To determine the possible outcomes of a genetic cross involving a Tt (heterozygous) and tt (homozygous recessive) individual, you can use a Punnett square to visualize the potential combinations of alleles.
Here's the step-by-step solution:
1. Set up the Punnett square grid:
We will create a 2x2 grid where each cell represents a possible genotype of the offspring.
[tex]\[
\begin{tabular}{|c|c|c|}
\hline & $t$ & $t$ \\
\hline $T$ & & \\
\hline $t$ & & \\
\hline
\end{tabular}
\][/tex]
2. Assign the alleles of each parent to the rows and columns:
For the Tt parent, the possible gametes (alleles) are T and t.
For the tt parent, the possible gametes are t and t.
3. Fill in the Punnett square:
- First cell (top left): Combine the first allele from the top (t) and the first allele from the side (T):
[tex]\[
Tt
\][/tex]
- Second cell (top right): Combine the second allele from the top (t) and the first allele from the side (T):
[tex]\[
Tt
\][/tex]
- Third cell (bottom left): Combine the first allele from the top (t) and the second allele from the side (t):
[tex]\[
tt
\][/tex]
- Fourth cell (bottom right): Combine the second allele from the top (t) and the second allele from the side (t):
[tex]\[
tt
\][/tex]
Now the Punnett square looks like this:
[tex]\[
\begin{tabular}{|c|c|c|}
\hline & $t$ & $t$ \\
\hline $T$ & $Tt$ & $Tt$ \\
\hline $t$ & $tt$ & $tt$ \\
\hline
\end{tabular}
\][/tex]
4. List the possible outcomes:
The possible genotypes of the offspring are Tt and tt.
Thus, the correct answer is:
A. Tt and tt only
