Question

A dihybrid plant with incomplete linkage on test cross may produce how many types of plants?

• A. 2
• B. 4
• C. 8
• D. 1

Answer 1

Answer: (B)

4

Total possible type of gametes produced by an organism is 2${}^n$ where "n" is the number of genes for which the person is heterozygous. A dihybrid is heterozygous for two chromosomes and thus forms four different types of gametes 2${}^2$ = 4 two parental types and two recombinant types. Here, the percent of parental types will be higher due to the linkage. On test cross, these four gametes may give rise to four different phenotypes. To form 8 different gametes, individual should be trihybrid; 2${}^3$ = 8. A monohybrid produces two types of gametes 2${}^1$ = 2 and homozygotes (AA) forms single type of gametes.

So, the correct answer is option B.