What do humans and animals primarily depend on for survival?

Humans and animals primarily depend on plants for survival due to the essential roles they play in ecosystems, particularly through the process of photosynthesis. Plants take in carbon dioxide and release oxygen, which is crucial for the respiration of humans and animals. This process not only sustains the atmospheric oxygen levels necessary for life but also forms the base of the food chain. Plants serve as the primary producers that convert sunlight into energy, which is stored in the form of carbohydrates, providing food for herbivores. Those herbivores, in turn, are consumed by carnivores, thus ensuring a flow of energy through the ecosystem.

Furthermore, plants contribute to various ecological functions such as producing food, providing habitat, and maintaining soil health, which are vital for the overall stability of the environment that humans and animals depend on. While water is essential for life, as humans and animals need it for hydration and many physiological processes, it is the plants that ultimately generate the oxygen and organic matter necessary for sustained survival.