The type of cellular respiration that occurs in the absence of oxygen is known as anaerobic respiration. This process allows organisms to generate energy in environments without oxygen by converting glucose into energy-rich molecules like ATP. Anaerobic respiration produces byproducts such as lactic acid in animals or ethanol and carbon dioxide in yeast. While less efficient than aerobic respiration, anaerobic processes enable organisms to survive in oxygen-deprived environments, showcasing the adaptability of life under varied conditions.