Photosynthesis and Pigments

Flashcards covering key concepts, terms, and processes related to photosynthesis and pigment functions in plants.

Photosynthetic pigments

Molecules that absorb light most efficiently at specific wavelengths, allowing organisms to capture more energy from the Sun.

Chlorophyll a and b

Pigments that absorb red light (650-700 nm) and blue light (400-450 nm), reflecting green light (500-550 nm).

Carotenoid pigments

Pigments that absorb blue light (400-450 nm) and reflect red, orange, and yellow (550-700 nm), giving plants like carrots, pumpkins, and tomatoes their color.

Absorption spectrum

Measures which wavelengths of light are absorbed by chlorophyll pigments.

Action spectrum

Measures the rate of photosynthesis occurring at specific wavelengths.

Photoactivation

The process by which two electrons in the chlorophyll molecule become excited due to absorption of light energy, leading to ionization of the chlorophyll.

Electron transport chain (ETC)

A series of electron carriers through which excited electrons from chlorophyll pass, releasing energy used to pump H+ ions.

Cyclic photophosphorylation

A process where excited electrons return to photosystem I, producing ATP without the reduction of NADP or photolysis of water.

Non-cyclic photophosphorylation

A process where electrons from photosystem II produce ATP and reduced NADP, requiring the photolysis of water.

Calvin cycle stages

The three stages of the light-independent stage: fixation of carbon dioxide, reduction, and regeneration.

Limiting factor

A factor that limits the rate of a reaction (e.g., photosynthesis), often because it is in short supply.

DCPIP

A redox indicator that, when reduced by H+ ions from photolysis of water, turns from blue to colorless.

Chloroplast structure adaptations

Thylakoid membranes provide a large surface area for light absorption; double membrane is permeable to gases; thylakoid space accommodates H+ ions.