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Answer the following questions from your knowledge of sexual reproduction in flowering plants - Leaving Cert Biology - Question c - 2019
Question c
Answer the following questions from your knowledge of sexual reproduction in flowering plants. (i) Describe in detail the development of the embryo sac from a megas... show full transcript
Worked Solution & Example Answer:Answer the following questions from your knowledge of sexual reproduction in flowering plants - Leaving Cert Biology - Question c - 2019
Step 1
Describe in detail the development of the embryo sac from a megaspore mother-cell.
Answer
The development of the embryo sac begins with a diploid megaspore mother-cell, which undergoes meiosis. This process results in the formation of four haploid daughter cells, but typically only one of these cells survives, while the other three degenerate. The surviving haploid cell then undergoes mitosis to divide, which can result in the formation of either two or eight nuclei, depending on the species. In the case of the embryo sac, two of these haploid nuclei become the polar nuclei, while one develops into the egg nucleus.
Step 2
Outline what happens during each fertilisation.
Answer
During the first fertilisation, one male gamete (or sperm nucleus) fuses with the egg cell, resulting in the formation of a diploid zygote. In the second fertilisation, another male gamete fuses with the two polar nuclei, which produces a triploid nucleus that develops into the endosperm.
Step 3
Step 4
Draw a large diagram of a seed and label the following parts:
Answer
To complete this section, draw a large diagram of a seed, ensuring to clearly label the following parts:
- Testa: the outer protective coat of the seed.
- Plumule: the embryonic shoot that will develop into the plant stem and leaves.
- Radicle: the embryonic root that will grow down into the soil.