Question

For a particular trait, the allele C is dominant over the allele c. The Punnett square shows the genetic cross of two parents, each with genotype Cc. What percentage of the offspring will show the phenotypes of the dominant allele and the recessive allele

Answer 1

There is no punnet square in this question but it can still be answered based on the information provided.

Phenotypes of the dominant allele= 75%

Phenotypes of the recessive allele= 25%

Step-by-step explanation:

This question involves a single gene that encodes a particular trait. The allele C is dominant over the allele c. This means an heterozygous (Cc) will have the phenotype encoded by allele C. A dominant allele is the allele that masks the phenotypic expression of another allele. The allele being masked is the recessive allele.

According to this question, two parents, each with genotype Cc were crossed. This means that each parent will produce the gametes: C and c. Using these gametes in a punnet square (see attached image), the following genotype of offsprings will be produced:

CC, Cc, Cc and cc.

- Offsprings with genotypes CC, Cc, Cc will show the phenotypes of the dominant allele (C) because allele C is dominant. Hence, the percentage is 3/4 × 100 = 75%.

- Offsprings with genotypes cc will show the phenotypes of the recessive allele (c). Hence, the percentage is 1/4 × 100 = 25%.