Which of the following is not true for double fertilization

Options

A. It was discovered by Nawaschin .
B. The male gamete and secondary nucleus fuse to form the endosperm nucleus.
C. The endosperm nucleus is diploid .
D. The endosperm provides nutrition to the embryo.

Answer

To solve the question "Which of the following is not true for double fertilization?", we will analyze each statement provided in the options.

### Step-by-Step Solution:

1. **Understanding Double Fertilization**:
- Double fertilization is a unique process in flowering plants where two fertilization events occur. One male gamete fuses with the egg cell to form the zygote (which develops into the embryo), and the other male gamete fuses with the two polar nuclei to form the endosperm.

2. **Analyzing the Statements**:
- **Statement 1**: "It was discovered by Navaschin."
- This statement is true. Double fertilization was indeed discovered by Navaschin in 1898 while studying plants like Fritillaria and Lilium.

- **Statement 2**: "The male gamete and secondary nucleus fuse to form the endosperm nucleus."
- This statement is also true. During double fertilization, one male gamete fuses with the secondary nucleus (two polar nuclei) to form the primary endosperm nucleus.

- **Statement 3**: "The endosperm nucleus is diploid."
- This statement is **not true**. The endosperm nucleus is actually triploid (3n) because it results from the fusion of one haploid male gamete (1n) with a diploid secondary nucleus (2n), leading to a triploid structure.

- **Statement 4**: "The endosperm provides nutrition to the embryo."
- This statement is true. The endosperm serves as a source of nutrition for the developing embryo.

3. **Conclusion**:
- The statement that is not true regarding double fertilization is: "The endosperm nucleus is diploid."

### Final Answer:
The correct option is: **The endosperm nucleus is diploid.**

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