(i) why does'nt plasmolysis occur in animal cells?

Question

ii)why don't the subsidary cells in the leaf posess chloroplast like the guard cells?

Answer 1

Plasmolysis in plant cells happens when the cells are in a hypertonic situation: more water goes out of the cells than the amount of water that goes into the cells. The cell contents shrink, and the cytoplasm and plasma membrane shrink away from the cell wall.

Animal cells have no cell wall, so an animal cell in a hypertonic situation simply shrinks. If it stays that way for long, it will die. There's no cell wall to shrink away from.

The fact that guard cells have chloroplasts and the surrounding cells do not is the very fact that lets the guard cells swell and open the stomata when light is available. When the guard cells make sugars during photosynthesis water diffuses into the guard cells from the surrounding cells. The guard cells swell unevenly and bend outward to open the stomata. If the surrounding cells were also carrying on photosynthesis, there wouldn't be a concentration gradient (a difference between concentrations) and water wouldn't diffuse into the guard cells.

Answer 2

Plasmolysis In Plant Cells