BIO exam 2022 questions and answers

Q1. Explain how evolutionary theory has changed over time using four key ideas from the chain of being, through the 1800s, the early to mid 1900s, to today. (8 marks)

The chain of being was a medieval concept that placed all living things in a hierarchical order with humans at the top and plants at the bottom. This idea persisted in the 1800s when naturalist began to observe and classify species based on physical characteristics. In the early to mid 1900s, Darwins theory of natural selection gained acceptance as an explanation for how species changed over time. However this theory did not fully account for genetic variation or the role of chance events in evolution. Today evolutionary theory incorporates ideas from genetics and molecular biology to explain how genetic variation drives evolution through natural selection.

Q2. Although we know evolution is ‘directionless’ and not forward-thinking, some traits have continuously ‘improved’ over time. Give an example of such a trait from two different species - two examples total. (3 marks)

An example of a trait that has continuously improved over time is eyesight. In humans, our eyes have evolved to be more efficient and complex at detecting light and colour, allowing us to see in greater detail and with more accuracy. Alternatively, in birds, such as eagles, their eyesight has evolved and adapted to their environments to be more sharp, enabling them to see prey from greater distances.

Q3. Which of these had the least influence on Darwin’s work and writing? (1 mark)

(a) Knowledge of inheritance, as discovered by Gregor Mendel

SECTION B

(Answer ALL questions – 22 marks. Make room under each question for your answer and/or

highlight the letter that represents the correct answer.)

Q4. Explain the Hardy-Weinberg equilibrium theory, including its assumptions, and then explain the microevolutionary processes of natural selection, genetic drift, and gene flow. (10 marks)

Q5. Which mutation is most likely to become fixed? (1 mark)

A beneficial mutation in a small population

Q6. Why is an understanding of evolutionary processes so important to conservation? Describe, using a real or theoretical example, two key ways in which evolutionary information could be used to inform conservation practices. (4 marks)

Understanding evolutionary processes is important for conservation because it helps identify which populations hold important genetic diversity and adaptive traits needed for long-term survival. One key use is identifying evolutionarily significant units (ESUs), so efforts can focus on preserving unique genetic lineages rather than treating all individuals as the same. For example, genetic studies of African elephants showed that forest and savannah populations are distinct and adapted to different environments, so conservation plans now treat them separately. Another use is predicting how species might respond to future changes, such as climate shifts, allowing managers to prioritise populations with the greatest adaptive potential.

Q7. Anthropogenic climate change is taking place at such a fast rate that many species will fail to adapt quickly enough to avoid extinction. Which of the following may constrain evolution in response to human-induced climate change? (1 mark)

(e) All of the above

Q8. For a certain species, FST has been measured at 0.337. Predict the dispersal ability (high/low), generation time (long/short), and population size (large/small) of this species. (3 marks)

Q9. Imagine a population of butterflies that vary in wing colour. Suddenly, butterflies with orange wings experience increased predation compared to those with grey wings. What type of selection would we expect to occur in this scenario, and what would the affect be on the frequency of each wing colour in the population? (3 marks)

This scenario describes directional selection, where one trait (grey wings) provides a survival advantage over another (orange wings). As a result, butterflies with orange wings are more likely to be eaten and less likely to reproduce, while those with grey wings are more likely to survive and pass on their genes. Over time, we would expect the frequency of grey wings to increase in the population and orange wings to decrease, potentially leading to grey wings becoming dominant.

SECTION C

(Answer ALL questions – 18 marks. Make room under each question for your answer.)

Q10. Living mammals have similar features to those that became extinct in the Mesozoic

era. This is an example of:

Convergent evolution

Q11. Examine the figure below. Using the species names (frog, human, cat, lizard, goose, shark), explain the following concepts: outgroup, sister taxa, monophyletic group, paraphyletic group. (6 marks)

The shark would be the outgroup, representing a lineage that diverged earlier than any other species in the tree. The humans and cats would be the sister taxa, indicating that they both share a more recent common ancestor than either do when any other species in the tree. The group consisting of the humans, cats and goose would be the monophyletic group, indicating a common ancestor and all of its descendants. The group consisting of lizard, shark and frog would be the paraphyletic group, indicating a common ancestor but not all of its descendants.

Q12. Use your understanding of comparative genomics to describe an experiment that would enable you to identify new genes (or old genes with new functions) that could allow an invasive species to eat a wider range of crops. Describe the comparative data you would require and what you would expect it to show. (5 marks)

To identify genes that have enabled an invasive species to eat a wide range of crops, we can use comparative genetics, by comparing the genomes and gene expressions of a non-invasive closely related species with a more limited diet. By sequencing genomes and using RNA sequencing we can identify gene duplications, novel genes or changes in expression especially in genes linked to digestion, detoxification, and taste. We would expect to find new genes or existing genes with new functions that helped the invasive species adapt and process a much broader range of plant compounds, giving it a dietary advantage.

Q13. Why are we able to perform experiments on model species (e.g., fruit flies and mice) to obtain information that can be applied to humans? (2 marks)

We can study model species like fruit flies and mice because all living organisms share a common evolutionary ancestor, meaning many genetic, cellular, and developmental processes are conserved across species. These models reproduce quickly and are easy to manipulate in labs, allowing researchers to uncover biological mechanisms that often apply to humans due to shared genes and pathways.

Q14. What is ‘phylogenetic conservatism’, and how does it explain why the tuatara can be considered a ‘living fossil’? (4 marks)

Phylogenetic conservatism refers to the tendency of species to retain ancestral characteristics over a long period of evolutionary time. This means that closely related species are likely to share more physical and biological characteristics, even if they diverged in other ways. The tuatara is considered a living fossil because it has many primitive features that remained unchanged over time. Its ancestors were already well adapted to their environment so there was no need for any major changes in morphology or behaviour.

