Gas exchange
/ɡæs ɪksˈtʃeɪndʒ/
Definition
Gas exchange refers to the movement of gases between a plant and the surrounding air, mainly carbon dioxide entering for photosynthesis and oxygen and water vapor leaving. It occurs mostly through stomata, the tiny pores in leaves, and also through stems and roots to a lesser extent. Unlike transpiration, which focuses on water loss, gas exchange includes the intake and release of multiple gases needed for photosynthesis and respiration.
Biological Role
- Link to photosynthesis and respiration: In daylight, leaves take in carbon dioxide for sugar production and release oxygen. Day and night, cells also use oxygen in respiration, the process that releases energy from stored sugars.
- Stomata as the main control points: Most movement of gases occurs through stomata, tiny adjustable pores in the leaf surface. When stomata close to limit water loss, carbon dioxide supply drops, which can slow photosynthesis.
- Roots need access to oxygen: This process is not limited to leaves. Roots exchange gases with air spaces in the soil, so waterlogged or compacted soil can reduce oxygen and impair root function.
- Air movement affects efficiency: Still, humid air can slow the diffusion, or passive movement, of gases around leaves. Good spacing and ventilation often help plants maintain steadier photosynthesis and transpiration.
Related Terms
Stoma
Stoma refers to a microscopic pore in the epidermis, the outer cell layer of leaves and young stems. Each stoma is…
Guard cell
Guard cell refers to one of the two specialized plant epidermal cells that surround a stoma, the tiny pore on a leaf or…
Transpiration
Transpiration is the plant process of losing water vapor to the air, mainly through tiny leaf pores called stomata, and…
Photosynthesis
Photosynthesis is the biological process in which plants, algae, and some bacteria use light energy to convert carbon…
Respiration
Respiration is the metabolic process in plant cells that breaks down sugars, usually using oxygen, to release usable…
Carbon dioxide
Carbon dioxide is a gas in the air and a key raw material for photosynthesis, the process plants use to make sugars…
Leaf
Leaf refers to a plant organ, usually flat and green, that grows from the stem or a branch and is specialized for…
Mesophyll
Mesophyll is the inner tissue of a leaf, located between the upper and lower epidermis. It consists mainly of…