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Autotrophs

Organisms that make their own food by harvesting energy from the environment.

Photoautotroph

Organisms such as plants, algae, and some bacteria that use light energy to produce food.

Heterotrophs

Organisms that cannot make their own food and must consume plants, animals, or decomposed material.

Photosynthesis

The process of converting light energy into chemical energy, primarily occurring in chloroplasts.

Chloroplasts

Organelles where photosynthesis takes place, containing chlorophyll and involved in light energy conversion.

Stroma

The thick fluid contained in the inner compartment of chloroplasts.

Thylakoids

Membrane structures within chloroplasts that contain chlorophyll and are the site of the light-dependent reactions.

Grana

Stacks of thylakoids found in chloroplasts.

Redox Reaction

A chemical reaction involving the transfer of electrons, seen in photosynthesis and cellular respiration.

Calvin Cycle

Light-independent reactions of photosynthesis that occur in the stroma, producing sugars from carbon dioxide.

Photophosphorylation

The process of generating ATP from ADP and inorganic phosphate using the energy derived from light.

Rubisco

An enzyme that fixes carbon by attaching CO2 to ribulose bisphosphate (RuBP) in the Calvin Cycle.

C3 plants

Plants that fix carbon only using the Calvin Cycle, resulting in a 3-carbon compound as the first stable intermediate.

Photorespiration

A process where Rubisco attaches O2 instead of CO2, consuming energy and releasing carbon dioxide.

C4 Plants

Plants that use a different carbon fixation process to minimize photorespiration and optimize the Calvin Cycle.

CAM Plants

Plants that open their stomata at night to take in CO2 and store it as a 4-carbon compound for use during the day.

Climate Change

Long-term changes in global climate patterns, often resulting from increased greenhouse gas concentrations.

Photosynthetic Pigments

Molecules that absorb light at specific wavelengths; include chlorophyll a and b.

Light Reactions

The stage of photosynthesis that uses light to generate energy in the form of ATP and NADPH.

Quantum of energy

The fixed quantity of energy carried by photons, which is inversely related to the wavelength of light.

ATP Synthase

An enzyme that synthesizes ATP through a chemiosmotic gradient created during the light reactions of photosynthesis.