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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
Certainly! Let's analyze the problem step by step based on the information provided about the plant's alleles and Punnett squares.

### Background Information
1. [tex]\( T \)[/tex] is the dominant allele for tall stems.
2. [tex]\( t \)[/tex] is the recessive allele for short stems.

### First Generation Punnett Square

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

From this Punnett square, we observe that:
- All offspring of the first generation have the genotype [tex]\( Tt \)[/tex].

### Second Generation Punnett Square

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

From this Punnett square, we observe that:
- The possible genotypes for the second generation are [tex]\( TT \)[/tex], [tex]\( Tt \)[/tex], and [tex]\( tt \)[/tex].

Now, let's address each statement:

#### 1. Plants with short stems are homozygous for that trait.
- Short stems are represented by the genotype [tex]\( tt \)[/tex], since [tex]\( t \)[/tex] is recessive.
- For a plant to exhibit the short stem trait, it must have two recessive alleles (homozygous recessive, [tex]\( tt \)[/tex]).
- This statement is true.

#### 2. Plants with tall stems are always homozygous for that trait.
- Tall stems can be represented by either genotype [tex]\( TT \)[/tex] (homozygous dominant) or [tex]\( Tt \)[/tex] (heterozygous).
- Therefore, plants with tall stems are not always homozygous; they can be heterozygous as well.
- This statement is false.

#### 3. Both parent plants in the second generation are heterozygous.
- The second generation Punnett square shows possible genotypes [tex]\( TT \)[/tex], [tex]\( Tt \)[/tex], and [tex]\( tt \)[/tex].
- However, the Punnett square itself does not specify the genotypes of both parents explicitly.
- Without additional information, we cannot assume that both parents are heterozygous ([tex]\( Tt \)[/tex]).
- This statement is false.

#### 4. Both parent plants in the second generation are homozygous.
- Similar to the previous statement, there's no indication from the Punnett square that both parents are homozygous.
- The parents could have had genotypes that combine to give [tex]\( TT \)[/tex], [tex]\( Tt \)[/tex], or [tex]\( tt \)[/tex] in offspring, suggesting variable homozygosity or heterozygosity.
- This statement is false.

### Conclusion
Based on our analysis:
- The statement "Plants with short stems are homozygous for that trait." is true.
- All other statements are false.

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

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