Water forms covalent bonds between sodium and chloride
2. Water converts the ions into non-polar molecules
3. The ions become hydrophobic when surrounded by water
4. Oppositely charged regions of water molecules interact with the ions

3. Which combination of properties makes carbon particularly suitable as the backbone of biological molecules?

1. It cannot bond with other carbon atoms
2. It is always positively charged and strongly hydrophilic
3. It forms only ionic bonds and readily dissolves in water
4. It forms stable covalent bonds with itself and many other elements

4. A plant produces a lipid coating that reduces water loss from the surface of its leaves. Which class of lipid most directly performs this function?

1. Triacylglycerols
2. Phospholipids
3. Steroids
4. Waxes

5. Which statement correctly compares O₂ and H₂O?

1. Neither is a molecule because each contains fewer than three atoms
2. Both are compounds, but only O₂ is a molecule
3. O₂ is a compound, whereas H₂O is only a molecule
4. Both are molecules, but only H₂O is a compound

6. A person who produces insufficient lactase will have difficulty performing which process?

1. Converting fatty acids into carbohydrates
2. Joining glucose molecules to form glycogen
3. Producing lactose by photosynthesis
4. Hydrolysing lactose into monosaccharides

7. A freshwater organism maintains a stable internal salt concentration even when the surrounding water changes. Which property of life does this demonstrate?

1. Homeostasis
2. Adaptation
3. Evolution
4. Reproduction

8. Two monosaccharides join while a molecule of water is released. Which process and product are involved?

1. Dehydration synthesis forming a hydrogen bond
2. Dehydration synthesis forming a glycosidic bond
3. Hydrolysis forming a glycosidic bond
4. Hydrolysis forming a peptide bond

9. Which function demonstrates that nucleotides have roles beyond forming DNA and RNA?

1. Waterproofing plant surfaces
2. Storing cellular energy as ATP
3. Forming bacterial cell walls
4. Forming polysaccharide fibres

10. An antibiotic prevents bacteria from constructing a major structural component of their cell walls. Which molecule is the most likely target?

1. Amylopectin
2. Glycogen
3. Chitin
4. Peptidoglycan

11. How are phospholipids arranged within a membrane separating two aqueous environments?

1. Both heads and tails face the water equally
2. Hydrophobic tails face the water while hydrophilic heads cluster internally
3. Phospholipids remain randomly distributed because they are entirely non-polar
4. Hydrophilic heads face the water while hydrophobic tails cluster internally

12. A molecule contains a long carbon–hydrogen chain attached to a polar head group. How should this molecule be classified?

1. Amphipathic
2. Hydrophobic
3. Hydrophilic
4. Ionic

13. Which structural feature distinguishes the sugar in RNA from the sugar in DNA?

1. RNA contains a phosphate group where DNA contains a nucleobase
2. RNA contains a hydroxyl group where DNA contains hydrogen at the 2′ carbon
3. RNA contains six carbon atoms while DNA contains five
4. RNA contains hydrogen where DNA contains a hydroxyl group at the 2′ carbon

14. Which combination correctly represents the amino and carboxyl groups of an amino acid in an aqueous solution at approximately pH 7?

1. –NH₃⁻ and –COO⁺
2. –NH₃⁺ and –COO⁻
3. –NH₂⁻ and –COOH⁺
4. –NH₂ and –COOH

15. The 20 common amino acids share the same basic alpha structure but have different chemical properties. Which part of their structure is primarily responsible for these differences?

1. The alpha carbon
2. The R group
3. The carboxyl group
4. The amino group

16. A large body of water warms slowly during the day despite absorbing substantial heat. Which property of water best explains this observation?

1. High specific heat
2. Versatility as a solvent
3. Expansion upon freezing
4. High surface tension

17. Which comparison between glycogen and plant starch is most accurate?

1. Glycogen is structural, whereas starch stores genetic information
2. Glycogen is unbranched, whereas all forms of starch are branched
3. Glycogen is generally more extensively branched than starch
4. Glycogen occurs in plants, whereas starch occurs in animals

1. Define monosaccharides, disaccharides and polysaccharides. (3 marks)

2. Describe the carbohydrate storage molecules found in plants and animals. (3 marks)

3. Identify three properties that characterise living organisms. (3 marks)

4. Name three of the four elements most commonly found in living organisms. (3 marks)

5. Compare starch and glycogen as carbohydrate storage molecules. (5 marks)

6. Compare the basic composition of a nucleotide and a nucleoside, and describe one biological role of nucleotides other than forming DNA or RNA. (5 marks)

7. Explain how the amphipathic properties of phospholipids allow them to form a lipid bilayer in an aqueous environment. (5 marks)

8. Explain why carbon is particularly well suited to forming the molecular backbone of living organisms. (5 marks)

9. A hypothetical change causes water molecules to become non-polar and prevents hydrogen bonding between neighbouring water molecules. Predict four consequences this would have for properties of water discussed in the lecture, and explain why each would be affected. (8 marks)

10. A newly discovered molecule contains a long carbon–hydrogen chain attached to a polar region containing oxygen and phosphorus. Predict how this molecule would interact with water and explain how its structure could allow it to contribute to a biological membrane. (8 marks)

11. A person cannot efficiently hydrolyse lactose after consuming dairy products. Use the chemistry of carbohydrates described in the lecture to explain the molecular basis of this problem. (8 marks)

12. At approximately pH 7, an α-amino acid is placed in aqueous solution. Describe its expected chemical structure and explain how amino acids can share a common basic structure while having different chemical properties. (8 marks)

1. A purified nucleic acid sample has an A260:A230 ratio of 1.3. What does this most strongly suggest?

1. The sample may contain organic compound contamination
2. The sample contains unusually high G-C content
3. The nucleic acid has completely denatured
4. The sample contains only pure DNA

2. A mutation changes a polar amino acid sidechain to a nonpolar sidechain. Which property of the resulting protein could be directly affected?

1. The identity of the peptide bond itself
2. The interactions made by that sidechain with its environment
3. The presence of the N-terminus
4. The repeating N-C-C arrangement of the backbone

3. Which combination correctly matches an RNA type with its function?

1. tRNA — acts as an adaptor that carries amino acids during protein synthesis
2. mRNA — structural component of ribosomes
3. tRNA — stores the cell's long-term genetic information
4. rRNA — carries amino acids to the ribosome

4. A single RNA molecule folds so that two complementary regions pair with one another. Which statement best explains this structure?

1. RNA can only base pair with a separate RNA molecule
2. RNA must first be converted into DNA
3. Complementary base pairing can occur between different regions of the same RNA strand
4. Peptide bonds form between complementary RNA bases

5. Which experimental observation is most directly explained by the negative charge of the nucleic acid backbone?

1. DNA migrates in an electric field during electrophoresis
2. Proteins absorb strongly near 280 nm
3. RNA can fold through complementary base pairing
4. Peptide bonds exhibit resonance

6. A purified sample has an A260:A280 ratio of 1.5. What is the most appropriate interpretation based on the lecture?

1. The sample must contain no nucleic acid
2. The sample likely contains excess RNA only
3. The sample likely contains protein contamination
4. The sample is pure DNA

7. Which feature of G-C base pairing best explains its greater contribution to DNA stability compared with A-T pairing?

1. G-C pairs contain more phosphate groups
2. G-C pairs form stronger phosphodiester bonds
3. G-C pairs contain larger sugars
4. G-C pairs form three hydrogen bonds rather than two

8. A student examines a nucleic acid molecule and finds that its sugar contains an additional hydroxyl group compared with deoxyribose. Which conclusion is most appropriate?

1. The molecule is DNA and is generally more susceptible to degradation
2. The molecule must be double-stranded DNA
3. The molecule is RNA and is generally less chemically stable than DNA
4. The molecule must contain thymine rather than uracil

9. A DNA nucleotide is incorporated into a growing nucleic acid strand. Which statement best describes how it becomes part of the backbone?

1. Its phosphate participates in a phosphodiester linkage between neighbouring sugars
2. Its sugar forms a hydrogen bond with the previous phosphate
3. Its base forms a phosphodiester bond with the next base
4. Its base forms a peptide bond with the previous nucleotide

10. Why does RNA generally not form the same B-type helical structure as DNA?

1. RNA contains peptide bonds in its backbone
2. RNA has no phosphates
3. The additional hydroxyl group in ribose affects its structural properties
4. RNA lacks nucleobases

11. A researcher heats double-stranded DNA above its melting temperature. What is the most direct expected outcome?

1. The phosphodiester backbone is converted into peptide bonds
2. The DNA becomes RNA
3. The bases are removed from the sugars
4. The two DNA strands separate from one another

12. A nucleic acid sequence is written as 5′-AGTCGA-3′. Which sequence represents the complementary DNA strand aligned antiparallel to it?

1. 5′-TCAGCT-3′
2. 3′-UCAGCU-5′
3. 3′-TCAGCT-5′
4. 5′-AGTCGA-3′

13. During ethanol precipitation, why is salt added to a nucleic acid sample?

1. To hydrolyse the nucleic acid backbone
2. To help neutralise the negative charge of the nucleic acid
3. To increase the number of phosphate groups
4. To create peptide bonds between nucleotides

14. Which statement best explains why DNA and proteins should not be considered chemically equivalent even though both can form helices?

1. Only proteins contain covalent bonds
2. DNA is built from nucleotides, whereas proteins are built from amino acids
3. DNA and proteins contain identical backbones but different side groups
4. Only DNA has directionality

15. Cytosine spontaneously deaminates to uracil in an RNA molecule. Why is this change more difficult to identify as an error than the same change in DNA?

1. Cytosine cannot be repaired in any nucleic acid
2. RNA contains no cytosine
3. Uracil is already a normal component of RNA
4. RNA lacks a sugar-phosphate backbone

1. Describe how nucleotides are linked together within a nucleic acid strand. (3 marks)

2. Describe the directionality convention used for nucleic acid sequences. (3 marks)

3. Describe the three main components of a nucleotide. (3 marks)

4. Explain why DNA with a higher G-C content generally has a higher melting temperature. (3 marks)

5. Cytosine can spontaneously deaminate to form uracil. Compare the consequences of this reaction occurring in DNA and RNA. (5 marks)

6. One strand of a double-stranded DNA molecule has the sequence 5′-ATGCCGTA-3′. Write the sequence and direction of the complementary strand and explain the principles used to determine it. (5 marks)

7. Three purified nucleic acid samples have A260:A280 ratios of 1.9, 1.6 and 2.2. Interpret these results and explain the basis of the A260:A280 purity measurement. (5 marks)

8. Two double-stranded DNA molecules are the same length, but one contains a much higher proportion of G-C base pairs. Predict which molecule will have the higher melting temperature and explain why. (5 marks)

9. A researcher compares two double-stranded DNA fragments of equal length. Fragment A contains 70% G-C base pairs, whereas Fragment B contains 30% G-C base pairs. Predict how the fragments will differ when progressively heated and explain the molecular basis for your prediction. (8 marks)

10. A researcher isolates both DNA and RNA from cells and then stores the purified molecules under identical conditions. Explain why the RNA would generally be expected to be less stable than the DNA, integrating structural and chemical differences between the two molecules. (8 marks)

11. Cytosine spontaneously deaminates to form uracil in both a DNA molecule and an RNA molecule. Analyse why the same chemical change has different implications for the two nucleic acids. (8 marks)

1. The codons CAU and CAC both encode histidine. Which property of the genetic code does this demonstrate?

1. The code is organism-specific
2. The code is overlapping
3. The code is redundant
4. The code is composed of doublets

2. An AUG codon occurs in the middle of an open reading frame after translation has already begun. How should this codon be interpreted?

1. It causes translation to restart from that position
2. It cannot be translated because AUG only functions as the first codon
3. It can encode methionine within the protein
4. It must terminate translation

3. An mRNA sequence contains the codon UGA within its open reading frame. What will occur when the ribosome reaches this codon?

1. Tryptophan will be incorporated
2. The reading frame will shift
3. Methionine will be incorporated
4. Protein synthesis will terminate

4. Two different cell types in the same organism contain the same genome but produce different sets of proteins. Which explanation best accounts for this difference?

1. Each cell type contains different nucleotide bases
2. Each cell type uses a different genetic code
3. Each cell type expresses a different subset of genes
4. Each cell type possesses a different number of codons

5. Consider the mRNA sequence 5′-CCCAUGCUAUUUUAA-3′. If translation begins at the AUG codon, which sequence represents the open reading frame?

1. AUG-CUA-UUU
2. CCA-UGC-UAU-UUU
3. CCC-AUG-CUA-UUU
4. AUG-CUA-UUU-UAA

6. A point mutation changes one nucleotide in a codon but the resulting codon still specifies the same amino acid. Which feature of the genetic code makes this possible?

1. Every amino acid is encoded by AUG
2. Each nucleotide belongs to multiple overlapping codons
3. Multiple codons can specify the same amino acid
4. Codons can be read in either the 5′→3′ or 3′→5′ direction

7. An mRNA sequence begins 5′-AUGCAUUGG-3′. How should this sequence be divided into codons when translation begins at the first nucleotide?

1. AUG-CAU-UGG
2. A-UGC-AUU-GG
3. AU-GCA-UUG-G
4. AUGC-AUUG-G

8. A point mutation changes one codon so that a different amino acid is incorporated into the polypeptide. Which type of protein-level mutation has occurred?

1. Nonsense
2. Silent
3. Frameshift
4. Missense

9. A single nucleotide is inserted into the coding region of an mRNA. What is the most likely consequence described in the lecture?

1. The transcriptome becomes identical in every cell
2. Only the inserted nucleotide is ignored during translation
3. The reading frame changes, altering downstream codons
4. The entire genome is duplicated

10. A molecule begins reading a typical circular bacterial chromosome and continues around the chromosome without stopping. What could theoretically occur?

1. It could eventually return to its original starting position
2. It would reach the physical end of the chromosome
3. It would convert the chromosome into a linear molecule
4. It would eventually encounter a eukaryotic chromosome

11. A newly studied organism has substantially more chromosomes than humans. What can be concluded about its biological complexity from this information alone?

1. It must have a larger proteome than humans
2. It must be more complex than humans
3. It must contain more protein-coding genes than humans
4. Chromosome number alone does not reliably indicate organismal complexity

12. A point mutation changes an mRNA codon from CUU to CUC. What is the expected effect on the encoded protein?

1. Leucine is replaced with isoleucine
2. The codon still encodes leucine, so the amino acid sequence is unchanged
3. A premature stop codon is introduced
4. The reading frame changes from the mutation onwards

13. What peptide would be produced from the mRNA sequence 5′-AUG CAU UGG UAA-3′ before translation terminates?

1. Met-His-Trp-Stop
2. Met-His-Trp
3. Met-Trp-His
4. His-Trp-Met

14. Why is identifying the start codon important when determining an open reading frame?

1. The start codon prevents mutations in downstream codons
2. The start codon identifies the final amino acid of the protein
3. The start codon determines which RNA molecule is transcribed
4. The start codon establishes the reading frame used for translation

15. A liver cell changes which genes it expresses after receiving a cellular stimulus. Which cellular feature would be expected to change as a result?

