gas exchange (plants)

• gas exchange is the process in which plants take in carbon dioxide and release oxygen through the stomata using diffusion
• spongy mesophyll has air pockets for efficient gas exchange. They have a large surface area for has exchange
• the stomata are pores found on the underside of the lead. they open in light and close in dark. they allow gas to enter and leave the cell
• the guard cells control the opening and closing of the stomata
• the stomatal pores open when guard cells enlarge and become turgid as a result of water absorption and close when guard cells shrink (become flaccid) as a result of water leaving
• in the dark, the glucose produced during the day will be used in respiration. water is drawn out by osmosis. the guard cells lose water, become flaccid and the stomata closes
• gas exchange depends on the time of day and light intensity
• in daytime, light is present which allows photosynthesis to occur so carbon dioxide will be taken in by photosynthesizing cells in plants and oxygen will be produced as a waste product
• in bright light the rate of photosynthesis is higher than the rate of respiration and there is a net release of oxygen and uptake of carbon dioxide
• in the dark, the rate of respiration is high and no photosynthesis