Which signal are you talking about?
Vertebrates have back bones or spines that give there body support.
Let a be Q, all which is homozygous recessive = Q∧2
A = p, AA which is homozygous recessive = Q∧2
2pq = heterozygous
It is derived from p+ q = 1
All those in a population which is Q = 20%
All A in the population (p) = 80%
Now that the disease is homozygous recessive therefore,
aa = qq or q × q = 0.20 × 2 = 4%
Then the answer is 4%.
