Scientists investigated the effect of regular exercise on skeletal muscle fibres in mice. The scientists compared the muscle fibres of mice after six weeks of regular exercise (trained mice) with those of mice that had not exercised (control mice). The scientists stained the muscle fibres from both sets of mice to show succinic acid dehydrogenase activity. The darker the stain the greater the succinic acid dehydrogenase activity.
The scientists then compared the length of time that the control mice and the trained mice could carry out prolonged exercise. The trained mice were able to exercise for a longer time period than control mice.
Explain why.
Answer:
1. (More aerobic respiration) produces more ATP;
2. Anaerobic respiration delayed;
3. Less or no lactate;
What I don't get is that both the control mice and trained mice exercised so surely both should be able to exercise for the same period of time. Or is it because the trained mice trained beforehand, so had experience? And how is there less Anaerobic respiration as O2 can become a limiting factor? Are they assuming that the control mice undergoed only Anaerobic respiration because they exercised so must undergo Aerobic respiration too??
Last edited by username4168516; 4 months ago
It's not suppossedly a hard question but I don't get what It is asking me. Are the scientists carrying out another experiment after the 6 week programme or during it?
(Original post by Sainsburysbasics)
Okay but do the control mice exericse at all in
either experiment? Also, the answer says that Anaerobic respiration was delayed.
From what you've written, yes they do. I can't see why that's a difficulty though.
Proceed from a hypothesis based on your current knowledge. An exercise programme increases the capacity for sustained exercise by, inter alia, increasing the number of mitochondria in a cell and thus increasing the amount of energy that can be produced, yes? That's fairly well known. This experiment aims to test that hypothesis (specifically, it would test the null hypothesis that there is no difference in the two groups).
So the experiment is testing whether there is a difference between the exercise capacity (and, as a proxy, the mitochondria) between the untrained 'control' group and the exercised group. If the control mice didn't take part, how could you tell whether there was a difference between your intervention group and control group?
However, I say again that I think some of this question is missing. You'd be better off taking a screenshot or photo of the question and posting it up, rather than copying it out. I think you've missed out some vital information, such as which group stained darker.
Last edited by Reality Check; 4 months ago
(Original post by Sainsburysbasics)
The trained mice was more darkly stained. You’re misunderstanding me, I agree with everything you’ve said but that’s not what I’m asking. According to your logic, both mice did prolonged exercise (both control and trained), so the same amount of ATP should be produced. More aerobic respiration occurs in the trained mice but that is in the first experiment, we know nothing in the second experiment?
Both control and trained will produce varying amounts of ATP.
Reality Check says it here...
(Original post by Reality Check)
They're not assuming there is no anaerobic respiration but that's not relevant to the question. The question told you the protocol involved succinate dehydrogenase: this is a enzyme in the citric acid cycle, so that tell you that we are talking about aerobic, not anaerobic respiration.
You should know that the TCA cycle takes place in the mitochondrial matrix. I think you must have missed copying out part of the question, because there is nothing about which group of mice had the 'darker' staining. But let's assume it was the trained group. Darker stain = greater amount of succinate DH = more mitochondria = greater capacity for ATP synthesis.
The second experiment results are taken from the first experiment. They are the same...in the first one the intensity of colour is measured while in the second one, time is measured.
Here's the brief gist.
if A is controlled and B is trained for six weeks...
At the end of the six week programme, they conduct an experiment,whereby both A and B are exposed to prolonged exercise. B will produce more ATP than A thus B can exercise for longer periods of time.
Last edited by Spannerin'moi; 4 months ago
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