1. The universal genetic code
2. The nucleotide sequence of its entire genome
3. Its transcriptome and potentially its proteome
4. The total number of chromosomes

16. Which combination correctly compares typical eukaryotic and prokaryotic chromosomes?

1. Eukaryotic chromosomes are circular, whereas prokaryotic chromosomes are linear
2. Both are usually linear, but only bacterial chromosomes contain genes
3. Both are usually circular and wrapped around histones
4. Eukaryotic chromosomes are typically linear, whereas most prokaryotic chromosomes are circular

17. A mature red blood cell lacks a nucleus. How does this distinguish it from most other cells in the same organism?

1. It contains RNA but cannot contain proteins
2. It uses a different genetic code to other cells
3. It has a larger genome than nucleated cells
4. It does not contain a nuclear copy of the organism's genome

1. Define the genome, transcriptome and proteome. (3 marks)

2. Describe three characteristics of typical prokaryotic genomes discussed in the lecture. (3 marks)

3. Describe three important features of the genetic code. (3 marks)

4. Explain what a frameshift mutation is and identify two types of DNA or RNA mutation that can cause one. (3 marks)

5. What is an open reading frame, and how are its beginning and end identified? (3 marks)

6. A cell increases production of a particular protein in response to a change in its environment. Explain how this response could alter the cell's transcriptome and proteome without changing its genome. (5 marks)

7. A point mutation changes an mRNA codon from UAU to UAA within an open reading frame. Explain how this mutation would affect translation and classify its protein-level outcome. (5 marks)

8. The mRNA sequence 5′-CUGAAGCAUGCUAUUUCUCCCCUAACGCGG-3′ has a number of possible reading frames. Explain how many possible reading frames there are, and why the reading frame containing AUG followed later by UAA is the most likely open reading frame. (5 marks)

9. The mRNA sequences 5′-AUG CAU-3′ and 5′-AUG CAC-3′ encode the same peptide. Explain how this is possible and identify the peptide produced. (5 marks)

10. A cell experiences an environmental change and increases production of one protein while decreasing production of another. Analyse how this observation relates to the central dogma and to the distinction between the genome, transcriptome and proteome. (8 marks)

11. A mutation duplicates part of a coding sequence. Explain why the effect of this duplication on the final protein cannot be predicted simply from knowing that a duplication occurred, and compare its possible effects with those of a single-nucleotide insertion or deletion. (8 marks)

12. A newly identified organism has 200 chromosomes and a genome containing 40 billion base pairs. A researcher concludes that it must be more biologically complex than humans. Evaluate this conclusion using the principles discussed in the lecture and compare the likely genome organisation of a eukaryote with that of a typical prokaryote. (8 marks)

13. Consider the mRNA sequence 5′-CUGAAGCAUGCUAUUUCUCCCCUAACGCGG-3′. Identify the open reading frame shown in the lecture, translate the encoded peptide, and explain why the other possible reading frames would produce different interpretations of the same nucleotide sequence. (8 marks)

14. The normal mRNA sequence 5′-AUG CUA UUU CUC CCC UAA-3′ is altered by deletion of one nucleotide within the coding region. Explain why this mutation may have a much greater effect on the amino acid sequence than a silent point mutation. (8 marks)

1. Which feature distinguishes RNA transcription from DNA replication?

1. Transcription generally copies one DNA strand for a gene rather than both strands of the genome
2. Transcription produces nucleic acid in the 3′→5′ direction
3. Transcription requires complementary base pairing but replication does not
4. Transcription requires multiple RNA primers

2. Why can a cell produce different amounts of RNA from different genes?

1. RNA polymerase permanently removes genes that are not required
2. Every gene must be transcribed at the same rate
3. DNA replication determines how many RNA molecules each gene produces
4. Transcription frequency can be regulated by factors such as promoter strength, repressors and activators

3. During transcription elongation, what happens to the DNA after RNA polymerase has moved through a region?

1. The template DNA is degraded
2. The two DNA strands reanneal
3. The DNA is converted into RNA
4. Both DNA strands are permanently separated

4. Why are regions rich in A/T bases commonly associated with origins of replication?

1. A/T-rich regions contain RNA primers before replication begins
2. A/T bases are only present in origins of replication
3. DNA polymerase specifically recognises A/T-rich sequences
4. A/T base pairs are easier to separate than G/C base pairs

5. During rho-independent termination, a G/C-rich region of the RNA forms a hairpin. What is the consequence of this structure?

1. It recruits DNA polymerase III
2. It causes RNA polymerase to produce an RNA primer
3. It begins DNA replication
4. It pauses transcription and contributes to RNA polymerase dissociation

6. Why are transcription factors important during bacterial transcription initiation?

1. They replace RNA primers with DNA
2. They join newly synthesised RNA fragments
3. They prevent the DNA strands from reassociating throughout the chromosome
4. They recognise specific promoter sequences and facilitate RNA polymerase binding

7. Which sequence of events correctly describes synthesis of the lagging strand?

1. Primase makes RNA primers → DNA polymerase III produces DNA fragments → DNA polymerase I replaces primers → ligase joins fragments
2. DNA polymerase III makes primers → primase extends them → DNA polymerase I joins them
3. Helicase synthesises RNA primers → DNA polymerase III removes them → ligase copies the DNA
4. DNA ligase makes a primer → DNA polymerase I synthesises fragments → primase joins them

8. Which comparison between DNA replication and RNA transcription is correct?

1. Replication and transcription both require DNA ligase to join fragments
2. Replication requires a primer, whereas transcription does not
3. Replication copies approximately one gene, whereas transcription copies the whole genome
4. Replication uses U instead of T during complementary base pairing

9. A DNA replication fork is moving along a chromosome. Why must the leading and lagging strands be synthesised differently?

1. DNA polymerase can only synthesise DNA in the 5′→3′ direction while the template strands are antiparallel
2. Only the lagging strand requires complementary base pairing
3. DNA polymerase can synthesise DNA in either direction, but only one strand contains a promoter
4. The leading strand contains RNA whereas the lagging strand contains DNA

10. A bacterial promoter contains regions located approximately at −35 and −10 relative to the transcription start site. What is the main significance of these regions?

1. They are origins from which DNA replication begins
2. They act as termination signals
3. They encode the final nucleotides of the RNA transcript
4. They contribute to recognition of the promoter during transcription initiation

11. Why does lagging-strand synthesis require multiple RNA primers?

1. The lagging strand is synthesised discontinuously as the replication fork progresses
2. Each nucleotide requires a separate primer
3. DNA polymerase changes direction after every few nucleotides
4. RNA primers are used to join completed DNA molecules together

12. Why do eukaryotic chromosomes generally contain multiple origins of replication?

1. Each origin replicates only the lagging strand
2. Their large linear genomes would be inefficient to replicate from only one starting location
3. Each gene must have its own origin of replication
4. Eukaryotic DNA polymerases synthesise DNA more slowly than bacterial polymerases

13. A protein blocks RNA polymerase from binding to a gene's promoter. How would this protein affect gene expression?

1. It would increase DNA replication at the gene
2. It would act as a repressor and decrease transcription
3. It would increase transcription of the gene
4. It would convert the promoter into a terminator

14. What would most likely happen if single-stranded binding proteins were unable to function during DNA replication?

1. Okazaki fragments would become longer
2. DNA replication would proceed without a template
3. The separated DNA strands would be more likely to reassociate
4. DNA polymerase would begin synthesising RNA

15. A researcher inhibits DNA ligase during replication. Which structure would be expected to remain unjoined?

1. The two parental DNA strands
2. RNA nucleotides within a primer
3. The two replication forks
4. Okazaki fragments on the lagging strand

1. Describe how Okazaki fragments are processed to produce a continuous DNA strand. (3 marks)

2. Describe three general features of DNA replication. (3 marks)

3. Outline the three main stages of RNA transcription. (3 marks)

4. State three differences between DNA replication and RNA transcription. (3 marks)

5. Compare rho-independent and rho-dependent termination of bacterial transcription. (5 marks)

6. Compare the organisation of origins of replication in typical prokaryotic and eukaryotic genomes and explain why they differ. (5 marks)

7. Explain why DNA replication is described as semi-conservative, bi-directional and semi-discontinuous. (5 marks)

8. Explain why synthesis of the lagging strand requires more processing than synthesis of the leading strand. (5 marks)

9. A bacterial RNA transcript cannot form the hairpin required for rho-independent termination, but it contains a functional C-rich rut site. Explain how transcription could still terminate. (8 marks)

10. A bacterial gene has an intact coding region, but mutations alter both its −10 and −35 promoter regions so that the sigma factor no longer recognises them effectively. Predict the effect on transcription and explain why the RNA sequence itself may remain unchanged in any transcripts that are produced. (8 marks)

11. A eukaryotic chromosome is experimentally modified so that nearly all of its origins of replication are inactive. Explain why this would reduce the efficiency of genome replication compared with a normal chromosome. (8 marks)

12. A student claims that DNA replication and RNA transcription are essentially identical because both copy information from DNA and synthesise nucleic acids in the 5′→3′ direction. Evaluate this claim by identifying important similarities and differences between the two processes. (8 marks)

1. A newly synthesised polypeptide consists of a particular sequence of amino acids linked by peptide bonds. Which level of protein structure has been produced directly by translation?

1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

2. Why is tRNA described as an adapter molecule during translation?

1. It forms the ribosome binding site on mRNA
2. It links mRNA codons with their corresponding amino acids
3. It directly catalyses peptide bond formation
4. It converts proteins back into RNA sequences

3. Two regions of the same polypeptide that are more than 100 amino acid residues apart contribute to the same β-sheet. Which feature of β-sheets does this demonstrate?

1. β-sheets can form only between neighbouring amino acids
2. β-sheets require covalent bonding between every participating residue
3. β-sheets cannot occur within a single polypeptide
4. Hydrogen bonding can occur between segments that are distant in the primary sequence

4. A protein functions as a single folded polypeptide and does not associate with other polypeptide subunits. Which statement is most appropriate?

1. The protein cannot form a functional three-dimensional shape
2. The protein has quaternary structure because every protein must contain four structural levels
3. The protein can have primary, secondary and tertiary structure without having quaternary structure
4. The protein cannot contain α-helices or β-sheets

5. Haemoglobin consists of four individual polypeptide subunits assembled into a functional protein. Which level of structure is specifically illustrated by this assembly?

1. Quaternary structure
2. Tertiary structure
3. Primary structure
4. Secondary structure

6. Which observation best explains why transcription and translation can be coupled in prokaryotic cells?

1. Prokaryotic mRNA does not need to be transported out of a nucleus before translation
2. Prokaryotes use the same enzyme for transcription and translation
3. Prokaryotic ribosomes are located inside the nucleus
4. Prokaryotic translation does not require mRNA

7. A newly charged tRNA has entered the A site of a ribosome and its anticodon correctly matches the mRNA codon. What is expected to occur next?

1. The ribosome immediately disassembles
2. The mRNA moves into the nucleus
3. Peptide bond formation occurs between the positioned amino acids
4. The tRNA exits directly through the E site

8. Which description best distinguishes the stabilisation of secondary structure from tertiary structure?

1. Secondary structure requires multiple polypeptides, whereas tertiary structure occurs only in monomers
2. Secondary structure involves hydrogen bonding between backbone groups, whereas tertiary structure involves interactions between amino acid R groups
3. Secondary structure is stabilised by R-group interactions, whereas tertiary structure involves only backbone hydrogen bonds
4. Secondary structure depends on peptide bonds, whereas tertiary structure depends only on phosphodiester bonds

9. During termination, peptidyl transferase contributes to release of the completed polypeptide by:

1. charging the final tRNA with ATP
2. adding water rather than another amino acid
3. breaking down the mRNA template
4. attaching another amino acid to the chain

10. A protein contains several α-helices and β-sheets that fold together into an overall three-dimensional shape. Which level of structure describes this overall spatial arrangement?

1. Secondary structure
2. Primary structure
3. Tertiary structure
4. Quaternary structure

11. An α-helix is disrupted when hydrogen bonding between peptide backbone groups is disturbed. Which level of protein structure is most directly affected?

1. Primary structure
2. Tertiary structure only
3. Secondary structure
4. Quaternary structure

12. A protein is exposed to conditions that cause denaturation but do not chemically break its peptide bonds. Which feature would be expected to remain intact?

1. Its original three-dimensional fold
2. Its complete tertiary structure
3. Its primary amino acid sequence
4. Its biological activity

13. Which feature distinguishes initiation of protein synthesis in eukaryotes from that in prokaryotes as described in the lecture?

1. Only eukaryotes use ribosomes
2. Eukaryotes do not require initiation factors
3. Eukaryotes begin translation with normal methionine rather than formylated methionine
4. Eukaryotes translate mRNA in the 3′ to 5′ direction

14. After peptide bond formation and movement of the ribosome by three bases, what happens to the tRNA that has donated its amino acid?

1. It remains permanently in the P site
2. It moves to the E site and exits the ribosome
3. It moves back to the A site to collect another amino acid
4. It binds a stop codon

15. Why does charging a tRNA contribute to the energy requirements of protein synthesis?

1. ATP is required to form the mRNA codons
2. ATP is used to move the ribosome along the mRNA
3. ATP is used by aminoacyl-tRNA synthetase when attaching an amino acid to its tRNA
4. ATP is incorporated directly into the growing polypeptide

16. A tRNA has successfully paired its anticodon with an mRNA codon during elongation. Which feature ensures that the amino acid carried by this tRNA is appropriate for that codon?

1. A release factor attaches the correct amino acid to the tRNA
2. An aminoacyl-tRNA synthetase charges the tRNA with its specific amino acid
3. Peptidyl transferase determines which amino acid the tRNA should carry
4. The ribosome directly selects the amino acid before tRNA binding

1. Describe primary, secondary and tertiary protein structure. (3 marks)

2. Describe the functions of the A, P and E sites of the ribosome during translation. (3 marks)

3. Describe the roles of mRNA, tRNA and rRNA during protein synthesis. (3 marks)

4. Describe three key events that occur during initiation of translation in bacteria. (3 marks)

5. Describe three key events that occur during the elongation stage of translation. (3 marks)

6. Compare translation in prokaryotic and eukaryotic cells using features described in the lecture. (5 marks)

7. Compare translation initiation and termination in bacteria. (5 marks)

8. Explain how protein denaturation can affect protein structure and biological activity without changing the amino acid sequence. (5 marks)

9. Explain how tRNA charging and codon-anticodon recognition work together to ensure that the correct amino acid is added during translation. (5 marks)

10. Explain what happens to tRNAs and the growing polypeptide during one cycle of translation elongation. (5 marks)

11. A mutation changes a stop codon in a bacterial mRNA into a codon that is recognised by a charged tRNA. Predict what would happen during translation and explain the molecular basis for your prediction. (8 marks)

12. An aminoacyl-tRNA synthetase incorrectly attaches the wrong amino acid to a tRNA, but the tRNA anticodon remains unchanged. Explain how this error could affect the primary structure and function of the resulting protein. (8 marks)

13. Compare the consequences of disrupting hydrogen bonds that stabilise an α-helix with breaking peptide bonds in the same region of a protein. (8 marks)

14. Haemoglobin is composed of four folded polypeptide subunits. Suppose each individual subunit retains its normal primary, secondary and tertiary structure, but the subunits can no longer associate with one another. Explain which level of protein structure is directly affected and how this illustrates the relationship between the four levels of protein structure. (8 marks)

1. An acid phosphatase has maximum activity at approximately pH 5. What would most likely happen if a strong base shifted the reaction mixture to a very high pH?

1. The enzyme concentration would automatically increase
2. Enzyme activity would fall substantially or stop
3. The equilibrium constant would increase
4. The reaction would become more exergonic

2. A reaction begins with mostly reactant and has a strongly negative ΔG. As product accumulates, what is expected to happen to ΔG?

1. It remains unchanged throughout the reaction
2. It rises towards zero
3. It becomes increasingly negative
4. It immediately becomes positive

3. Sucrose hydrolysis is exergonic but can proceed extremely slowly in sterile water. What does this demonstrate?

1. All reactions with negative ΔG occur rapidly
2. Activation energy determines whether ΔG is positive or negative
3. Thermodynamic favourability does not determine reaction speed
4. Exergonic reactions cannot occur spontaneously

4. Two theoretical enzyme reactions are performed under the same experimental conditions with infinite substrate concentration. The second reaction contains twice the enzyme concentration. What is expected for the initial reaction rate?

1. It will remain unchanged
2. It will approximately double
3. It will become zero
4. It will be half as fast

5. A biochemical reaction has a positive ΔG and therefore cannot proceed favourably on its own. How can cells drive such a reaction?

1. Increase its activation energy
2. Allow entropy within the universe to decrease
3. Couple it to an exergonic reaction that provides energy
4. Remove all enzymes from the pathway

6. In a reversible reaction, the forward and reverse reactions continue to occur at equal rates. What does this indicate?

1. The system is at dynamic equilibrium
2. The reaction has stopped
3. The reaction is necessarily exergonic
4. All reactants have been converted into products

7. Which change would most directly increase the rate of a thermodynamically favourable reaction without changing its overall ΔG?

1. Making ΔG more negative
2. Changing the equilibrium constant
3. Increasing the Gibbs free energy of the products
4. Lowering the activation energy

8. During an energy transformation, some energy becomes dispersed as heat. Which principle best explains this observation?

1. Energy transformations are inefficient and entropy increases
2. Gibbs free energy always increases
3. Energy is created during cellular reactions
4. Equilibrium prevents energy loss

9. A contracting muscle converts stored chemical energy into movement. Which energy transformation is occurring?

1. Kinetic energy is being converted into chemical energy
2. Potential energy is being converted into kinetic energy
3. Thermal energy is being converted into potential energy
4. Entropy is being converted into chemical energy

10. Why can an enzyme be used repeatedly to catalyse the same type of reaction?

1. It changes into a new enzyme after each reaction
2. It permanently binds to each product
3. It increases its own concentration during the reaction
4. It is not consumed in the overall reaction

11. An enzyme normally functions within a specific cellular compartment but is detected at an unusual location. Why might this be biologically important?

1. Enzyme location determines the overall ΔG of its reactions
2. Enzyme compartmentalisation can contribute to regulation, and abnormal location may indicate a problem
3. Enzymes function identically regardless of location
4. Enzymes can only function outside cells

12. A mutation causes an enzyme within a metabolic pathway to lose activity. What is a possible consequence described in the lecture?

1. The enzyme automatically changes into a different enzyme
2. The equilibrium constant of all cellular reactions changes
3. An alternative pathway may partly compensate because of biological redundancy
4. Every metabolic pathway in the cell must stop

13. ATP hydrolysis has a ΔG of approximately −30.5 kJ/mol. Why is this useful for cellular energy coupling?

1. ATP hydrolysis prevents any energy from being lost as heat
2. ATP hydrolysis is exergonic and can provide energy to drive endergonic processes
3. ATP hydrolysis changes the equilibrium constant of all coupled reactions
4. ATP hydrolysis is endergonic and absorbs energy

14. Two identical reactions are performed with and without an enzyme. Which feature should remain unchanged between the reactions?

