Chapter7

Photosynthesis

The process by which organisms use light energy to build high-energy organic molecules.

Autotrophs

Organisms that can make their own food using light; includes plants, algae, and some bacteria.

Heterotrophs

Organisms that eat autotrophs to obtain energy.

Chloroplasts

Organelles in plant cells where photosynthesis occurs.

Chlorophyll

The pigment found in chloroplasts that captures light energy for photosynthesis.

Thylakoids

Membranous sacs within chloroplasts where light-dependent reactions occur.

Granum

A stack of thylakoids in chloroplasts.

Stroma

The fluid-filled space in chloroplasts where light-independent reactions occur.

Light-dependent reactions

Reactions in photosynthesis that use light energy to make ATP and NADPH.

Light-independent reactions

Reactions that use ATP and NADPH to convert carbon dioxide into glucose.

RuBisCO

An enzyme that combines carbon dioxide with ribulose in the Calvin cycle.

Glyceraldehyde-3-phosphate

A 3-carbon molecule formed in the light-independent reactions, used to make sugars and other molecules.

Electron transport chain

A series of proteins in the thylakoid membrane that facilitate the transfer of excited electrons to produce ATP.

ATP synthase

An enzyme that uses a proton gradient to synthesize ATP from ADP.

Calvin cycle

Also known as the dark reactions; a series of light-independent reactions in photosynthesis.

Pigments

Molecules that absorb specific wavelengths of light, reflecting others.

Photosystems

Structures in the thylakoid membranes that capture light energy.

Photon

A packet of light energy that excites electrons in pigment molecules.

Carbon fixation

The process of converting CO2 into organic molecules during the Calvin cycle.

Vascular bundles

Structures in leaves that contain xylem and phloem, facilitating transport.

Mesophyll

The tissue in leaves where photosynthesis primarily occurs.

Cuticle

A waxy layer on leaf surfaces that helps reduce water loss.

Epidermis

The outer layer of cells on leaves that provide protection.