Photosynthesis

Photosynthesis

Process by which photoautotrophs convert solar energy, CO₂, and H₂O into glucose and O₂.

Photoautotrophs

Organisms like plants, algae, and cyanobacteria that perform photosynthesis.

Autotroph

Organism that produces its own food using light or chemical energy.

Heterotroph

Organism that consumes other organisms for energy (e.g., animals).

Chloroplast

Organelle in plant cells where photosynthesis occurs; contains pigments and enzymes.

Thylakoid

Membranous sac inside chloroplasts; site of light-dependent reactions.

Grana

Stacks of thylakoids within the chloroplast.

Stroma

Fluid-filled space surrounding thylakoids; site of the Calvin cycle.

Chlorophyll

Green pigment in chloroplasts that absorbs light energy for photosynthesis.

Pigment Molecule

Protein that absorbs specific wavelengths of light; includes chlorophyll a, b, and carotenoids.

Electromagnetic Spectrum

Range of all types of electromagnetic radiation, including visible light used in photosynthesis.

Light Reaction

First stage of photosynthesis; converts light energy into ATP and NADPH; occurs in thylakoids.

Calvin Cycle

Second stage of photosynthesis; uses ATP and NADPH to fix carbon and produce sugars; occurs in stroma.

Carbon Fixation

Process of converting inorganic CO₂ into organic compounds during the Calvin cycle.

RuBisCO

Enzyme that catalyzes carbon fixation in the Calvin cycle.

G3P (Glyceraldehyde-3-phosphate)

Three-carbon sugar produced in the Calvin cycle; precursor to glucose.

Photosystem II & I

Protein-pigment complexes in thylakoids that absorb light and transfer electrons.

Electron Transport Chain

Series of proteins that transfer electrons and pump H⁺ ions to generate ATP.

Stomata

Pores in leaves that regulate gas exchange (CO₂ in, O₂ out) and water loss.

C4 Plants

Plants that fix carbon into a 4-carbon compound to minimize photorespiration.

CAM Plants

Plants that fix carbon at night to conserve water in arid environments.

Carbon Cycle

Biogeochemical cycle where photosynthesis and cellular respiration exchange CO₂ and O₂.

Climate Change

Long-term alteration of temperature and weather patterns; linked to rising CO₂ levels.

Greenhouse Effect

Trapping of heat by atmospheric gases like CO₂; contributes to global warming.