If an Individual Is Heterozygous at Two Loci (Ab/aB) Which

question 47

Multiple Choice

If an individual is heterozygous at two loci (Ab/aB) which are on the same chromosome arm with the A locus closest the centromere under what conditions would a crossover in a somatic cell generate a twin spot?

• A)The crossover would have to occur between the A locus and the centromere locus and involve two homologous (non-sister) chromatids.
• B)The crossover would have to occur between the A locus and the B locus and involve two homologous (non-sister) chromatids.
• C)The crossover would have to occur between the B locus and the end of the chromosome locus and involve two homologous (non-sister) chromatids.
• D)A double crossover would have to occur, with one crossover between the A locus and the centromere and a second crossover between the A and B loci locus and both crossovers would have to involve two homologous (non-sister) chromatids.
• E)No crossover in a somatic cell could generate a twin spot.

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Definitions:

Oxytocin

A hormone and neuropeptide that plays a role in social bonding, sexual reproduction, and during and after childbirth.

Calcitonin

A hormone produced by the thyroid gland that helps regulate calcium levels in the blood by inhibiting bone resorption.

Glucagon

A substance secreted by the pancreas which increases blood sugar levels by encouraging the liver to break down glycogen and release glucose.

Uterine Contractions

The tightening and relaxing of the uterine muscles, important in childbirth and menstruation.