Question

what are the expected phenotypes of the offspring if two hybrid tall (tt) pea plants are crossed?
1/4 will be short, 3/4 will be tall
2/4 will be short, 2/4 will be tall
3/4 will be short, 1/4 will be tall
4/4 will be short, 0/4 will be tall

Explanation:

To determine the expected phenotypes of the offspring when two hybrid tall (\(Tt\)) pea plants are crossed, we use a Punnett square. The possible gametes from each parent are \(T\) and \(t\).

• When we set up the Punnett square:
• The top row (gametes from one parent) and left column (gametes from the other parent) are \(T\) and \(t\).
• Filling in the Punnett square, the genotypes of the offspring are \(TT\), \(Tt\), \(Tt\), and \(tt\).
• For the phenotype:
• The dominant allele \(T\) (for tall) is expressed in \(TT\), \(Tt\), and \(Tt\) (so 3 out of 4 offspring will be tall).
• The recessive allele \(t\) (for short) is only expressed in \(tt\) (so 1 out of 4 offspring will be short).

Answer:

1/4 will be short, 3/4 will be tall