1. The reaction rate
2. The time required to reach equilibrium
3. The activation energy
4. The overall ΔG

15. An enzyme is added to a reaction that would otherwise proceed very slowly. What is the expected effect?

1. The enzyme supplies energy to make the reaction favourable
2. The reaction reaches equilibrium more quickly
3. The equilibrium position shifts towards products
4. The overall ΔG becomes more negative

16. An enzyme specifically binds a substrate because its active site interacts appropriately with the substrate's transition-state form. Which property of enzymes does this demonstrate?

1. Enzymes alter equilibrium constants
2. Enzymes make all reactions spontaneous
3. Enzymes are highly specific
4. Enzymes are consumed during reactions

17. A cell uses ATP to move ions against their concentration gradient. Which cellular process is being powered by ATP?

1. Active transport
2. Thermoregulation
3. Signal transduction
4. Equilibrium

18. A chemical reaction has a negative ΔG but occurs extremely slowly at room temperature. Which explanation is most appropriate?

1. The reaction must actually have a positive ΔG
2. The reaction cannot occur without changing its equilibrium constant
3. The reaction is thermodynamically favourable but has a high activation energy
4. The reaction has already reached equilibrium

1. Define activation energy and explain its relationship to reaction rate. (3 marks)

2. Distinguish between kinetic energy and potential energy. (3 marks)

3. Explain the basic concept of energy coupling in cells. (3 marks)

4. Explain the difference between thermodynamics and kinetics when considering a chemical reaction. (3 marks)

5. A cellular reaction has a positive ΔG and therefore does not proceed favourably on its own. Explain how energy coupling involving ATP can allow the reaction to occur. (5 marks)

6. Explain how catabolic and anabolic processes are linked through ATP in cells. (5 marks)

7. Two enzyme reactions are performed under identical experimental conditions with a high substrate concentration. The second reaction contains twice the enzyme concentration of the first. Predict how their initial reaction rates should compare and explain how the rates would be measured. (5 marks)

8. A cellular reaction has ΔG = +20 kJ/mol. The cell couples this reaction to ATP hydrolysis, which has ΔG = −30.5 kJ/mol. Explain how energy coupling can allow the cellular reaction to proceed and determine the overall ΔG of the coupled processes. (8 marks)

9. A reversible reaction begins with a high concentration of reactant and very little product. Its initial ΔG is strongly negative. Explain how the reaction and its ΔG are expected to change as the system progresses towards equilibrium. (8 marks)

10. An enzyme normally functions within a particular cellular compartment and is initially produced as an inactive zymogen. A mutation causes the enzyme to become active before it reaches its normal location. Explain why both compartmentalisation and zymogen formation can regulate enzyme activity, and predict why premature activation could be problematic. (8 marks)

1. What is the functional significance of water oxidation at photosystem II?

1. It replenishes electrons lost from the reaction centre while releasing oxygen and protons
2. It generates the final sugar products of the Calvin cycle
3. It consumes oxygen to create glucose in the thylakoid lumen
4. It converts ATP directly into NADP⁺

2. Why did oxygenic photosynthesis profoundly alter early Earth?

1. It stopped all organisms from using redox chemistry
2. Water-splitting photosynthesis released oxygen that accumulated and changed atmospheric chemistry
3. It made biological carbon fixation independent of light or chemical energy
4. It converted atmospheric oxygen permanently into nitrogen

3. Why are two photon-absorbing photosystems involved in the non-cyclic light reactions?

1. Both photosystems are used exclusively to export ATP from the chloroplast
2. Light-driven excitation at successive reaction centres supports electron flow from water towards NADP⁺
3. One photosystem absorbs carbon dioxide while the other directly synthesises glucose
4. Two photosystems cancel the need for a redox reaction

4. Why is photosystem II called “II” even though it operates before photosystem I?

1. Photosystem II absorbs no light until after photosystem I has ceased working
2. The Roman numeral refers to the number of membranes surrounding each photosystem
3. The photosystems were named in discovery order rather than functional order
4. Photosystem I belongs to respiration whereas photosystem II belongs to photosynthesis

5. Which event initiates charge separation within a photosystem?

1. Carbon dioxide reacts with a proton to form NADPH
2. An antenna pigment hydrolyses ATP to produce a photon
3. An excited reaction-centre chlorophyll transfers an electron to an acceptor
4. Oxygen accepts ATP from the thylakoid lumen

6. Why does excitation energy move through an antenna complex towards the reaction centre?

1. The same electron travels sequentially through every antenna pigment to the stroma
2. Energy is transferred between pigments before the first actual electron-transfer event at the centre
3. Antenna pigments release carbon dioxide to transport excitation
4. ATP synthase transports the excited electron through chlorophyll molecules

7. Which set of products correctly links the light reactions to carbon fixation?

1. Glucose provides the energy and carbon dioxide supplies the electron acceptor for ATP synthase
2. ADP provides reducing power and oxygen provides phosphate
3. ATP provides usable chemical energy and NADPH provides reducing power
4. Water provides all carbon atoms and oxygen directly reduces NADP⁺

8. What does the label P680 signify in photosystem II?

1. A protein consisting of 680 amino acids in every photosystem
2. The number of ATP molecules produced by a chloroplast
3. A reaction-centre chlorophyll with strongest absorption near 680 nm
4. The wavelength of oxygen released by water oxidation

9. Which sequence correctly links the two principal stages of photosynthesis?

1. The Calvin cycle oxidises water, then the antenna fixes carbon dioxide
2. Light reactions directly assemble glucose without a subsequent carbon-fixation stage
3. Light reactions generate ATP and NADPH, which can support carbon fixation in the Calvin cycle
4. The Calvin cycle generates light, which is absorbed by the photosystems

10. Which direction best describes proton movement through thylakoid ATP synthase during ATP formation?

1. From the chloroplast into the cytosol through the nuclear envelope
2. From the stroma into the mitochondrial matrix
3. From the stroma towards the lumen through ATP synthase
4. From the lumen towards the stroma

11. Why must cells continuously regenerate ATP?

1. Cells cannot couple energy-releasing and energy-requiring reactions
2. Energy-releasing reactions always require a new chlorophyll molecule
3. ATP is rapidly recycled as an energy carrier rather than maintained as a large long-term reserve
4. ATP is biologically stable only in the complete absence of water

12. Which comparison of NADH and NADPH reflects their roles in the lecture?

1. Both are structural pigments in the chloroplast antenna
2. NADPH is the principal electron sink of aerobic respiration and NADH fixes carbon
3. NADH is prominent in catabolic energy capture, whereas NADPH supplies reducing power for biosynthesis
4. Neither can donate electrons after being reduced

13. Why are electron carriers often absent from the overall equations for respiration or photosynthesis?

1. They move energy only as heat rather than through reactions
2. They are used and regenerated across individual steps and cancel in the net equation
3. They do not participate in either pathway
4. They are always consumed completely before products appear

14. Which observation would identify glucose synthesis from carbon dioxide as anabolic rather than catabolic?

1. It produces ATP through hydrolysis of ADP
2. It releases stored chemical energy by oxidising glucose
3. It constructs an energy-rich organic molecule and requires an energy input
4. It transfers electrons to oxygen during glucose breakdown

15. During aerobic glucose breakdown, which change best identifies the oxidation of glucose?

1. All glucose carbon atoms become part of ATP
2. Glucose acquires electrons from NADH without being degraded
3. Electrons are removed from glucose-derived intermediates and transferred to carriers
4. Electrons are created from chemical energy rather than transferred

1. Describe the role of water in the light reactions. (3 marks)

2. Distinguish heterotrophy from autotrophy as introduced in the lecture. (3 marks)

3. Explain the function of a photosystem antenna complex. (3 marks)

4. Identify the order and principal reaction-centre labels of the two photosystems. (3 marks)

5. Explain how PSII supplies electrons for non-cyclic photosynthetic electron transport. (5 marks)

6. Explain how an apparently simple overall equation can conceal the mechanisms of metabolism. (5 marks)

7. Explain the importance of chloroplast compartmentalisation for ATP production. (5 marks)

8. Explain why photosynthesis is an anabolic process and how it differs energetically from the breakdown of glucose. (5 marks)

9. Trace the transfer of energy from sunlight to reaction-centre electron transfer in a photosystem. (5 marks)

10. A chloroplast mutant has normal light absorption and electron transport but a thylakoid membrane that leaks protons. Predict its effects on the proton gradient, ATP formation and carbon fixation, explaining each link. (8 marks)

11. A researcher can measure proton concentrations in the thylakoid lumen and stroma but cannot measure ATP directly. Explain how the readings could inform a prediction of ATP formation and identify relevant limitations. (8 marks)

12. An investigator finds that a chloroplast continues receiving photons but the Calvin cycle has very little ATP or NADPH available. Using the lecture mechanisms, propose how failures at different locations could explain the observation. (8 marks)

13. Design the key labels and arrows for a simplified chloroplast schematic showing non-cyclic photophosphorylation and justify the direction of each major flow. (8 marks)

1. What is the immediate fate of the unstable six-carbon intermediate made during Rubisco carboxylation?

1. It is oxidised to molecular oxygen by Rubisco
2. It is exported from the leaf as sucrose without further reactions
3. It becomes PEP and then returns to the mesophyll as pyruvate
4. It splits into two three-carbon 3-phosphoglycerate molecules

2. Which description correctly links 3-phosphoglycerate and G3P in the Calvin cycle?

1. G3P is oxidised by photosystem II to release water
2. 3-phosphoglycerate is the long-term vacuolar store of night-time carbon
3. ATP and NADPH support conversion of 3-phosphoglycerate into G3P
4. ATP is unnecessary because the conversion is driven only by CO₂ diffusion

3. What does the return of pyruvate to mesophyll cells achieve in the depicted C4 pathway?

1. It allows regeneration of PEP to sustain the carbon-concentrating cycle
2. It replaces all ATP and NADPH in the Calvin cycle
3. It permanently removes three carbon atoms from the plant
4. It delivers oxygen for the photorespiratory pathway in chloroplasts

4. Why is most Calvin-cycle G3P retained instead of exported for sugar synthesis?

1. It is the primary product of photorespiratory oxygenation
2. It directly opens stomata by replacing guard cells
3. It is needed to regenerate RuBP and maintain continued carbon fixation
4. It is required to split water in photosystem II

5. In the two-stage redox description, what happens to NADPH during Calvin-cycle carbon reduction?

1. NADPH becomes the five-carbon acceptor RuBP
2. NADPH donates electrons and is oxidised to NADP⁺
3. NADPH releases oxygen from water in the stroma
4. NADPH accepts electrons from CO₂ and becomes NADP⁺

6. What is the main biochemical difference between Rubisco carboxylation and oxygenation?

1. Carboxylation uses oxygen as substrate whereas oxygenation uses carbon dioxide
2. Carboxylation releases all fixed carbon as CO₂ whereas oxygenation makes sugars efficiently
3. They compete for Rubisco activity, with oxygenation initiating wasteful photorespiration
4. Only oxygenation can occur inside chloroplasts

7. Why is night-time stomatal opening beneficial for CAM plants in dry habitats?

1. Cooler, more humid night air reduces water loss per unit CO₂ uptake
2. Water vapour can no longer diffuse through stomata at night under any conditions
3. It eliminates the need to assimilate carbon dioxide
4. Stomata become permanently impermeable to all gases

8. Which sequence correctly represents the general C4 carbon-concentrating pathway described?

1. Calvin-cycle fixation in mesophyll, oxygen transfer to bundle sheath, nightly malate storage
2. Initial bicarbonate fixation in mesophyll, C4-acid transfer, CO₂ release in bundle sheath, Calvin-cycle fixation
3. Stomatal closure by day, vacuolar malate storage by night, all in the same photosynthetic cell
4. Carbon dioxide fixation by Rubisco in air, followed by sugar transfer into PEP carboxylase

9. Why is C4 photosynthesis effective at suppressing photorespiration?

1. It removes the Calvin cycle and therefore removes all RuBP
2. It reduces carbon dioxide availability specifically at Rubisco active sites
3. It converts all atmospheric oxygen into water in mesophyll stomata
4. It raises CO₂ concentration around bundle sheath Rubisco so carboxylation outcompetes oxygenation

10. A leaf has a photosynthetic CO₂ uptake of 17.9 µmol m⁻² s⁻¹ and water loss of 2.4 mmol m⁻² s⁻¹. Which approximate molar water-use efficiency follows?

1. 135 mol CO₂ fixed per mol H₂O lost
2. 0.75 mol CO₂ fixed per mol H₂O lost
3. 7.5 mol CO₂ fixed per mol H₂O lost
4. 0.0075 mol CO₂ fixed per mol H₂O lost

11. Why is the Calvin cycle described as light-independent although photosynthesis requires light?

1. It can only operate when all chloroplasts are kept in darkness
2. It fixes carbon without any demand for chemical energy
3. It does not directly absorb photons but uses ATP and NADPH supplied by the light reactions
4. It directly oxidises water instead of receiving reduced electron carriers

12. Why does the Calvin cycle require regeneration of RuBP?

1. RuBP is needed to open guard cells rather than for carbon fixation
2. Every sugar molecule is directly formed by irreversible breakdown of RuBP without replacement
3. RuBP must be replenished to continue accepting carbon dioxide in new turns
4. RuBP is the sole terminal electron acceptor of the light reactions

13. Which comparison correctly distinguishes the chief separation strategies of C4 and CAM?

1. Neither pathway uses PEP carboxylase or Rubisco
2. C4 separates initial and Calvin-cycle fixation across cell types; CAM separates initial capture and Calvin-cycle use across night and day
3. C4 separates the reactions by time only; CAM separates them by different mesophyll and bundle sheath cells
4. C4 and CAM both require stomata to remain open throughout midday

14. What is the functional role of vacuolar malic-acid storage in CAM plants?

1. It permanently replaces NADPH in all biosynthetic reactions
2. It allows the Calvin cycle to operate only in bundle sheath cells
3. It directly stores the oxygen released by light-driven water splitting
4. It holds carbon captured at night until CO₂ can be released for daytime Calvin-cycle fixation

15. Why did the oxygenase activity of ancient Rubisco become problematic as Earth changed?

1. Early Rubisco evolved only after modern oxygen concentrations were reached
2. Atmospheric oxygen accumulated after oxygenic photosynthesis evolved, increasing competition with CO₂
3. Carbon dioxide no longer existed once oxygenic photosynthesis began
4. Photorespiration occurs only if all atmospheric oxygen disappears

1. Describe the main night-time events of CAM photosynthesis. (3 marks)

2. Explain the basic photosynthesis–transpiration compromise. (3 marks)

3. Explain why the Calvin cycle is called C3 photosynthesis. (3 marks)

4. State where the Calvin cycle takes place and identify its principal energy and electron supplies. (3 marks)

5. Compare C3, C4 and CAM photosynthesis in the environments to which the lecture links them. (5 marks)

6. Explain the physiological link between stomatal opening, CO₂ uptake and water loss. (5 marks)

7. Explain the relationship between light reactions and the Calvin cycle, tracing the main energy and electron carriers. (5 marks)

8. Explain why lower atmospheric CO₂ could favour the evolution of C4 photosynthesis. (5 marks)

9. Trace the major movement of carbon through the representative C4 pathway described. (5 marks)

10. A mutation disrupts Calvin-cycle RuBP regeneration while light reactions remain active. Explain the expected metabolic consequences, distinguishing immediate from downstream effects. (8 marks)

11. A researcher measures photosynthesis of 17.9 µmol CO₂ m⁻² s⁻¹ and transpiration of 2.4 mmol H₂O m⁻² s⁻¹ in wheat. Calculate water-use efficiency and explain its physiological significance. (8 marks)

12. Compare the carbon-concentrating solutions used by C4 and CAM plants, including their roles in conserving carbon and water. (8 marks)

13. Explain how oxygenic photosynthesis ultimately created an evolutionary disadvantage for the ancient enzyme Rubisco, and how later pathways evolved in response. (8 marks)

1. Why is the Krebs cycle a cycle rather than a linear pathway?

1. It generates new carbon atoms that replace all released carbon dioxide
2. The four-carbon acceptor is regenerated so another acetyl group can enter
3. All metabolic products leave the pathway without reuse
4. Its reactions occur only when light drives a photosystem

2. How does the respiratory electron transport chain contribute energy to ATP synthesis?

1. It directly attaches electrons to ADP to generate ATP without a proton gradient
2. Electron transfers release energy used to pump protons and establish a gradient
3. It converts oxygen into chlorophyll to absorb light
4. It makes the matrix and intermembrane space chemically identical

3. Which description best captures the electrochemical nature of the mitochondrial proton gradient?

1. The only difference is in glucose concentration because protons are uncharged
2. The intermembrane space differs from the matrix in both proton concentration and electrical potential
3. An electrochemical gradient is the physical movement of ATP between organelles
4. The matrix and intermembrane space must have exactly equal proton concentrations

