NATIONAL OPEN UNIVERSITY OF NIGERIA

UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
APRIL/MAY 2019 EXAMINATION

COURSE CODE: BIO403

COURSE TITLE: POPULATION CYTOGENETICS

CREDIT: 2 Units

TIME ALLOWED: 2 Hours

INTRUCTION: Answer Question ONE (1) and any other THREE (3) Questions

1a. In a population, the initial allelic frequencies are p = 0.9 and q = 0.1 and the forward and

     reverse mutation rates are u = 5x10^-5 and v = 2x10^-5 respectively. Calculate the:

      i. change in allelic frequency in the first generation. (3 marks)  

     ii. frequency of a allele at equilibrium. (3 marks)

  b. In a population of 100,000 people carrying the recessive allele, a for albinism, there are 100    

     aa albinos, 98,100 AA homozygous none albino carriers and 1,800 Aa heterozygous carriers.    

       i. Compute the allelic frequencies in the parent population. (7 marks)

       ii Using Hardy-Weinberg equation, predict the number of individuals of each 

           genotype in the next generation. (3 marks)

c. Write short notes on the following: 

        i. Complete dominance. (3 marks)

       ii. Incomplete dominance. (3 marks) 

                  iii. Co-dominance. (3 marks)

2a. How can allelic frequency be calculated? (3 marks)

 b. Briefly describe the following:

     i. Small Populations. (4 marks)

    ii. Founder Effect. (4 marks)

  iii. Bottleneck Effect. (4 marks)

3a. How does mutation affect evolution? (1 mark)

 b. Distinguish between population genetics and transmission genetics. (6 marks)

c. Write short notes on the following: 

       (i) Natural selection. (4 marks)

      (ii) Darwinian fitness. (4 marks)

4a. How can genotype frequencies of the next generation be predicted from the genotype and  

      allele frequencies?  (3 marks)

  b. Consider a locus that code for transferring a blood protein in Clethrinomys gapperis where

      three genotypes are found at the transferring locus: MM, MJ and JJ. In a population of C.

      gapperis trapped in Asia in 2015 are 12 MM, 53 MJ, 12 JJ individuals. Calculate the:

      i. allelic frequencies of the population. (9 marks)

     ii. expected number of individuals with each of the observed genotypes. (3 marks)

5a. Define sex-linked traits (3 marks)

  b. The hemoglobin variants among Egyptians where multiple alleles are present are shown in the Table below.

Hemoglobin genotypes:

AA            AS                 SS                    AC                 SC                  CC            Total

2,017         783                  4                     173                 14                   11             3,002    

Calculate:

 i. the genotypic frequencies. (6 marks)

ii. the allelic frequencies. (6 marks)