When a kettle is placed on the stove and water begins to boil, the hotter water at the bottom begins to rise and the cooler water above it begins to sink. what type of heat transfer does this situation represent?

This motion is caused by convection. It is the movement only by fluid. It happens because hotter fluid expands, making it less dense, therfore it rises. Meanwhile cooler fluid contracts, making it denser, resulting in sinking. That's why a convection current is created.

This is processs of convection

During photosynthesis, plants transform electromagnet energy from the sun into chemical energy.

I'm pretty sure the answer is alcohol