A particular plant has two alleles that control the length of its stem. [tex]\( T \)[/tex] represents the dominant allele for a tall stem, and [tex]\( t \)[/tex] represents the recessive allele for a short stem. Based on the Punnett squares, which two statements are true about the genotype of the plant's stem length?
[tex]\[
\begin{array}{|c|c|c|}
\hline
\text{First Generation} & t & t \\
\hline
T & Tt & Tt \\
\hline
T & Tt & Tt \\
\hline
\end{array}
\][/tex]
[tex]\[
\begin{array}{|c|c|c|}
\hline
\text{Second Generation} & T & t \\
\hline
T & TT & Tt \\
\hline
t & Tt & tt \\
\hline
\end{array}
\][/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.
Let's analyze the provided information and determine the correct statements based on the Punnett squares for the first and the second generation.
### First Generation
Punnett Square: [tex]\[
\begin{tabular}{|c|c|c|}
\hline
& t & t \\
\hline
T & Tt & Tt \\
\hline
T & Tt & Tt \\
\hline
\end{tabular}
\][/tex]
In the first generation: - All offspring have the genotype [tex]\( Tt \)[/tex], which means all have tall stems since [tex]\( T \)[/tex] (tall) is the dominant allele.
### Second Generation
Punnett Square: [tex]\[
\begin{tabular}{|c|c|c|}
\hline
& T & t \\
\hline
T & TT & Tt \\
\hline
t & Tt & tt \\
\hline
\end{tabular}
\][/tex]
In the second generation: - There are four possible genotypes: [tex]\( TT \)[/tex], [tex]\( Tt \)[/tex], [tex]\( Tt \)[/tex], and [tex]\( tt \)[/tex]. - The phenotypes of these genotypes are as follows: - [tex]\( TT \)[/tex] - Homozygous tall - [tex]\( Tt \)[/tex] - Heterozygous tall - [tex]\( tt \)[/tex] - Homozygous short
### Analysis of Statements
1. Plants with short stems are homozygous for that trait. - True, because the only genotype that results in short stems is [tex]\( tt \)[/tex], which is homozygous recessive.
2. Plants with tall stems are always homozygous for that trait. - False, because plants with tall stems can be either [tex]\( TT \)[/tex] (homozygous dominant) or [tex]\( Tt \)[/tex] (heterozygous).
3. Both parent plants in the second generation are heterozygous. - False, the Punnett square shows that the parents in the second generation are [tex]\( T \)[/tex] and [tex]\( t \)[/tex] (derived from the first generation which produced only [tex]\( Tt \)[/tex]) therefore, one of the parents would necessarily be heterozygous [tex]\( Tt \)[/tex].
4. Both parent plants in the second generation are homozygous. - False, as explained above, neither can both parents be [tex]\( TT \)[/tex] or [tex]\( tt \)[/tex] in the second generation since the first generation produced all [tex]\( Tt \)[/tex].
### Conclusion The correct statement(s) about the genotype of the plant's stem length are: 1. Plants with short stems are homozygous for that trait.
