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?
- BB
- bb
- Bb
- BB/Bb
Answer
(2) bb
Solution
The genotype of an organism showing the dominant phenotype is found by a test cross, i.e. crossing it with the homozygous recessive (bb).
If all progeny are black, the plant is BB; if black and white appear in 1 : 1 ratio, the plant is Bb.
Answer: (2)