4. Which observation supports thermogenesis by sacred lotus flowers?

1. Flower temperatures always track ambient temperatures exactly
2. Their heat production is exclusively from sunlight stored in stomata
3. Flower receptacles can remain warmer than surrounding air while respiration increases in cooler air
4. Lotus flowers release no carbon dioxide or consume no oxygen when warm

5. How do AOX and uncoupling proteins differ mechanistically?

1. Both directly fix carbon dioxide in mitochondria
2. Both are alternative names for Rubisco
3. AOX bypasses proton-pumping electron-transfer steps; uncoupling proteins provide proton leak pathways
4. AOX carries protons through ATP synthase; uncoupling proteins directly oxidise pyruvate

6. Which statement best explains why NADH and FADH₂ production in the Krebs cycle is important?

1. They are the two principal products of oxygen reduction at complex IV
2. They directly fix carbon dioxide into sugars during respiration
3. They act as the structural phospholipids of the inner mitochondrial membrane
4. They deliver electrons from carbon oxidation to the respiratory electron transport chain

7. Why can mitochondrial uncoupling promote heat production?

1. The protein converts all NADH directly into ATP
2. An uncoupler increases the ATP yield by preventing proton return
3. Protons dissipate gradient energy through a route that bypasses ATP synthase
4. Protons are created from heat and stored as oxygen

8. Why might AOX or uncoupling pathways benefit a plant when reducing power exceeds ATP demand?

1. They make oxygen unnecessary as the terminal acceptor of respiration
2. They prevent all redox reactions and all electron transfer indefinitely
3. They require the chloroplast Calvin cycle to operate inside mitochondria
4. They allow electron flow or gradient dissipation without forcing all available energy into ATP production

9. What connects glycolysis to the Krebs cycle?

1. Fixation of carbon dioxide by Rubisco
2. Conversion of pyruvate to acetyl-CoA with CO₂ release and NADH production
3. Movement of citrate into the thylakoid lumen
4. Conversion of oxygen directly into glucose in the matrix

10. Which comparison identifies the different terminal electron acceptors in the two organelles?

1. Both terminate with Rubisco accepting electrons
2. Mitochondrial NADP⁺ is reduced to glucose; chloroplast oxygen is reduced to water
3. Mitochondrial oxygen is reduced to water; chloroplast NADP⁺ is reduced to NADPH
4. Both terminate with FADH₂ being irreversibly destroyed

11. Why is oxygen indispensable to sustained normal aerobic oxidative phosphorylation?

1. It is the source of carbon atoms released from acetyl-CoA
2. It directly phosphorylates ADP without ATP synthase
3. It accepts electrons at the chain end, allowing upstream electron transfer to continue
4. It is reduced to carbon dioxide as the major product

12. Which general carbon progression occurs between glycolysis and the Krebs cycle?

1. Oxygen is converted into a two-carbon acetyl group
2. Carbon dioxide is converted to glucose, then enters the link reaction
3. Glucose is converted to pyruvate, then to an acetyl group that enters the cycle
4. Glucose carbon moves directly into the intermembrane space for oxidation

13. Which electron-source comparison between mitochondria and chloroplasts is correct?

1. Both rely on carbon dioxide as the terminal electron donor
2. Mitochondria receive electrons from NADH/FADH₂; oxygenic chloroplasts obtain electrons from water
3. Neither system uses reduced electron carriers
4. Mitochondria obtain electrons only from sunlight; chloroplasts use NADH as their ultimate donor

14. Which proton-flow comparison correctly distinguishes photosynthetic and respiratory ATP synthase?

1. Mitochondrial H⁺ returns into the matrix; thylakoid H⁺ returns into the stroma
2. In both, ATP synthase eliminates the need for a separating membrane
3. Both organelles require protons to return into the thylakoid lumen
4. Mitochondrial H⁺ moves into the stroma; chloroplast H⁺ moves into the matrix

15. Why is coenzyme A released after it delivers an acetyl group to the Krebs cycle?

1. It becomes the terminal acceptor of mitochondrial electrons
2. It converts NADH into a chlorophyll pigment
3. It stores the proton gradient across the inner membrane
4. It acts as a reusable carrier rather than the carbon substrate that is oxidised

16. Why does cellular respiration release usable energy more controllably than burning glucose?

1. It bypasses electron transfer and releases all energy at once
2. It creates energy from ADP without using the stored energy in glucose
3. It oxidises substrates through a series of coupled reactions that transfer energy to carriers and ATP
4. It converts all heat directly into carbon dioxide

17. Why does the folding of the mitochondrial inner membrane support respiration?

1. Cristae create carbon atoms needed by the Krebs cycle
2. Membrane folds make glycolysis occur inside mitochondria
3. Folding eliminates the separation of matrix and intermembrane space
4. Cristae increase membrane surface area available for electron-transport proteins and ATP synthase

1. Describe how uncoupling proteins can generate heat. (3 marks)

2. Explain the effect of alternative oxidase on respiration. (3 marks)

3. Explain the role of oxygen in mitochondrial electron transport. (3 marks)

4. State three mechanistic similarities between photosynthetic and respiratory ATP production. (3 marks)

5. State where glycolysis occurs and identify its main products. (3 marks)

6. Compare how proton gradients are generated and used in chloroplasts and mitochondria. (5 marks)

7. Compare the sources and fates of electrons in chloroplast and mitochondrial electron transport. (5 marks)

8. Explain the evidence and mechanism for thermogenesis in sacred lotus flowers. (5 marks)

9. Explain the relationship between electron transport, oxygen reduction and the mitochondrial proton gradient. (5 marks)

10. Explain why oxygen limitation strongly reduces normal aerobic ATP production. (5 marks)

11. A sacred lotus receptacle remains warm despite cooler surrounding air. Evaluate how measured oxygen uptake and the respiratory mechanism could support thermoregulation. (8 marks)

12. Explain the difference between capturing electrons during carbon oxidation and using their energy to synthesise ATP, using the Krebs cycle and ETC. (8 marks)

13. Trace how oxidation of glucose supports mitochondrial ATP synthesis, following carbon, electron carriers, protons and oxygen. (8 marks)

1. Which summary best describes the carbon flow from glucose to fatty acid presented in the lecture?

1. Glucose becomes lysine and then glycogen without intermediary reactions
2. All glucose carbons become phosphate groups before entering fat
3. Glucose is translated directly into fatty acid by ribosomes
4. Glucose is converted through pyruvate and acetyl units, which can be used for fatty acid synthesis

2. Which enzyme activity reverses the addition of a phosphate group to many proteins?

1. A protein phosphatase removes the phosphate group
2. A glycogen synthase removes the phosphate group
3. A DNA polymerase removes the phosphate group
4. A ribosome removes the phosphate group

3. What is the scientific weakness in the film’s claim that a lysine-dependent animal could not survive outside a facility?

1. Animals can obtain lysine only by photosynthesis
2. Lysine occurs in ordinary foods, so escaped animals could potentially obtain it by eating
3. Lysine is non-essential in all animals
4. Lysine cannot be present in either plants or animals

4. How is ATP hydrolysis often coupled to biosynthetic reactions?

1. ATP functions only as a structural lipid
2. ATP always releases energy by converting its ribose to carbon dioxide
3. ATP supplies all carbon atoms incorporated into new fatty acids
4. ATP can phosphorylate a substrate or a protein, helping drive an otherwise unfavourable step

5. Why is glycogen stored in skeletal muscle not simply equivalent to a liver glucose reserve?

1. Liver glycogen is used only for muscle contraction
2. Muscle glycogen is assembled from amino acids rather than glucose
3. Skeletal muscle cannot break down glycogen
4. Muscle glycogen is used predominantly to support local muscle energy needs

6. After a carbohydrate-rich meal, blood glucose rises. Which response supports short-term glucose storage?

1. Insulin directly hydrolyses every glycogen bond
2. Glucagon converts fatty acids into intact glycogen without intermediates
3. Glucagon causes immediate conversion of all glycogen into protein
4. Insulin signalling promotes glucose uptake and glycogen synthesis in responsive tissues

7. How can a varied plant-based diet supply essential amino acids if one food is relatively low in a particular amino acid?

1. Other plant foods can contribute complementary essential amino acids
2. The body can manufacture every essential amino acid from water
3. Essential amino acids are unnecessary when dietary protein is plant-derived
4. All plant proteins contain identical proportions of amino acids

8. A triglyceride is formed by joining three fatty acids to glycerol. How is this related to fat storage?

1. It turns fatty acids into essential amino acids without a nitrogen source
2. It hydrolyses the glycerol backbone into glucose immediately
3. It builds an energy-rich lipid molecule that can be stored in adipose tissue
4. It yields a molecule that is identical to glycogen

9. Which structural feature explains why fatty acid chains tend to be hydrophobic?

1. They carry multiple permanent positive charges along the chain
2. They are made mainly of charged phosphate groups
3. They contain repeated peptide bonds exposed to water
4. They contain predominantly non-polar carbon–hydrogen bonds

10. How can transfer of phosphate from ATP to a protein change protein function?

1. Added negative charge can alter electrostatic interactions and protein conformation
2. Phosphorylation permanently destroys every enzyme
3. ATP inserts an extra amino acid into the protein backbone
4. The phosphate always replaces the entire polypeptide chain

11. Two glucose molecules join with the removal of water. How should this reaction be classified?

1. A catabolic reaction that releases free amino acids
2. An anabolic condensation reaction that produces a glycosidic bond
3. An anabolic reaction that removes a fatty acid
4. A catabolic hydrolysis reaction that breaks a peptide bond

12. During a period between meals, which response helps the liver supply glucose?

1. Insulin stimulates hepatic glycogen synthesis as the only available process
2. Glucagon signalling promotes hepatic glycogen breakdown
3. All blood glucose is converted immediately into triglyceride
4. Liver cells use skeletal-muscle glycogen directly as circulating glucose

13. When comparing 100 g of lean beef with 86 g of roasted soybeans in the lecture table, what is the most defensible interpretation?

1. The table proves that no other dietary factors should influence food choice
2. The soybeans contain no methionine
3. The data show that beef supplies every amino acid in greater amounts
4. Both foods supply the listed essential amino acids, though quantities differ among amino acids

14. Why can digested protein from a meal contribute to new human proteins?

1. Absorbed amino acids can be assembled into human-specific polypeptide sequences
2. Dietary proteins retain their original sequence and function in human cells
3. Only plant-derived amino acids can enter human protein synthesis
4. The digestive tract transfers intact meat proteins directly into muscle fibres

15. Why is a phosphate group generally hydrophilic?

1. It is composed solely of non-polar C–H bonds
2. It has the same structure as a fatty acid chain
3. It is completely electrically neutral at physiological pH
4. Its negatively charged oxygens interact favourably with water

16. Why does ATP commonly link catabolic and anabolic metabolism?

1. ATP is a permanent store that never needs replenishment
2. ATP replaces all catalysts in synthetic reactions
3. ATP converts every absorbed nutrient directly into protein
4. Energy released by breakdown pathways can support ATP regeneration, and ATP-dependent reactions can drive biosynthesis

1. Describe glycogen and identify the two principal tissues highlighted for glycogen storage. (3 marks)

2. Describe how two glucose units can be joined by a glycosidic bond. (3 marks)

3. Explain the meaning of an essential amino acid using lysine as an example. (3 marks)

4. Identify the components of ATP and state one way ATP can support cellular work. (3 marks)

5. Compare lean beef and soybeans as sources of essential amino acids, using the lecture table cautiously. (5 marks)

6. Compare macronutrients and micronutrients in terms of examples and functions. (5 marks)

7. Explain how catabolism and anabolism cooperate in continual protein maintenance. (5 marks)

8. A research proposal states that dietary carbohydrates can replace all dietary essential amino acids because nutrients are interconvertible. Assess the claim. (8 marks)

9. Design a conceptual explanation of how one dietary protein molecule can contribute both to replacement tissue protein and to general metabolism rather than remaining intact in the body. (8 marks)

10. Evaluate the claim that eating plant protein cannot supply a complete set of essential amino acids. (8 marks)

11. Explain how glycogen breakdown, ATP recycling and ATP-mediated phosphorylation can be linked when a cell must activate a transport protein. (8 marks)

12. Use carbon accounting to explain how six-carbon glucose can supply precursors for fatty acid synthesis without directly turning into a lipid polymer. (8 marks)

1. Which process requires both a flexible membrane and cellular machinery to engulf an external particle?

1. Transcription of DNA into RNA
2. Passive diffusion of a gas across a bilayer
3. Synthesis of peptidoglycan in the nucleolus
4. Phagocytic uptake by membrane extension around the particle

2. Why can plant cell walls contribute to shape support without replacing plasma-membrane transport functions?

1. The cell wall acts as a second nucleus
2. The cellulose wall provides external support, while the plasma membrane still regulates exchange
3. The plant cell wall consists mainly of transmembrane proteins
4. Cellulose performs all ATP-dependent membrane transport

3. How can a prokaryotic membrane carry out functions even without internal membrane-bound organelles?

1. Prokaryotes rely exclusively on nuclei for energy metabolism
2. Membrane-embedded proteins can perform transport and energy-related processes at the cell boundary
3. Prokaryotes lack all proteins associated with membranes
4. Their cell walls perform all intracellular translation

4. What is the principal contribution of peptidoglycan to many bacterial cells?

1. A nuclear envelope that encloses DNA
2. A protein complex that translates mRNA
3. An internal reserve of triglyceride
4. A supportive external cell wall built from sugar chains cross-linked by peptides

5. A microorganism has no nucleus and its cell wall lacks peptidoglycan. Which group is most consistent with these observations?

1. Archaea
2. Flowering plants
3. Bacteria with a typical peptidoglycan wall
4. Multicellular animals

6. Why are evolutionary models for the origin of the nucleus considered hypotheses rather than direct observations?

1. They claim that membranes cannot change shape
2. They have been directly photographed in ancient living cells
3. They reconstruct ancient events from present-day evidence rather than witnessed historical processes
4. They require every cell to be completely identical today

7. Which feature best supports an endosymbiotic origin for mitochondria?

1. Their location exclusively outside living cells
2. The absence of any membrane surrounding them
3. Their function as the plant cellulose wall
4. Their bacterial-like ancestry and retention of a double membrane

8. A scientist observes carbohydrates projecting from the external face of a membrane protein. How should this structure be described?

1. A triglyceride converted into a chromosome
2. A glycoprotein that contributes to surface carbohydrate display
3. A bare phospholipid with no polar head
4. A peptidoglycan chain forming the nucleus

9. Why does an apparently simple textbook animal-cell drawing often under-represent actual cell structure?

1. It omits the bacterial peptidoglycan layer from all animal cells
2. It omits extensive cytoskeletal organisation, membranes and dynamic organelle arrangements
3. It incorrectly shows genetic material in a nucleus
4. It exaggerates the fact that cells have a plasma membrane

10. Why can a phospholipid bilayer act as a selective barrier rather than an unrestricted opening?

1. Its hydrophobic interior impedes many ions and polar solutes
2. All dissolved molecules diffuse through the interior at identical rates
3. The bilayer contains no transport proteins
4. The bilayer is made only of solid cellulose

11. What is the likely contribution of carbohydrates attached to external membrane proteins and lipids?

1. They make all membrane proteins hydrophobic throughout
2. They contribute to a cell-surface glycocalyx involved in recognition and surface interactions
3. They prevent any interaction with extracellular water
4. They replace the plasma membrane with a rigid DNA coat

12. A cell has a plasma membrane and ribosomes but no membrane-enclosed nucleus. Which classification is best supported?

1. Animal cell
2. Fungal cell with a nucleus
3. Prokaryotic cell
4. Plant cell

13. Which comparison of plant and animal cell boundaries is accurate?

1. Animal cells have cellulose cell walls while plants have only cholesterol
2. Plant cells typically have cellulose cell walls outside the plasma membrane; animal cells lack cellulose walls
3. Neither group has a plasma membrane
4. Both cell types normally contain bacterial peptidoglycan walls

14. A bacterium swims towards a nutrient source. Which cellular feature may enable its directed movement?

1. Contraction of multicellular muscle tissue
2. Movement of a nucleus along microtubules
3. Rotation of flagella powered by a membrane-associated motor
4. Cellulose growth without membrane transport

15. Why is cholesterol important for animal plasma membranes?

1. It helps modulate membrane organisation and fluidity over changing conditions
2. It catalyses translation of mRNA
3. It replaces all phospholipid molecules
4. It forms a peptidoglycan cell wall

16. An animal membrane loses its integral transport proteins but retains phospholipids. What would be most directly affected?

1. Regulated transport of solutes that require protein-mediated passage
2. The presence of DNA in the nucleus
3. The existence of a hydrophobic bilayer interior
4. The construction of cellulose microfibrils

17. A phospholipid in an aqueous environment has its hydrophobic tails directed towards neighbouring tails. What physical principle explains this?

