Plant Gas Exchange Structures Flashcards
How is the structure and physiology of leaves suited to gas exchange?
Flat and large for large SA
Open air spaces within spongy mesophyll for gas movement
Surface of leaf cells are moist so that gases are dissolved
Through what structures does gaseous exchange occur in plants?
Stomata and lenticels.
What are stomata?
Pores in the epidermis of the leaf through which gases move. These pores are found on the underside of the leaf. These pores are bordered by two bean-shaped guard cells, that contain chloroplasts.
How are stomata opened and closed?
To open, the guard cells fill with water and become turgid, stretching the outer walls of the cell and widening the gap between them. To close, water moves out of the guard cells.
How does light affect the opening and closing of the stomata?
Stomata generally open during the day and close at night.
How does temperature affect the opening and closing of the stomata?
When temperature increases, there is an increase in water loss by evaporation from the open stomata. This causes the stomata to close.
How does water availability affect the opening and closing of the stomata?
When water availability decreases, photosynthesis is limited and CO2 builds up. The stomata will close to prevent any CO2 from entering leaf.
How does humidity affect the opening and closing of the stomata?
In high humidity, the rate of water evaporating from the leaf is reduced, enabling stomata to remain open.
What are lenticels?
Pores the in the woody parts of plants, such as the branches of trees. They are pores through which gaseous exchange occurs, and appear as small dots to the naked eye. They are clusters of loose cells in the cork layer of bark,. Diffusion through lenticels is relatively slow.
