A cross between a plant heterozygous for two factors and a plant recessive for both the factors, gives a phenotypic ratio of

Options

A. `9:1:1:7`
B. `9:3:3:1`
C. `1:1:1:1`
D. `1:7:7:1`

Answer

To solve the question regarding the phenotypic ratio from a cross between a plant heterozygous for two factors and a plant recessive for both factors, we can follow these steps:

### Step 1: Define the Genotypes
- Let's denote the two traits as follows:
- Round seed (R) is dominant over wrinkled seed (r).
- Yellow seed (Y) is dominant over green seed (y).

- The heterozygous plant will have the genotype RrYy (heterozygous for both traits).
- The recessive plant will have the genotype rryy (homozygous recessive for both traits).

### Step 2: Determine the Gametes
- The heterozygous plant (RrYy) can produce four types of gametes:
- RY
- Ry
- rY
- ry

- The recessive plant (rryy) can only produce one type of gamete:
- ry

### Step 3: Set Up the Punnett Square
- To visualize the cross, we can set up a Punnett square with the gametes from both parents.

| | ry | ry |
|-------|------|------|
| RY | RrYy | RrYy |
| Ry | Rryy | Rryy |
| rY | rrYy | rrYy |
| ry | rryy | rryy |

### Step 4: Determine the Phenotypes
- Now, we can determine the phenotypes from the genotypes:
- RrYy: Round Yellow
- Rryy: Round Green
- rrYy: Wrinkled Yellow
- rryy: Wrinkled Green

### Step 5: Count the Phenotypes
- From the Punnett square, we can count the phenotypes:
- Round Yellow (RrYy): 2
- Round Green (Rryy): 2
- Wrinkled Yellow (rrYy): 2
- Wrinkled Green (rryy): 1

### Step 6: Calculate the Phenotypic Ratio
- The phenotypic ratio can be summarized as:
- Round Yellow: 2
- Round Green: 2
- Wrinkled Yellow: 2
- Wrinkled Green: 1

Thus, the phenotypic ratio is 2:2:2:1.

### Final Answer
The phenotypic ratio from the cross is **2:2:2:1**.

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