Photosynthesis
/ˌfoʊtoʊˈsɪnθəsɪs/
Definition
Photosynthesis is the biological process in which plants, algae, and some bacteria use light energy to convert carbon dioxide and water into sugars. In plants, it occurs mainly in chloroplasts, especially in leaf cells containing chlorophyll, the green pigment that captures light. Oxygen is released as a byproduct. Unlike respiration, which breaks down sugars for energy, photosynthesis builds them for growth and metabolism.
Biological Role
- Sugar supply for growth: In plants, photosynthesis provides the sugars that fuel cell division, root extension, new leaves, flowering, and fruit development. Some of this energy is stored as starch for later use when light is limited.
- Leaf structure and light capture: Most photosynthesis happens in leaves, especially in chloroplast-rich mesophyll tissue. Leaf size, thickness, angle, and internal air spaces influence how efficiently light and carbon dioxide are used.
- Link to water loss: Photosynthesis depends on open stomata, the tiny pores that also let water vapor escape. In heat, drought, or very dry air, plants may close stomata, which slows carbon dioxide uptake and reduces sugar production.
- Practical light response: Indoor and outdoor growth often reflects how much photosynthesis a plant can sustain. Low light can lead to slower growth and longer gaps between leaves, while appropriate light supports sturdier, more compact growth.
Related Terms
Stoma
Stoma refers to a microscopic pore in the epidermis, the outer cell layer of leaves and young stems. Each stoma is…
Transpiration
Transpiration is the plant process of losing water vapor to the air, mainly through tiny leaf pores called stomata, and…
Mesophyll
Mesophyll is the inner tissue of a leaf, located between the upper and lower epidermis. It consists mainly of…
Respiration
Respiration is the metabolic process in plant cells that breaks down sugars, usually using oxygen, to release usable…