AP BIOLOGY

PHOTOSYNTHESIS

LIGHT DEPENDENT REACTIONS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
How do electrons get from PS II to PS I?
A
They diffuse from high to low
B
they follow the ATP synthase channel
C
they follow the ETC
D
NADP+ guides them
Explanation: 

Detailed explanation-1: -The electrons must travel through special proteins stuck in the thylakoid membrane. They go through the first special protein (the photosystem II protein) and down the electron transport chain. Then they pass through a second special protein (photosystem I protein).

Detailed explanation-2: -From photosystem II, electrons are carried by plastocyanin (a peripheral membrane protein) to photosystem I, where the absorption of additional photons again generates high-energy electrons. Photosystem I, however, does not act as a proton pump; instead, it uses these high-energy electrons to reduce NADP+ to NADPH.

Detailed explanation-3: -Photosystem II is the first link in the chain of photosynthesis. It captures photons and uses the energy to extract electrons from water molecules.

Detailed explanation-4: -In (a) photosystem II, the electron comes from the splitting of water, which releases oxygen as a waste product.

Detailed explanation-5: -To replace the electron in the reaction center, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O2) and hydrogen ions (H+) in the thylakoid space.

There is 1 question to complete.