Anury is the absence or abbreviation of the tail in sheep (and also other animals).It is inherited in an autosomal dominant fashion.A ram with anury is mated to a ewe with a normal tail.The ram's father had anury,his mother did not.What is the probability that the ram and ewe will produce a lamb with anury? (ram = male;ewe = female)
A)25%
B)50%
C)75%
D)100%
E)No chance

Question

Quizplus · Accepted Answer

Since anury is inherited in an autosomal dominant fashion, the ram with anury must be heterozygous (Aa) as his father had anury. When the ram with anury is mated to a ewe with a normal tail, we can assume that the ewe is homozygous recessive for the trait (aa). The Punnett square for this cross would be:

| A | a
---|---|---
a  |aa |aa
a  |Aa |Aa

As we can see from the Punnett square, there is a 50% chance that the offspring will inherit the dominant allele from the ram and have anury. Therefore, the answer is B) 50%.

Anury Is the Absence or Abbreviation of the Tail in Sheep