AQA GCSE Biology Paper 1 2026 – 400 Free Practice Questions to Pass the Exam

During intense physical activity, the body relies on anaerobic respiration when oxygen levels are insufficient. This process results in the production of lactic acid in muscles, which can lead to fatigue. Once the activity ceases, lactic acid is transported to the liver. In the liver, lactic acid undergoes a process called gluconeogenesis, where it is converted back into glucose. This newly formed glucose can be either released into the bloodstream to be utilized by the body for energy or stored as glycogen for later use.

The conversion of lactic acid back to glucose is vital because it helps to replenish the energy reserves of the body and prevents potential acidosis that can occur from accumulating lactic acid. This metabolic pathway illustrates the body's ability to restore balance and manage energy efficiently following strenuous exercise.

Thus, the correct answer illustrates the key physiological process that ensures the body can recover and prepare for future energy demands.