Select all the correct answers.

A particular plant has two alleles that control the length of its stem. [tex]T[/tex] represents the dominant allele that codes for a tall stem, and [tex]t[/tex] 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?

\begin{tabular}{|c|c|c|}
\hline First Generation & [tex]$t$[/tex] & [tex]$t$[/tex] \\
\hline [tex]$T$[/tex] & [tex]$Tt$[/tex] & [tex]$Tt$[/tex] \\
\hline [tex]$T$[/tex] & [tex]$Tt$[/tex] & [tex]$Tt$[/tex] \\
\hline
\end{tabular}
\begin{tabular}{|c|c|c|}
\hline Second Generation & [tex]$T$[/tex] & [tex]$t$[/tex] \\
\hline [tex]$T$[/tex] & [tex]$TT$[/tex] & [tex]$Tt$[/tex] \\
\hline [tex]$t$[/tex] & [tex]$Tt$[/tex] & [tex]$tt$[/tex] \\
\hline
\end{tabular}

A. Plants with short stems are homozygous for that trait.
B. Plants with tall stems are always homozygous for that trait.
C. Both parent plants in the second generation are heterozygous.
D. Both parent plants in the second generation are homozygous.



Answer :

Let's carefully evaluate each of the given statements based on the provided Punnett squares.

### Punnett Squares:
#### First Generation:
[tex]\[ \begin{array}{|c|c|c|} \hline & t & t \\ \hline T & Tt & Tt \\ \hline T & Tt & Tt \\ \hline \end{array} \][/tex]

#### Second Generation:
[tex]\[ \begin{array}{|c|c|c|} \hline & T & t \\ \hline T & TT & Tt \\ \hline t & Tt & tt \\ \hline \end{array} \][/tex]

### Analyzing Each Statement:

1. Plants with short stems are homozygous for that trait.
- For a plant to have short stems, it must have the genotype "tt", which is a homozygous recessive genotype.
- This statement is true.

2. Plants with tall stems are always homozygous for that trait.
- A plant with tall stems can have either "TT" (homozygous dominant) or "Tt" (heterozygous) genotype.
- Therefore, this statement is false.

3. Both parent plants in the second generation are heterozygous.
- In the second generation Punnett square, the parent plants used are "T" and "t", which represent the genotypes "TT" and "Tt" respectively.
- Not both of them are heterozygous.
- This statement is false.

4. Both parent plants in the second generation are homozygous.
- In the second generation Punnett square, the parent plants are "T" (which includes the homozygous "TT") and "t" (which includes the heterozygous "Tt"). Only one of the parents is homozygous.
- This statement is false.

Given the analysis, the true statements are:

- Plants with short stems are homozygous for that trait.

Therefore, the correct answers are:
- Plants with short stems are homozygous for that trait.