The earth is an almost closed system. Atoms do not wear out, but chemical changes require energy. Energy eventually gets transformed into heat and lost. Fortunately for us, the earth does receive energy from the sun, which comes into our closed system and makes life possible. Plants are the primary producers on earth.
Plant cells contain chloroplasts, which work as tiny energy capturing factories.
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.