Answer: Chlorophyll which are enclosed in the thylakoids captures light energy from the sun. Because of this chlorophyll becomes excited and vibrates and releases free electrons. Because of this vibrations water molecule is also split into H and O2 molecules due to photolysis the splitting of water. Oxygen gas is released out of the leaf as the by product of photosynthesis and H is added to NADPH.
3. In the photosynthetic process under light reaction the plant takes in carbon dioxide and water to produce NADPH and ATP
For plants under dark reaction it occurs in the stroma the outer part of the thylakoids. Since there is no light energy during night time the cell uses ATP and NADPH to fix CO2 to produce sugar molecules and other organic molecules for cell metabolism. The dark reaction cannot function without the products formed under light reaction.
4. The actual or approximate size of an organelle is important because it is an indicator for cellular metabolism such as absorption of food. Larger organelles requires more amount of space inside a cell compared to smaller organelles. Also it requires more energy to sustain cellular activities for much bigger cell organelles compared to smaller ones.
This is actually not a question. You are going to have to re-read it. If you are asking it as a question it will look like this: "When a rigid body rotates about a fixed axis, do all the points in the body have the same angular acceleration?"
