A students mother is homozygous for attached earlobes, a recessive trait. The students father is a heterozygous for the detached earlobes. What is the percent likelihood that this student has attached earlobes?

MONOHYBRID CROSS

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

A student’s mother is homozygous for attached earlobes, a recessive trait. The student’s father is a heterozygous for the detached earlobes. What is the percent likelihood that this student has attached earlobes?

A	100%
B	75%
C	50%
D	25%

Explanation:

Detailed explanation-1: -Final answer: There is a 25% chance that the next child will have attached earlobes.

Detailed explanation-2: -The answer is c) 50%. This can be visualized with a Punnett square.

Detailed explanation-3: -If a person has a free earlobe, then its genotype would be either UU or Uu. If a person has an attached earlobe then its genotype would be uu. So, if parents (male as well as female) have free earlobes and offspring have attached earlobes, then surely both parents would be heterozygous for this trait.

Detailed explanation-4: -Being a recessive trait the presence of attached earlobes is quite rare, it happens only when the genotype consists of two recessive alleles which result in the expression of the attached earlobes. Additional Information:-Other autosome controlled traits include Hitchhiker’s thumb and widow’s peak.

Detailed explanation-5: -Free earlobes are the most common form of ear lobes in humans. This type of earlobe is often large and hangs below the point of attachment to the head. This happens due to the influence of a dominant allele. If the parents’ genes express the dominant allele, the child will be born with free earlobes.

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AP BIOLOGY

HEREDITY

MONOHYBRID CROSS