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iii) If you cross a homozygous recessive short plant with a heterozygous purple flower to a heterozygous tall plant with a heterozygous purple flower, what will be the expected phenotypic ratio?

a) [tex]9:3:3:1[/tex]

b) [tex]4:4:2:2[/tex]

c) [tex]3:1:3:1[/tex]

d) [tex]1:2:1:2:4:2:1:2:1[/tex]



Answer :

GinnyAnswer
To answer the question, let's analyze the genetic cross described:

1. Genotype of parents:
- One parent is homozygous recessive short plant with heterozygous purple flowers.
- Short (tt)
- Heterozygous purple (Pp)
- Genotype: ttPp
- The other parent is heterozygous tall plant with heterozygous purple flowers.
- Tall (Tt)
- Heterozygous purple (Pp)
- Genotype: TtPp

2. Determine the possible gametes:
- For parent ttPp:
- Possible gametes: tP, tp
- For parent TtPp:
- Possible gametes: TP, Tp, tP, tp

3. Use the Punnett Square to find the genotype combinations of offspring:
- Create a Punnett Square listing all combinations of gametes from both parents.
```
| TP | Tp | tP | tp |
--------------------------
tP |TPtP|TptP|ttPp|tptP|
--------------------------
tp |TPtp|Tptp|ttpp|tptp|
```

4. Phenotypic analysis:
- Purple flowers (P_) are dominant over white flowers (pp), and tall plants (T_) are dominant over short plants (tt).
- Analyze the Punnett Square for phenotypes:

Phenotypic Combinations:
- As we calculated the phenotypic ratios considering independent assortment (purple tall, purple short, white tall, white short), we find:
- 9 plants will show the purple tall phenotype.
- 3 plants will show the purple short phenotype.
- 3 plants will show the white tall phenotype.
- 1 plant will show the white short phenotype.

5. Phenotypic Ratio:
- Therefore, the expected phenotypic ratio is:
- [tex]\(9: 3: 3: 1\)[/tex]

So, the correct answer is:
[tex]\[ \boxed{(a) \ 9: 3: 3: 1} \][/tex]

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