Question

In lizards, there is a scale color gene. There are two alleles that are incompletely dominant to each other. The (B) allele codes for lizards with black scales, whereas the (b) allele codes for lizards with white scales.

Two lizards with grey scales mate.
What percentage of the offspring will have grey scales?
075%
0 0%
• 100%
0 25%
0 50%

Answer 1

Since the (B) allele codes for black scales and the (b) allele codes for white scales, the heterozygous (Bb) genotype will produce lizards with grey scales due to incomplete dominance. Therefore, if two lizards with grey scales mate, they must both be heterozygous (Bb).

The Punnett square for this cross is:

| | B | b |
|---|---|---|
| B | BB | Bb |
| b | Bb | bb |

The offspring will have the following genotypes: BB, Bb, Bb, and bb.

Therefore, 50% of the offspring will have grey scales (Bb genotype), and the other 50% will have either black scales (BB genotype) or white scales (bb genotype).

So the correct answer is 50%.