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3.7 Natural Selection — Test 1
Q1. Darwinian evolutionary fitness is measured in terms of an individual's:✓ Reproductive success
Q2. The type of natural selection that eliminates both extremes and favours the intermediate phenotype is:✓ Stabilizing selection
Q3. Selection in which two extreme phenotypes leave more offspring than the intermediate phenotype is called:✓ Disruptive selection
Q4. Antibiotic resistance evolving in a bacterial population under continuous antibiotic exposure is an example of:✓ Directional selection
Q5. Darwin's finches with large, intermediate and small beaks feed on seeds with a bimodal size distribution. Natural selection will favour finches with:✓ Both large and small beaks
Q6. The formation of many species from a single common ancestor, each adapted to a different niche, is termed:✓ Adaptive radiation
Q7. The mean and standard deviation of body size in a population changed from 8.5 ± 2.2 mm to 8.5 ± 0.8 mm over several generations. This indicates:✓ Stabilizing selection
Q8. In a population, heterozygotes are favoured over homozygous dominants, which are favoured over homozygous recessives. Over generations:✓ Both alleles remain in the population
Q9. A person heterozygous for the sickle-cell allele has resistance to malaria. This is an example of:✓ Heterozygote advantage
Q10. Under which condition of natural selection will NO allele be lost from the population?✓ Heterozygotes favoured
Q11. Selection that acts against any deviation from the existing mean is termed:✓ Stabilizing
Q12. Body weight of a Drosophila population was 1.8 ± 0.45 mg. After selection, three groups arose: A (1.8 ± 0.08 mg), B (bimodal at 1.4 and 2.2 mg), C (2.2 ± 0.08 mg). The types of selection are:✓ A-Stabilizing; B-Disruptive; C-Directional
Q13. Directional selection for a trait will tend to produce a trait distribution that is:✓ Right- or left-skewed (shifted toward one extreme)
Q14. In pre-industrial England the peppered moth was mostly pale; during the industrial revolution dark moths became common. This change occurred because:✓ Natural selection favoured dark moths that were initially present in small numbers
Q15. The replica-plating experiment of Lederberg and Lederberg demonstrated that antibiotic-resistant mutants:✓ Are pre-existing and then selected by the antibiotic
Q16. In a region of Africa, 'AS' individuals (sickle-cell carriers) are maintained at high frequency. This is best explained by:✓ Heterozygote advantage
Q17. A change in allele frequency at or below the species level is termed:✓ Microevolution
Q18. Which statement about evolution by natural selection is NOT true?✓ It is goal-directed toward 'better' organisms
Q19. The Galapagos finches, which differ in beak shape and size, are best explained as an example of:✓ Adaptive radiation with beak variation generated by mutation and shaped by selection
Q20. Match each mode of selection with its effect and select the correct option.✓ A-ii, B-iii, C-i, D-iv