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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 :

GinnyAnswer
To answer this question, we need to understand the information provided by the first and second-generation Punnett squares about the genotypes and phenotypes of the plants.

### Punnett Squares Analysis

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

From this Punnett square, all offspring are [tex]\(Tt\)[/tex], which means they all have tall stems, as the tall trait (T) is dominant over the short trait (t).

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

From this Punnett square, the possible genotypes and corresponding phenotypes of the offspring are:
- [tex]\(TT\)[/tex]: Homozygous tall
- [tex]\(Tt\)[/tex]: Heterozygous tall
- [tex]\(tt\)[/tex]: Homozygous short

### Evaluation of Statements

Statement 1: Plants with short stems are homozygous for that trait.
This is correct because only the genotype [tex]\(tt\)[/tex] produces short stems, and [tex]\(tt\)[/tex] is a homozygous recessive genotype.

Statement 2: Plants with tall stems are always homozygous for that trait.
This is incorrect because tall stems can be produced by both [tex]\(TT\)[/tex] (homozygous) and [tex]\(Tt\)[/tex] (heterozygous) genotypes.

Statement 3: Both parent plants in second generation are heterozygous.
This is incorrect. The second generation in the Punnett square shows a cross between [tex]\(Tt\)[/tex] and [tex]\(Tt\)[/tex], not necessarily both parents being heterozygous.

Statement 4: Both parent plants in second generation are homozygous.
This is incorrect because the cross [tex]\(Tt \times Tt\)[/tex] involves heterozygous parents, not homozygous parents.

### Conclusion

The correct answers are:
1. Plants with short stems are homozygous for that trait.
2. Plants with tall stems are always homozygous for that trait.

Therefore, the two statements that are true about the genotype of the plant's stem length are:

1. Plants with short stems are homozygous for that trait.
2. Plants with tall stems are always homozygous for that trait.

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