Photosynthesis

Photosynthesis definition

Reaction where light energy is used to produce glucose from carbon dioxide and water, releasing oxygen

Word equation for photosynthesis

Carbon dioxide + water -> glucose + oxygen

Balanced symbol equation

6CO2 + 6H2O -> C6H12O6 + 6O2

Stages of photosynthesis

Light dependent reaction and light independent reaction

Limiting factors of photosynthesis

Light intensity, carbon dioxide concentration, temperature

Site of photosynthesis

Chloroplast

Outer membrane function

Controls movement of substances into and out of chloroplast

Inner membrane function

Separates stroma from cytoplasm

Stroma definition

Fluid-filled space containing enzymes for the light independent reaction

Thylakoid definition

Flattened membrane sacs containing chlorophyll

Granum definition

Stack of thylakoids increasing surface area

Why grana increase efficiency

Large surface area for chlorophyll, enzymes and electron carriers

Role of chlorophyll

Absorbs light energy and excites electrons

Chloroplast DNA and ribosomes purpose

Allows synthesis of proteins needed for light dependent reactions

ATP synthase location

Granal (thylakoid) membrane

ATP synthase function

Synthesises ATP from ADP and Pi using proton gradient

Light dependent reaction location

Thylakoid membrane

Photoionisation definition

Light excites electrons in chlorophyll causing them to leave the molecule

Photosystem II role

Initial excitation of electrons and drives photolysis

Photolysis definition

Splitting of water using light energy

Photolysis products

Oxygen, protons, electrons

Fate of oxygen from photolysis

Diffuses out through stomata or used in respiration

Fate of electrons from photolysis

Replace electrons lost from chlorophyll

Fate of protons from photolysis

Contribute to proton gradient

Electron transport chain definition

Series of protein complexes electrons pass through

Purpose of electron transport chain

Releases energy to pump protons across membrane

Proton pumping direction

From stroma into thylakoid space

Photosystem I role

Re-excites electrons to a higher energy level

NADP role

Final electron acceptor

Reduced NADP formation

Electron combines with proton to reduce NADP

Proton gradient definition

Difference in proton concentration across membrane

High proton concentration location

Thylakoid space

Low proton concentration location

Stroma

Chemiosmosis definition

Diffusion of protons through ATP synthase

Photophosphorylation definition

Synthesis of ATP using energy from proton movement

Light independent reaction location

Stroma

Calvin cycle definition

Series of enzyme-controlled reactions producing sugars

Carbon fixation definition

CO2 combines with RuBP

RuBP definition

Five-carbon sugar that accepts CO2

Rubisco role

Catalyses carbon fixation

Unstable 6C compound outcome

Splits into two glycerate-3-phosphate molecules

Reduction phase definition

GP is reduced to triose phosphate

Inputs for reduction stage

Reduced NADP and ATP

Triose phosphate definition

Three-carbon sugar used to make glucose

Regeneration stage definition

Triose phosphate regenerates RuBP

ATP use in regeneration

Provides energy to reform RuBP

Organic molecule production

Two triose phosphates combine to form hexose sugars

Hexose sugar produced

Glucose

Number of Calvin cycle turns

6

CO2 molecules needed for one glucose

6

Overall purpose of light dependent reaction

Produce ATP and reduced NADP

Overall purpose of light independent reaction

Produce glucose using ATP and reduced NADP