To determine the probability of obtaining an offspring with the genotype [tex]\(TT\)[/tex] from the cross [tex]\(Tt \times Tt\)[/tex], we can use a Punnett square to visualize the potential genotypes of the offspring.
Here are the steps in our calculation:
1. Set up the Punnett Square:
- Each parent contributes one of their two alleles to the offspring.
- The alleles for one parent [tex]\(Tt\)[/tex] are [tex]\(T\)[/tex] and [tex]\(t\)[/tex], and the alleles for the other parent [tex]\(Tt\)[/tex] are also [tex]\(T\)[/tex] and [tex]\(t\)[/tex].
2. Fill in the Punnett Square:
[tex]\[
\begin{array}{c|c|c}
& T & t \\
\hline
T & TT & Tt \\
\hline
t & tT & tt \\
\end{array}
\][/tex]
- The first cell (top left) represents the combination of [tex]\(T\)[/tex] from the first parent and [tex]\(T\)[/tex] from the second parent, resulting in [tex]\(TT\)[/tex].
- The second cell (top right) represents the combination of [tex]\(T\)[/tex] from the first parent and [tex]\(t\)[/tex] from the second parent, resulting in [tex]\(Tt\)[/tex].
- The third cell (bottom left) represents the combination of [tex]\(t\)[/tex] from the first parent and [tex]\(T\)[/tex] from the second parent, resulting in [tex]\(tT\)[/tex].
- The fourth cell (bottom right) represents the combination of [tex]\(t\)[/tex] from both parents, resulting in [tex]\(tt\)[/tex].
3. Determine the genotype proportions:
- There are four equally likely genotypes in the Punnett square:
- [tex]\(TT\)[/tex]
- [tex]\(Tt\)[/tex]
- [tex]\(tT\)[/tex]
- [tex]\(tt\)[/tex]
4. Count and calculate the probability:
- Out of the four possible outcomes, one is [tex]\(TT\)[/tex].
- The probability of an offspring having the genotype [tex]\(TT\)[/tex] is [tex]\( \frac{1}{4} \)[/tex] or 0.25.
Therefore, the probability that an offspring will have the [tex]\(TT\)[/tex] genotype is [tex]\(0.25\)[/tex].
The correct answer is:
A. 0.25
