Question

If a gene has four alleles, possible number of genotypes are

• A. 8
• B. 10
• C. 20
• D. 6

Hint:

To determine the total genotypes for multiple alleles, always count homozygotes separately and use combination formula \(nC2\) for heterozygotes. Total genotypes = homozygotes + heterozygotes.

Answer 1

The Correct Option is C

For a gene with four alleles (A1, A2, A3, A4), the number of genotypes is calculated using formula: \(\frac{n(n+1)}{2}\) for homozygous and heterozygous combinations. Here \( n = 4 \), so number of genotypes = \(\frac{4(4+1)}{2} = 10\) for heterozygotes plus 4 homozygotes = 14? Wait, let's carefully calculate: - Homozygotes: A1A1, A2A2, A3A3, A4A4 → 4 - Heterozygotes: A1A2, A1A3, A1A4, A2A3, A2A4, A3A4 → 6 Total = 4 + 6 = 10.