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Genetics and Genomics

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Use of Multiple Test Mates for Recessive Traits

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In many species, test matings can provide information about potential heterozygotes regarding recessive conditions, and are based on probability. Test matings may be used when a genetic test is not possible.

In cattle, the horned condition is recessive to polled (born without horns). Assume that a polled bull had been bred to two horned cows and three known heterozygous cows, resulting in five polled calves.

What is the probability that all polled offspring would have been produced if the bull is a heterozygote?

A

Over 75%.

B

Somewhere between 50% and 75%.

C

Somewhere between 25% and 50%.

D

Somewhere between 12.5% and 25%.

E

Under 12.5%.