Question

Question 3a & 3b are uploaded as pictures here!

n/n Your friend bought two polydactyl gerbils from a breeder who said it was pure breeding stock with a recessive allele for an extra two digits on each paw. n/n 1 n/ n n/ nn /n O n/n The genotype of both parents is n/n. Your friend drew up a pedigree. He knows that you are studying genetics, and he is puzzled about a few gerbils that have paws with a normal number of digits. He asks what you think. What would you say is a possible explanation? The allele seems to be epistatic to another allele. O The allele is clearly sex-linked. O It looks as if there is 75% penetrance for this allele. O d. It looks as if the allele has 25% penetrance. O e. This allele has a range of expressivity.

Answer 1

31. Option C is correct
Penetrance = The proportion of progeny that exhibit the phenotype with respect to their corresponding genotype
If a genotype is 100% penetrant, all the individuals with the given genotype exhibit the expected phenotype.

In the given case,
Number of individuals with the 'nn' genotype = 13
Number of individuals expressing the corresponding phenotype = 10

Penetrance = (10/13) X 100
= 76.9%

3b. Option B is correct
P is epistatic to Q = P acts downstream to Q in the pathway
In the given case,
B is epistatic to A
C is epistatic to A
D is epistatic to C and A

Please provide a POSITIVE RATING. Thank you