Photosynthesis Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What is photosynthesis?
The process by which plants convert light energy into chemical energy, stored in glucose.
What is the importance of photosynthesis?
Photosynthesis provides energy for the plant and releases oxygen as a by product, necessary for aerobic respiration in other organisms.
Where does photosynthesis occur?
Chloroplasts of plant cells, within the thylakoid membranes and stroma.
Where does the light dependant reaction take place?
In the thylakoid membranes
What is the process of the light dependant reaction?
1) Light energy excites electrons in chlorophyll in PSII (photoionisation).
2) Photolysis of water occurs to replace these electrons, producing 4 electrons, 4 protons (H⁺ ions), and 1 oxygen molecule.
3) Excited electrons move down the ETC to PSI, releasing energy which pumps protons into the thylakoid lumen, creating a proton gradient.
4) Protons diffuse back through ATP synthase (chemiosmosis) , generating ATP.
5) Electrons from PSI reduce NADP to NADPH with protons from the stroma.
6) ATP and NADPH enter the light-independent reactions.
What is chemiosmosis?
The movement of hydrogen ions (protons) across the membrane via ATP synthase.
What is photolysis?
The process by which water molecules are split into oxygen, protons (H⁺ ions), and electrons using light energy.
What is photoionisation?
The process by which a molecule absorbs light energy (photons) and releases high-energy electrons (excites electrons) - electrons are lost.
Where does the light independent reaction take place?
Stroma.
What is another name for the light independent reaction?
The Calvin Cycle.
What is the process of the light independant reaction?
1) CARBON DIOXIDE FIXATION - Carbon dioxide combines with a 5C sugar known as ribulose bisphosphate (RuBP) - an enzyme called rubisco catalyses this reaction, forming 2 molecules of glycerate 3-phosphate (GP).
2) REDUCTION PHASE - Energy from ATP and hydrogen from reduced NADP are used to reduce glycerate 3-phosphate (GP) to a phosphorylated 3C sugar known as triose phosphate (TP).
3) REGENERATION OF RuBP - 5/6 of the triose phosphate (TP) molecules are used to regenerate ribulose bisphosphate (RuBP) - this process requires ATP
4) ORGANIC MOLECULE PRODUCTION - 2 molecules of triose phosphate can combine to form the intermediate hexose sugar fructose 1,6 bisphosphate where after it forms molecules of glucose.
How many turns of the Calvin Cycle are required to produce 1 molecule of glucose?
6.
What are the limiting factors for photosynthesis?
Temperature, light intensity, carbon dioxide concentration.
Which chemicals are needed for the light dependent reaction?
NADP, ADP, Pi, and water.
