LIFE SCIENCE

Detailed explanation-1: -The “TT” and “Tt” crosses both have at least one “T” allele, so they are tall plants. However, the last cross “tt” doesn’t have any “T” alleles and is short, because it is homozygous recessive . Since 1 out of 4 pea plants are short, or 1/4, the probability of a short pea plant from a heterozygous cross is 25%.

Detailed explanation-2: -Explanation: When a homozygous tall pea plant and a homozygous short pea plant are crossed, the next generation are all heterozygous and the dominant allele is expressed in all the plants, and the recessive trait seems to disappear.

Detailed explanation-3: -A homozygous short pea plant will have the genotype tt. A cross between a homozygous tall tree plant and a homozygous short tree plant will give the following genotypes of the offspring: 100% Tt. Since the offspring has at least one allele that is dominant for tall trees, all the offspring will be tall.