In a cross between a pure tall pea plant with green pod and a pure short plant with yellow pod, how many short plants out of 16 are expected in `F_(2)` generation?

Options

A. One
B. Four
C. Nine
D. Three

Answer

To solve the problem of how many short plants out of 16 are expected in the F2 generation from a cross between a pure tall pea plant with green pods and a pure short plant with yellow pods, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parent Plants:**
- The pure tall pea plant with green pods has the genotype: **TTGG** (where T = tall, G = green).
- The pure short pea plant with yellow pods has the genotype: **ttgg** (where t = short, g = yellow).

2. **Determine the F1 Generation:**
- When we cross TTGG with ttgg, all offspring in the F1 generation will have the genotype: **TtGg**.
- Thus, all F1 plants will be tall with green pods.

3. **Selfing the F1 Generation:**
- To obtain the F2 generation, we perform self-fertilization of the F1 plants (TtGg x TtGg).

4. **Use a Punnett Square for F2 Generation:**
- We will create a Punnett square to determine the phenotypic ratios.
- For the traits:
- Tall (T) is dominant over short (t).
- Green (G) is dominant over yellow (g).
- The possible gametes from TtGg are TG, Tg, tG, and tg.

5. **Calculate the F2 Generation Phenotypes:**
- The phenotypic ratio from the cross TtGg x TtGg is:
- Tall green (TTGG, TTGg, TtGG, TtGg) = 9
- Tall yellow (TTgg, Ttgg) = 3
- Short green (ttGG, ttGg) = 3
- Short yellow (ttgg) = 1
- This gives a total of 16 offspring.

6. **Count the Short Plants:**
- The total number of short plants (both green and yellow) is:
- Short green (3) + Short yellow (1) = 4 short plants.

### Conclusion:
In the F2 generation, out of 16 offspring, we expect **4 short plants**.