Question

Photosystem I and II work together to transfer electrons from which molecule to which other?

A. Water to NADPH

B. Glucose to NADP+

C. Glucose to Water

D. ADP to ATP

Answer 1

EXPLANATION

First let us understand what is photosystem ?

In plant Photosynthesis process occur which convert light energy into chemical energy and by the process of photosynthesis plant make food.

Light energy initiates the process of photosynthesis when pigments absorb the light. Light energy is converted into chemical energy in a multiprotein complex called a photosystem.

Two types of photosystems, photosystem I (PSI) and photosystem II (PSII), are found in the thylakoid membrane inside the chloroplast.

Each photosystem consists of multiple antenna proteins that contain a mixture of 300–400 chlorophyll a and b molecules, as well as other pigments like carotenoids. Cytochrome b6f complex and ATP synthase are also major protein complexes in the thylakoid membrane that work with the photosystems to create ATP and NADPH.

The two photosystems absorb light energy through proteins containing pigments, such as chlorophyll. The light-dependent reactions begin in photosystem II.

In PSII, energy from sunlight is used to split water, which releases two electrons, two hydrogen atoms, and one oxygen atom. When a chlorophyll a molecule within the reaction center of PSII absorbs a photon, the electron in this molecule attains a higher energy level. Because this state of an electron is very unstable, the electron is transferred to another molecule creating a chain of redox reactions called an electron transport chain (ETC). The electron flow goes from PSII to cytochrome b6f to PSI; as electrons move between these two photosystems, they lose energy. Because the electrons have lost energy prior to their arrival at PSI, they must be re-energized by PSI. Therefore, another photon is absorbed by the PSI antenna. That energy is transmitted to the PSI reaction center. This reaction center, known as P700, is oxidized and sends a high-energy electron to reduce NADP+ to NADPH. so in whole process electron Flow from water to NADP+ which can be explained by Z scheme for photosynthetic electron flow from water to NADP+

The electron transport carriers are placed in series on a scale of midpoint potentials. The reaction center P680 take an electron from tyrosine Tyr Z, which obtains an electron from water via the four manganese ions. On the acceptor side of PS II, the pheophytin (Pheo) reduces the primary acceptor, Q A , which is a plastoquinone molecule bound to a protein. Two electrons are sequentially transferred from Q A to the secondary acceptor Q B. The reduced plastoquinone is oxidised by the cyt b 6 /f complex. Plastocyanin (PC) carries one electron to the reaction centre of PSI, P700. On the acceptor side of PS I, the electron is passed through a series of carriers to ferredoxin, resulting finally in the reduction of NADP to NADPH so final acceptor of electron is NADP+ and first electron donar is water

So we can easily eliminate option a ,b ,c and d as electron is transfered from water to NADP+ so none of the option is correct

option a will be correct if in place of NADPH ,NADP+ is given so i think there is correction in this option

Triazines Pheorylureas Uracis Dipyridylliums P680 NADP++ POH Energy (V) NADPH +0.44 Photolysis DEMIE Reaction center (P700) Light PSI +0.8- 2H+02 Reaction center (P680) PSTI