Question
Biology Question on Genetics and Evolution
Which of the following represents a test cross in which half the offspring is heterozygous and half would be homozygous recessive?
A
TT × tt
B
Tt × tt
C
Tt × Tt
D
tt × tt
Answer
Tt × tt
Explanation
Solution
A test cross is used to determine the genotype of an individual showing a dominant trait. When a heterozygous (Tt) individual is crossed with a homozygous recessive (tt) individual, the offspring will show a 1:1 ratio. Half of the progeny will be heterozygous (Tt), displaying the dominant trait, and the other half will be homozygous recessive (tt), showing the recessive trait.