Detailed
The diploid structure in the ovule of Capsella just before fertilization is the Nucellus/Sec.nucleus. Here is a detailed explanation:
1. Introduction:
The ovule is the female reproductive structure in plants, which contains the egg cell and other supporting structures.
2. Structure of the ovule:
The ovule consists of several parts, including the integuments, micropyle, funiculus, and nucellus.
3. Nucellus:
The nucellus is a diploid tissue present in the ovule. It is located inside the integuments and surrounds the megasporangium. The nucellus contains various cells, including the secondary nucleus.
4. Function of the nucellus:
The nucellus plays a crucial role in the process of fertilization. It provides nourishment to the developing embryo sac and facilitates the growth and development of the female gametophyte.
5. Just before fertilization:
Just before fertilization, the nucellus is present in the ovule and is responsible for providing nutrients to the developing embryo sac.
6. Other options:
The other options mentioned in the question, including the pollen tube, synergids, and antipodals, are not diploid structures in the ovule of Capsella. The pollen tube is a structure formed by the pollen grain during pollination and is involved in the delivery of sperm cells to the ovule. Synergids and antipodals are cells present in the female gametophyte or embryo sac, which are haploid structures.
In conclusion, the diploid structure in the ovule of Capsella just before fertilization is the nucellus or secondary nucleus. It provides nourishment to the developing embryo sac and facilitates the process of fertilization.