Ques. 10-12. You cross an Aa Bb Cc individual with an individual of genotype Aa
ID: 262214 • Letter: Q
Question
Ques. 10-12. You cross an Aa Bb Cc individual with an individual of genotype Aa Bb CC. All genes assort independently :
10. The number of different gam etes expected from the Aa Bb CC parent is a) 2 b) 4 c) 8 d) 16 e) 32
11. The expected proportion of offspring of genotype Aa BB CC is a) 1/2 b) 1/4 c) 1/8 d) 1/16 e) 1/32.
12. The number of different genotypes expected among offspring of the cross is a) 3 b) 6 c) 9 d) 18 e) 27.
13. With complete dominance of capital letters over lower case letters, which of the following crosses will produce a 9:3:3:1 ratio of phenotypes among offspring
a) Aa X Aa b) Aa Bb X Aa Bb c) Aa Bb X aa bb d) AA BB X aa bb e) aa BB X Aa bb.
14. If the B allele is dominant to the b allele, a 1:1 phenotypic ratio is expected in which of the following crosses?
a) BB x BB b) BB x Bb c) Bb x Bb d) Bb x bb e) bb x bb.
Explanation / Answer
10. Option B is correct.
Number of gametes produced = 2^n
n = number of heterozygous alleles.
Parent = AaBbCC
n = 2
= 2^2 = 4
11. Option D is correct.
Parental cross: AaBbCC X AaBbCc
Expected number of progeny with the genotype AaBBCC = 1/2 X 1/4 X 1/2 = 1/16
12. Option E is correct.
Parental cross: AaBbCC X AaBbCc
Number of gametes: 4 X 8
Number of genotypes = 3^n
n = number of heterozygous genes; n = 3
= 3^3 = 27
13. Option B is correct.
AaBb X AaBb cross would produce the phenotypic ratio of 9:3:3:1.
14. Option D is correct.
Bb X bb cross would produce the phenotypic ratio of 1:1.