Practice Exam 8
VCE Biology Units 1 & 2 | Comprehensive Integration: Cells, Genetics, Biochemistry & Evolution
✎ Complete ALL questions on paper before opening the Model Answers lesson. No notes. Aim for 1 minute per mark.
MULTIPLE CHOICE
Question 1 (1 mark)
A mutation changes a single base within a gene coding for a metabolic enzyme, altering the folding of the resulting polypeptide chain. Which level of protein structure is most directly disrupted?
✎ Circle your answer
A) Primary structure only, with no effect on higher levels
B) Secondary and/or tertiary structure, since amino acid sequence changes can alter folding patterns and overall 3D shape
C) Quaternary structure only, in enzymes with a single polypeptide chain
D) None; single base changes never affect protein structure
Question 2 (1 mark)
Small non-polar molecules such as O2 and CO2 can diffuse directly across the phospholipid bilayer without a transport protein mainly because:
✎ Circle your answer
A) They are actively pumped by ATP
B) Their non-polar nature allows them to pass through the hydrophobic fatty acid tail region of the bilayer
C) They are too large to require a protein channel
D) They carry a strong negative charge that repels the membrane
Question 3 (1 mark)
A population of bacteria is exposed to an antibiotic. Some individuals already carried a mutation (present before exposure) conferring resistance, and these survive and reproduce while susceptible bacteria die. This scenario is best described as an example of:
✎ Circle your answer
A) Genetic drift
B) Natural selection acting on pre-existing genetic variation
C) Use and disuse of characteristics acquired during an individual’s lifetime
D) Gene flow between populations
Question 4 (1 mark)
A key reason cells remain relatively small is that:
✎ Circle your answer
A) Small cells have a lower surface area to volume ratio, reducing diffusion distances
B) Small cells have a higher surface area to volume ratio, allowing efficient exchange of materials across the membrane relative to the cell’s metabolic needs
C) Small cells require less DNA to function
D) Surface area to volume ratio has no effect on diffusion efficiency
Question 5 (1 mark)
During aerobic respiration, which molecule is produced at the end of glycolysis in the cytoplasm and then enters the mitochondrion to link glycolysis with the Krebs cycle?
✎ Circle your answer
A) Glucose
B) Pyruvate, subsequently converted to acetyl-CoA
C) ATP synthase
D) Oxaloacetate directly from glycolysis
Question 6 (1 mark)
A small number of birds from a mainland species colonise a remote, previously uninhabited island. Over many generations, geographic isolation and different selection pressures lead to the evolution of a new, distinct species. This process is best described as:
✎ Circle your answer
A) Sympatric speciation
B) Allopatric speciation
C) Genetic drift with no natural selection involved
D) Convergent evolution
Question 7 (1 mark)
A molecular biologist wants to cut a specific human gene out of a longer piece of genomic DNA so that it can be inserted into a bacterial plasmid. The tool best suited for this step is a:
✎ Circle your answer
A) DNA polymerase
B) Restriction enzyme
C) Ribosome
D) tRNA molecule
Question 8 (1 mark)
An individual who is homozygous recessive for a non-functional allele of a gene coding for a digestive enzyme is unable to break down a particular biomolecule in their diet. This scenario illustrates the relationship between:
✎ Circle your answer
A) Genotype and phenotype, mediated by the protein product of the gene
B) Mitosis and meiosis
C) Codominance and incomplete dominance
D) Osmosis and active transport
Question 9 (1 mark)
Which sequence correctly represents the flow of genetic information within a eukaryotic cell during gene expression?
✎ Circle your answer
A) Protein to mRNA to DNA
B) DNA to mRNA to Protein
C) mRNA to DNA to Protein
D) DNA to Protein to mRNA
Question 10 (1 mark)
A student compares the amino acid sequence of the cytochrome c protein in several species and finds that humans and chimpanzees differ by very few amino acids, while humans and yeast differ by many more. This pattern provides evidence for:
✎ Circle your answer
A) Convergent evolution only
B) The degree of evolutionary relatedness between species, with more similar sequences indicating more recent common ancestry
C) That mutation rates are identical in all species
D) That cytochrome c has no biological function
Question 11 (1 mark)
Which pairing of cellular process and correct location is accurate?
