OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is the result of anaerobic respiration in animal cells?

1. Glucose and Oxygen

2. Lactic Acid

3. Carbon Dioxide and Energy

4. Ethanol

The correct answer is: Lactic Acid

In animal cells, the result of anaerobic respiration is the production of lactic acid. This process occurs when oxygen is in short supply, such as during intense physical activity. In the absence of oxygen, the body converts glucose into lactic acid to generate energy. This conversion allows cells to continue producing ATP, which is the energy currency needed for various cellular functions despite the lack of oxygen. Lactic acid accumulation can lead to muscle fatigue and discomfort; this is often experienced during strenuous exercise. When oxygen becomes available again, the lactic acid can be converted back to glucose through a process called gluconeogenesis, allowing the body to restore its energy stores. Thus, lactic acid is a key byproduct of anaerobic respiration in animals, highlighting how cells adapt their metabolic pathways to cope with varying oxygen levels.