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

\begin{tabular}{|c|c|c|c|c|}
\hline \multicolumn{1}{|c|}{} & 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{tabular}

What is the phenotypic ratio you would expect to see in the offspring?

A. 9 tall purple : 3 tall white : 3 short purple : 1 short white

B. 3 tall purple : 1 short white



Answer :

GinnyAnswer
To find the phenotypic ratio in the offspring, we need to examine all the possible combinations from the Punnett square based on dominant and recessive alleles for both height and flower color.

Let's break down the combinations in the Punnett square and categorize them based on phenotype:

1. Tall Plants with Purple Flowers (T_P_):
- TTPP
- TTPp
- TtPP
- TtPp (4 combinations)

2. Tall Plants with White Flowers (T_pp):
- TTpp
- Ttpp (2 combinations)

3. Short Plants with Purple Flowers (ttP_):
- ttPP
- ttPp (2 combinations)

4. Short Plants with White Flowers (ttpp):
- ttpp (1 combination)

Based on the breakdown:

- Tall Purple (T_P_) combinations: 8 possibilities
- Tall White (T_pp) combinations: 2 possibilities
- Short Purple (ttP_) combinations: 2 possibilities
- Short White (ttpp) combinations: 1 possibility

Thus, the phenotypic ratio in the offspring is:

- 8 tall purple
- 1 short white

The phenotypic ratio we observe is 8 tall purple : 1 short white. This answers the question regarding the expected phenotypic ratio in the offspring from two heterozygous pea plants crossed.

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