Module: | Pollination & Outbreeding Devices
Q52: Consider the following statements regarding the mitotic division during the formation of the male gametophyte:
1. The first mitotic division of the microspore utilizes a highly symmetric spindle, ensuring the resulting cells are of identical size.
2. This division is characterized by unequal cytokinesis, which results in a massive vegetative cell and a tiny generative cell.
3. The generative cell initially attaches to the intine but eventually loses its connection and floats freely in the cytoplasm of the vegetative cell.
Which of the above statements is/are correct?
2. This division is characterized by unequal cytokinesis, which results in a massive vegetative cell and a tiny generative cell.
3. The generative cell initially attaches to the intine but eventually loses its connection and floats freely in the cytoplasm of the vegetative cell.
Which of the above statements is/are correct?
✅ Correct Answer: B
The correct option is B. Statements 2 and 3 are correct, whereas Statement 1 is strictly incorrect.
The transition from a single-celled microspore to a mature 2-celled pollen grain is a highly regulated developmental milestone.
As the microspore matures, its nucleus moves to the periphery.
Crucially, the cell forms an asymmetric (highly unequal) mitotic spindle, directly contradicting Statement 1. This mechanical asymmetry drives unequal cytokinesis (cytoplasmic division). The causal result is a large vegetative cell, which retains the vast majority of the nutrient-rich cytoplasm and organelles, and a much smaller generative cell that is pinched off against the cell wall.
Following this division, the generative cell detaches from the microspore wall (intine) and is completely engulfed, floating freely within the cytoplasm of the vegetative cell to be transported down the pollen tube.
The transition from a single-celled microspore to a mature 2-celled pollen grain is a highly regulated developmental milestone.
As the microspore matures, its nucleus moves to the periphery.
Crucially, the cell forms an asymmetric (highly unequal) mitotic spindle, directly contradicting Statement 1. This mechanical asymmetry drives unequal cytokinesis (cytoplasmic division). The causal result is a large vegetative cell, which retains the vast majority of the nutrient-rich cytoplasm and organelles, and a much smaller generative cell that is pinched off against the cell wall.
Following this division, the generative cell detaches from the microspore wall (intine) and is completely engulfed, floating freely within the cytoplasm of the vegetative cell to be transported down the pollen tube.