Ratio of progeny when a red coloured heterozygote is crossed with a white coloured plant in which red colour in dominant to white colour:

Options

A. `3 : 1`
B. `1 : 1`
C. `1 : 2 : 1`
D. `9 : 3 : 3 : 1`

Answer

To solve the problem of determining the ratio of progeny when a red-colored heterozygote is crossed with a white-colored plant (where red color is dominant to white color), we can follow these steps:

### Step 1: Define the Genotypes
- Let’s denote the allele for red color as "R" (dominant) and the allele for white color as "r" (recessive).
- The red-colored heterozygote will have the genotype "Rr".
- The white-colored plant, being homozygous recessive, will have the genotype "rr".

### Step 2: Set Up the Cross
We will perform a cross between the red-colored heterozygote (Rr) and the white-colored homozygote (rr).

### Step 3: Use a Punnett Square
To visualize the genetic cross, we can use a Punnett square:

```
R r
----------------
r | Rr | rr |
----------------
r | Rr | rr |
```

### Step 4: Determine the Progeny Genotypes
From the Punnett square, we can see the possible genotypes of the offspring:
- 50% Rr (red-colored)
- 50% rr (white-colored)

### Step 5: Calculate the Phenotypic Ratio
Now, we can determine the phenotypic ratio of the progeny:
- Red-colored progeny (Rr): 2
- White-colored progeny (rr): 2

Thus, the phenotypic ratio of red to white progeny is 1:1.

### Final Answer
The ratio of progeny when a red-colored heterozygote is crossed with a white-colored plant is **1:1**.

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