Reproduction In Plants

To solve the problem, we need to understand the process of fertilization in plants and the result of the fusion of the male gamete with the secondary nucleus.

1. Understanding Fertilization in Plants:
In plants, fertilization occurs when the male gamete (sperm) fuses with the female gamete (egg). However, in angiosperms (flowering plants), a unique process called double fertilization also occurs. During this process, one male gamete fuses with the egg cell, forming the zygote, while the other male gamete fuses with the secondary nucleus of the central cell in the embryo sac, resulting in the formation of the endosperm.

2. The Result of Fusion with the Secondary Nucleus:
The fusion of the male gamete with the secondary nucleus results in the formation of the endosperm, which provides nourishment to the developing embryo.

3. Evaluating the Options:
- Option (A): Spores – Incorrect, spores are reproductive units, not a result of fertilization.
- Option (B): Cotyledons – Cotyledons are seed leaves, not formed by fusion with the secondary nucleus.
- Option (C): Embryo sac – This is the structure where fertilization occurs, but it is not the product of the fusion.
- Option (D): Endosperm – Correct, the fusion with the secondary nucleus leads to the formation of the endosperm.

Final Answer:
The correct answer is option (D): Endosperm.

To solve the problem, we need to identify how many cells are present in the embryo sac of the majority of flowering plants.

1. Structure of the Embryo Sac:
The embryo sac in flowering plants is typically formed within the ovule. It contains seven cells, including:

• One egg cell
• Two synergids
• Three antipodal cells
• One central cell with two polar nuclei

This arrangement results in a total of seven cells in the majority of flowering plants.

Final Answer:
The embryo sac contains 7 cells (Option C).