Question

Which one gives the most valid and recent explanation for stomatal movements?

• A. Starch hydrolysis
• B. Potassium influx and efflux
• C. Transpiration
• D. Guard cell photosynthesis

Answer 1

The correct option is B

Potassium influx and efflux

The correct option is B.

Explanation of correct option:

1. The opening and closing of stomata are known as stomatal movements.
2. When guard cells are turgid, stomata open, and when they are flaccid, they close.
3. The exterior (convex) wall of the guard cell is thin, while the interior (concave) wall is thick.
4. The influx of potassium ions increases the concentration of the sap in the guard cells leading to endosmosis and then the opening of the stomata.

Explanation of incorrect option:

Option A:

1. In the starch hydrolysis test, the test microorganisms are grown on starch-containing agar plates.
2. If the bacteria can hydrolyze starch, they do so in the medium, especially around their development, whereas the rest of the plate contains non-hydrolyzed starch.

Option C:

1. Osmotic diffusion transports water from the leaf's xylem to the intercellular space above the stomata.
2. The stomata open and close.

Option D:

1. Guard cells use osmotic pressure to open and close stomata, which allows plants to regulate the amount of water and solutes in their tissues.
2. To produce energy and maintain cellular function, plant cells engage in the immensely intricate process of photosynthesis.

Final answer: Potassium influx and efflux are the most valid and recent explanations for stomatal movements.