Photosynthesis: Stomata and Guard Cells

What do the guard cells contain that allow them to function in different lighting conditions?

Guard cells contain chloroplasts but the cells in the epidermis do not. The chloroplasts allow the guard cells to be "activated" where there is sunlight.

How do the guard cells behave in dry and wet climates?

When the plant is well hydrated, the guard cells fill with water, opening the stroma. When the plant needs to conserve water, the guard cells close the stoma. An example of a plant with closed guard cells is cacti.

What is the plural of stomata?

stomates

Where would you expect to find stomates on the leaves of a floating water lily? Why?

CO2 would be unable to diffuse into the leaf with water underneath. Most of the stomata would be located on the top of the leaves so that gas exchange can occur.

What are guard cells?

Stomata are controlled by two banana-shaped cells called guard cells.

Define stomata. What is its function?

Stomata, or stomates, are special openings on the surface of leaves, mostly in the lower epidermis to minimize water loss. They allow gas exchange (through diffusion) to occur: CO2 diffuses into the leaf for photosynthesis and water and O2 diffuse out. They have the ability to open and close depending on how much water is needed.