Video Transcript
Which of the following examples is
a situation where the muscle cells in the body are most likely to be relying mainly
on anaerobic respiration to supply their energy requirements? (A) A rabbit in a garden spotting a
fox and immediately jumping away. (B) A hiker carrying his heavy
backpack and walking a steep mountain trail for five hours. Or (C) a person running a marathon
distance of 26 miles over four hours.
Most often in human cells, energy
is produced via aerobic respiration. This is a process in which oxygen
is required in the breakdown of glucose to produce energy for cells in the form of
ATP. However, if sufficient oxygen is
not available, the muscle cells can perform cellular respiration in the absence of
oxygen, in a process known as anaerobic respiration.
So which of these listed activities
will most likely rely on anaerobic respiration to supply its energy
requirements? Well, anaerobic respiration occurs
when an animal cannot inhale sufficient oxygen to meet the demands of its muscle
cells. A common reason for this to happen
is very strenuous activity, where oxygen is being used by the muscle cells faster
than it can be replaced by the blood. This situation can only be
supported for a short time, generally during short bursts of intense effort, like
sprints.
All of the provided answer choices
are activities that use energy, where this could potentially happen. However, the best answer would be
the most intense strenuous activity, and one that is occurring over a short period
of time. This is because in very intense,
strenuous activities, it is more likely that, even with a person breathing heavily
and their heart pumping rapidly, their cells may be using oxygen in cellular
respiration faster than the oxygen can be replaced by the blood.
The most intense, strenuous over
the short term activity in this list would be a rabbit jumping away from a fox. We can imagine this would be a very
high-speed sprint. So the correct answer is (A). A rabbit in a garden spotting a fox
and immediately jumping away will be the most likely to be, for a short time,
relying mainly on anaerobic respiration to supply its energy requirements.
