CBSE Class 10 Answered

Cells require carbon-based food sources from the environment to get energy. They break this food into water and carbon dioxide. (Cells can actually use many different types of food; the food just needs to be carbon based.)

Cells release energy from food through the process of cellular respiration. There are three steps to cellular respiration: glycolysis, the krebs cycle (also called the citric acid cycle), and the electron transport chain.

In glycolysis, the cell turns the carbon-based food source into ATP (adenosine 5 triphosphate) for energy and other byproducts. The second step in cellular respiration is Krebs cycle, whereby carbon molecules are converted into ATP, water and CO2

Since cells can only break down carbon-based food (via cellular respiration) to release energy, the food sources are carbon-based.