10% These light and heat energy are then used for photosynthesis and other cell processes.Plant can go through photosynthesis because they contain chloroplasts. A chloroplast is an organelle found only in plant cells and which enables photosynthesis to occur.Insides chloroplasts, there are found structures called thylakoids also known as grana or stroma. It is these thylakoids that contain chlorophyll, the green pigment that helps capture light energy from the sun which provides the fuel to run the first stage of photosynthesis.