there is a family of five including the parents and 3 children. Straight thumb is denoted by (H), and hitchhiker's thumb is denoted by (h). The genotypes of the children are expressed as follows:
Child #1 - (HH)
Child #2 - (Hh)
Child #3 - (hh)
Which phenotype will each child exhibit based on the expressed genotypes?
A
Child #1 will express a straight thumb (a dominant trait), child #2 will express a straight thumb (a dominant trait),and child #3 will express a hitchhiker’s thumb (a recessive trait).
B
Child #1 will express a straight thumb (a dominant trait), child #2 will express a hitchhiker’s thumb (a recessive trait), and child #3 will express a straight thumb (a dominant trait).
C
-- Child #1 will express a hitchhiker’s thumb (a recessive trait), child #2 will express a hitchhiker’s thumb (a recessive trait), and child #3 will express a straight thumb (a dominant trait).
D
Child #1 will express a straight thumb (a dominant trait), child #2 will express a hitchhiker’s thumb (a recessive trait), and child #3 will express a hitchhiker’s thumb (a recessive trait).
The correct answer is B: Child #1 will express a straight thumb (a dominant trait), child #2 will express a hitchhiker’s thumb (a recessive trait), and child #3 will express a straight thumb (a dominant trait).
In genetics, the dominant trait (H) is expressed when present in the genotype, while the recessive trait (h) is only expressed when there are two copies of the recessive allele.
Child #1 has the genotype (HH), meaning they have two copies of the dominant allele and will express the dominant trait, which is a straight thumb.
Child #2 has the genotype (Hh), indicating one copy of the dominant allele and one copy of the recessive allele. They will still express the dominant trait and have a straight thumb.
Child #3 has the genotype (hh), with two copies of the recessive allele. They will express the recessive trait and have a hitchhiker's thumb.