Question

humans are typically fueled by aerobic respiration. in which scenario might anaerobic respiration begin instead?
○ after walking across a basketball court
○ after eating a high fat meal
○ after sitting at a desk for 3 hours
○ after running 20 miles

Explanation:

Aerobic respiration occurs when there is sufficient oxygen available. Running 20 miles (a long - distance, endurance activity) is an aerobic exercise for most of the time (assuming proper pacing). Sitting at a desk for 3 hours is a sedentary activity with normal oxygen supply (aerobic). Eating a high - fat meal doesn't directly relate to the switch to anaerobic respiration. Walking across a basketball court is a light activity that is still aerobic. However, running 20 miles, especially towards the end when energy demands are extremely high and oxygen supply might be relatively insufficient compared to the energy need (in a very intense effort at the end of a long run), there could be a greater reliance on anaerobic respiration.

Answer:

after running 20 miles