When a man has an allele combination Ww for a trait, what percentage of his gametes will have a dominant allele for the trait?

a.) 75%

b.) 100%

c.) 25%

d.) 50%

The correct answer is option d) 50%.

Explanation:

Humans are diploid organisms who have 23 pairs or 46 chromosomes in their genome. Each pair of chromosomes can also called as a pair of alleles. Alleles are alternating forms of the same gene. Of the 46 chromosomes, 23 are obtained from the mother and rest 23 from the father. According to Mendel's law of dominance, the alleles can be either dominant or recessive. A dominant allele can show its character even if only a single copy of it is present in the diploid organism, while a recessive allele gets expressed only when both the allele present are recessive. Unlike somatic cells which are diploid, gametes are haploid, that is, they possess only one allele for one gene. According to Mendel's law of segregation, the allele representing each gene separate from each other during gamete formation, such that, each gamete gets a single allele representing each gene. The man having an allele combination Ww for a particular trait, has one dominant allele (W) and the other recessive allele (w). The gametes produced by this man will have either a dominant allele (W) or a recessive allele (w). Out of the two types of gametes (W and w), produced by the man, one has the dominant allele (W). The ratio of dominant allele (W) containing gamete to number of gametes possible (W or w) is 1 : 2. Therefore, percentage of the man's gametes that will have a dominant allele is 50% (by converting the ratio into percentage).