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Q1) The term \'molecular clock\' is used to describe the rate of gene duplicatio

ID: 269626 • Letter: Q

Question

Q1) The term 'molecular clock' is used to describe

the rate of gene duplication events

Q2) Research on the Medium ground finch (Geospiza fortis) on the island of Daphne Major in the Galapagos demonstrated that the population evolved smaller beak size in response to an outbreak of tiny insects.

False

Q3) Crosses among blind cave fish from geographically separated caves (i.e., Molino and Pachon) produce F1 hybrids with a(n) __________ phenotype, indicating __________.

wild type; complementation

Q4) The HbS allele is observed at higher than expected frequency in many populations in Africa, the Mediterranean and India because of

genetic drift

higher oxygen affinity of hemoglobin encoded by HbS versus HbA

heterozygote superiority whereby HbAS individuals cope better with malaria infections

a constant rate of neutral substitutions over evolutionary time

Explanation / Answer

1. a constant rate of neutral substitutions over evolutionary time

The observation of a clock-like rate of molecular change was originally purely phenomenological. Later, the work of Motoo Kimura developed the neutral theory of molecular evolution, which predicted a molecular clock. Let there be N individuals, and to keep this calculation simple, let the individuals be haploid (i.e. have one copy of each gene). Let the rate of neutral mutations (i.e. mutations with no effect on fitness) in a new individual be µ . The probability that this new mutation will become fixed in the population is then 1/N, since each copy of the gene is as good as any other.

2. False

The medium ground finch population on the island of Daphne Major has provided compelling evidence of evolution in action. In particular, the beak morphology of the island's medium ground finch population has fluctuated dramatically in response to climatic conditions and competition with other ground finches.

3. ALBINO COMPLEMENTATION

4. d HETEROZYGOTE SUPERIORITY WHEREAS HbAS individuals cope better with malaria infections.

As RBC become sickle-shaped so malarial parasite is not able to survive.