Endosperm in angiosperms is formed from secondary nucleus

Options

A. (a) after fertilization but prior to embryo formation
B. (b) before fertilization but after but after embryo formation
C. (c) after embryo formation
D. (d) during fertilization

Answer

**Step-by-Step Solution:**

1. **Understanding Double Fertilization**: In angiosperms, a unique process called double fertilization occurs. This involves two male gametes from the pollen tube.

2. **Fertilization Events**: One male gamete fuses with the egg cell, which is haploid, to form a zygote. This zygote will eventually develop into the embryo.

3. **Formation of Endosperm**: The second male gamete fuses with the two polar nuclei present in the central cell of the embryo sac. These polar nuclei are diploid and together with the haploid male gamete, they form a triploid cell, which develops into the endosperm.

4. **Timing of Endosperm Formation**: The endosperm is formed after the fertilization of the egg cell but before the embryo is fully formed. This timing is crucial as the endosperm provides the necessary nutrition to the developing embryo.

5. **Evaluating Options**:
- Option A states that endosperm is formed after fertilization but prior to embryo formation, which is correct.
- Option B suggests it is formed before fertilization but after embryo formation, which is incorrect.
- Option C claims it is formed after embryo formation, which contradicts the purpose of endosperm.
- Option D indicates it is formed during fertilization, which is misleading as the main fertilization event occurs first.

6. **Conclusion**: The correct answer is Option A, as it accurately describes the timing of endosperm formation in relation to fertilization and embryo development.