Question

Also in lizards, color is controlled by a different gene. There are two alleles that are incompletely dominant to each other. The B allele codes for black lizards, whereas the b allele codes for white lizards.
Two grey lizards mate.

What percentage of the offspring will be black?

Answer 1

Answer:

25% percentage of the offspring will be black.

Explanation:

Let the genotype of  homozygous black color lizard  be "BB"

Let the genotype of homozygous white color lizard  be "bb"

Thus the genotype of heterogeneous grey color lizard will be "Bb"

Due to incomplete dominance, a recessive allele also expresses its trait when both dominant and recessive allele occur together.

Here two heterogeneous grey color lizard with genotype "Bb" reproduce. The offsprings produced are shown in the punnet square table as given below -

        B  b

B BB Bb

b Bb bb

The genotye "BB" will have black color

Thus out of 4 offspring only one is having black color

The percent chance that the offspring will have black color is

$\frac{1}{4} * 100\\= 25$%

Answer 2

Since between the two alleles (B for black and b for white) there is an incomplete dominance this means that the homozygotes for the one dominant trait (BB genotype) will be black, the homozygotes for the other trait (bb) will be white, and the heterozygotes (Bb) would be intermediate- grey.

So, the two grey lizards have the Bb genotypes.
When they cross we will get Bb x Bb
1 : BB  ( black lizards)
2: Bb  ( grey lizards)
1: bb ( white lizards)