Answer :
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.
### 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.
