Select all the components of the photosynthetic electron transport chain.
Multiple select question.
photosystem I
proton pump protein
rubisco
ribulose bisphosphate (RuBP)
enzyme that produces NADPH
photosystem II
The Correct Answer and Explanation is :
The correct components of the photosynthetic electron transport chain are:
- Photosystem I (PSI)
- Photosystem II (PSII)
- Proton pump protein
- Enzyme that produces NADPH
Explanation:
Photosynthesis is the process by which plants, algae, and certain bacteria convert light energy into chemical energy. The electron transport chain (ETC) is a crucial part of the light-dependent reactions of photosynthesis, which occur in the thylakoid membranes of chloroplasts. Below is an explanation of the correct components:
- Photosystem II (PSII):
PSII is the starting point of the photosynthetic electron transport chain. It absorbs light energy, which excites electrons to a higher energy level. These high-energy electrons are passed to the electron transport chain, while water molecules are split (photolysis) to replace the lost electrons, releasing oxygen as a byproduct. - Proton Pump Protein (Cytochrome b6f Complex):
This protein complex acts as a proton pump. As electrons move through the ETC, the energy released is used to pump protons (H⁺ ions) from the stroma into the thylakoid lumen, creating a proton gradient. This gradient drives ATP synthesis. - Photosystem I (PSI):
After passing through the cytochrome b6f complex, electrons reach PSI. PSI absorbs additional light energy to re-energize the electrons, which are then passed to the enzyme ferredoxin-NADP⁺ reductase (FNR). - Enzyme that Produces NADPH (Ferredoxin-NADP⁺ Reductase):
FNR uses the high-energy electrons from PSI to reduce NADP⁺ into NADPH. NADPH is an essential electron carrier used in the Calvin cycle for carbon fixation.
Why Not Rubisco or RuBP?
- Rubisco and Ribulose Bisphosphate (RuBP) are involved in the Calvin cycle, which is the light-independent phase of photosynthesis. They play no role in the electron transport chain, as their function is focused on carbon fixation and sugar production rather than light-dependent reactions.