A homogamous tall pistilltate plant (TT) is crossed with homogamous dwarf staminate plant (tt). What is the genotype of endosperm?

Options

A. `"TTT"`
B. `"TTt"`
C. `"Ttt"`
D. `"ttt"`

Answer

To determine the genotype of the endosperm formed from the cross between a homogamous tall pistillate plant (TT) and a homogamous dwarf staminate plant (tt), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parents:**
- The tall pistillate plant is homozygous tall (TT).
- The dwarf staminate plant is homozygous dwarf (tt).

2. **Understand the Formation of Endosperm:**
- The endosperm is formed from the fusion of one male gamete with two polar nuclei (central cells) in the ovule.
- The polar nuclei contribute to the triploid (3N) nature of the endosperm.

3. **Determine the Male Gamete:**
- The male gamete comes from the staminate plant (tt). Since it is homozygous for the dwarf trait, the male gamete will carry the allele 't'.

4. **Determine the Contribution from the Female Gamete:**
- The female gamete comes from the pistillate plant (TT). Since it is homozygous tall, it will contribute the allele 'T'.

5. **Combine the Contributions:**
- The endosperm will be formed by the fusion of the male gamete (t) with the two polar nuclei (which are both T from the female gamete).
- Therefore, the genotype of the endosperm will be T (from the first polar nucleus) + T (from the second polar nucleus) + t (from the male gamete).

6. **Write the Genotype of the Endosperm:**
- The genotype of the endosperm will be TTT (from the two polar nuclei) + t (from the male gamete), resulting in the genotype TTT.

### Final Answer:
The genotype of the endosperm is TTT.