A homozygous sweet pea plant with blue flowers (RR) and long pollen `(R_0R_0)` is crossed with a homozygous plant having red flowers (rr) and round pollen `(r_0r_0)` . The resultant `F_1` hybrid is test crossed. Which of the following genotype does not appear in its progeny?

Options

A. `Rrrr_0`
B. `RrRr_0`
C. `Rrr_0 r_0`
D. `rrR_0 r_0`

Answer

To solve the problem step-by-step, we will analyze the genetic cross between the given sweet pea plants and determine the genotypes that appear in the progeny of the test cross.

### Step 1: Identify the Parent Genotypes
We have two parent plants:
1. Homozygous blue flowers and long pollen: **RR R₀R₀**
2. Homozygous red flowers and round pollen: **rr r₀r₀**

### Step 2: Determine the Gametes of Each Parent
- The gametes produced by the first parent (RR R₀R₀) will be:
- **Gametes from Parent 1:** R, R, R₀, R₀

- The gametes produced by the second parent (rr r₀r₀) will be:
- **Gametes from Parent 2:** r, r, r₀, r₀

### Step 3: Perform the Cross to Get F1 Generation
When we cross the gametes from both parents, we get the F1 generation:
- **F1 Generation Genotype:** Rr R₀r₀

### Step 4: Determine the Gametes of the F1 Generation
The F1 hybrid (Rr R₀r₀) can produce the following gametes:
- **Gametes from F1:** R, r, R₀, r₀

### Step 5: Test Cross the F1 Hybrid
To perform a test cross, we will cross the F1 hybrid with a homozygous recessive plant (rr r₀r₀):
- **Test Cross:** (Rr R₀r₀) x (rr r₀r₀)

### Step 6: Determine the Gametes for the Test Cross
The gametes from the homozygous recessive parent will be:
- **Gametes from Homozygous Recessive Parent:** r, r, r₀, r₀

### Step 7: Combine the Gametes to Find Progeny Genotypes
Now we will combine the gametes from the F1 hybrid and the homozygous recessive parent:
1. R (from F1) + r (from recessive) = Rr
2. R (from F1) + r (from recessive) = Rr
3. R₀ (from F1) + r₀ (from recessive) = R₀r₀
4. r (from F1) + r (from recessive) = rr
5. r (from F1) + r₀ (from recessive) = r₀r

### Step 8: List All Possible Genotypes from the Test Cross
The possible genotypes from the test cross are:
1. Rr
2. R₀r₀
3. rr
4. Rr₀

### Step 9: Identify the Genotype That Does Not Appear
From the combinations, we can see that the genotype **Rr₀** does not appear in the progeny.

### Final Answer
The genotype that does not appear in the progeny is **Rr₀**.