Question

Which one gives the most valid explanation for guard cell movements

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

Answer 1

The correct option is C

Potassium influx and efflux

The potassium influx and efflux theory has been proven to be responsible for the opening and closing of the stomata. When there is daylight, potassium ions are pumped into the guard cells, which leads to endosmosis and turgidity. The turgidity causes the opening of the stoma. During nighttime, potassium ions leak out, leading to exosmosis and flaccidity. This leads to closing of the stoma.