Feedback provided to student N.M. (example 1 - see student answers on previous page)
Evaluation of TRIPSE
Hypothesis Generation (10): 5.5
Design of Exptl.Test (10): 5
Re-assessment (10): 7.5
Total (30): 18
You proposed 3 explanations. The first stated that RHW is not a reversible, competitive antagonist. I presume you mean that it is an irreversible, non-competitive one? You argue that there are two sets of receptors, one located on the endothelium to which RHW and PE bind and another set exposed when the endothelium is removed. This would have made sense if you had clearly stated that RHW did not bind to the second set. You wrote, however, that these receptors were not specific for RHW. Does this mean that the first set were? Did you think through this explanation?
The second explanation was that RHW abolished the effect of PE by binding to receptors on the endothelium. Once the sub-endothelium is exposed, a new type of receptor allowed for reversible, competitive binding. This was totally illogical, since the data showed that there was NO inhibition after removal of the endothelium.
The third explanation was that removal of the endothelium exposed receptors less specific for RHW.
I am afraid that your thinking was so loose that you never came up with a credible explanation. This was a real pity as you clearly realised the significance of the endothelium.
You chose to test the second hypothesis. Since the hypothesis was weak, your test was not particularly strong either. Again you misunderstood the situation, because you said that you would do a Schild analysis. Since the data provided show that in the presence of RHW, there is a significant reduction in maximal response, a Schild analysis would have been unhelpful. You mentioned other forms of antagonism such as pharmacokinetic and functional. Why did you not think of these when you were providing explanations in the first stage?
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