Question

When a parent is heterozygous for a trait and the other parent is normal, what are the chances that the trait will be found in offspring?

a) 25%
b) 50%
c) 75%
d) 100%

Answer 1

With one parent heterozygous for a trait and the other parent normal (often homozygous dominant), there is a 50% chance that an offspring will inherit the trait. The offspring will either inherit the dominant or the recessive allele from the heterozygous parent resulting in a 50% chance of displaying the trait.

Step-by-step explanation:

When a parent is heterozygous for a trait and the other is normal, which typically means homozygous dominant, there is a 50% chance that an offspring will inherit the trait in question. This is because the heterozygous parent has one dominant and one recessive allele for the trait, and at each conception, there is an equal chance that either allele will be passed down to the offspring. Since the other parent is considered normal (most often homozygous dominant), the inheritance of the dominant allele would result in offspring with the normal phenotype, so the trait of interest will only be observed if the recessive allele is inherited from the heterozygous parent.

Predicting Offspring Genotypes:

• If the trait is recessive, the presence of the trait depends on the offspring receiving the recessive allele from the heterozygous parent. With one heterozygous parent (Bb) and one homozygous dominant parent (BB or BB), there is a split probability with 50% of the offspring being Bb (heterozygous like the first parent) and the other 50% being BB (homozygous dominant).
• If it's a dominant trait, every child receiving the dominant allele from the heterozygous parent will express the trait, resulting in a 50% chance as well.