Question

Stomata on the surface of a plant leaf open when water flows
Out from the guard cells.
Into the guard cells.
c
From the xylem to palisade mesophyll cells.
From the xylem to the leaf surface.​

Answer 1

Answer:

Stomata on the surface of a plant leaf opens when water flows: (b) into the guard cells

Explanation:  

• Stomata are tiny apertures which are present on the surface of the leaves. Stomata is governed by two cells called as guard cells, which regulate the opening and closing of stomata.
• The phenomenon of opening and closing of guard cells happens due to changes in the turgor of the guard cells which depends on the concentration and exchange of solutes and water present around them.
• Stomata open when there is a substantial increase in the inflow of solutes into the guard cells, which in turn increases the influx of water into the guard cells, resulting into an increase in the volume of the guard cells. This increase in volume makes both the guard cells inflated like a balloon and hence the stomata opens up.  
• The reverse happens when the stomata closes. An efflux in solutes and water from the guard cells leads to deflation of the guard cells, which results in the closing of the stomata.