Question

Stomata opens during daytime because guard cells ______.

Options

• help in photosynthesis and synthesize osmotically active substances.

• have thin walls.

• are of bean shape.

• help in exchange of gases.

Answer 1

Stomata opens during daytime because guard cells help in photosynthesis and synthesize osmotically active substances.

Explanation:

During the daytime, chloroplasts within the guard cells perform photosynthesis, which produces sugars and drives the accumulation of osmotically active substances (like potassium ions and malate). This lowers the water potential inside the guard cells, causing water to rush into them via endosmosis. The resulting high turgor pressure forces the guard cells to swell and curve outward, safely opening the stomatal pore.