Question

While one type of electron transport chain is used to form molecules of ATP (photosystem II), a second electron transport chain (photosystem I) is used?

1) in forming molecules of NADPH
2) to migrate to another proton pump
3) to produce water
4) as a fuel for forming another chlorophyll molecule

Answer 1

Photosystem I is primarily responsible for the formation of NADPH by using the energy from electrons transported by the electron transport chain and additional energy from absorbed photons.

Step-by-step explanation:

In the process of photosynthesis, photosystems located within the thylakoid membranes of chloroplasts are responsible for absorbing light and converting it into chemical energy. Photosystem II (PSII) captures photons and uses their energy to extract electrons from water molecules. These electrons are then passed along an electron transport chain (ETC) to Photosystem I (PSI). In PSI, the electrons are re-energized by absorbing another photon.

This added energy allows the electrons to reduce NADP+ to NADPH, which is an energy carrier molecule that, along with ATP generated by PSII, is used in the Calvin cycle to synthesize glucose from CO2. Thus, the primary function of Photosystem I is to assist in the formation of NADPH, which is essential for the light-independent reactions.