Question

Suppose, a disease in birds is Z linked recessive. If a female parent is affected and male parent is homozygous normal, what is the percentage of unaffected progeny and carrier progeny respectively?

• A. 50%, 50%
• B. 25%, 75%
• C. 75%, 25%
• D. 0%, 100%

Answer 1

The correct option is A 50%, 50%

In birds, females show heterogamety and males are ZZ.
Since the disease is Z-linked and recessive, females need only one copy of the defective allele to be affected. Males with one defective copy would be carriers and the require two copies to be affected.
Affected Female - $Z^A$W
Normal Homozygous Male - ZZ