Question

Choose the correct sequence of events in pollen-pistil interaction from the options given below:
i. Entry of pollen tube into synergid.
ii. Development of pollen tube.
iii. Deposition of pollen grains on the stigma.
iv. Release of contents from pollen tube.

• A. iii $\rightarrow$ iv $\rightarrow$ i $\rightarrow$ ii
• B. iii $\rightarrow$ i $\rightarrow$ iv $\rightarrow$ ii
• C. iii $\rightarrow$ ii $\rightarrow$ i $\rightarrow$ iv
• D. iii $\rightarrow$ ii $\rightarrow$ iv $\rightarrow$ i

Hint:

Sequence trick: Pollination $\rightarrow$ Tube formation $\rightarrow$ Entry $\rightarrow$ Release (PTER).

Answer 1

The Correct Option is C

Concept:
Pollen-pistil interaction involves a series of well-defined steps from pollination to fertilization in flowering plants.

Step 1: Identify the first event. Pollination begins with the deposition of pollen grains on the stigma. \[ \text{First step: Deposition of pollen (iii)} \]

Step 2: Understand pollen germination. After reaching the stigma, the pollen grain germinates and forms a pollen tube. \[ \text{Next step: Development of pollen tube (ii)} \]

Step 3: Entry into ovule. The pollen tube grows through the style and enters the ovule via the synergid. \[ \text{Next step: Entry into synergid (i)} \]

Step 4: Final event. The pollen tube releases its contents (male gametes) into the embryo sac. \[ \text{Final step: Release of contents (iv)} \]

Step 5: Conclusion. Thus, the correct sequence is: \[ \text{iii} \rightarrow \text{ii} \rightarrow \text{i} \rightarrow \text{iv} \]