Question

Assume a phenotype is determined by one gene with a dominant allele and a recessive allele. If one parent is homozygous recessive and the other is heterozygous, what is the probability that an offspring will have the recessive phenotype?

a. 50%b. 100%c. 25%d. 0%e. 75%

Answer 1

a. 50% will be homozygous recessive

Explanation

as phenotype is dominant so suppose R allele for dominant and r allele for recessive

so cross between homozygous recessive (rr) and heterozygous (Rr)

r r

R Rr Rr

r rr rr

(heterozygous ------- 50 %

( homozygous recessive)------------------50 %