49.Influx of K+ ions into guard cells and efflux of H+ ions from guard cells lead to: A. Exosmosis B. Plasmolysis C. Closing of stomata D. Opening of stomata
Option D. Stomata opens and closes due to water and ion movement. When the light falls on the parts of plant, chloroplast carries out photosynthesis. ATP from photosynthesis powers sodium and potassium pump. Then the K+ ions are pumped into the guard cells, by creating a concentration gradient. For this uptake of K+ ions it requires protons (H+) ions then, K+ ions are exchange for the protons H+. Uptake of K+ ions is referred as influx of K+ ions into guard cells and outward movement of H+ ions is referred as efflux of H+ ions. This is an active ionic exchange and requires ATP energy and cytokinin (a plant hormone). In this way, the concentration of K+ ions increases in guard cells and at the same time, the concentration of H+ ions decreases in guard cells. As a result of this, guard cells swells and stomata opens.
