Question

select all the correct answers.
a particular plant has two alleles that control the length of its stem. t represents the dominant allele that codes for a tall stem, and t represents the recessive allele that codes for a short stem. based on the punnett squares, which two statements are true about the genotype of the plant’s stem length?

first generation	t	t
t	tt	tt

second generation	t	t
t	tt	tt

• plants with short stems are homozygous for that trait.
• plants with tall stems are always homozygous for that trait.
• both parent plants in second generation are heterozygous.
• both parent plants in second generation are homozygous.

Explanation:

Step1: Analyze short - stem plants

The recessive allele for short stem is \(t\). For a plant to have a short stem, its genotype must be \(tt\) (homozygous recessive), because the recessive trait is only expressed when there are two recessive alleles. So plants with short stems are homozygous for that trait.

Step2: Analyze tall - stem plants

Tall stem is a dominant trait, coded by \(T\). A plant with a tall stem can have a genotype of \(TT\) (homozygous dominant) or \(Tt\) (heterozygous), since the dominant allele masks the recessive one. So the statement "Plants with tall stems are always homozygous for that trait" is false.

Step3: Analyze second - generation parent plants

Looking at the second - generation Punnett square, the parents' alleles are \(T\) and \(t\) for one parent (since the row is \(T\) and \(t\)) and \(T\) and \(t\) for the other parent (since the column is \(T\) and \(t\)). So the genotype of each parent is \(Tt\), which means both parent plants in the second generation are heterozygous. The statement "Both parent plants in second generation are homozygous" is false.

Answer:

• Plants with short stems are homozygous for that trait.
• Both parent plants in second generation are heterozygous.