In pea plants, the allele for tall plants (T) is dominant over the allele for short plants (t). The allele for purple flowers (P) is dominant over the allele for white flowers (p). Two plants that are heterozygous for both traits are crossed, as shown in the Punnett square.

[tex]\[
\begin{array}{|c|c|c|c|c|}
\hline & TP & Tp & tP & tp \\
\hline TP & TTPP & TTPp & TtPP & TtPp \\
\hline Tp & TTPp & TTpp & TtPp & Ttpp \\
\hline tP & TtPP & TtPp & ttPP & ttPp \\
\hline tp & TtPp & Ttpp & ttPp & ttpp \\
\hline
\end{array}
\][/tex]

What is the probability of an offspring being short and having white flowers?

A. [tex]\(\frac{3}{16}\)[/tex]

B. [tex]\(\frac{9}{16}\)[/tex]

C. [tex]\(\frac{3}{4}\)[/tex]

D. [tex]\(\frac{1}{16}\)[/tex]



Answer :

To determine the probability of an offspring being short and having white flowers, we need to focus on the specific genotype that corresponds to these traits.

1. Trait Analysis:
- The allele for tall plants ( [tex]\( T \)[/tex] ) is dominant over the allele for short plants ( [tex]\( t \)[/tex] ). Hence, for the plant to be short, its genotype must be [tex]\( tt \)[/tex].
- The allele for purple flowers ( [tex]\( P \)[/tex] ) is dominant over the allele for white flowers ( [tex]\( p \)[/tex] ). Hence, for the flowers to be white, the genotype must be [tex]\( pp \)[/tex].

Therefore, an offspring needs to have the genotype [tex]\( ttpp \)[/tex] to be short and have white flowers.

2. Identifying the Desired Genotype:
We need to look at the given Punnett square and count the occurrences of [tex]\( ttpp \)[/tex]:
[tex]\[ \begin{array}{|c|c|c|c|c|} \hline \cline { 2 - 5 } & TP & Tp & tP & tp \\ \hline TP & TTPP & TTPp & TtPP & TtPp \\ \hline Tp & TTPp & TTpp & TtPp & Ttpp \\ \hline tP & TtPP & TtPp & ttPP & ttPp \\ \hline tp & TtPp & Ttpp & ttPp & ttpp \\ \hline \end{array} \][/tex]

Within the Punnett square, the total number of possible genotypes is [tex]\( 4 \times 4 = 16 \)[/tex].

Next, we need to find [tex]\( ttpp \)[/tex] in the Punnett square:
- The genotype [tex]\( ttpp \)[/tex] occurs only once (in the bottom right cell).

3. Calculating the Probability:
The total number of possible offspring from this Punnett square is [tex]\( 16 \)[/tex].
The number of occurrences of the [tex]\( ttpp \)[/tex] genotype is [tex]\( 1 \)[/tex].

Therefore, the probability of an offspring being short and having white flowers is:
[tex]\[ \text{Probability} = \frac{\text{Number of } ttpp \text{ occurrences}}{\text{Total number of possible offspring}} = \frac{1}{16} \][/tex]

Given these steps and conclusions, the correct answer is:

D. [tex]\(\frac{1}{16}\)[/tex]