SECTION D

(Answer ONE question from Part I and ONE question from Part II – 20 total marks. Make room under each question for your answer.)

Q15b. Describe how the Godley hypothesis relates to the Sophora genus and what the significance of the hypothesis is (should it be proven) for the evolution of relevant species in the genus you have chosen. (10 marks)

PART II

Q16. Using Rimu (Dacrydium cupressinum) as an example, and the information provided

below, describe two similarities and three differences between whakapapa and

phylogeny. (10 marks)

Both whakapapa and phylogeny use a hierarchical system to categorise organisms. They also both describe the evolutionary relationships between organisms. Whakapapa is specific to maori culture, whereas phylogeny is a universal scientific concept used by biologists globally. Whakapapa includes spiritual and cultural relationships between organisms, whereas phylogeny only considers biological relationships based on evolutionary history. Whakapapa includes non-living entities such as mountains and rivers, whereas phylogeny only includes living organisms.

SECTION E

(Answer ALL questions – 28 marks. Make room under each question for your answer.)

Q17. Describe how traits like bright colours and ornamentation might become fixed in a population, including the name for this process. (2 marks)

The process by which bright colours and ornamentation become fixed in a population is called sexual selection. This occurs when individuals with certain desirable traits reproduce and pass on these traits to their offspring. In the case of bright colours and ornamentation, these traits may signal health, strength, or reproductive success to potential mates. Over time, as individuals with these traits sexually mate and produce offspring, the frequency of these traits increases until they become fixed.

Q18. Describe how ecological and sexual selection could affect different male morphs of guppy (colourful vs drab) in a Trinidadian stream. Predict the dominant morph you would expect under each type of selection. (4 marks)

Ecological selection in a Trinadian stream can affect different male morphs of guppies by favouring bright coloured males over drab ones. This is because bright colours may help attract mates and deter predators, while drab coloured males make them more vulnerable. Sexual selection, however, can favour bright coloured or drab males based on female preference. Females may prefer bright coloured males as this trait may suggest fitness, strength, and reproductive success. Alternatively, they may prefer drab males who are able to blend into the environment, increasing their chances of survival. If ecological selection dominates then we would expect the frequency of bright coloured males to increase and they would be dominant in the population. If sexual selection dominates and the females preference is for bright coloured males then we would expect the same outcome. However, if the preference shifted to drab coloured males we would expect the frequency of this trait to increase meaning that the drab males would be dominant in the population.

Q19. Hamilton’s rule specifies the conditions under which reproductive altruism evolves. State this formula and describe how it supports the notion that natural selection favours genetic success, not reproductive success per se. (2 marks)

Hamilton’s rule is: r × B > C, where r is relatedness between the actor and recipient, B is the fitness benefit to the recipient, and C is the fitness cost to the actor. This rule supports the idea that natural selection favors genetic success because it predicts altruism evolves only when the genetic gain from helping relatives outweighs the personal reproductive cost, emphasizing gene propagation over individual reproduction.

Q20. The geographic mosaic theory of coevolution considers that the long-term dynamics of coevolution may occur over large geographic ranges rather than within local populations. Describe the three main sources of variation that affect interactions among species and provide an example from nature for each. (6 marks)

The geographic mosaic theory of co-evolution identifies three sources of variation that affect species interactions. First, trait variation means populations differ in important characteristics such as flower color in different populations of columbine plants. Second, selection mosaics happen because the strength or type of natural selection varies across locations. For example, some populations of monarch butterflies experience higher predation pressure than others. Third, coevolutionary hotspots and coldspots occur when some areas show strong reciprocal evolutionary interactions, like between figs and fig wasps in certain regions, while other areas show little or no co-evolution. These sources of variation influence how species evolve together across large geographic areas.

Q21. The Red Queen Hypothesis posits that a species must adapt and evolve not just for reproductive advantage, but also for survival because competing organisms also are evolving. What are three key predictions of the hypothesis in the context of sexual evolution? Describe an example from nature that supports each of these three predictions. (6 marks)

The Red Queen Hypothesis suggests that species must continuously evolve to survive, especially through sexual reproduction. One key prediction is that sexual selection promotes the evolution of traits that increase mating success, such as the colourful tails of male peacocks, which help them attract mates. A second prediction is that coevolutionary arms races will occur between males and females, leading to adaptations and counter-adaptations in reproductive traits; for example, in ducks, males have evolved complex genitalia to increase mating success, while females have developed anatomical defences to retain control over fertilisation. A third prediction is that sexual reproduction increases genetic diversity, allowing populations to adapt to rapidly changing environments. This is seen in many plant species, where genetic variation from sexual reproduction improves resistance to pathogens and environmental stress.

Q22. Eco-evolutionary dynamics refer to the reciprocal interactions between ecological and evolutionary processes:

(a) Define the term “niche construction”. (1 mark)

(b) Describe the four aspects considered necessary for eco-evolutionary dynamics to take place. (4 marks)

(c) Describe evidence for eco-evolutionary dynamics using three examples from nature.

Niche construction is when organisms modify their environment, influencing their own evolution and that of other species. Examples include beavers building dams that create wetlands, corals forming reefs that provide habitat, and earthworms aerating soil to improve nutrients. Eco-evolutionary dynamics require four key aspects: ecological interactions driving evolution, evolutionary changes affecting ecology, feedback between the two, and these changes happening on similar timescales. Evidence includes alewife fish evolving feeding traits that alter zooplankton communities, guppies in Trinidad evolving life histories based on predation that affect stream ecosystems, and plants evolving defenses that influence herbivore populations and further plant evolution.