Final answer:
Animals and humans need to eat food to obtain energy, supply building materials, and maintain homeostasis. The energy is primarily used in the form of glucose, which is converted into ATP through cellular respiration. Food also provides the necessary nutrients for growth, repair, and bodily functions.
Step-by-step explanation:
Why Animals, Including Humans, Need to Eat Food
Animals, like humans, need to eat food primarily to obtain energy. The process of eating and digesting food allows us to extract glucose from what we consume. This glucose is then used in a process known as cellular respiration, which converts the energy stored in glucose molecules into adenosine triphosphate (ATP), the usable form of energy for cells. Besides providing energy, food supplies the essential building materials needed for the body to grow and repair itself. Moreover, eating food helps in maintaining homeostasis, the regulation of a stable internal environment within the body, like keeping a consistent body temperature regardless of external conditions.
Plants generate energy differently through photosynthesis, using light energy from the sun, while animals must consume plants or other animals to get their energy. Other organisms such as fungi extract energy from rotting organic matter. In humans and animals, the necessity of food goes beyond just energy; it also includes getting the necessary building blocks for bodily functions and materials for cellular production and maintenance.