Question

How many different offspring genotypes are expected in a trihybrid cross between parents heterozygous for all three traits when the traits behave in a dominant and recessive pattern? How many phenotypes?

Answer 1

Answer:

27 genotypes; 8 phenotypes

Explanation:

1. Trihybrid cross contain three genes

as given; parents are hybrid for all the traits;

and one allele is dominant over other allele

So, take three genes named Aa, Bb and Cc; assume i)  allele A is dominant over a, ii) allele B is dominant over b and iii) allele C is dominant over c.

2. Heterozygous parents are: AaBbCc and AaBbCc

there cross produce offspring like; AABBCC, AABBCc, AABbCC, AABbCc, AaBBCC, AaBBCc, AaBbCC, AaBbCc, aaBBCC, aaBBcc, etc

3. So the total phenotype are  8 phenotypes, because dominant allele show their effect in heterozygous condition too.

4.Total genotypes are  27 genotypes;