1. Non-polar tails minimise contact with water while polar heads remain hydrated
2. Phosphate groups spontaneously become proteins
3. All tails are permanently positively charged
4. Water becomes hydrophobic after touching a membrane

1. Distinguish prokaryotic and eukaryotic cells using three defining features or examples. (3 marks)

2. Outline how information encoded in nuclear DNA leads to protein synthesis in the cytoplasm. (3 marks)

3. State three features distinguishing Bacteria from Archaea and eukaryotic organisms. (3 marks)

4. Explain how a cell membrane can act as a barrier while still supporting exchange and signalling. (5 marks)

5. Explain how glycoproteins and glycolipids contribute to the outer cell surface. (5 marks)

6. Explain how the structure of a phospholipid produces a stable bilayer in water. (5 marks)

7. Explain why the endoplasmic reticulum and nuclear envelope illustrate the value of compartmentalisation. (5 marks)

8. A cell contains a bacterial-type chromosome, has motile flagella and lacks a nuclear envelope. Analyse what can and cannot be concluded about its classification. (8 marks)

9. A drug removes much of the cholesterol from an animal cell membrane. Predict potential consequences for membrane dynamics and transport. (8 marks)

10. A synthetic cell membrane contains amphipathic lipids but no membrane proteins. Predict its physical properties and functional limitations. (8 marks)

11. Critically evaluate membrane infolding and endosymbiosis as explanations for features of early eukaryotic cell evolution. (8 marks)

1. Why are intermediate filaments often associated with mechanical resilience?

1. They function as open sodium channels
2. They are the only molecules capable of generating ATP
3. Their rope-like arrangements help distribute mechanical stresses through cells
4. They replace plasma membranes with solid walls

2. A ligand opens a membrane channel and sodium ions move down their electrochemical gradient. How should this be classified?

1. Synthesis of sodium ions by osmosis
2. Channel-mediated passive transport
3. ATP-powered pumping against the gradient
4. Exocytosis of sodium vesicles

3. Why is a vesicle an effective carrier of protein cargo in an aqueous cytoplasm?

1. It works by dissolving proteins into free fatty acids
2. It transports cargo only as unprotected nuclear DNA
3. Its lipid membrane encloses cargo while separating it from surrounding cytosol
4. It lacks any boundary separating it from the cytoplasm

4. Why must descriptions of osmosis consider membrane permeability to solutes?

1. An impermeant solute can establish a sustained osmotic difference across the membrane
2. Osmosis is the movement of salt alone through protein channels
3. Water transport requires a direct ATP pump in all situations
4. Every solute moves freely across every biological membrane

5. Two compartments are separated by a membrane permeable to water but not salt. Which way will water move if salt concentration is higher on the right?

1. Only towards the side with more mitochondria
2. Net movement towards the left because salt repels all water
3. No movement because water is polar
4. Net movement towards the right until water potential differences are reduced

6. Why can ATP generation and ATP utilisation be considered coupled cellular processes?

1. ATP cannot donate phosphate to substrates or proteins
2. Energy-releasing reactions support ATP regeneration, and ATP hydrolysis can drive energy-demanding work
3. All ATP production is itself an ATP-dependent protein export event
4. ATP synthase consumes DNA to generate ATP

7. Which association of filament, constituent and location is most consistent with the lecture?

1. Actin is the major mineral building block of mitochondria
2. Microtubules are made of cellulose and found only outside cells
3. Actin microfilaments frequently contribute to the cell cortex near the plasma membrane
4. Intermediate filaments are composed only of ATP

8. A protein is produced in the secretory pathway and released outside the cell. Which final event is required?

1. Conversion of protein cargo into peptidoglycan
2. Breakdown of the nuclear chromosome
3. Fusion of a cargo-containing vesicle with the plasma membrane
4. Active transport of the entire ribosome through an ion channel

9. Which set of functions correctly reflects the lecture’s account of mitochondria?

1. Oxidative ATP production, participation in apoptosis and steroidogenesis
2. Translation of every cellular protein, osmosis and exocytosis
3. Protein secretion, cellulose synthesis and bacterial flagellar assembly
4. Glycogen storage only, DNA export and peptidoglycan formation

10. A microscope shows elongated interconnected mitochondria. What should a student infer?

1. The observed structures must be bacterial peptidoglycan
2. The sample cannot contain mitochondria because they are not bean-shaped
3. Mitochondria are dynamic structures that may form networks
4. The mitochondria cannot participate in ATP production

11. A cell internalises extracellular cholesterol within a membrane-bounded compartment. Which process is most likely involved?

1. Exocytosis
2. Passive oxygen diffusion
3. Endocytosis
4. Direct translation of cholesterol

12. What is the main difference between an ion channel and a membrane pump?

1. Every channel uses ATP to move ions against a gradient
2. A channel provides a pathway for downhill movement; a pump can couple energy to uphill transport
3. Channels internalise vesicles but pumps secrete proteins
4. Pumps are made of lipid alone whereas channels contain only DNA

13. Which situation most clearly requires an energy-coupled transporter?

1. Moving an ion from a lower electrochemical potential to a higher one
2. Oxygen crossing a lipid bilayer down its concentration gradient
3. Water moving passively towards higher effective solute concentration
4. A small solute moving through an open channel down its gradient

14. A cell must both move secretory vesicles and maintain its surface shape. Which pairing is most plausible?

1. Triglycerides as tracks and ATP molecules as surface filaments
2. Peptidoglycan as the only intracellular cytoskeleton
3. Chromosomal DNA as tracks and free calcium as a membrane scaffold
4. Microtubules for transport tracks and cortical actin for surface support

15. How can ATP-dependent phosphorylation change the function of a transport protein?

1. ATP removes the plasma membrane so no transport protein is needed
2. Phosphorylation always means the protein diffuses out of the cell
3. ATP replaces the transporter with a cellulose fibre
4. Phosphate transfer alters the transporter’s interactions or conformation, allowing a transport step

16. Why might mitochondria be positioned along microtubules near sites of high cellular demand?

1. ATP can only be made inside the nuclear envelope
2. Motor-associated redistribution can place ATP-producing organelles where they are useful
3. Mitochondria are permanently fixed in one position in every cell
4. Microtubules convert mitochondria into plant cell walls

17. Why are cristae relevant to mitochondrial ATP production?

1. They contain cellulose needed for ATP hydrolysis
2. They are extracellular secretory vesicles
3. Their folds provide extensive inner-membrane area associated with oxidative phosphorylation
4. They act as nuclear pores for importing mRNA

1. Define osmosis and explain the direction of water movement between two solutions separated by a suitable membrane. (3 marks)

2. Describe channel-mediated transport and distinguish it from active pumping. (3 marks)

3. Distinguish endocytosis from exocytosis. (3 marks)

4. Explain how cytoskeletal microtubules and motor proteins assist intracellular transport. (3 marks)

5. Describe how a newly synthesised protein can travel in a vesicle to a different cellular location. (5 marks)

6. Describe why channel opening need not be equivalent to ATP-driven pumping. (5 marks)

7. Explain osmosis in a system with two compartments and an impermeant solute concentrated on one side. (5 marks)

8. Explain why the lecture challenged the standard bean-shaped depiction of mitochondria. (5 marks)

9. A cell has normal ATP synthesis but defects in both tubulin polymerisation and vesicle motor proteins. Predict consequences for trafficking and organelle distribution. (8 marks)

10. A student claims that oxygen, sodium ions and large protein cargo must all use the same membrane transport mechanism. Explain why this is incorrect. (8 marks)

11. A tissue undergoes rapid ATP demand near one end of a long cell. Discuss why mitochondrial networks and cytoskeleton-mediated positioning could be advantageous. (8 marks)

12. An ATP-driven ion pump creates a gradient that later drives ion entry through a gated channel. Analyse how the two transport mechanisms work together. (8 marks)

13. Analyse why mitochondrial function extends beyond ATP production in a cell responding to stress signals. (8 marks)

1. How does Desmosomes, basal lamina and invasion contribute to the wider biological or ecological process discussed?

1. Desmosomes are identical to endocrine hormones
2. The basal lamina is the exposed apical surface
3. Epithelial cells rely on cell junctions to resist physical stress
4. Desmosomes are pores that pump ATP into cells

2. How does Four animal tissue classes contribute to the wider biological or ecological process discussed?

1. All animal tissues are variants of epithelium
2. Connective tissue lacks extracellular components
3. Muscle tissue is limited to the brain
4. Nervous tissue coordinates responses through electrical and chemical signalling

3. An ion channel opens in an excitable neurone and the membrane becomes less negative. Which interpretation best explains this observation?

1. Selective ion movement can produce depolarisation and initiate electrical signalling.
2. Nervous tissue cannot communicate with muscles
3. Neurons depolarise only by synthesising new DNA
4. Action potentials travel through extracellular collagen rather than cells

4. How does Vectorial epithelial transport contribute to the wider biological or ecological process discussed?

1. The apical and basal membranes are a single continuous transport channel
2. Passive movement may then occur down a gradient on the opposite side
3. Active transport and passive transport are synonyms
4. Directional epithelial transport requires both faces to be impermeable

5. Adjacent epithelial cells experience repeated mechanical strain without separating. Which interpretation best explains this observation?

1. Intercellular adhesive junctions such as desmosomes help maintain the sheet.
2. Desmosomes are pores that pump ATP into cells
3. Cancer spread is permanently impossible while any cell junction exists
4. Desmosomes are identical to endocrine hormones

6. An epithelial solute is pumped across its apical membrane and later leaves across the basal membrane. Which interpretation best explains this observation?

1. Directional epithelial transport requires both faces to be impermeable
2. The apical and basal membranes are a single continuous transport channel
3. Energy-dependent and gradient-driven steps can cooperate to achieve net transport.
4. Solutes must move uphill through both membranes without energy

7. Stress activates a sequence involving the brain, pituitary gland and adrenal cortex. Which interpretation best explains this observation?

1. This is the coordinated hypothalamic-pituitary-adrenal endocrine axis.
2. Cortisol is the neurotransmitter responsible for every immediate nerve impulse
3. Pituitary peptide hormones leave cells by simple diffusion through phospholipids
4. The adrenal cortex makes CRH to activate the hypothalamus

8. How does Epithelial sheets and polarity contribute to the wider biological or ecological process discussed?

1. The apical and basal surfaces are functionally identical
2. The basal surface associates with the basal lamina
3. Epithelial sheets are always electrically excitable neurons
4. Epithelial cells are defined by abundant extracellular matrix between cells

9. A tissue sample has relatively dispersed cells surrounded by fibres and a hydrated background material. Which interpretation best explains this observation?

1. All connective tissues contain no living cells
2. Connective tissue consists exclusively of tightly packed cell membranes
3. The combination is characteristic of connective tissue with extracellular matrix.
4. Ground substance refers to nuclear DNA

10. A sheet of cells has an exposed surface and a second face anchored to supportive material. Which interpretation best explains this observation?

1. Epithelial sheets are always electrically excitable neurons
2. The basal lamina sits inside the cell nucleus
3. This is a polarised epithelium with distinct apical and basal domains.
4. The apical and basal surfaces are functionally identical

11. How does Steroid and protein hormone signalling contribute to the wider biological or ecological process discussed?

1. All hormone receptors sit inside the nucleus
2. Steroid hormones cannot cross a lipid bilayer under any circumstances
3. Protein hormones always enter directly through the membrane's hydrophobic core
4. Protein hormones are generally hydrophilic and bind cell-surface receptors

12. A section from an intestine contains contractile fibres in the wall but no heart tissue. Which interpretation best explains this observation?

1. Smooth muscle is the relevant contractile tissue for that organ.
2. Skeletal muscle generates most hormonal signals in blood
3. Cardiac muscle is the main contractile tissue in intestinal walls
4. All muscle tissue has identical microscopic organisation and control

13. A hormone binds a receptor inside the cytoplasm and changes gene transcription. Which interpretation best explains this observation?

1. All hormone receptors sit inside the nucleus
2. Steroid hormones cannot cross a lipid bilayer under any circumstances
3. Cyclic AMP is the same molecule as a steroid receptor
4. A lipid-soluble steroid acting via an intracellular receptor is a plausible mechanism.

14. A cell responds to a cue within seconds by activating an existing enzyme. Which interpretation best explains this observation?

1. Receptors cannot alter cytoplasmic enzyme activity
2. Apoptosis always prevents normal tissue development
3. Every signal has an identical effect in all cells
4. Rapid signalling can change pre-existing protein activity without waiting for new transcription.

15. How does Nervous tissue and depolarisation contribute to the wider biological or ecological process discussed?

1. Neurons depolarise only by synthesising new DNA
2. Depolarisation means every ion gradient disappears permanently
3. Nervous tissue cannot communicate with muscles
4. Opening suitable ion channels can permit depolarisation

1. Describe three important features or roles of epithelial sheets and polarity as covered in this lecture. (3 marks)

2. Describe three important features or roles of four animal tissue classes as covered in this lecture. (3 marks)

3. Describe three important features or roles of steroid and protein hormone signalling as covered in this lecture. (3 marks)

4. Describe three important features or roles of the HPA stress-response axis and secretion as covered in this lecture. (3 marks)

5. Explain cell-to-cell signalling and development using relevant mechanisms or relationships from the lecture. Apply your explanation to this observation: A cell responds to a cue within seconds by activating an existing enzyme. (5 marks)

6. Explain desmosomes, basal lamina and invasion using relevant mechanisms or relationships from the lecture. Apply your explanation to this observation: Adjacent epithelial cells experience repeated mechanical strain without separating. (5 marks)

7. Explain the HPA stress-response axis and secretion using relevant mechanisms or relationships from the lecture. Apply your explanation to this observation: Stress activates a sequence involving the brain, pituitary gland and adrenal cortex. (5 marks)

8. Compare and analyse cell-to-cell signalling and development and steroid and protein hormone signalling in the context of this lecture. Use the following cases to explain mechanisms and predict consequences: (i) During digit formation, cells between developing fingers are not removed despite otherwise normal growth. (ii) A hormone binds a receptor inside the cytoplasm and changes gene transcription. (8 marks)

9. Compare and analyse epithelial sheets and polarity and desmosomes, basal lamina and invasion in the context of this lecture. Use the following cases to explain mechanisms and predict consequences: (i) An epithelial layer loses its basal attachment yet remains in contact with a lumen. (ii) Adjacent epithelial cells experience repeated mechanical strain without separating. (8 marks)

10. Compare and analyse nervous tissue and depolarisation and connective tissue and extracellular matrix in the context of this lecture. Use the following cases to explain mechanisms and predict consequences: (i) Channel function is blocked while neuronal structure remains intact. (ii) A tissue sample has relatively dispersed cells surrounded by fibres and a hydrated background material. (8 marks)

1. A microscopic predator has a nucleus and feeds on other cells. Which group best fits?

1. A filamentous mould
2. A bacteriophage
3. A photosynthetic bacterium
4. A predatory protist

2. Two patients have the same symptoms, but distinct microorganisms are recovered. Which concern does this raise for a simple causal claim?

1. Agar culture always produces identical isolates
2. Microscopy cannot reveal any microbial differences
3. Similar symptoms need not establish the same causative agent
4. Every disease must have exactly two causative agents

3. A scientist sees several cell types in a mixed broth culture. Why would isolating colonies on agar improve the investigation?

1. It removes the need to examine cell characteristics
2. It makes every microbe produce identical symptoms
3. It guarantees that all microbes will grow
4. It helps separate populations for subsequent identification

4. A microbe is detected on a person's hands immediately after touching a door handle but is absent after washing. What is the best interpretation?

1. It must have reproduced within the skin
2. It was probably a transient microbe
3. It was necessarily an obligate pathogen
4. It was necessarily a permanent member of skin microbiota

5. A flask remains free of growth when sealed but develops growth after opening. What explanation is most consistent with Pasteur's position?

1. Air itself transformed into new living cells
2. Sterile broth generated cells once exposed to light
3. Microorganisms entered from the surroundings
4. The flask walls converted nutrients into microbes

6. A person acquires microbes from diet and environmental contact, and the community changes over time. Which property of microbiota does this illustrate?

1. Its composition is dynamic and varies among individuals
2. Its composition is fixed permanently at birth
3. Its members are all obligate pathogens
4. Its members are exclusively fungi

7. A bacterium causes disease mainly in patients whose immune defences are weakened. How is it best described?

1. Non-living infectious particle
2. Obligate pathogen in every host
3. Transient microbe incapable of infection
4. Opportunistic pathogen

8. A microorganism has a nucleus and mitochondria and can occur as a single-celled yeast. Which group best fits?

1. Bacteria
2. Viruses
3. Archaea
4. Fungi

9. A photosynthetic microscopic organism has a nucleus. Which classification is compatible with the lecture?

1. An acellular virus
2. A eukaryotic alga
3. A prokaryotic bacillus
4. A bacterial cell lacking organelles

10. A microorganism is recovered from healthy skin over many months and is adapted to that body site. Which category fits best?

