Module: | Pre-fertilization: Micro/Megasporogenesis
Q8: Consider the following statements regarding the ploidy levels of various pre-fertilization structures:
1. The ploidy level of the microspore mother cell (MMC) and megaspore mother cell is diploid.
2. The cells of the tapetum are strictly haploid to match the developing pollen grains they nourish.
3. The functional megaspore, which gives rise to the female gametophyte, is haploid.
Which of the above statements is/are correct?
2. The cells of the tapetum are strictly haploid to match the developing pollen grains they nourish.
3. The functional megaspore, which gives rise to the female gametophyte, is haploid.
Which of the above statements is/are correct?
✅ Correct Answer: C
The correct option is C. Statements 1 and 3 are correct, while Statement 2 is incorrect.
Understanding ploidy (the number of sets of chromosomes in a cell) is foundational to angiosperm reproduction.
Both the microspore mother cell and the megaspore mother cell are part of the sporophyte generation and are therefore diploid (2n). They undergo meiosis to produce haploid (n) spores, such as the functional megaspore.
However, the tapetum is a unique somatic tissue.
Far from being strictly haploid, tapetal cells often become bi-nucleate or polyploid (having more than two sets of chromosomes) due to endomitosis or failure of cytokinesis after nuclear division.
The causal reasoning for this polyploidy is the massive requirement for mRNA and protein synthesis to produce nutrients, enzymes, and sporopollenin precursors for the rapidly developing microspores.
Understanding ploidy (the number of sets of chromosomes in a cell) is foundational to angiosperm reproduction.
Both the microspore mother cell and the megaspore mother cell are part of the sporophyte generation and are therefore diploid (2n). They undergo meiosis to produce haploid (n) spores, such as the functional megaspore.
However, the tapetum is a unique somatic tissue.
Far from being strictly haploid, tapetal cells often become bi-nucleate or polyploid (having more than two sets of chromosomes) due to endomitosis or failure of cytokinesis after nuclear division.
The causal reasoning for this polyploidy is the massive requirement for mRNA and protein synthesis to produce nutrients, enzymes, and sporopollenin precursors for the rapidly developing microspores.