HL questions

light: affects the light-dependent stage; at low intensities insufficient ATP; and insufficient NADPH + H+ produced; this stops the Calvin cycle operating (at maximum rate); temperature: affects light-independent stage / Calvin cycle; temperature affects enzyme activity; less active at low temperatures / maximum rate at high temperatures; but will then be denatured (as temperature rises further);

chemiosmosis is synthesis of ATP coupled to electron transport and proton movement photophosphorylation is the production of ATP with energy from light light energy causes photolysis/splitting of watter electrons energized (from chlorophyll)/photoactivation photolysis provides (replacement) electrons for those lost from excited chlorophyll photolysis provides protons/H+ (for thylakoid gradient) electron transport (carriers on membrane of thylakoid) causes pumping of protons/H+ across thylakoid membrane/ into thylakoid space protons/H+ accumulate in thylakoid space/proton gradient set up protons/H+ move down concentration gradient into stroma flow through ATPase/synthetase leading to ATP formation

• Explain why the light-independent reactions of photosynthesis can only continue for a short time in darkness. 6 mark light independent reaction involve ATP/NADPH + H+ / intermediates which are made in light dependent reactions supply of ATP/NADPH + H+ / intermediates used up / runs out in the dark ATP and NADPH + H+ GP therefore not reduced / converted to triose phosphate RuBP therefore not regenerated carbon dioxide fixation therefore stops GP accumulates stomata close in the dark carbon dioxide is therefore not absorbed

water is a substrate / reactant / raw material / for photosynthesis / equation for photosynthesis water is a source of electrons to replace those lost by chlorophyll / photosystem II water is a source of H+ needed to produce NADPH + H+ photolysis / splitting / breaking of water water for non-cyclic photophosphorylation / ATP production

Autotrophs are known as producers because they are able to make their own food from raw materials and energy. Examples include plants, algae, and some types of bacteria. Heterotrophs are known as consumers because