Question

17.    You bring a sample of flies from a natural population into the laboratory and begin selecting for high body weight by using the heaviest 20% of the population as parents each generation for five generations. If mean body weight remains the same in each generation

         a) phenotypic variation is due only to effects of the environment b) phenotypic variation is due only to genetic variation among individuals c) VG > 0 d) VE = 0

18.    Given the observations described in the previous question you would conclude that for body weight

         a) heritability is zero b) heritability is greater than zero but less than 1 c) heritability is 1 d) heritability is greater than 1

19.    The heritability of body weight in cows a) can be measured on a single individual b) is the proportion of VG which is due to VE  c) is the proportion of VP which is due to VG   d) is the proportion of VE transmitted to offspring e) all of the above.

    

20.    When we say that the heritability of a trait in a particular population is zero a) the trait is not affected by genes b) the trait is not affected by the environment c) all individuals are genetically identical for genes affecting the trait d) individuals differ in genotype for the genes affecting the trait.

21.    In the Hardy-Weinberg equilibrium formula (p2 + 2pq + q2), p² and q² are

         a) genotype frequencies b) fitnesses c) allele frequencies d) numbers of individuals.

22.    The reproductive fitness of an individual is determined mainly by

         a) strength b) life span c) number of offspring d) owning a BMW

23.    In a population with 980 AA, 840 Aa, and 180 aa individuals the genotype frequency of Aa individuals is a) 0.49 b) 0.98 c) 0.42 d) 0.81 e) 0.18

24.    The frequency of the A allele in the population above is a) 0.49 b) 0.5 c) 0.6 d) 0.7.

Answer 1

17. if mean body weight remains same in each generation even after changing its environment from a natural habitat to lab, it means

VE= 0

18. heritability = genotypic variance/phenotypic variance

Phenotypic variance= variance due to environment + variance due to genotype + variance due to interaction between environment and genotype.

Since the environment effect is zero, here heritability becomes genotypic variance/genotypic variance = 1

Option C.

19. proportion of VP which is due to VG.

Option C

20. heritability value close to 0 indicates that the environment has been solely responsible for the observed phenotypic variations.

The trait is not affected by genes (option a)

21. genotype frequencies (option a)

22. number of offsprings (option c)

23. frequency of Aa genotype = 840/2000= 0.42 (option c)

24. frequency of genotype AA= 980/2000 = 0.49

Frequency of A allele = square root of 0.49 = 0.7

(option d)