A pure dwart plant was subjected to X-ray treatment,which mutated them to reach the height of a pure tall plant. This new plant was crossed with a hybrid tall. What will be the result of progeny?

Options

A. (a) all tall
B. (b) Tall and dwarf in 1:1 ratio
C. (c) All dwarf
D. (d) Tall and dwarf in 2:1 ratio

Explanation

To solve the problem step by step, we will analyze the genetic information provided and apply the principles of inheritance.

### Step 1: Identify the Genotypes
- We start with a pure dwarf plant, which is homozygous recessive (let's denote the dwarf allele as 'd'). Therefore, its genotype is **dd**.
- After X-ray treatment, this plant mutates to a pure tall plant, which means it has become homozygous dominant (let's denote the tall allele as 'D'). Thus, its new genotype is **DD**.
- The hybrid tall plant is heterozygous, meaning it has one dominant and one recessive allele. Its genotype is **Dd**.

### Step 2: Cross the New Tall Plant with the Hybrid Tall Plant
- We now need to cross the new tall plant (DD) with the hybrid tall plant (Dd).
- The possible gametes from the new tall plant (DD) are only **D** (since it can only contribute the dominant allele).
- The possible gametes from the hybrid tall plant (Dd) are **D** and **d**.

### Step 3: Create a Punnett Square
- We set up a Punnett square to visualize the offspring from this cross:

```
D D
__________
D | DD | DD |
__________
d | Dd | Dd |
__________
```

### Step 4: Analyze the Offspring
- The results from the Punnett square show:
- 2 offspring with genotype **DD** (homozygous tall)
- 2 offspring with genotype **Dd** (heterozygous tall)
- All offspring will exhibit the tall phenotype because both genotypes (DD and Dd) express the dominant trait.

### Step 5: Conclusion
- Therefore, all progeny from this cross will be tall plants.

### Final Answer
The result of the progeny will be **all tall plants**.

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