You could say your favorite food is steak which is part of a cow. What do cows eat to survive and sustain themselves? Grass. Grass is a plant that uses photosynthesis, which requires sunlight, carbon dioxide, and oxygen to synthesize carbohydrates. These carbohydrates are broken down further for the plant to use in cellular respiration. The cow eats these plants and matter/energy is transferred from plant to cow, and from steak to you when u ingest it