Question

Albinoism is an autosomal recessive trait. What is the probability of two
heterozygous parents having a heterozygous offspring? What is the genotypic
and phenotypic ratio from this cross? What type of cross is this?

Answer 1

Answer:

1. Probability is 50% or 1/2

2. a) Genotypic ratio= 1 AA: 2Aa : 1aa

   b) Phenotypic ratio = 3 normal pigment : 1 albino

3. Monohybrid cross

Explanation:

This question involves a single gene coding for pigment in humans. The allele for normal pigmentation (A) is dominant over the allele for albinism (a).  

According to this question, if two heterozygous parents (Aa) are crossed i.e. Aa × Aa. The following proportion of offsprings will be produced:

AA, Aa, Aa, and aa

- Hence, the probability of having a heterozygous offspring is 2/4 or 1/2 or 50%

- Genotypic ratio= 1 AA: 2Aa : 1aa

  Phenotypic ratio = 3 normal pigment : 1 albino

c. This type of cross is called MONOHYBRID CROSS because it involves a single gene