Question

Having straight ears (E) is dominant over having droopy ears (e). A parent with straight ears is crossed with a parent with droopy ears. The Punnett square shows the possible genotypes of the offspring.

What is the probability that an offspring will have a heterozygous genotype?
%

What is the probability that an offspring will have a homozygous dominant genotype?
%

What is the probability that an offspring will have a homozygous recessive genotype?
%

Answer 1

Assuming the straight‑eared parent is heterozygous (Ee) and the droopy parent is ee, the cross is Ee × ee. Punnett square: Ee, ee, Ee, ee.

- Heterozygous (Ee): 2/4 = 50%
- Homozygous dominant (EE): 0/4 = 0%
- Homozygous recessive (ee): 2/4 = 50%