Question

A tetrahybrid plant AaBbCcDd is self-pollinated. How many different types of gametes will be produced by the plant? What is the probability that an offspring will have the dominant phenotype for all four (4) loci?

Answer 1

AaBbCcDd     X      AaBbCcDd

Number of gametes = 2ⁿ

n= number of heterozygous= 4

number of gametes = 2⁴ = 16

gametes : ABCD ; ABCd ; ABcD ; ABcd; AbCD ;AbcD ; AbCd ; Abcd ; abcd ; abcD; abCD; abCd; aBcd; aBCD; aBCd; aBcD.

Bothe parents will produce the same gametes.

Phenotypic ratio of tetrahybrid cross = 81:27:27:27:27:9:9:9:9:9:9:3:3:3:3:1

here we know that 81 represents the dominant phenotype; so the probability = 81/256