Question

Assuming that within a population of beetles where Hardy Weinberg conditions are met, the colour black (B) is dominant over the colour red (b). 40% of all beetles are red (bb).

Given this information, answer the questions below:

1. What is the frequency of red beetles?   (1)
2. Calculate is the percentage of beetles in the population that are heterozygous.   (2)
   Attempt either subpart C or D.
3. What is the frequency of homozygous dominant individuals?   (1)
                                        OR
4. Assuming that Hardy Wienberg conditions are met in the beetle population consisting of 1500 beetles. How many beetles would you expect to be black and red in colour respectively?    (1)

Answer 1

1. Given is bb = q² = 0.4.
   To determine q, which is the frequency of the recessive allele in the population, simply take the square root of q² which works out to be 0.632 (i.e. 0.632 x 0.632 = 0.4).
   So, q = 0.63
2. As we know that p + q = 1,
   then p must be 1 - 0.63 = 0.37.
   The percentage of beetles in the population that are heterozygous would be 2pq.
   2 (0.37) (0.63) = 0.47
3. Given is BB = p² = (0.37)² = 0.14
                          OR
4. As, 1500 is the total population, 40% is the red population.
   Hence, the number of beetles with red color will be 1500 × 0.4 = 600
   If the total population is 1500 and red is 600, then black would be 1500 - 600 = 900