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6.3 Genetic Drift, Selection & Variation โ Test 1
Q1. Random changes in allele frequencies within a small population is known as:โ Genetic drift
Q2. Fluctuation in gene frequencies caused by a small, non-representative group founding a new population is called the:โ Founder effect (a form of genetic drift)
Q3. Genetic drift is also known as the:โ Sewall Wright effect
Q4. Genetic drift has its greatest effect in:โ Small populations
Q5. Which statement about genetic drift is NOT correct?โ It selectively eliminates only harmful alleles and fixes only beneficial ones
Q6. The key difference between the bottleneck effect and the founder effect is that:โ A bottleneck follows a drastic population reduction; a founder effect follows a few individuals starting a new population
Q7. In a finite closed population, f(PP) shifts 0.40โ0.50 and f(pp) 0.40โ0.41 over ten generations, with no selection. The most likely cause is:โ Random genetic drift
Q8. In 100 independent Drosophila populations of 10 flies (each starting with one Aa and nine AA), with drift the only force, the number of populations expected to become fixed for 'a' is about:โ 5
Q9. Sampling of the gene pool occurs during sexual reproduction mainly because:โ Only a subset of gametes actually form zygotes
Q10. Balancing selection maintains variation by favouring the reproductive success of which individuals?โ Heterozygous
Q11. Sickle-cell trait in humans is a classic example of:โ Selection favouring heterozygotes (heterozygote advantage)
Q12. The condition that confers a survival advantage against malaria (in carriers) is:โ Sickle-cell anaemia (the HbS trait)
Q13. Which mechanism most plausibly prevents the extinction of a rare allele that is lethal when homozygous?โ Balanced polymorphism (heterozygote advantage)
Q14. The gradual change in a trait or allele frequency across a geographic gradient is called a:โ Cline
Q15. Which process typically does NOT increase genetic variation within a population?โ Genetic drift
Q16. At a locus with three alleles A1, A2, A3 (p = 0.2, q = 0.5, r = 0.3) at HWE, the frequencies of A1A1 and A3A3 are:โ 0.04, 0.09
Q17. With n equally frequent alleles at a locus, the total proportion of homozygotes is ___ , and if the alleles are unequal it is ___ :โ 1/n and > 1/n
Q18. Heritable genetic variability ultimately originates from:โ Mutation
Q19. Which factor has the LEAST impact on changing allele frequencies in a small population?โ Random mating
Q20. Match each evolutionary force/term with its effect and select the correct option.โ A-ii, B-i, C-iv, D-iii