Question

The trait of “freckles” is dominant and represented by A. No freckles is recessive and represented by a. A researcher crossed two individuals, one homozygous dominant and the other heterozygous for freckles. Based on the data in the Punnett square, the researcher concluded that all offspring would have dominant as well as the recessive alleles. What comment would you make about his conclusion? A) He is correct. Fifty percent of the offspring are heterozygous dominant. B) He is correct. The dominant allele for the trait is preset in all the offspring. C) He is incorrect. The homozygous dominant individual cannot provide a recessive allele. D) He is correct. Both parents contribute at least one dominant allele to their offspring.

Answer 1

Based on the Punnett square I've just created from the two individuals' phenotypes for freckles, all possible offspring phenotypes would have freckles, as all possible genotypes for offspring contain the dominant allele. The possible genotypes are 50 percent homozygous dominant and 50 percent heterzygous. The researcher claims that all possible offspring would have dominant and recessive alleles; he is wrong. While all possible offspring phenotypes do have the dominant allele, only 50 percent has the recessive allele.

Answer:
C) He is incorrect. The homozygous dominant individual cannot provide a recessive allele.