The ability of the Venus Flytrap to capture insects is due to

Question

Accepted Answer

D. 1. **Recall the type of movement shown by Venus Flytrap**: this plant shows a **thigmonastic movement**, a non-directional response to touch, which is also seen in other insectivorous plants like *Dionaea* and *Drosera*, and is triggered by sensitive tentacle-like trigger hairs.

2. **Understand the mechanism behind the trap closing**: when the trigger hairs are touched, an action potential is generated, causing **hydrogen ions to be rapidly pumped** into the walls of cells on the outside of each leaf.
Given this,
$$
	ext{Touch stimulus} ightarrow 	ext{Action potential} ightarrow 	ext{Rapid H}^+ 	ext{ pumping into outer cell walls}
$$

3. **Trace the consequence of this ion pumping**: the protons loosen the cell walls so rapidly that the tissue becomes flaccid, allowing the cells to quickly absorb water, causing the outer side of each leaf to expand.
Therefore,
$$
	ext{Rapid turgor pressure change} ightarrow 	ext{Trap snaps shut}
$$

4. **Eliminate the other options**: plants do not have true muscle cells (option A); mere chemical stimulation by prey (option B) is not the direct mechanical cause of closing; and this is clearly not a passive process (option C), since it involves an active, rapid physiological response.

Hence, the correct answer is **D. rapid turgor pressure changes**.