MS-LS1-6. Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
The epidermis of a leaf has microscopic openings, which are the “pores” of the plant’s skin on the undersides of leaves called stomata (sing. stoma or stomate). Stomata allow the exchange of gases such as oxygen and carbon dioxide between the plant and the outside environment. Water vapor is also released through the stomata in a process called transpiration.
The rate of gas and water vapor diffusion is regulated by two guard cells. The shape of the guard cells will change when water enters the plant by the process of osmosis. When the stomata are open, diffusion rates of carbon dioxide, water vapor, and oxygen are greater. Therefore, when water exits, the guard cells relax, the stomata close, and diffusion rates are reduced.
The closing of the stomata help the plant by preventing dehydration due to loss of water vapor, and helps with maintaining the water necessary for photosynthesis and the homeostasis, or internal balance of the plant. It is also important to mention that this process is a crucial step in the Earth’s water cycle. Generally stomata are open during the day and close at night. Functioning of the stomata could be affected by light intensity, stress (disease, insects, etc.), climate, and/or latitude.
Lily Sepal Stomata
Oak Leaf Stomata
Read the following article for information about the role of stomata in photosynthesis.
Take Notes as you read.
MS-LS1-6. Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
Now that you have learned about the role of stomata in photosynthesis complete the following CER to demonstrate your understanding.