N garden peas, the allele for tall plants is dominant over the allele for short plants. Suppose that a true-breeding tall plant is crossed with a short plant, and one of their offspring is crossed with a short plant. Out of 20 offspring resulting from the cross, about should be tall. a. 0 b. 5 c. 10 d. 15 e. 20

25% of the heterozygous cross are short, and the offspring of a homozygous dominant and homozygous recessive pea plant will always display the dominant trait (phenotype), because they are heterozygous.

Explanation:

In this explanation, I'm assuming that the allele "T" for tall plants is dominant to the allele "t" for short plants, like in Gregor Mendel's pea plant experiment.

A homozygous tall pea plant will have the genotype "TT" and a homozygous short plant will have the genotype "tt" because homozygous means that both alleles are identical. Since "T" is dominant over "t", any plant with at least one "T" allele will be tall (the dominant trait), regardless of what the other allele is. Let's look at a Punnett square for this cross:

Explanation: