Question

Choose the correct answers from the alternatives given.
Stomata open when guard cells

• A. Sense an increase in CO2 in the air spaces of the leaf
• B. Flop open due to a decrease in turgor pressure
• C. Become more turgid due to an influx of $K^{+}$ followed by the osmotic flow of water
• D. Accumulate water by active transport

Answer 1

The correct option is C Become more turgid due to an influx of $K^{+}$ followed by the osmotic flow of water

When the concentration of the potassium ions and malate ions increase guard cells form potassium malate and stores it in vacuoles of the guard cells. This increases the osmotic concentration and hence water enters the guard cells by endosmosis. The turgor pressure of the guard cells increases due to endosmosis which finally leads to the opening of the stomata.

Hence,the correct answer is 'Become more turgid due to an influx of $K^{+}$ followed by the osmotic flow of water'.