Stomata: the tiny pores in a leaf
Look at a peel from the underside of a leaf under the microscope and label the epidermal cells, guard cells, chloroplasts and open and closed stomata.
Core concept
Stomata are tiny pores, mostly on the underside of leaves, opened and closed by a pair of guard cells to let gases in and out and control water loss
Topic: Plants
The surface of a leaf is covered by a thin layer of epidermal cell: The tiny building block that every living thing is made of. All key words, which fit together like a jigsaw. Scattered among them, especially on the underside, are tiny pores called stomata (one is a stoma). Each stoma lies between two bean-shaped guard cells. Unlike the other epidermal cells, guard cells contain chloroplasts. When the guard cells swell with water they curve apart and open the stoma; when they lose water they straighten and close it. Through open stomata, carbon dioxide: A gas we breathe out. Plants take it in to make their food. All key words enters for photosynthesis: How green plants make their own food from light, water and carbon dioxide. All key words and oxygen: A gas in the air that living things need to breathe and that fire needs to burn. All key words and water vapour leave.
What you will learn
- Identify stomata and guard cells under the microscope.
- Explain how guard cells open and close a stoma.
- Describe what passes through stomata.
Before you start
- Know that leaves make food by photosynthesis.
Materials
- Leaves with an easily peeled underside (such as Tradescantia, spinach or a fleshy leaf)
Equipment
- Microscope, slide, cover slip, forceps, dropper
Procedure
- Peel a thin layer from the underside of a leaf and look at it under the microscope.
- Choose a part name card, find out what it does, and place it on the matching letter.