Question

22. Imagine that a new population of humans is established on a new planet from ten randomly selected people in your genetics class (five males and five females). Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of inbreeding b) assortative mating c) the founder effect d) the bottleneck effect 23. Which of the following involve nuclear genes? Matemal effect b) Trinucleotide repeat diseases c) Both A and B d) Neither A nor B 24. In the Hardy-Weinberg model, the ideal population is a) large and randomly mating. b) large and non-randomly mating. c) small and randomly mating. d) small and non-randomly mating. 25. In a large, randomly mating herd of cattle, 16 percent of calves are bom with an autosomal recessive form of dwarfism. Assume this population is in Hardy-Weinberg equilibrium. What is the frequency of the recessive dwarfing allele? a) 0.16 b) 0.32 c) 0.40 d) 0.48 0.60 e) 26. A population has 20 AA, 30 Aa, and 50 aa individuals. How many A alleles are present? 50 70 c) 80 d) 90 e) 100 27. The genotypic frequencies of A4, Aa and aa are 0.5, 0.2 and 0.3, respectively. Therefore a) the frequency of allele A is 0.4; the frequency of allele a is 0.6 b) the frequency of allele A is 0.45; the frequency of allele a is 0.55 the frequency of allele A is 0.5; the frequency of allele a is 0.5 the frequency of allele A is 0.55; the frequency of allele a is 0.45 the frequency of allele A is 0.6; the frequency of allele a is 0.4

Answer 1

22. C. The Founder Effect

Note: When a population of few members establishes a new community solely by mating within themselves, it decreases the genetic variability. This phenomena is known as Founder Effect. One very popular example is the Amish Community.

23. B. Trinucleotide Repeat Disease

Note: Trinucleotide Repeat Disease is caused when the number of trinuleotide repeats increases beyond their threshold in a gene. This kind of mutation makes the gene unstable. One such common example is expansion of CAG repeats, which codes for glutamine and hence gives rise to Polyglutamine disorder, such as seen in Hungtinton's disorder. So this kind of genetic change happens in nuclear gene.

Maternal effect is a phenomena, when some trait of the child is governed by mothers genotype. This is basically happened because of the maternal deposition of RNA and not nuclear gene.

24. A. Large and Randomly Mating.

Note: Hardy Weinberg's Principle states that, the genetic variation in a population will remain constant from one generation to other if no external variability disrupts the equilibrium.

This principle is applicable if the population is infinitely large and individuals are mating randomly.  

25. C. 0.40

Solution: According to Hardy Weinberg principle: p² + 2pq + q² = 1, where p is the frequency of dominant allele A and q is the frequency of recessive allele a.

Hence, the frequency of dwarfism allele, q² = 16% = 16/100

q = 4/10 = 0.4

26. B. 70

Solution: Homozygous (AA) individuals contain two copies of allele A and Heterozygous (Aa) individuals contain one copy of allele A. Hence The total number of allele A present in the population, according to the information given, is (20 x 2) + 30 = 70.

27. E. The frequency of allele A is 0.6;
The frequency of allele a is 0.4

Solution: According to Hardy Weinberg principle: p² + 2pq + q² = 1, where p is the frequency of dominant allele A and q is the frequency of recessive allele a.

So the frequency of allele A is = freq(AA) + (1/2) freq(Aa) = 0.5 + 0.2/2 = 0.6.

And the frequency of allele a = 1 - freq(A) = 1 - 0.6 = 0.4.