Photosynthesis Flashcards
Describe the light dependent reaction
- Chlorophyll absorbs light energy & Excites electrons
- Chlorophyll loses electrons (Oxidation of chlorophyll) via photoionisation;
- Electrons move along electron transport chain releasing energy (Series of REDOX reactions)
- Energy released (by electrons) used to form proton gradient;
- H+ ions move through ATP synthase;
- providing energy to join ADP and Pi to form ATP;
- Photolysis (occurs in thylakoid space) of water produces 2 protons, 2 electrons and ½ oxygen (replace e- lost during photoionisation)
- NADP reduced by electrons and protons
Describe the light independent reaction (Calvin Cycle)
- Carbon dioxide combines with ribulose bisphosphate/RuBP (5C)
- Produces two glycerate (3-)phosphate/GP;
- GP reduced to triose phosphate;
- Using reduced NADP;
- Using energy from ATP;
- Triose phosphate converted to glucose/RuBP/ other named organic substance;
ATP is produced in the light dependant reaction, suggest why this is not their (plants) only source of ATP.
- Plants don’t photosynthesis in the dark;
- Not all the parts (e.g. roots) of the plants photosynthesise;
- Plants require more ATP than is produced in the light dependant reaction;
- ATP used in Active Transport (accept other named processes)
Describe the effect of introducing a herbicide/inhibitor on the electron transport chain
- Reduced transfer of protons across thylakoid membrane
- (So) less ATP produced;
- (So) less reduced NADP produced;
- (So) light-independent reaction rate decreases
- Less reduction of GP to triose phosphate;
Describe what happens during PHOTOIONISATION in the light dependent reaction.
- Chlorophyll absorbs light, excites electrons
- Electrons are lost
Role of ATP
- provides energy for active transport/ muscle contraction
- releases energy in small amounts
- one step
- makes energy available rapidly
- phosphorylates
- reformed
Where does photolysis occur
thylakoid space
Fluorescence
excited e- cannot lose energy via the ETC so releases the energy as light or heat
When producing a chromatogram explain why the origin is marked using a pencil rather than ink.
- Ink and (leaf) pigments would mix OR (With ink) origin/line in different position
OR - (With pencil) origin/line in same position OR (With pencil) origin/line still visible;
While making a chromatogram, describe the method used to separate the pigments after the solution of pigment had been applied to the origin.
- Level of solvent below origin/line;
- Remove/stop before (solvent) reaches to end
Suggest and explain the advantage to plants of having different colour pigments in leaves.
- Absorb different/more wavelengths of light for faster rates of photosynthesis;
Name the two products of the light-dependent reaction that are required for the light-independent reaction.
- ATP;
- Reduced NADP;
Where precisely is rubisco found in a cell?
Stroma
Explain why scientists measure the rate of production of oxygen in this investigation. (Rate of photosynthesis)
- Oxygen produced in light-dependent reaction;
- The faster (oxygen) is produced, the faster the light-dependent reaction.
Explain why plants that have more chlorophyll will grow faster than plants with less chlorophyll.
- Have faster production of ATP and reduced NADP;
- (So) have faster / more light-independent reaction;
- (So) produce more sugars that can be used in respiration;
- (So) have more energy for growth;
- Have faster / more synthesis of new organic materials.