✎ Circle your answer
A) Translation – nucleus; DNA replication – ribosome
B) Krebs cycle – cytoplasm; glycolysis – mitochondrial matrix
C) DNA replication – nucleus; translation – ribosome; Krebs cycle – mitochondrial matrix
D) Light-dependent reactions – mitochondrial matrix; Krebs cycle – thylakoid
Question 12 (1 mark)
A plant cell placed in a hypertonic solution loses water by osmosis, causing the plasma membrane to pull away from the cell wall. This condition is called:
✎ Circle your answer
A) Turgidity
B) Plasmolysis
C) Haemolysis
D) Cytokinesis
Question 13 (1 mark)
Two closely related plant species grow in the same geographic area, but one flowers in early spring and the other in late summer, preventing cross-pollination between them. This is an example of:
✎ Circle your answer
A) Postzygotic reproductive isolation
B) Prezygotic reproductive isolation (temporal/seasonal isolation)
C) Allopatric speciation
D) Genetic drift
Question 14 (1 mark)
Only around 10% of energy is typically transferred from one trophic level to the next in a food chain, mainly because:
✎ Circle your answer
A) Producers photosynthesise inefficiently
B) Most energy at each trophic level is lost as heat via cellular respiration, or is used for movement, or is lost in faeces/undigested material, rather than being converted into new biomass
C) Consumers refuse to eat all available food
D) Decomposers absorb 90% of all energy directly from the sun
Question 15 (1 mark)
In a very small population, allele frequencies can change markedly from one generation to the next purely due to random chance events, rather than due to selection pressure. This describes:
✎ Circle your answer
A) Natural selection
B) Genetic drift
C) Gene flow
D) Mutation pressure
Question 16 (1 mark)
A gene therapy technique successfully inserts a functional gene into the bone marrow cells of a patient with a blood disorder. This change will NOT be passed on to the patient’s children because:
✎ Circle your answer
A) Bone marrow cells are somatic cells, not reproductive (germline) cells
B) The gene is destroyed before the patient can have children
C) All gene therapy is automatically inherited
D) Bone marrow cells divide by meiosis
Question 17 (1 mark)
Which of the following is an example of a density-independent limiting factor on population size?
✎ Circle your answer
A) Competition for food
B) Predation
C) A severe bushfire
D) Spread of an infectious disease
Question 18 (1 mark)
A base substitution changes the third base of a codon, but the same amino acid is still produced in the resulting protein. This is best explained by:
✎ Circle your answer
A) The mutation being a frameshift mutation
B) The degeneracy (redundancy) of the genetic code, in which several codons can specify the same amino acid
C) The mutation occurring in an intron
D) DNA repair enzymes reversing the mutation immediately
Question 19 (1 mark)
The exchange of segments of DNA between non-sister chromatids of homologous chromosomes, which directly contributes to genetically unique gametes, occurs during:
✎ Circle your answer
A) Anaphase II of meiosis
B) Crossing over in prophase I of meiosis
C) Cytokinesis
D) DNA replication in S phase
Question 20 (1 mark)
Classifying two organisms into the same genus is based mainly on:
✎ Circle your answer
A) Living in the same geographic location
B) Sharing a close evolutionary relationship, reflected in shared derived morphological and molecular (e.g. DNA sequence) characteristics
C) Having identical diets
D) Being the same size
SHORT ANSWER
Question 21 (4 marks)
Explain how a single point mutation in a gene could ultimately affect an organism’s ability to survive in its environment, linking DNA sequence, protein structure and natural selection.
✎ Write your answer on paper
Question 22 (4 marks)
Using the concept of surface area to volume ratio, explain why multicellular organisms require specialised exchange surfaces and transport systems rather than relying on diffusion alone.
✎ Write your answer on paper
Question 23 (4 marks)
Explain the relationship between enzyme active site shape, gene expression and phenotype, using a named metabolic condition as an example.
✎ Write your answer on paper
Question 24 (4 marks)
Explain how homologous structures provide evidence for evolution from a common ancestor, and distinguish these from analogous structures.
✎ Write your answer on paper
Question 25 (4 marks)
Describe how DNA replication, mitosis and the cell cycle work together to ensure genetically identical daughter cells are produced during growth.
✎ Write your answer on paper
Question 26 (4 marks)
Explain how genetic variation generated during meiosis provides the raw material for natural selection to act upon in a population.
✎ Write your answer on paper
Question 27 (3 marks)
Outline how PCR and gel electrophoresis together allow scientists to compare DNA samples, for example in a forensic or evolutionary relatedness investigation.
✎ Write your answer on paper
Question 28 (5 marks)
Explain how photosynthesis and cellular respiration are linked biochemically and energetically within an ecosystem, referring to matter and energy flow between producers and consumers.
✎ Write your answer on paper
EXTENDED RESPONSE
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance
Question 29 (3 marks)
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance (a)
Explain, at the molecular level, how a mutation could arise in a bacterium that results in an allele conferring resistance to a particular antibiotic.
✎ Write your answer on paper
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance
Question 30 (4 marks)
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance (b)
Explain how natural selection would change the allele frequency for antibiotic resistance in the bacterial population following exposure to the antibiotic.
✎ Write your answer on paper
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance
Question 31 (3 marks)
Extended Response 1: Integrated Case Study – Evolution of Antibiotic Resistance (c)
Describe how scientists could use PCR and gel electrophoresis to confirm the presence of the resistance gene in the surviving bacteria.
✎ Write your answer on paper
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder
Question 32 (3 marks)
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder (a)
Phenylketonuria (PKU) is an autosomal recessive metabolic disorder. Explain the molecular basis of PKU in terms of gene mutation and enzyme function.
✎ Write your answer on paper
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder
Question 33 (3 marks)
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder (b)
Two unaffected parents, both known to be carriers of the PKU allele, have children. Using appropriate genetic notation, determine the probability that a child of theirs will be affected by PKU.
✎ Write your answer on paper
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder
Question 34 (3 marks)
Extended Response 2: Integrated Case Study – Inherited Metabolic Disorder (c)
Despite being a harmful condition when untreated, the allele for PKU persists at a low frequency in human populations rather than being eliminated entirely by natural selection. Suggest an explanation for this.
✎ Write your answer on paper
✓ Finished? Open the next lesson – Model Answers – to mark your work.
