Assessment and Qualifications Alliance (AQA) GCSE Biology Paper 1 Practice Exam

The removal of carbon dioxide from the blood primarily occurs during increased respiration, which is closely linked to metabolic activity in the body. When the body engages in increased respiration, such as during physical activity or exercise, cells require more energy, leading to higher rates of aerobic respiration. This process produces more carbon dioxide as a waste product, which must be transported back to the lungs for exhalation.

As respiration increases, the rate of circulation also intensifies, helping to transport carbon dioxide more efficiently from tissues to the lungs. Therefore, under conditions of increased respiration, the body is more effective at removing carbon dioxide from the blood, maintaining acid-base balance and preventing respiratory acidosis.

In contrast, anaerobic respiration occurs when oxygen levels are low and leads to less efficient removal of carbon dioxide, as it produces lactic acid instead of carbon dioxide. High oxygen levels might not directly correlate with an increase in carbon dioxide removal, especially if respiration rates are not elevated. Additionally, a decrease in exercise intensity would lead to lower levels of respiration and, correspondingly, reduced carbon dioxide removal from the blood.