Module: | Embryo, Seed, Fruit & Apomixis
Q87: Consider the following statements regarding the molecular physiology of stored mRNAs in mature pollen:
1. Mature, dormant pollen grains contain large quantities of pre-synthesized, long-lived messenger RNAs (mRNAs) in their cytoplasm.
2. These stored mRNAs are critical for the rapid, almost instantaneous synthesis of proteins required immediately upon hydration on the stigma.
3. A pollen grain relies entirely on the stylar tissue to transcribe new RNA before it can physically initiate the growth of the pollen tube.
Which of the above statements is/are correct?
2. These stored mRNAs are critical for the rapid, almost instantaneous synthesis of proteins required immediately upon hydration on the stigma.
3. A pollen grain relies entirely on the stylar tissue to transcribe new RNA before it can physically initiate the growth of the pollen tube.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, whereas Statement 3 is physiologically incorrect.
The transition from a dormant, dehydrated pollen grain to a rapidly growing pollen tube requires explosive metabolic activity.
Structurally, there is no time for the pollen nucleus to undergo de novo transcription (making new RNA from DNA) to start this process.
To solve this causally, during the final stages of maturation in the anther, the vegetative cell transcribes massive amounts of mRNA.
These transcripts are masked and stored safely in the cytoplasm during dormancy.
The moment the pollen grain hydrates on a receptive stigma, these stored mRNAs are immediately translated into the necessary enzymes and structural proteins to push the tube out of the germ pore.
Statement 3 is false because the initial emergence of the pollen tube is entirely independent of new transcription, relying strictly on this pre-packaged molecular payload.
The transition from a dormant, dehydrated pollen grain to a rapidly growing pollen tube requires explosive metabolic activity.
Structurally, there is no time for the pollen nucleus to undergo de novo transcription (making new RNA from DNA) to start this process.
To solve this causally, during the final stages of maturation in the anther, the vegetative cell transcribes massive amounts of mRNA.
These transcripts are masked and stored safely in the cytoplasm during dormancy.
The moment the pollen grain hydrates on a receptive stigma, these stored mRNAs are immediately translated into the necessary enzymes and structural proteins to push the tube out of the germ pore.
Statement 3 is false because the initial emergence of the pollen tube is entirely independent of new transcription, relying strictly on this pre-packaged molecular payload.