1. Resident microbiota
2. Transient contaminant
3. Obligate pathogen
4. Acellular virus

11. A patient and an experimentally infected animal have similar symptoms. What additional evidence is needed for the final Koch postulate?

1. Demonstrating that the animal was exposed to air
2. Proving that the organism can grow without nutrients
3. Recovering the same candidate organism from the animal
4. Showing that the organism is found on healthy skin

12. Why does a negative agar-culture result not always show that a sample contains no microorganisms?

1. Some microorganisms cannot grow under the chosen culture conditions
2. Agar automatically destroys any organism present
3. Microscopy cannot detect microorganisms in samples
4. All microbes must grow in every agar medium

13. A normally harmless skin bacterium enters a deep wound and causes infection. Which explanation best fits?

1. An obligate pathogen must have been present from birth
2. The bacterium has become a virus in the wound
3. An opportunistic pathogen has reached an unusual body location
4. All normal microbiota always cause disease after contact

14. An infectious agent contains RNA within a protein coat and cannot replicate without a host cell. How should it be classified?

1. Protist
2. Virus
3. Fungus
4. Bacterium

15. Why did sealed-flask experiments matter to debates about spontaneous generation?

1. They demonstrated that agar is necessary for growth
2. They tested whether new growth required contamination from outside
3. They established that microbes arise from sterile nutrients
4. They proved that all microbes need oxygen to survive

16. A candidate pathogen is consistently present in sick hosts but cannot be grown in a cell-free medium. Which conclusion is most defensible?

1. Its presence in patients alone establishes causation
2. Failure to culture it limits application of the classical postulates
3. The organism must be a harmless member of the microbiota
4. Its inability to grow on agar proves it cannot cause disease

17. A disease emerges in people following increased contact with infected wildlife. Which approach best reflects One Health?

1. Investigate wildlife exposure alongside human infection patterns
2. Study wildlife without considering human transmission
3. Examine human cases without recording animal contact
4. Restrict the investigation to hospital equipment

1. Describe three different bacterial cell shapes using their standard names. (3 marks)

2. Distinguish a transient microorganism from resident microbiota using three relevant points. (3 marks)

3. State three features of the human microbiota. (3 marks)

4. State three key distinctions between a predatory protist and a virus. (3 marks)

5. A bacterium causes disease in immunocompromised people but not most healthy carriers. Distinguish opportunistic from obligate pathogenicity using this example. (5 marks)

6. A patient develops an infection after a normally harmless skin bacterium enters a deep wound. Explain why this is an opportunistic infection and identify two relevant contributing conditions. (5 marks)

7. A suspected pathogen is found in every sick animal sampled. Explain why this observation is not enough to demonstrate causation using Koch’s postulates. (5 marks)

8. A swab from healthy skin and a swab taken after touching a public surface yield different microorganisms. Explain how resident and transient communities could account for the findings. (5 marks)

9. Explain why a photosynthetic microscopic organism should not be classified as a protist solely because it photosynthesises. (5 marks)

10. A bacterium is recovered from 90% of sick animals and 40% of healthy animals. Design a cautious investigation to test whether it contributes to disease, and explain why prevalence alone is insufficient. (8 marks)

11. A candidate infectious agent is detected by microscopy but cannot grow on nutrient agar and replicates only inside host cells. Evaluate how the classical Koch framework should be applied. (8 marks)

12. A person carries an opportunistic bacterium without symptoms, then becomes immunosuppressed and develops disease. Explain how host and microbial factors interact, and assess what would be needed to establish causation. (8 marks)

13. A student claims that cloudy broth in an open flask proves spontaneous generation. Construct an experimental comparison that distinguishes this claim from environmental contamination. (8 marks)

1. A cook cuts raw chicken and then slices cooked vegetables on the same unwashed board. Which pathway is the principal concern?

1. Fermentation of the raw chicken by yeast
2. Microbial decomposition of soil organic matter
3. Nitrogen fixation in the cooked vegetables
4. Cross-contamination of ready-to-eat food

2. A food producer wants to slow microbial spoilage during transport without changing the recipe. Which intervention best targets microbial growth rate?

1. Package food only after spoilage becomes visible
2. Allow raw and cooked products to share utensils
3. Maintain appropriate refrigeration throughout transport
4. Increase the time food spends at room temperature

3. A plant receives additional phosphorus and water through a fungal network attached to its roots. What does the fungus most likely obtain in return?

1. Atmospheric nitrogen fixed by the leaves
2. Oxygen released by bacterial fermentation
3. Cellulose digested in the animal rumen
4. Sugars produced by the plant

4. Two genetically uniform banana plantations are exposed to the same fungal pathogen. One contains a mixture of resistant varieties, while the other contains one susceptible clone. What is the likely difference?

1. Disease may spread less extensively in the genetically mixed plantation
2. The susceptible clone must develop resistance after the first infection
3. Disease must spread equally because the pathogen is identical
4. Genetic diversity prevents fungal spores from reaching either plantation

5. A manufacturer ferments milk with lactic acid bacteria. Which change contributes directly to preservation?

1. Oxygen release prevents all bacterial growth
2. Acid production lowers the pH and inhibits some spoilage microbes
3. Nitrogen fixation removes every food-borne pathogen
4. Alcohol production raises the pH and sterilises the milk

6. A tick carries Borrelia from an infected animal to a person. What role does the tick play?

1. Vector transmitting the pathogen
2. Primary source of atmospheric nitrogen
3. Host that necessarily develops the same symptoms as the person
4. Fermentation organism preserving the pathogen

7. A baker adds yeast to dough and allows it to ferment. Which product chiefly causes the dough to rise?

1. Oxygen produced during anaerobic metabolism
2. Lactic acid produced by fungal photosynthesis
3. Nitrogen gas fixed by yeast cells
4. Carbon dioxide released from sugar metabolism

8. A person contracts rabies after an infected animal bites them. Which route of zoonotic transmission is illustrated?

1. Transfer by a tick carrying a bacterial pathogen
2. Transmission only through a food-processing surface
3. Exposure to a harmless resident gut microbe
4. Direct transmission from an infected animal

9. A chilled meal is left at 25°C for several hours before serving. Why is this a concern?

1. The temperature prevents transfer of microorganisms from hands
2. The temperature destroys all microbial spores
3. The temperature permits growth of many food-associated microorganisms
4. The temperature makes any preformed toxin harmless

10. A company claims its probiotic product improves every digestive disorder because it contains live bacteria. Which appraisal best fits the lecture?

1. A probiotic is effective whenever it survives packaging
2. All live bacterial strains produce identical clinical effects
3. The presence of bacteria alone proves a health benefit
4. Benefits depend on the particular strain and outcome, so broad claims need evidence

11. A legume grows poorly in nitrogen-poor soil but improves after inoculation with compatible root-nodule bacteria. Which process most directly explains the improvement?

1. Transfer of photosynthetic oxygen into bacterial protein
2. Release of carbon dioxide as the plant's nitrogen source
3. Conversion of atmospheric nitrogen into ammonium
4. Conversion of soil phosphate into atmospheric nitrogen

12. A stool sample is analysed by sequencing microbial DNA rather than culturing on agar. What advantage does this provide?

1. Identification of every organism's contribution to human health
2. Measurement of toxin concentration without further testing
3. Proof that every detected microbe is alive and active
4. Detection of taxa that do not grow under the selected culture conditions

13. A person develops gastroenteritis after eating contaminated chicken; bacteria multiply in the intestine. Which mechanism best describes the illness?

1. Non-infectious food spoilage alone
2. Food-borne infection
3. Food-borne intoxication from preformed toxin
4. Allergic response to bacterial fermentation

14. A food sample looks and smells normal, but a pathogen is detected. Which conclusion is best supported?

1. Normal appearance proves that microbial toxins are absent
2. Food can be unsafe without obvious spoilage
3. Only spoiled food can contain infectious organisms
4. Food is safe whenever no mould is visible

15. Several diners develop symptoms soon after eating a dish in which bacteria had produced a toxin before serving. Which mechanism is most consistent with this observation?

1. Food-borne intoxication
2. Spoilage that cannot cause illness
3. A beneficial fermentation with no health risk
4. Food-borne infection requiring intestinal multiplication

1. Give three contrasting ways microorganisms affect food production, preparation or consumption. (3 marks)

2. Identify three ways diet or environmental factors can influence gut microbial communities. (3 marks)

3. State three key characteristics or consequences of foot-and-mouth disease in livestock systems. (3 marks)

4. Explain how a bacterium can be part of the normal microbial flora of one animal yet cause disease in a person consuming contaminated food. (5 marks)

5. Explain why a cow can use cellulose-rich forage even though host-produced cellulase is inadequate, identifying the roles of microbes and fermentation products. (5 marks)

6. Explain why contaminated animal products arriving from an affected region may justify biosecurity action before any local animal shows symptoms. (5 marks)

7. A treatment suppresses rumen microbial activity without changing feed consumption. Predict nutritional consequences and discuss the trade-off between rumen fermentation and methane emissions. (8 marks)

8. Design a microbial food-safety strategy that extends from farm soil to consumers. Evaluate beneficial microbial activities alongside the risks that would be overlooked by focusing only on packaged foods. (8 marks)

9. Explain why detection of foot-and-mouth disease in livestock after a suspected importation could affect animal health, agricultural production and international trade. Propose proportionate border precautions. (8 marks)

10. Two patients have similar symptoms after a shared meal, but one ingested a pre-formed toxin and the other ingested viable pathogens. Compare the biological mechanisms and identify implications for prevention and interpretation of food appearance. (8 marks)

1. Antibiotic runoff enters a river microbial community. What selective effect is possible?

1. Selection for antimicrobial resistance
2. Prevention of gene exchange among environmental bacteria
3. Conversion of antibiotics into photosynthetic pigments
4. Guaranteed elimination of all resistant bacteria

2. A marine bloom converts dissolved carbon dioxide into biomass. Which process is occurring?

1. Production of methane from carbon dioxide
2. Release of carbon dioxide by decomposition
3. Photosynthetic carbon fixation
4. Oxidation of methane to carbon dioxide

3. A lichen grows on exposed rock despite intermittent drying. Which fungal function is important?

1. Production of all photosynthetic sugars
2. Structure and water retention
3. Methane oxidation as the sole carbon source
4. Production of oxygen by photosynthesis

4. A cyanobacterium fixes carbon dioxide in illuminated water. Which energy source drives fixation?

1. Light
2. Oxidation of organic detritus
3. Methane oxidation
4. Hydrogen oxidation without light

5. Lichens decline near a source of sulphur dioxide pollution. Which characteristic explains their use in monitoring?

1. Obligate growth in heavily polluted air
2. Ability to remove every pollutant without damage
3. Dependence on petroleum hydrocarbons
4. Sensitivity to atmospheric pollutants

6. A microbial cell builds organic material using dissolved inorganic carbon. Which carbon strategy does it use?

1. Carbon dioxide
2. Dead plant material
3. Preformed organic molecules
4. Methane as an obligatory organic nutrient

7. A microbe fixes carbon dioxide in a dark environment. What can power this metabolism?

1. Light captured by chlorophyll
2. Energy from inorganic chemical reactions
3. Heat alone without a chemical energy source
4. Digestion of preformed organic carbon as its sole carbon source

8. A soil sample yields few colonies but contains many microbial cells. Which method best reveals uncultured diversity?

1. Measuring colony diameter on agar
2. Environmental DNA sequencing
3. Counting colonies on one nutrient agar
4. Recording only visible organisms in soil

9. Methanotrophs can also transform some industrial solvents. Which enzyme supports this activity?

1. Rubisco
2. Nitrogenase
3. DNA ligase
4. Methane monooxygenase

10. A survey identifies microbial bacteria, archaea and unicellular algae. Which domain-level classification fits?

1. Bacteria, Archaea and Eukaryota
2. Bacteria, fungi and protists as three domains
3. Archaea, Plantae and Animalia
4. Bacteria, Archaea and viruses

11. Dead organic matter accumulates when microbial decomposition is inhibited. Which process has slowed?

1. Preventing organic matter from entering food webs
2. Converting all soil nitrogen directly into atmospheric oxygen
3. Recycling nutrients from dead organic material
4. Fixing carbon dioxide using light

12. An anaerobic digester contains archaea using carbon dioxide and hydrogen. Which gas is produced?

1. Methane oxidation to carbon dioxide
2. Oxygenic photosynthesis
3. Methane production
4. Aerobic decomposition requiring oxygen

13. Coral turns white after a marine heatwave. Which change explains the loss of colour?

1. Loss of symbiotic algae under heat stress
2. Enhanced photosynthesis within the coral skeleton
3. Replacement of coral polyps by lichens
4. Increased nitrogen fixation by coral tissue

1. Define bioremediation and describe two microbial capabilities used to transform pollutants. (3 marks)

2. Describe three components of the exchange between corals and their photosynthetic symbionts. (3 marks)

3. Give three features of methanotrophs and their role in methane cycling. (3 marks)

4. State three ways ecosystem conditions can influence human or animal health. (3 marks)

5. Explain how heterotrophic fungi and other decomposers return resources from leaf litter to a forest ecosystem. (5 marks)

6. Explain how the location of methanotrophs within an oxygen gradient can influence methane emissions from a wetland. (5 marks)

7. Explain why methane can be released from an oxygen-poor wetland and identify the relevant microbial metabolism. (5 marks)

8. Explain why molecular sequencing may detect many more soil microorganisms than traditional plate counts. (5 marks)

9. A contaminant inhibits methane-oxidising bacteria at the wetland surface, while anaerobic methane production is unchanged. Predict consequences for net atmospheric release and describe the microbial processes involved. (8 marks)

10. Assess the feasibility of using naturally occurring oil-degrading microbes in a coastal clean-up. Identify environmental constraints and explain how targeted microbial enzymes might complement the strategy. (8 marks)

11. During a marine heatwave, a reef experiences widespread bleaching. Trace how disruption of the coral–algal mutualism could affect energy supply, colony survival and reef-dependent organisms. (8 marks)

12. Predict ecological consequences when forest-soil microbial decomposition remains suppressed for several years. Trace potential effects on organic carbon, mineral nutrients and primary production. (8 marks)

1. A plasmid must be cut at a chosen DNA sequence. Which enzyme type is used?

1. Select transformed cells by antibiotic resistance
2. Express an inserted gene as protein
3. Join DNA fragments through peptide bonds
4. Cut DNA at particular recognition sequences

2. A yeast expression system produces a hepatitis B surface component. Which antigen is made?

1. HIV envelope glycoprotein gp120
2. Hepatitis B viral DNA polymerase
3. Influenza haemagglutinin
4. HBsAg, the hepatitis B surface antigen

3. A researcher wants to deliver a target gene into a host cell. What does the vector do?

1. Carries DNA of interest into a host
2. Replaces the need for a host cell
3. Destroys the target gene before insertion
4. Translates proteins outside living cells

4. A food manufacturer uses living microbes to ferment a substrate. Which type of biotechnology is involved?

1. Studying DNA sequences without organisms
2. Using whole living cells in production
3. Using only synthetic DNA outside cells
4. Producing materials without biological activity

5. Only some cells take up the plasmid. Which feature helps identify carriers?

1. Converts foreign DNA into a protein without expression
2. Prevents plasmid replication in every host
3. Allows identification or selection of plasmid-containing cells
4. Replaces the gene of interest during cloning

6. A plasmid has been joined to a foreign gene. What is the resulting DNA called?

1. A host cell lacking the cloning vector
2. A purified protein without any DNA
3. A vector joined to an inserted DNA sequence
4. An unmodified plasmid lacking an insert

7. A host cell uses an introduced gene to make its encoded protein. Which stage is this?

1. Isolation of a host chromosome without transcription
2. Production of RNA and protein from introduced genetic information
3. Purification of a protein before it has been made
4. Insertion of DNA into a plasmid without cellular activity

8. A manufacturer needs many batches of a recombinant protein. Which property makes microbes attractive?

1. Inability to express foreign genes
2. Guaranteed absence of all production contaminants
3. Rapid growth and scalable cultivation
4. Requirement for harvesting organs from animals

9. A vector and insert have compatible ends. Which enzyme joins them?

1. Breaks down a purified vaccine antigen
2. Translates mRNA into a protein
3. Cuts DNA at specific recognition sites
4. Joins DNA fragments together

10. Recombinant yeast produces the intended surface protein. What must be done to obtain the vaccine antigen?

1. Isolation and purification of the antigen
2. Removal of the antigen-coding DNA before expression
3. Deliberate infection of recipients with hepatitis B virus
4. Re-insertion of the antigen into the viral genome

11. A vaccine contains a viral surface protein recognised by the immune system. What is the protein's role?

1. Acts only as an antibiotic against bacteria
2. Stimulates a specific immune response
3. Replaces all immune memory with immediate digestion
4. Replicates as a complete infectious virus

12. A company uses living cells to manufacture a useful compound. Which field does this illustrate?

1. Studying organisms without producing a product
2. Manufacturing only with non-biological raw materials
3. Using biological systems to produce useful products
4. Using only inorganic catalysts without cells

13. A recombinant plasmid must be maintained in growing host cells. Which feature allows copying?

1. Determines the amino-acid sequence of the antigen
2. Purifies the expressed protein
3. Enables plasmid DNA replication in a compatible host
4. Cuts the inserted gene into fragments

14. A scientist places a chosen gene into a plasmid. What is the chosen gene called?

1. The DNA sequence of interest
2. The antibiotic used for selection
3. The host cell receiving the plasmid
4. The entire host chromosome

15. A bacterium is made to take up plasmid DNA. Which step is this?

1. Copying a protein sequence into DNA
2. Introduction of DNA into a host cell
3. Purifying a protein after expression
4. Joining two DNA fragments with ligase

16. A bacterium takes up a plasmid carrying an inserted gene. How is the cell described?

1. A purified antigen outside the host
2. A cell with no introduced DNA
3. An isolated gene before transformation
4. A host cell containing recombinant DNA

1. Identify three defining features or approaches used in biotechnology. (3 marks)

2. Identify three steps or components in the preparation of recombinant DNA. (3 marks)

3. Identify three steps or considerations linking a recombinant gene to a usable biotechnology product. (3 marks)

4. Name three functional components commonly used in plasmid vector design. (3 marks)

5. Describe how restriction enzymes and DNA ligase can be used to insert a gene into a plasmid vector. (5 marks)

6. Distinguish successful gene delivery from successful expression, and explain why a manufactured protein commonly requires purification. (5 marks)

7. Explain how acquisition of a plasmid could give a bacterium a new resistance trait, distinguishing horizontal transfer from vertical inheritance. (5 marks)

8. Explain how expression of hepatitis B surface antigen in yeast can provide a component for a vaccine. (5 marks)

9. A manufacturer compares bacteria, yeast and algae for several production goals. Evaluate the trade-offs among rapid growth, protein processing and light-driven carbon fixation before recommending appropriate hosts. (8 marks)

10. A vaccine developer aims to stimulate immunity against a virus while avoiding administration of the whole infectious agent. Evaluate recombinant antigen production, purification and immune recognition as steps towards this goal. (8 marks)

11. Explain how a manufacturer could improve the consistency of mixed-culture fermentation by selecting production organisms and controlling growth conditions. Identify limitations that would still require monitoring. (8 marks)

12. Recommend how to establish stable recombinant production when a gene-delivery procedure transfers DNA into microbial cells but yields no stable modified population. Consider vector–host compatibility and verification. (8 marks)

1. A bird selects a food item yielding more energy but requiring substantially longer handling. What must be compared to evaluate its choice under optimal foraging theory?

