Question

7.   Suppose that a dominant allele (P) codes for a polka-dot tail and a recessive allele (p) codes for a solid colored tail. If two heterozygous individuals with polka-dot tails mate, what's the probability of the phenotype and genotype combinations of the offspring? 

A. 75 percent chance of a polka-dot tail and 25 percent chance of a solid colored tail (25 percent PP; 50 percent Pp; 25 percent pp)  B. 50 percent chance of a polka-dot tail and 50 percent chance of a solid colored tail (50 percent PP; 50 percent pp)  C. 75 percent chance of a polka-dot tail and 25 percent chance of a solid colored tail (75 percent Pp; 25 percent pp)  D. 25 percent chance of a polka-dot tail and 75 percent chance of a solid colored tail (25 percent PP; 50 percent Pp; 25 percent pp)

Answer 1

Hi!

The correct answer would be A.

Step-by-step explanation:

As the allele P for polka dot is dominant to the allele p for solid color, it would yield a Polka dot tail in the individual in the presence of just one allele of P, while masking the effect of p for solid color.

So the possible genotypes and phenotypes would be as follows:

1. PP (Polka dot tail)
2. Pp (Polka dot tail)
3. pP (Polka dot tail)
4. pp (Solid color tail)

Following a cross by two heterozygous individuals, there would be 25 percent chance (1/4) of having the genotype pp , 25 percent (1/4) chance of having the genotype PP and 50 percent (2/4) chance of having the genotype Pp.

But the phenotype yielded by Pp and PP offspring would be polka dots, so there is a 75 percent (3/4) chance of having polka dot offspring, and 25 percent chance of having solid colored tail offspring.

Hope this helps!