Question
Biology Question on monohybrid cross
In a plant, black seed color (BB/Bb) is dominant over white seed color (bb). In order to find out the genotype of the black seed plant, with which of the following genotype will you cross it?
A
BB
B
bb
C
Bb
D
BB/Bb
Answer
bb
Explanation
Solution
To determine the genotype of a black-seeded plant (BB/Bb), a test cross should be performed with a homozygous recessive (bb) plant. This is because the recessive genotype (bb) will allow the expression of the recessive trait if the black-seeded plant is heterozygous (Bb).
- If the black-seeded plant is homozygous dominant (BB), all progeny will show black seeds.
- If the plant is heterozygous (Bb), 50% of the progeny will have black seeds and 50% will have white seeds.