VCE-BIO-U34 6.1 📋 – Practice Exam 3: Question Paper

The Hardy-Weinberg principle states that allele frequencies in a population remain constant across generations only if:

In a population at Hardy-Weinberg equilibrium, if the frequency of allele A is p = 0.7, the expected frequency of heterozygotes (Aa) is:

Genetic drift has the greatest effect on allele frequencies in:

The founder effect occurs when:

Molecular phylogenetics constructs evolutionary trees primarily using:

Synapomorphies are:

A key difference between allopatric and sympatric speciation is that:

A molecular clock is used by biologists to estimate:

Sexual selection is a form of natural selection that results specifically from differences in:

Which type of natural selection acts to maintain two or more distinct phenotypes within a population?

The bottleneck effect occurs when:

In the construction of a phylogenetic tree, an outgroup is included in order to:

Prezygotic reproductive isolating mechanisms include:

Microevolution refers to:

Which piece of evidence most strongly supports that all life on Earth shares a common ancestor?

Gene flow between two populations tends to:

In evolutionary biology, an organism’s ‘fitness’ refers to:

Adaptive radiation occurs when:

What is the main significance of transitional fossils (e.g. Tiktaalik, Archaeopteryx) in evolutionary biology?

Stabilising selection acts to:

Postzygotic reproductive isolating mechanisms include:

Which pair of structures is best described as homologous?

Convergent evolution is best illustrated by which of the following?

Vestigial structures (e.g. the human appendix, whale pelvic bones) provide evidence for evolution because they:

The change in colour frequency of the peppered moth (Biston betularia) during the industrial revolution in Britain is a classic example of:

In human populations from historically malaria-endemic regions, the sickle cell allele has persisted at a relatively high frequency mainly due to:

Which statement correctly distinguishes gradualism from punctuated equilibrium as models of the tempo of evolutionary change?

Ring species are of particular interest to evolutionary biologists because they:

Assortative mating, which violates one of the Hardy-Weinberg conditions, occurs when:

Allopolyploidy, a mechanism of sympatric speciation common in plants, arises when:

A phylogenetic tree diagram in which branch lengths are drawn proportional to the estimated amount of genetic (molecular) change is best described as a:

On a phylogenetic tree, two taxa that share the most recent common ancestor, to the exclusion of all other taxa on the tree, are called:

A monophyletic group (clade) is defined as:

The principle of maximum parsimony, applied when constructing a phylogenetic tree from character data, states that:

Darwin’s finches of the Galapagos Islands are a classic example of:

Which of the following would most likely INCREASE genetic variation within a population?

A researcher samples 200 individuals of a plant species and finds that 25% display the recessive homozygous phenotype for a flower-colour gene. Assuming the population is in Hardy-Weinberg equilibrium, the expected frequency of the dominant allele (p) is:

Using the same population as the previous question (p = q = 0.5), how many of the 200 sampled individuals are expected to be heterozygous?

Which scenario best illustrates the founder effect, as distinct from a population bottleneck?

In the context of speciation, reinforcement refers to:

Explain the Hardy-Weinberg equilibrium. State the five conditions required and explain what happens when each is violated.

In a population of 500 people, 18% have recessive phenotype (aa). Using Hardy-Weinberg, calculate the frequency of each allele and each genotype.

Compare allopatric and sympatric speciation, explaining the mechanisms of reproductive isolation in each.

Describe three types of natural selection (directional, stabilising, disruptive) and give an example of each.

Explain how molecular evidence supports evolutionary relationships. Use cytochrome c as an example.

Explain the role of genetic drift in small populations. Describe the bottleneck effect and founder effect as examples.

Describe the evidence from the fossil record that supports evolution, including its limitations.

Explain how gene flow can prevent speciation between two geographically close populations.

<strong>Extended Response 1: Phylogenetics (a)</strong><br>Explain how phylogenetic trees (cladograms) are constructed and interpreted. Define key terms: clade, node, branch length, outgroup.

<strong>Extended Response 1: Phylogenetics (b)</strong><br>Using DNA sequence data, explain how molecular phylogenetics has revised traditional classification systems. Give one example.

<strong>Extended Response 2: Human Evolution (a)</strong><br>Describe the key anatomical and archaeological evidence for human evolution from a common ancestor with other great apes.

<strong>Extended Response 2: Human Evolution (b)</strong><br>Explain what the ‘Out of Africa’ model proposes and describe the molecular evidence supporting it.

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes (a)
A population of 1000 mosquitoes is monitored for resistance to a pyrethroid insecticide. Resistance is conferred by homozygosity for a recessive allele (r); susceptible individuals are RR or Rr. BEFORE insecticide spraying began, 4% of the mosquito population showed the resistant phenotype. Assuming Hardy-Weinberg equilibrium, calculate the allele frequencies (p and q) and the expected genotype frequencies (RR, Rr, rr) in this population before spraying.

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes (b)
After 10 generations of continuous insecticide spraying, the resistant phenotype (rr) is now found in 49% of the population. Calculate the new allele and genotype frequencies.

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes (c)
Identify and explain the type of natural selection responsible for the change in allele frequencies observed between (a) and (b), referring to the role of the insecticide as a selective pressure.

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes

Extended Response 3: Directional Selection in Insecticide-Resistant Mosquitoes (d)
Explain why this change in allele frequency is NOT an example of genetic drift, and outline one strategy that could be used to slow the evolution of insecticide resistance in pest populations.

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers (a)
Mitochondrial DNA (cytochrome b gene) sequence comparisons indicate that two lineages of Hawaiian honeycreeper diverged from a common ancestor approximately 3.6 million years ago, and differ by an average of 2 amino acid substitutions per lineage since that divergence. A molecular clock calibration for this gene, based on other bird lineages with known fossil divergence dates, gives a substitution rate of 1 amino acid change per 1.8 million years per lineage. Explain how molecular clock data is used to estimate divergence times between lineages, and use the calibration rate to check whether the honeycreeper data (2 substitutions in 3.6 million years) is consistent with it.

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers (b)
Explain the process of adaptive radiation, using the diversification of Hawaiian honeycreepers (from a single ancestral finch-like colonising species into many species with markedly different beak shapes and diets) as your example.

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers (c)
Explain the role of allopatric speciation, including the founder effect and geographic isolation between islands, in generating the diversity of honeycreeper species across the Hawaiian archipelago.

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers

Extended Response 4: Adaptive Radiation and Phylogenetics in Hawaiian Honeycreepers (d)
The table below shows the number of nucleotide differences in the same mitochondrial gene region between four hypothetical honeycreeper species (A-D).

Species pair | Nucleotide differences
A-B | 2
A-C | 5
A-D | 9
B-C | 4
B-D | 8
C-D | 6

Using this data, identify which two species are most closely related, and explain how this type of molecular data, together with morphological data, would be used to construct a phylogenetic tree (cladogram) for these species.