Question

Raw materials required for light reactions are
A)ADP and $H_2O$
B)ADP, $H_2O$ and NADP
C)ADP and $NADPH_2$
D)ATP and NADP.

Answer 1

Light reaction is the first stage of photosynthesis process in which solar energy is converted into chemical energy in the form of ATP and NADPH. The protein complexes and also the pigment molecules which are present in them assist in the production of NADPH and ATP.

Complete answer:
The process of light reaction is takes place by the following processes
1.In light reactions, energy from the sunlight is absorbed by the pigment chlorophyll and is converted into chemical energy in the form of electron charge carrier molecules such as NADPH and ATP.
2.Light energy is utilized in both the Photosystems I and II, present inside thylakoid membranes of the chloroplasts.
3.The carbohydrate molecules are obtained from the carbon dioxide from the use of chemical energy gathered during the reactions.
4.The Light energy tends to split into the water and later extracts the electrons from the photosystem II. Then the electrons move from the PSII to b6f that is cytochrome to the photosystem I which is also called the PSI and reduce in the form of energy.
5.The electrons are re-energized in the Photosystems I and the electrons of high energy reduce NADP+ into NADPH.
6.In the process of non-cyclic photophosphorylation, the cytochrome uses the electron energy from Photosystem II to pump the ions of hydrogen from the lumen to stroma; later, this energy give permission for the ATP synthase to bind to third phosphate group into the ADP molecule, which inturn forms the ATP.
7.In the process of cyclic photophosphorylation, the cytochrome b6f uses electron energy from both the Photosystems I and II to create a number of ATP and stops the production of the NADPH, by this way maintaining the right quantities of ATP and NADPH.

The light reactions assist the light energy to drive the transport of electrons and also the pumping of the proton which in turn convert the energy from the light to the biologically useful form as ATP and gives out a usable source of reducing the power NADPH.

Hence, the correct answer is option (A)

Note: The general function of light dependent reactions include the following . The first step of photosynthesis is to convert solar energy to chemical energy in the form of NADPH and ATP which are then used in light independent reactions and then fuel the assembly of sugar molecules.