The element crucial for the respiration process in animals and plants is oxygen. In aerobic respiration, cells utilize oxygen to convert glucose into energy (ATP), carbon dioxide, and water. This process is vital for the survival of most organisms, as it supports cellular activities and metabolism. In plants, oxygen is released as a byproduct of photosynthesis, contributing to the oxygen supply necessary for animal life. Thus, oxygen serves as a fundamental element in the interdependence of life forms.