IB Photosynthesis (HL)

light-dependent reactions

reactions that use energy from light to produce ATP and NADPH.

light-independent reactions

reactions that fix carbon-dioxide to compounds to form glucose

action spectrum

A diagram that shows the amount of photosynthesis occurring at the different visible wavelengths of the electromagnetic spectrum

absorption spectrum

Diagram showing the amount of light absorbed by photosynthetic pigments at different wavelengths of the Electromagnetic Spectrum

photosynthesis equation

6CO2 + 6H2O ------> C6H12O6 + 6O2

chlorophyll

The green pigment inside a thylakoid's photosystems that activates from light energy - however cannot absorb green light.

photosystem II

One of two light-harvesting units of a chloroplast's thylakoid membrane

ATP

Produced when ATP synthase uses H+ ions flowing from the high thylakoid concentration to low concentrated stroma during the Light Dependent reactions.

ADP

Converted to ATP with the help of ATP synthase

NADPH

Reduces GP to TP during the Calvin cycle. Carries H+ and e- from Light dependent to Light Independent reactions.

NADP+

Accepts e- from the end of the ETC and excess H+ in order to make NADPH for the light independent reactions

H+

Ions are pumped by active transport into the small thylakoid space and flow through ATP synthase provide ATP for photosynthesis.

thylakoid

Area where light-dependent reaction occurs, and is arranged in stacks in the chloroplast.

stroma

inside the chloroplast - the location of Calvin Cycle enzymes

thylakoid space

small space bound by the membrane of the thylakoid organelle where H+ concentration is built for ATP production

e-

Energized by sunlight absorption. Comes from photolysis of water;

water

the source of oxygen, H+, and e- in the light-dependent reactions

photolysis

The splitting of water molecules to replenish e- to photosystem II

oxygen

produced during the light dependent reaction as a bi-product of photolysis

rubisco

The enxyme that catalyzes the reaction of carbon fixation of carbon dioxide and RuBP

RuBP

Starting molecule of the Calvin Cycle / iight-independent reaction, combines with CO2 during fixation and is regenerated from TP

Carbon dioxide

Increases in this limiting factors increases the collisions of enzymes and substrate, increasing the rate of photosynthesis until it reaches a maximum rate / plateaus due to the enzyme Rubisco's saturation

TP

A molecule that is generated through the Calvin Cycle when GP gains electrons (is reduced) with NADPH and ATP.

reduction

Gain of electrons and H+

Limiting factor

Factor that is responsible for decreasing the maximum rate of photosynthesis.

temperature

Increases in this limiting factors increases the collisions of enzymes and substrate, increasing the rate of photosynthesis. Increases beyond optimum can denature enzymes, decrease photosynthesis.

light intensity

One of the limiting factors; when this is poor, there is a shortage of ATP and NADPH. Without these products, the light independent reactions can't occur as GP cannot be reduced.

NADP+ reductase

Enzyme that reduces NADP+ to NADPH

ATP synthase

Large protein that uses energy from H+ ions flowing from high to low to bind ADP and a phosphate group together to produce ATP