High School

In garden peas, tall (T) is dominant over short (t). A homozygous tall plant is crossed with a short plant. Out of 20 offspring, how many should be tall?

a) 0
b) 5
c) 10
d) 15
e) 20

Answer :

When a homozygous tall pea plant (TT) is crossed with a short plant (tt), all offspring will be heterozygous (Tt) and tall, as tall is dominant. Therefore, out of 20 offspring, all 20 should be tall. Hence, the correct answer is option e) 20.

In garden peas, tall (T) is dominant over short (t). A homozygous tall plant has the genotype TT, and a short plant will have the genotype tt.

When these two plants are crossed, all the offspring will receive a T allele from the tall parent and a t allele from the short parent, resulting in a genotype of Tt for all offspring. These offspring will exhibit the tall phenotype since tall is dominant over short.

Hence, the correct answer is option e) 20.