Student Response | Pivot Interactives

Photosynthesis

The biological process by which autotrophic organisms convert light energy into chemical energy stored in glucose.

Overall Chemical Equation for Photosynthesis

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

Chloroplast

The membrane-bound organelle in plant and algal cells where photosynthesis takes place.

Thylakoid

A flattened, membrane-bound sac inside the chloroplast where the light-dependent reactions occur.

Granum

A stack of thylakoids within a chloroplast.

Stroma

The dense fluid-filled space surrounding thylakoids inside the chloroplast where the Calvin cycle takes place.

Chlorophyll

The primary green pigment in plants that absorbs light energy to drive photosynthesis.

Autotroph

An organism that produces its own organic food molecules from inorganic substances using light or chemical energy.

Heterotroph

An organism that obtains organic food molecules by consuming other organisms or their organic byproducts.

Light-Dependent Reactions

The initial stage of photosynthesis that converts light energy and water into $ATP$, $NADPH$, and oxygen gas ($O_2$).

Calvin Cycle (Light-Independent Reactions)

The metabolic process in the stroma that uses $ATP$ and $NADPH$ to synthesize sugar from carbon dioxide ($CO_2$).

Photosystem II (PSII)

The first protein complex in the light-dependent reactions that absorbs light energy to split water molecules into oxygen, protons, and electrons.

Photosystem I (PSI)

The protein complex in light-dependent reactions that absorbs light energy to re-energize electrons for reducing $NADP^+$ to $NADPH$.

Photolysis

The light-driven reaction that splits water molecules into oxygen gas, electrons, and hydrogen ions.

ATP Synthase

An membrane enzyme that synthesizes $ATP$ from $ADP$ and inorganic phosphate driven by a proton gradient.

NADP^+

An electron carrier molecule that accepts high-energy electrons and a hydrogen ion to form $NADPH$.

NADPH

An energy-carrying molecule produced in light reactions that provides reducing power for sugar synthesis in the Calvin cycle.

RuBisCO

Ribulose-1,5-bisphosphate carboxylase-oxygenase; the primary enzyme that catalyzes carbon fixation in the Calvin cycle.

RuBP (Ribulose 1,5-bisphosphate)

A 5-carbon sugar molecule that combines with $CO_2$ during the initial step of the Calvin cycle.

G3P (Glyceraldehyde 3-phosphate)

A 3-carbon sugar intermediate produced in the Calvin cycle used to construct glucose and other organic compounds.

Stomata

Microscopic pores on leaf surfaces that regulate gas exchange of $CO_2$, $O_2$, and water vapor.

Carbon Fixation

The conversion process of inorganic carbon ($CO_2$) into organic compounds by living organisms.

Photophosphorylation

The production of $ATP$ from $ADP$ using light energy absorbed during photosynthesis.

Absorption Spectrum

A spectrum showing the specific wavelengths of light absorbed by pigments such as chlorophyll.

Primary Role of Water in Photosynthesis

Water serves as the electron donor to replace excited electrons in Photosystem II, releasing oxygen gas as a byproduct.