Question

Cells are the basic units of structure and function in all organisms. A key feature in the life cycle of plants is the alternation of multicellular haploid and diploid generations. Imagine a lineage of flowering plants in which mitotic cell division did not occur between the events of meiosis and fertilization. Describe how this change in the timing of cell division would affect the structure and life cycle of plants in this lineage.

Answer 1

Ques: Cells are the basic units of structure and function in all organisms. A key feature in the life cycle of plants is the alternation of multicellular haploid and diploid generations. Imagine a lineage of flowering plants in which mitotic cell division did not occur between the events of meiosis and fertilization. Describe how this change in the timing of cell division would affect the structure and life cycle of plants in this lineage.

Answer: In flowering plants, meiosis is followed by 3 mitotic cell divisions that divide the cell into the 7 celled 8 nucleate stage having 3 antipodal cells, 2 synergids, 2 polar central cells, and an egg cell. If there is no mitosis between the meiosis and the fertilization, these cells would not be formed.

So a single haploid egg cell might undergo fertilization to form a zygote, but there will be no polar nuclei for triple fusion, thus no double fertilization will take place which is a characteristic of flowering plants. And therefore there will be no triploid endosperm formation which plays a very important role in providing nutrients to the developing zygote. So we can say that the developing zygote won't have sufficient nutrients for its growth and may lead to seed inviability. And even if they survive initially, their germination would get difficult and they will die later due to lack of nutrients.

Also, antipodal cells and Synergid cells won't be there as well, which might even affect the fertilization process since synergids are essential to guide the male nuclei inside the female gamete.

Essentially, that means that without mitosis, plant cells won't be able to effectively reproduce.

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