Module: | Double Fertilization & Endosperm
Q80: Consider the following statements regarding the metabolic reserves of the pollen grain cytoplasm:
1. The massive vegetative cell acts as the primary metabolic reservoir, heavily packed with starch grains, lipids, and proteins prior to shedding.
2. Upon landing on the stigma, these complex stored reserves are rapidly hydrolyzed to provide the massive energy required for pollen tube construction.
3. The generative cell contains an equally massive volume of starch reserves to independently sustain its own high-speed transport through the style.
Which of the above statements is/are correct?
2. Upon landing on the stigma, these complex stored reserves are rapidly hydrolyzed to provide the massive energy required for pollen tube construction.
3. The generative cell contains an equally massive volume of starch reserves to independently sustain its own high-speed transport through the style.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, but Statement 3 is biologically incorrect.
The 2-celled pollen grain is highly asymmetric in its resource allocation.
Structurally, the vegetative cell is enormous and takes up the vast majority of the intra-exine space.
Its primary causal function is to build the pollen tube.
To achieve this, its cytoplasm is densely packed with vacuoles containing starch, lipid droplets, and proteins.
When hydration occurs on the stigma, amylases and lipases immediately break down these reserves, fueling the rapid synthesis of the tube's cellulose/pectin wall.
Statement 3 describes a physical impossibility.
The generative cell is tiny, spindle-shaped, and mostly consists of a dense nucleus with a very thin layer of cytoplasm.
It possesses practically zero food reserves of its own; it survives entirely as a parasite, floating within and drawing metabolic support from the cytoplasm of the vegetative cell.
The 2-celled pollen grain is highly asymmetric in its resource allocation.
Structurally, the vegetative cell is enormous and takes up the vast majority of the intra-exine space.
Its primary causal function is to build the pollen tube.
To achieve this, its cytoplasm is densely packed with vacuoles containing starch, lipid droplets, and proteins.
When hydration occurs on the stigma, amylases and lipases immediately break down these reserves, fueling the rapid synthesis of the tube's cellulose/pectin wall.
Statement 3 describes a physical impossibility.
The generative cell is tiny, spindle-shaped, and mostly consists of a dense nucleus with a very thin layer of cytoplasm.
It possesses practically zero food reserves of its own; it survives entirely as a parasite, floating within and drawing metabolic support from the cytoplasm of the vegetative cell.