1. Its reproductive age relative to other birds
2. Net energy gained relative to the time spent obtaining it
3. The number of other species living near the food item
4. The food’s colour relative to available alternatives

2. A lizard alternately lifts its feet from very hot sand. Which explanation best connects its action with environmental conditions?

1. The behaviour allows the lizard to absorb more nutrients
2. The behaviour helps manage heat gained from the substrate
3. The lizard is displaying to potential mates
4. The lizard is increasing exposure to a predator

3. A small mammal feeds less in an exposed meadow despite abundant grass. Which interpretation best reflects the lecture?

1. It is necessarily incapable of digesting meadow grasses
2. It may sacrifice food intake to reduce exposure to predators
3. Its diet breadth must have narrowed to a single plant species
4. Its reduced feeding proves that it has no energy requirements

4. Why might a specialist forager be more constrained in its choice of feeding locations than a generalist?

1. A specialist can use a narrower range of acceptable foods
2. A specialist must forage alone to locate food
3. A specialist always moves more slowly than a generalist
4. A specialist necessarily has a higher metabolic rate than a generalist

5. What makes food mixed into an inedible matrix useful for a giving-up-density experiment?

1. Finding the remaining food becomes harder as food is removed, creating diminishing returns
2. The matrix supplies extra energy each time food becomes scarce
3. The matrix keeps the nutritional quality of all food items constant by changing it over time
4. The matrix ensures the forager must consume every food item before leaving

6. Why does an ambush predator benefit from camouflage?

1. It can remain less detectable while prey approaches
2. It can increase its maximum pursuit speed
3. It can consume a wider range of plant tissues
4. It can remove all energetic costs of predation

7. Which observation most directly connects individual behaviour with community-level ecology?

1. A desert animal raising its feet to cool down
2. A bird increasing its time spent resting
3. A predator changing its feeding behaviour and thereby altering prey interactions
4. A plant root extending towards soil nutrients

8. When might a forager leave a profitable-looking patch even though edible items remain?

1. When the current harvest rate has declined relative to alternatives
2. When the forager can no longer perceive any predators
3. Only when no edible items are left anywhere
4. Only after all food items become nutritionally worthless

9. The lecture reports fewer pademelon scats farther from vegetation. What does this evidence most directly indicate?

1. Predators capture every pademelon that crosses an exposed site
2. Open sites contain no suitable food
3. Pademelons use locations closer to cover more frequently under the measured conditions
4. Pademelons are physiologically unable to enter open habitat

10. Which statement most accurately links parental care to natural selection?

1. Care must increase the number of breeding attempts to be beneficial
2. Care always evolves only in species with two caregiving parents
3. Care improves parental survival but does not influence reproductive fitness
4. Care can be favoured when increased offspring success compensates for parental investment costs

11. Why might grouping reduce an individual’s risk of predation?

1. Group members may detect threats and dilute an individual’s chance of being targeted
2. Grouping removes all costs associated with competition for food
3. Predators always avoid groups regardless of group size or behaviour
4. Group members no longer need to respond to potential threats

12. A student claims all adaptive behaviours are beneficial in every respect. Which response best reflects the lecture?

1. Adaptations arise only when there are no energetic costs
2. All behaviours that increase survival necessarily maximise reproduction
3. Behaviour cannot be selected because it changes with context
4. A behaviour may have costs but still be favoured if its fitness benefits exceed them

13. Why can an increase in vigilance reduce food intake?

1. Vigilance makes all food items harder to digest
2. Vigilance necessarily causes prey to move farther from shelter
3. Time spent scanning for predators cannot simultaneously be spent collecting food
4. Vigilance removes the need for nutritional intake

14. Which comparison correctly distinguishes acting costly from being costly to a predator?

1. Acting costly requires a physical toxin; being costly requires mimicry only
2. Acting costly reduces prey energy gain; being costly reduces predator food supply
3. Acting costly means hiding; being costly means escaping by running
4. Acting costly can involve mimicking an unpalatable organism; being costly can involve actual toxins or spines

15. Male redback spiders that somersault into a female’s mouth can fertilise more eggs. Why can this behaviour be favoured by selection despite the male being eaten?

1. The behaviour increases the male’s survival through repeated mating
2. The female becomes unable to produce offspring after consuming the male
3. The behaviour removes the need for any inherited variation
4. Extended mating and reduced subsequent mating by the female can increase the male’s paternity

16. An animal forages in a patch where food becomes increasingly difficult to find as items are removed. Which model directly addresses when it should leave?

1. The marginal value theorem
2. The model of reproductive investment in parental care
3. The model of mimicry in predator avoidance
4. The model of sexual selection by mate choice

17. Why might a conspicuous peacock tail persist despite costs of production and predation exposure?

1. Sexual selection acts only on traits that improve survival
2. The tail is maintained because all males with shorter tails are infertile
3. Predator avoidance must always outweigh any reproductive disadvantage
4. Greater mating success can outweigh the survival and energetic costs

1. Define behavioural ecology and identify the two broad kinds of pressure that shape behaviour. (3 marks)

2. Define fitness and explain why behaviour can be acted on by natural selection. (3 marks)

3. Describe three ways foraging strategies can differ among organisms. (3 marks)

4. State the central prediction of optimal foraging theory and the environmental assumption used in the lecture. (3 marks)

5. A prey animal forages less after predators become active in its habitat. Explain the benefits and costs of this behavioural change. (5 marks)

6. Explain how hiding, mimicry and actual defences differ as ways to avoid predation. (5 marks)

7. Explain how male redback spider somersaulting may affect fitness, despite the risk of being consumed. (5 marks)

8. Explain why a peacock’s tail is an example of sexual selection rather than a trait that must maximise survival. (5 marks)

9. A group-living prey species detects predators sooner than solitary individuals but competes more intensely for food. Analyse why group living could evolve in some conditions but not others. (8 marks)

10. A rodent’s mean food intake rate is initially high in a patch but declines with time. A nearby patch is replenished regularly and requires travel. Explain how you would test the marginal value theorem’s departure prediction. (8 marks)

11. A small mammal forages in two patches containing equal amounts of food. One is open and exposed to predators; the other is sheltered. Design a giving-up-density comparison and predict how predation risk could affect the results. (8 marks)

12. A species can either provide prolonged parental care to its current offspring or attempt another breeding event. Explain how ecological conditions could change which strategy is favoured. (8 marks)

13. In a feeding experiment, small mammals leave exposed patches with more food remaining than sheltered patches. Analyse what can be concluded and how the experimental design could be strengthened. (8 marks)

1. Under the logistic model, what happens to the growth factor (1 − N/K) as N approaches K from below?

1. It approaches one
2. It approaches zero
3. It stays constant while population size increases
4. It becomes progressively larger than one

2. A population has N = 200 and K = 400. What is the logistic density-limitation factor (1 − N/K)?

1. 2.00
2. 0.50
3. 0.25
4. 1.50

3. Which information is represented by a life table?

1. The geographic position of every individual
2. The daily movement route of each disperser
3. The abundance of all species in a community
4. Survivorship probabilities across age classes

4. A researcher tags reef fish that remain close to one coral patch and later checks for survivors. Why is this useful?

1. Limited movement guarantees that tagged fish never die
2. Limited movement removes variation in individual survival
3. Limited movement ensures all new fish are detected
4. Limited movement makes disappearance easier to interpret

5. Why might a seasonal breeding population show a saw-tooth trajectory?

1. All individuals survive until the following breeding season
2. Breeding pulses increase numbers between periods of mortality
3. Immigration remains constant between breeding events
4. Carrying capacity increases after each breeding event

6. Why are mortality rates often harder to estimate than birth rates in wild animals?

1. Mortality only occurs during the breeding season
2. Dead animals are consistently easier to count than young
3. Every birth necessarily occurs outside the study area
4. Disappearing individuals may have died or moved elsewhere

7. An open population starts with 80 individuals; 12 are born, 7 die, 6 immigrate and 4 emigrate. What is the final size?

1. 101 individuals
2. 91 individuals
3. 83 individuals
4. 87 individuals

8. How can dispersal influence a metapopulation after a local patch becomes empty?

1. Individuals from occupied patches can recolonise it
2. Dispersal prevents extinction in every occupied patch
3. All local populations become closed after extinction
4. The empty patch must remain permanently unoccupied

9. In mark–release–recapture, 30 animals are initially marked, and 10 of 50 animals in the second sample bear marks. What population is estimated?

1. 60 individuals
2. 250 individuals
3. 150 individuals
4. 90 individuals

10. Why does the proportion of reproductive adults matter when forecasting population growth?

1. Individuals of different ages differ in fecundity
2. Total population size alone determines every birth rate
3. Age structure influences movement but not births
4. All individuals contribute equally to births at every age

11. A population grows by the same percentage each year. How will the number of individuals added annually change?

1. It will increase as the population becomes larger
2. It will decrease as the population becomes larger
3. It will alternate between gains and losses each year
4. It will remain the same because the percentage is fixed

12. Why can a population of sessile trees still show movement across generations?

1. Mature trees routinely migrate between habitat patches
2. Individual trunks relocate when resources are depleted
3. Sessile populations cannot change their spatial distribution
4. Seeds can disperse before establishing as sessile plants

13. Which parameter set would be most relevant when building a PVA model?

1. Predator diet, colour patterns and soil texture alone
2. Species richness, trophic diversity and leaf morphology
3. Individual behaviour, food preference and habitat colour alone
4. Fecundity, age-specific mortality and environmental variation

14. Which change would most directly violate a closed-population assumption during mark–release–recapture?

1. Retention of marks on recaptured individuals
2. Thorough mixing of animals after release
3. Substantial immigration between the two sampling events
4. Equal likelihood of capture among marked animals

15. An isolated population begins with 120 animals, has 18 births and 11 deaths. What is its new size?

1. 131 animals
2. 113 animals
3. 149 animals
4. 127 animals

16. A habitat has K = 600 individuals. Which population size is expected to show zero growth under the logistic model with r > 0?

1. 450 individuals
2. 600 individuals
3. 150 individuals
4. 300 individuals

17. Two bird flocks occur together because both use a temporary feeding site, without social attraction. What type of grouping is this?

1. A single-species population defined by reproduction
2. Indirect grouping around a shared resource
3. Positive grouping through social attraction
4. Accidental grouping unrelated to resources

1. Define a population in ecology and identify two properties used to describe it. (3 marks)

2. Describe three ways organisms can come together in groups. (3 marks)

3. Distinguish discrete from continuous population growth. (3 marks)

4. Explain what is meant by positive, zero and negative population growth. (3 marks)

5. Give three examples of biological structures used to estimate age. (3 marks)

6. Explain how PVA can inform management of a threatened mammal population. (5 marks)

7. Explain how a group of organisms can differ from an ecological population, using an example of organisms gathering at a water source. (5 marks)

8. For a closed population initially containing 180 animals, with 28 births and 16 deaths, calculate the final size and explain the model. (5 marks)

9. In a mark–release–recapture study, 24 animals are marked initially, then 30 are caught of which 6 are marked. Estimate population size and state the relevant assumptions. (5 marks)

10. Outline how birth and death rates can be estimated in wild bird or fish populations and why mortality is especially challenging. (5 marks)

11. A population follows logistic growth with r = 0.2 per year, N = 200 and K = 500. Calculate its instantaneous growth and predict the consequence if habitat loss reduces K to 150, with r and N unchanged. (8 marks)

12. A team marks 40 animals and later captures 50, including 10 marked animals. Estimate population size, then analyse how trap-shyness and mark loss may affect the estimate. (8 marks)

13. Two bird populations each contain 500 individuals. One contains mostly juveniles, while the other contains mostly breeding adults. Analyse why equal population size may conceal different conservation prospects and propose how to improve predictions. (8 marks)

1. A park survey is conducted only in dry weather. Which limitation is most likely?

1. All recorded species will be misidentified
2. Species active after heavy rain may be overlooked
3. A greater proportion of wet-weather specialists will be recorded
4. Richness cannot be compared with any other site

2. A biodiversity map shows many records around Sydney and very few in remote bushland. Which inference is safest?

1. Observer effort may be greater around populated areas
2. Remote habitats contain fewer species of every group
3. Species are intrinsically restricted to city centres
4. All remote areas have been sampled comparably

3. A survey of a rare, burrowing species produces few records. Which strategy best addresses potential under-detection?

1. Replace all sampling with historical records
2. Treat missing observations as confirmed extinction
3. Include only more conspicuous species
4. Repeat surveys using methods matched to its ecology

4. Researchers compare plant species counts in 0.1-hectare plots across habitats. What is the principal benefit?

1. Identical plot size removes all detectability differences
2. A consistent area makes richness comparisons more meaningful
3. It allows direct comparison of animal abundance
4. All species in each habitat will be recorded

5. Two samples each contain ten species and 100 individuals. Site A has one dominant species; site C has equal abundances. Which site is more diverse?

1. Site A, because rare species contribute more individuals
2. Site C, because individuals are distributed more evenly
3. Both, because species richness is the same
4. Site A, because a dominant species increases richness

6. Two equally sampled habitats each have six species, but only two are shared. What does this indicate?

1. The habitats contain no locally restricted species
2. Identical species composition despite equal richness
3. Substantial species turnover between habitats
4. Low gamma diversity despite high richness

7. For counting canopy insects rather than ground insects, what is the strongest survey-design choice?

1. Adapt the sampling method to reach the canopy
2. Use only soil cores for both habitats
3. Use identical pitfall traps at ground level
4. Use only night-time bird observations

8. A camera survey records mammals that a daytime visual survey missed. What is the main explanation?

1. Visual surveys always underestimate species richness by half
2. Camera surveys detect only nocturnal species
3. Detection probability depends on method and animal behaviour
4. Cameras always detect every species present

9. Two taxonomists disagree about whether genetically distinct dingo populations merit separate species status. What does this illustrate?

1. Species classifications are independent of conservation policy
2. Reproductive compatibility always settles classification
3. All genetically distinct populations must belong to separate species
4. Species boundaries can involve judgement when evidence differs in interpretation

10. The cumulative species curve has nearly levelled off. What does this suggest?

1. Each new sample adds many common species
2. Sampling effort can no longer affect detection
3. Further sampling is finding relatively few new species
4. The habitat contains no undetected species

11. A species-rich habitat contains mostly individuals from one species. Which statement is accurate?

1. Richness must therefore be low
2. Its gamma diversity must equal its abundance
3. All habitats with that richness are equally diverse
4. Its diversity may be low because evenness is low

12. An eDNA survey fails to detect an elusive fish in a stream. Which conclusion is most justified?

1. The species has become locally extinct
2. The fish is absent throughout the catchment
3. The species is present in another stream
4. Non-detection alone does not demonstrate absence

13. A botanist identifies two visually distinct garden plants that readily hybridise. What challenge does this pose?

1. The biological concept may not give a clear species boundary
2. The phylogenetic concept requires identical DNA
3. The morphological concept cannot compare them
4. The ecological concept forbids hybridisation

14. Two cat populations look similar but have consistently different DNA profiles. Which additional species concept could help distinguish them?

