What is the primary product of anaerobic respiration in animals?

In animals, the primary product of anaerobic respiration is lactic acid. Anaerobic respiration occurs when oxygen levels are insufficient for aerobic respiration, often during intense exercise when muscle cells require energy but cannot receive enough oxygen to produce ATP efficiently.

During this process, glucose is broken down without the use of oxygen, resulting in the production of lactic acid. This conversion is essential for generating energy quickly in the absence of oxygen, albeit less efficiently than aerobic respiration. The accumulation of lactic acid in the muscles can lead to fatigue and discomfort, which is why athletes often experience a burning sensation during strenuous activities.

Glucose, while utilized in the process, is not the primary product—it's the substrate for anaerobic respiration. Carbon dioxide is produced in aerobic respiration but not as a primary product in the anaerobic pathway. Oxygen is not produced in anaerobic respiration, as it is the very limitation that defines this form of energy production. Thus, lactic acid stands out as the principal byproduct of anaerobic respiration in animals.