Photosynthesis and Exam Preparation Notes

Photosynthesis

The process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose.

Photosystem II (PSII)

The first protein complex in the light-dependent reactions of photosynthesis that absorbs light and initiates the electron transport chain.

P680

A chlorophyll molecule in Photosystem II that absorbs light most effectively at a wavelength of 680 nm.

Electron Transport Chain (ETC)

A series of protein complexes and other molecules that transfer electrons through a membrane, generating a proton gradient that drives ATP synthesis.

Photosystem I (PSI)

The second protein complex in the light-dependent reactions that absorbs light to generate NADPH.

ATP Synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate using the energy from the proton gradient.

NADPH

A reducing agent that provides the high-energy electrons for the Calvin cycle, created during the light-dependent reactions.

Calvin Cycle

The set of light-independent reactions in photosynthesis that occur in the stroma, utilizing ATP and NADPH to convert CO₂ into glucose.

Rubisco

An enzyme that catalyzes the first step of carbon fixation in the Calvin cycle by fixing CO₂ to ribulose bisphosphate (RuBP).

Photorespiration

A process in plants where Rubisco fixes oxygen instead of carbon dioxide, leading to a less efficient photosynthetic process.

C3 Plants

Plants that exclusively use the Calvin cycle for CO₂ fixation, exemplified by rice and wheat.

C4 Plants

Plants that use an alternative pathway to minimize photorespiration, exemplified by corn and sugarcane.

CAM Plants

Plants that open their stomata at night and close them during the day to reduce water loss, such as cacti and jade plants.

G3P

Glyceraldehyde-3-phosphate, a three-carbon sugar produced in the Calvin cycle and used to form glucose.

Six Turns of the Calvin Cycle

The number of turns needed to produce one glucose molecule during photosynthesis.