It is believed that chloroplasts were once independent prokaryote cells that moved into larger eukaryote cells long ago. Chloroplasts are tiny and green, and they contain chlorophyll. They reproduce themselves inside cells by simply dividing into two identical parts. Well, let's think for a minute. Plants are made mostly out of carbohydrates.
Carbon is a very important component of plant tissues.
Chloroplasts capture the energy from the sun and also capture the carbon dioxide molecules in the air. They make food for the plant and for whatever animal eats that plant. Well, they have the air. There is carbon in the air in carbon dioxide. There is also water in the ground and light from the sun.