Photosynthesis: Practice Questions

• a.

  Triose phosphate (TP)

• b.

  Glycerate 3-phosphate (GP)

• c.

  Rubisco

• d.

  Ribulose bisphosphate (RuBP)

• a.

  Glycerate 3-phosphate (GP) is transported from the stroma to the thylakoid membranes to be phosphorylated by ATP.

• b.

  ATP produced in the stroma is used to provide the energy for the photolysis of water in the thylakoid space.

• c.

  Reduced NADP produced in the thylakoid space is used by rubisco to fix carbon dioxide in the stroma.

• d.

  ATP and reduced NADP produced in the thylakoid membranes are used to reduce glycerate 3-phosphate (GP) in the stroma.

• a.

  Photoactivation of chlorophyll in photosystem II (PSII) releases electrons that cycle back to PSII after generating ATP through an electron transport chain. Protons are actively transported from the thylakoid space to the stroma, creating a gradient that drives \( \text{NADP}^+ \) reduction.

• b.

  Electrons are released from the photolysis of water by the oxygen-evolving complex, replacing those lost from photosystem II (PSII). These electrons pass along an electron transport chain, releasing energy that pumps protons from the stroma into the thylakoid space. The protons then diffuse back into the stroma through ATP synthase, generating ATP. Finally, the electrons from photosystem I (PSI), which are replenished by electrons from PSII, combine with protons and \( \text{NADP}^+ \) to form reduced NADP.

• c.

  Photosystem I (PSI) absorbs light energy and excites electrons, which are then passed along an electron transport chain. The energy released is used to pump protons across the thylakoid membrane, leading to ATP synthesis. These electrons then reduce \( \text{NADP}^+ \) to reduced NADP, while new electrons are continually supplied from the stroma.

• d.

  Photosystem I (PSI) is responsible for all ATP production, while photosystem II (PSII) is solely involved in reducing \( \text{NADP}^+ \). Water molecules are split to provide protons for both ATP synthesis and \( \text{NADP}^+ \) reduction directly.

• a.Light-dependent stage: stroma; Light-independent stage: cytoplasm
• b.Light-dependent stage: thylakoids; Light-independent stage: stroma
• c.Light-dependent stage: thylakoids; Light-independent stage: thylakoid space
• d.Light-dependent stage: stroma; Light-independent stage: thylakoids

• a.

  the reduction of glycerate 3-phosphate (GP) to triose phosphate (TP)

• b.

  the splitting of water to release oxygen and electrons

• c.

  the regeneration of ribulose bisphosphate (RuBP) from triose phosphate (TP)

• d.

  the fixation of carbon dioxide by ribulose bisphosphate (RuBP)

Write your answer out first, then check it against the worked solution.

Write your answer out first, then check it against the worked solution.

Write your answer out first, then check it against the worked solution.

Write your answer out first, then check it against the worked solution.