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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?

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

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

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



Answer :

GinnyAnswer
Let's analyze each statement carefully to determine their validity based on the information provided about the genotypes of the plants.

### Statement 1: Plants with short stems are homozygous for that trait.
In genetics, a recessive trait (in this case, short stems represented by [tex]\( t \)[/tex]) is expressed only when an organism has two copies of the recessive allele, i.e., [tex]\( tt \)[/tex].
- Conclusion: This statement is true because only homozygous [tex]\( tt \)[/tex] will show short stems.

### Statement 2: Plants with tall stems are always homozygous for that trait.
Tall stems can be represented by either the genotype [tex]\( TT \)[/tex] (homozygous dominant) or [tex]\( Tt \)[/tex] (heterozygous), since the allele [tex]\( T \)[/tex] is dominant over [tex]\( t \)[/tex].
- Conclusion: This statement is false because tall stems can also be heterozygous [tex]\( Tt \)[/tex].

### Statement 3: Both parent plants in second generation are heterozygous.
Here, we need to examine the Punnett square for the second generation:
[tex]\[ \begin{tabular}{|c|c|c|} \hline Second Generation & $T$ & $t$ \\ \hline $T$ & $TT$ & $Tt$ \\ \hline $t$ & $Tt$ & $tt$ \\ \hline \end{tabular} \][/tex]
From this Punnett square, the genotypes of the parent plants are [tex]\( Tt \)[/tex] and [tex]\(Tt\)[/tex].
- Conclusion: This statement is true because both parents are indeed heterozygous (Tt).

### Statement 4: Both parent plants in second generation are homozygous.
As addressed in the above analysis, the parents in the second generation are [tex]\( Tt \)[/tex] and [tex]\( Tt \)[/tex]. Given that they are heterozygous, they are not homozygous.
- Conclusion: This statement is false because neither of the parent plants are homozygous (neither [tex]\( TT \)[/tex] nor [tex]\( tt \)[/tex]).

### Summary
Based on the detailed step-by-step analysis:
- Correct Statements:
- Plants with short stems are homozygous for that trait.
- Both parent plants in the second generation are heterozygous.

Thus, the correct answers are:

Plants with short stems are homozygous for that trait.

Both parent plants in second generation are heterozygous.

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