- Specification route
- 3.4.4
- Question bank
- 24 questions
- Course stage
- AS / Year 12
Sample questions
How is genetic diversity formally defined in a biological context?
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It relates to the variety of gene variants within a specific group of organisms.
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Answer: The number of different alleles of genes in a population.
Genetic diversity as the number of different alleles of genes in a population.
In the process of natural selection, what is the ultimate source of new alleles in a population?
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Meiosis shuffles existing alleles, but this process creates entirely new ones.
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Answer: Random mutation
Random mutation can result in new alleles of a gene. This is a factor enabling natural selection to occur.
Antibiotic resistance in bacteria is a classic example of which type of natural selection?
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The extreme phenotype (high resistance) is favoured, shifting the population mean over time.
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Answer: Directional selection
Directional selection, exemplified by antibiotic resistance in bacteria, and stabilising selection, exemplified by human birth weights.
Natural selection results in species better adapted to their environment. These adaptations can be classified into which three categories?
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Adaptations can relate to body structure, internal chemistry, or actions.
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Answer: Anatomical, physiological or behavioural
Natural selection results in species that are better adapted to their environment. These adaptations may be anatomical, physiological or behavioural.
A population of plants experiences a sudden, severe drought. Over several generations, the average root depth of the population increases significantly. What type of selection has occurred?
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The environment has changed, favouring an extreme phenotype over the mean.
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Answer: Directional selection
Directional selection occurs when environmental conditions change, favouring individuals at one extreme of the phenotypic range, thus shifting the population mean over time.
Human birth weight is a classic example of stabilising selection. How does this type of selection affect the phenotypic variation within the population?
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Stabilising selection punishes both extremes (too small or too large).
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Answer: It preserves the mean phenotype and reduces the standard deviation (narrowing the spread).
Stabilising selection, exemplified by human birth weights, favours average individuals and selects against extremes, keeping the mean stable but narrowing the spread (reducing standard deviation).
The long, sticky tongue of a chameleon allows it to efficiently catch rapidly moving insects. What type of adaptation is this?
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This relates to the physical structure of the organism's body.
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Answer: Anatomical adaptation
Adaptations may be anatomical (physical structures like a long tongue), physiological (internal processes like venom production), or behavioural (actions like mating dances).
In the context of natural selection, what happens to individuals that possess an allele resulting in an advantageous phenotype?
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Evolution by natural selection relies on differential reproductive success.
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Answer: They are more likely to survive, reproduce, and pass on the advantageous allele to their offspring.
Natural selection occurs as individuals with alleles for advantageous phenotypes are more likely to survive and reproduce, passing on these advantageous alleles and increasing their frequency in the population.
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