1. Ecological, based on resource use
2. Phylogenetic, based on genetic differentiation
3. Morphological, based on habitat choice
4. Biological, based only on appearance

15. A landscape contains three habitats with overlapping species lists. Which count represents gamma diversity?

1. The mean number of species per habitat
2. The number of unique species across all three habitats
3. The number exclusive to one habitat
4. The sum of individuals across all habitats

1. Describe three approaches for estimating the total number of undescribed species. (3 marks)

2. Explain the meanings of alpha, beta and gamma diversity. (3 marks)

3. Explain why a biodiversity observation map may contain many records near cities. (3 marks)

4. Give three reasons why species classification matters in ecology and conservation. (3 marks)

5. Assess the strengths and limitations of eDNA when testing whether an invasive fish occurs in a stream. (5 marks)

6. Design a bird survey in a local park that accounts for variation in detectability. (5 marks)

7. Explain why species richness comparisons require attention to sampling area, effort and season. (5 marks)

8. Explain why the dingo presents a challenge for species delimitation and describe one conservation implication. (5 marks)

9. A dingo management policy depends on treating dingoes as either a separate species or domestic dogs. Critically evaluate why classification can be contested and how managers should use the evidence. (8 marks)

10. A field team aims to count all insect species in a bushland reserve but has one week of sampling. Propose a survey strategy and critically assess its likely biases. (8 marks)

11. Habitats A and B each contain six species. They share only two species, and habitat A is dominated by one species while B is relatively even. Explain what richness, evenness, beta diversity and gamma diversity reveal. (8 marks)

12. Two taxonomists disagree over whether a cryptic glider complex is one species or two. Develop a defensible assessment using the species concepts from the lecture and explain the conservation implications. (8 marks)

1. Ants protect sap-feeding insects and consume their honeydew. What explains the mutual benefit?

1. The ants and insects eat each other
2. Protection is exchanged for a food reward
3. Both species are unaffected by the association
4. The insects gain light and ants lose food

2. In the tree-hollow experiment, what was measured as a response to productivity?

1. The mass of surrounding trees
2. The number of trophic links
3. The temperature of incoming rain
4. The annual rainfall at each site

3. A large animal accidentally crushes a small plant without experiencing an effect. What sign combination applies?

1. (0, −)
2. (+, 0)
3. (+, −)
4. (−, −)

4. A seal eats penguins that feed on krill, which consume phytoplankton. What is the seal's role in that chain?

1. Primary consumer
2. Secondary consumer
3. Primary producer
4. Tertiary consumer

5. A mite eats both eucalypt leaves and springtails. How should its trophic position be described?

1. It is always a primary consumer
2. It must be a tertiary consumer
3. It depends on which food is consumed
4. It is always a secondary consumer

6. A harmless mite lives on a mammal, gaining shelter without affecting its host. What is the interaction?

1. Competition
2. Amensalism
3. Commensalism
4. Predation

7. In the moose–birch study, which measure was reduced under heavy browsing even though hatching numbers were not significantly different?

1. Moose reproductive rate
2. Great tit fledgling numbers
3. Tree-hollow rainfall
4. Pollinator visits

8. Two mutualist species gain benefits together but can each survive separately. What type is this?

1. Facultative mutualism
2. Obligate parasitism
3. Obligate mutualism
4. Interspecific competition

9. A drought causes the longest food chains in a pond system to shorten. Which hypothesis does this most directly support?

1. Ecological species concept
2. Obligate mutualism hypothesis
3. Dynamic stability hypothesis
4. Energy hypothesis only

10. An ecosystem supports numerous producers but few high-level predators. Which explanation is most consistent with energy transfer?

1. Predators convert all prey biomass to growth
2. Energy increases with consumer body size
3. Producers lose all energy before being eaten
4. Less energy remains at successive levels

11. A predator suppresses herbivores, allowing plants to increase. What kind of ecological effect does the predator have on plants?

1. Direct consumption
2. Direct competition
3. Indirect positive effect
4. Indirect parasitism

12. Moose prefer willow and aspen over spruce. What community response is consistent with this preference?

1. Spruce may increase relative to browsed trees
2. Aspen gains an advantage over spruce
3. Willow must increase because it is eaten
4. All tree species must decline equally

13. In a food web, a fox eats a rodent that feeds on seeds. Which link shows a direct energy transfer to the fox?

1. Rodent → fox
2. Fox → seeds
3. Fox → rodent
4. Seeds → fox

14. Two wallaby species use the same limited pasture. What is the most appropriate interaction classification?

1. Interspecific competition
2. Obligate commensalism
3. Facultative parasitism
4. Intraspecific competition

15. Why can two explanations for short food chains both receive experimental support?

1. One hypothesis must be mathematically wrong
2. Energy and environmental stability can both matter
3. Chain length is independent of conditions
4. Only the most recent hypothesis can apply

1. Describe how energy moves through a simple food chain consisting of a plant, a herbivore and a predator. (3 marks)

2. Distinguish an autotroph from a heterotroph and give one example of each. (3 marks)

3. Distinguish interspecific and intraspecific competition and state the sign of their effects. (3 marks)

4. Explain why a food web provides a more realistic representation of feeding interactions than a single food chain. (3 marks)

5. Explain why herbivory is considered a form of predation and identify one plant defence. (3 marks)

6. Ants defend sap-feeding scale insects and collect their honeydew. Explain the ecological classification and when it would be facultative. (5 marks)

7. Compare the energy and dynamic stability hypotheses for why food chains are generally short. (5 marks)

8. Describe how moose feeding preferences could benefit spruce while harming willow and aspen. (5 marks)

9. In a woodland, moose browse birch leaves and insectivorous birds feed on arthropods associated with birch. Explain a plausible indirect consequence of increased browsing. (5 marks)

10. Two species share a limited food resource, while another pair exchanges pollination services. Compare the interactions and their fitness effects. (5 marks)

11. A fish feeds on algae and herbivorous invertebrates, and is itself eaten by a bird. Construct the relevant feeding pathways and explain why a fixed trophic label for the fish is misleading. (8 marks)

12. Darwin noted that villages with many cats also had many flowers. Develop a plausible indirect trophic explanation involving cats, small mammals, pollinators and plants, and identify how it could be tested. (8 marks)

13. In an experiment, heavily browsed birch stands have lower canopy cover and fewer great tit fledglings than lightly browsed controls, but similar hatchling numbers. Explain the ecological mechanism and interpret this result. (8 marks)

1. A forest canopy tree falls, increasing light at ground level. Which change is expected first?

1. Establishment of light-demanding colonisers
2. Permanent cessation of plant succession
3. Immediate dominance by shade-tolerant hardwoods
4. Loss of all seed dispersal from the opening

2. Why might moderate patchy fires maintain more species than complete fire exclusion?

1. Every patch is repeatedly reset to bare soil
2. Different successional stages can coexist
3. Pioneer species are permanently removed
4. The whole area remains at climax stage

3. What happens during denitrification?

1. Organic carbon is converted to methane
2. Nitrate is returned to gaseous nitrogen
3. Nitrogen gas is converted to plant protein
4. Phosphate is released from rock surfaces

4. What is a likely outcome of fires repeated before plants can replace their seeds?

1. Some resprouting and reseeding species decline
2. Recovery becomes independent of fire frequency
3. All successional stages become equally common
4. More late-successional trees establish

5. A soil nutrient is recycled locally with no large atmospheric reservoir. Which cycle is most consistent?

1. Water
2. Carbon
3. Nitrogen
4. Phosphorus

6. A trap captures several insect species at one site, but their interactions are unknown. What term best describes this sample?

1. Population
2. Ecosystem
3. Assemblage
4. Community

7. Why may vegetation maps be imperfect substitutes for maps of all animal communities?

1. Abiotic conditions affect only animal species
2. Animal distributions need not match vegetation types
3. Vegetation communities never change over time
4. Vegetation has no links to other taxa

8. A bare quarry wall has little soil and almost no organic matter. What challenge particularly affects early colonists?

1. Excessive canopy shade
2. Limited nutrients and rooting sites
3. A surplus of soil nitrogen
4. High competition from hardwoods

9. Which observation most strongly suggests facilitation during primary succession?

1. Pioneers and newcomers never influence each other
2. Pioneers build soil that supports later colonists
3. Early shrubs exclude all arriving seedlings
4. Late trees prevent soil from accumulating

10. Why can open oceans have low NPP per unit area despite covering large areas?

1. Oceanic producers never photosynthesise
2. Ocean water cannot support autotrophs
3. All ocean energy is stored in consumers
4. Nutrient supply can limit producer growth

11. What happens to kelp when sea otter abundance rises and sea urchin grazing falls?

1. Kelp stops taking up carbon dioxide
2. Kelp carbon storage must disappear
3. Kelp biomass and carbon storage can increase
4. Kelp biomass becomes independent of grazing

12. How can mycorrhizal fungi benefit plants growing in low-phosphorus soils?

1. They remove the need for all root uptake
2. They transform atmospheric CO2 into nitrate
3. They convert plant sugars directly into rainfall
4. They enhance phosphorus acquisition

13. Dense introduced shrubs prevent native seedlings establishing beneath them. Which model is illustrated?

1. Intermediate disturbance
2. Facilitation
3. Inhibition
4. Tolerance

14. Why is the water cycle global even though water may be scarce within an ecosystem?

1. Atmospheric movement transfers water between regions
2. Rainfall permanently traps water within regions
3. Soil water is always recycled in place
4. Only oceans participate in the water cycle

1. Define resilience in the context of ecological disturbance and state one difficulty in measuring it. (3 marks)

2. Describe ecological succession and name two stages in the classical abandoned-field sequence. (3 marks)

3. Explain why nitrogen fixation matters for plant productivity. (3 marks)

4. Identify three typical characteristics of pioneer plant species. (3 marks)

5. State the intermediate disturbance hypothesis and describe its predicted pattern of richness. (3 marks)

6. A researcher records plant species in several traps but does not know whether they interact. Explain whether assemblage or community is the more defensible term, and how interactions could change that interpretation. (5 marks)

7. Compare facilitation, tolerance and inhibition as mechanisms underlying succession. (5 marks)

8. Explain how sea otters can affect carbon storage without directly photosynthesising. (5 marks)

9. Explain why a landscape with patchy intermediate disturbance can support more species than landscapes with very little or very frequent disturbance. (5 marks)

10. An area mapped as one vegetation community contains distinct fungi and animal species on opposite slopes. Explain why vegetation-based community classification may be insufficient and design a more robust survey. (8 marks)

11. An ecologist proposes that all ecological communities naturally converge to a permanent hardwood climax. Critically evaluate this claim using succession, disturbance and time. (8 marks)

12. In a woodland model, every patch advances towards mature trees unless a disturbance resets it. Explain how varying disturbance frequency and spatial extent could generate a non-linear relationship with species richness. (8 marks)

1. Researchers find persistent industrial chemicals in remote Arctic wildlife. Which explanation is supported by the lecture?

1. Pollutants are produced naturally by sea-ice formation
2. Predators remove all chemicals from their prey
3. Only local Arctic manufacturing could explain detection
4. Atmospheric transport followed by cold-region deposition

2. Raptor breeding success falls despite few adult deaths after pesticide use. Which mechanism best matches the lecture example?

1. Eggshell thinning lowers successful recruitment
2. Habitat corridors prevent new nest formation
3. Food chain shortening raises the adult death rate
4. Adult birds increase their investment in eggs

3. A bird refuses to cross farmland separating two forest patches. What landscape feature is limiting connectivity?

1. A short food chain
2. A high predator abundance within both patches
3. An inhospitable matrix
4. A large interior habitat area

4. Why may a national ban fail to eliminate exposure to a volatile persistent pollutant?

1. All contaminants are generated by natural local sources
2. Ocean currents prevent cross-border contaminant transport
3. National bans immediately remove stored chemicals globally
4. Emissions elsewhere can travel through the atmosphere

5. A forest survey records temperature changes and earlier insect emergence. Which conclusion is most justified?

1. A single correlation excludes all other ecological influences
2. The biological shift is consistent with warming but needs wider context
3. The insect shift proves temperature is its sole cause
4. The temperature data cannot inform ecological interpretation

6. What distinguishes biomass collapse from the predator-loss cascade in the lecture case studies?

1. Both arise solely from reduced sunlight reaching the canopy
2. One requires climate warming; the other requires ocean acidification
3. One centres on edge-driven tree loss; the other on disrupted trophic control
4. Both are direct effects of heavy-metal pollution

7. Predatory fish contain higher concentrations of a persistent toxin than their prey. Which concept is illustrated?

1. Succession after habitat disturbance
2. Atmospheric transport across latitudes
3. Recolonisation through a habitat corridor
4. Biomagnification across trophic levels

8. A narrow native-vegetation strip connects two reserves. What is its most likely advantage and limitation?

1. It supports only interior specialists and excludes mobile taxa
2. It eliminates isolation and recreates extensive core forest
3. It prevents dispersal while removing surrounding disturbances
4. It permits movement but may consist mostly of edge habitat

9. Policy changes reduce native-vegetation clearing. What ecological benefit is most directly expected?

1. Complete prevention of climate-related range shifts
2. Instant elimination of all existing edge effects
3. Immediate recovery of all locally extinct species
4. Less habitat loss and fragmentation for native species

10. After an oil spill, dispersant application reduces visible oil but harms marine larvae. What does this show?

1. Visible shoreline condition measures all biological effects
2. Removing surface oil always restores all affected species
3. Dispersants prevent pollutants entering food chains
4. Clean-up interventions can create additional ecological impacts

11. A chemical is detected above background levels but no harmful effect is established. Which description is most appropriate?

1. It is a contaminant; its pollutant status is unresolved
2. It is a biomagnified toxin because it is widespread
3. It is harmless because it has not caused death
4. It is necessarily a pollutant because it is detectable

12. Why are small fragments particularly vulnerable to edge effects?

1. Their interiors are always wetter than continuous forests
2. They contain a higher total area than larger fragments
3. They receive no sunlight from outside the fragment
4. A greater proportion of their area lies near boundaries

13. Why can long-lived marine mammals be significant sources of dietary pollutant exposure?

1. Persistent substances can build up in their tissues
2. Cold seawater makes all pollutants biologically inactive
3. Long lifespans prevent their tissues absorbing toxins
4. Their high trophic level destroys chemical pollutants

14. Why are expected climate-driven range shifts often towards higher latitudes or altitudes?

1. Species are compelled to follow national boundaries
2. Higher latitudes always contain more habitat area
3. Organisms may track suitable temperature conditions
4. Lower altitudes always experience less competition

15. Two reserves have equal total habitat area: one large square and four small squares. Which likely has more core habitat?

1. Neither can contain any edge habitat
2. The four small squares
3. Both have identical perimeter relative to area
4. The single large square

1. Define biomagnification and explain why top predators may have high contaminant concentrations. (3 marks)

2. Describe one mechanism by which rodenticides can poison powerful owls indirectly. (3 marks)

3. Describe the basic predator–herbivore–plant cascade expected after predators disappear. (3 marks)

4. Describe what an edge effect is and give two changes that can occur at a forest edge. (3 marks)

5. Identify three landscape properties that affect the consequences of habitat fragmentation. (3 marks)

6. Describe how researchers could investigate whether tree biomass declines towards forest edges after fragmentation. (5 marks)

7. Explain how pesticides reduced bald eagle populations without necessarily causing widespread adult mortality. (5 marks)

8. Explain how the loss of predators from newly isolated islands can eventually affect forest regeneration. (5 marks)

9. Explain why the lecture treats the evidence for ecological climate change as stronger across many systems than in a single case. (5 marks)

10. A chemical manufacturer argues that a national PCB ban makes further national and international action unnecessary. Evaluate this claim using the Arctic case study. (8 marks)

11. A local government can protect either a large circular forest patch or an equal area distributed among four thin strips. Evaluate the options for forest specialists and landscape connectivity. (8 marks)

12. Researchers attribute forest biomass loss after clearing solely to reduction in patch area. Critique their inference and propose a stronger study. (8 marks)

1. Fox populations expand following rabbit establishment. What ecological process may help explain this?

1. Two invaders must occupy different trophic levels
2. One invader facilitates another through food supply
3. Fox spread is unrelated to prey availability
4. Rabbits directly suppress fox reproduction

2. A species has not been assessed for the IUCN Red List. What follows from that fact?

1. Its extinction risk has not been formally assessed
2. It is necessarily extinct in the wild
3. It has already recovered from previous decline
4. It must be classified as Least Concern