THE MUSCLE CELL FLUID OF AN ATHLETE WAS TESTED IMMEDIATELY AFTER A 10 M RACE AND WAS FOUND TO CONTAIN A HIGH CONCENTRATION OF LACTIC ACID. EXPLAIN WHAT COULD HAVE CAUSED THIS. THE

• A. athlete must have eaten food containing lactic acid just before the race
• B. Athlete must have injected lactic acid into his blood just before the race
• C. athletes muscle must have carried out anaerobic respiration during the race ✓
• D. athlete must have inhaled lactic acid from the environment during the race

During intense physical activities like a 10m race, the body’s demand for energy increases significantly. When the oxygen supply to the muscles cannot meet this increased demand, the muscle cells switch from aerobic respiration (which requires oxygen) to anaerobic respiration. Anaerobic respiration is less efficient but allows for rapid ATP production without the need for oxygen.

In other words, Anaerobic respiration occurs when there is not enough oxygen available to sustain aerobic respiration, which is the usual process for producing energy in muscles during exercise. When the body cannot supply enough oxygen to meet the demands of exercise, it resorts to anaerobic respiration, which produces lactic acid as a byproduct. This buildup of lactic acid in the muscles leads to muscle fatigue and soreness.

In anaerobic respiration, glucose is broken down into pyruvate through glycolysis. However, when there is not enough oxygen present to fully oxidize pyruvate in the mitochondria, it gets converted into lactic acid as a byproduct. This process helps regenerate NAD+ so that glycolysis can continue producing ATP in the absence of oxygen.

As a result, during intense exercise such as a sprint, muscle cells rely more on anaerobic respiration to generate energy quickly. The accumulation of lactic acid in the muscle cell fluid is a direct consequence of this metabolic pathway and serves as an indicator of the increased reliance on anaerobic processes during high-intensity exercise.

Therefore, in this scenario, the high concentration of lactic acid found in the athlete’s muscle cell fluid after the 10m race is most likely due to the muscles carrying out anaerobic respiration during the race.