Question

In photosynthesis, light-independent reactions take place at
A. Thylakoid lumen
B. Photosystem I
C. Photosystem II
D. Stromal Matrix

Answer 1

Hint: The light reaction is also known as photolysis reaction which occurs in the presence of light. It usually occurs or takes place in the grana (sing: granum) of the chloroplast.

Step by step answer:The light reaction is a process in photosynthesis which converts energy received from the sun into chemical energy in the form of ATP and NADPH. It includes a series of reactions like absorption of light, hydrolysis, and oxygen is released, the formation of NADPH and ATP.
Photosystems have the pigment molecules for light reactions. In plants, chlorophyll is considered to be the active pigment which takes place in light reactions in photosynthesis. The accessory pigment is carotenoid. Now the energy from the sun is absorbed by the chlorophyll which is present in the thylakoid membrane of the chloroplast. The light reactions occur in this thylakoid membrane which is a part of the chloroplast. The electron transfer chain generates energy for ATP and NADPH production. During this process, water and oxygen are released. Light energy is used in both photosystems I and photosystem II present in the thylakoid membrane. When the light hits chlorophyll-a gets excited because of the photolysis of water to hydrogen ion and oxygen. Leading to a series of reactions. By the end of the reaction, NADP is converted to NADPH and ADP to ATP as mentioned earlier.
Hence option A is correct.

Note: In light-dependent reaction energy from the sun is trapped and converted into chemical energy in the form of NADPH and ATP which are later used in dark reactions. Also, oxygen here released is a waste product.