Plants are called producers because they make their own food through the process of photosynthesis. plants use carbon dioxide from the air and to convert solar energy into chemical energy called glucose.

Plants take in water, carbon dioxide, and sunlight and turn them into glucose and oxygen. Called photosynthesis, one of the results of this process is that carbon dioxide is removed from the air. It is nature's process for returning carbon from the atmosphere to the earth.

I believe the answer would be sunlight.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."