Question

Both male and female rats have genotype Bb. Based on the Punnett square, Carol concluded that the phenotypic ratio of the monohybrid cross is 2:1:1. What mistake did Carol make? A) The ratio should be 2:1 B) The ratio should be 3:1 C) The ratio should be 2:1:1 D) The ratio should be 1:1:1:1

Answer 1

Answer: The ratio should be 3:1.

Explanation:

When the male and female rates with genotype Bb are crossed we get,

Bb X Bb ----> BB Bb Bb bb

• Since B is dominant over b, the offsprings with genotype BB and Bb will have dominant phenotype and the ones with bb will have recessive phenotype.
• Since 3 offsprings have dominant phenotype as seen from the cross (One BB and 2 Bb) and one has a recessive phenotype (bb) the phenotypic ratio would be 3: 1.

Answer 2

The ratio should be 3:1