Question

Photochemical phase of photosynthesis occurs in

• A. Stroma
• B. Grana
• C. Plastoglobules
• D. Matrix

Answer 1

The Correct Option is B

The photochemical phase of photosynthesis specifically occurs within the grana of chloroplasts.
Grana are like stacks of tiny pancakes found inside structures called chloroplasts. These stacks are made of layers called thylakoid membranes.
In the grana, there are special pigments like chlorophyll that absorb light energy from the sun. This absorbed light energy is used to start a process that creates energy molecules like ATP and NADPH. These energy molecules are crucial for plants to make food during photosynthesis.
So, in simple terms, the grana are where plants capture sunlight and start turning it into energy they can use.

So, the correct option is (B): Grana

Answer 2

Explanation: Grana are stacks of thylakoids within chloroplasts.

• These are prominent in eukaryotic algae and plants, playing a role in starch production. Intergrana thylakoids, or lamellae, connect these grana.
• The photochemical phase, also called the light reaction, occurs in the granal thylakoids. 

This phase involves several steps:

1. Light reaction, the initial stage, converts solar energy into chemical energy (ATP and NADPH).
2. Chlorophyll absorbs solar energy, transforming it into chemical energy in electron-carrying molecules.
3. Photosystems I and II, located in the chloroplast's thylakoid membrane, use light energy. 
4. Electrons are removed from PSII by splitting of water molecules.
5. Extracted electrons move from PSII to cytochrome, then to PSI, where they are reduced into energy. PS I energizes the electrons again.
6. The final step involves electron reduction to form NADPH and NADP+.