In: Biology
Suppose the following genotypes are in a 1:1:1:1 ratio. TTDD, TtDD, ttDD, TdDd If there are a total of 160 individuals, how many of them have the genotype TdDD?
The ratio given in the question is the ratio of dihybrid test cross.
A test cross is a type of backcross in which the individual is specifically crossed to a recessive parent. In phenotypic ratio in dihybrid, test cross is 1:1:1:1. Test cross is used to identify the heterozygosity of an individual
Four genotypes = TTDD, TtDD, ttDD, TdDd
Total individuals are = 160
No of individuals with TTDD genotype = ?
All four genotypes are in 1:1:1:1 ratio so = 1/4*160
= 40
The No of individuals with TTDD genotype is 40.
Other genotypes having individuals are
TtDD =1/4*160 = 40
ttDD =1/4*160 = 40
TdDd= 1/4*160 = 40