Respire Expired

So many things have happened in the past two weeks (and beyond) that I did not have time to sit down and think. But the memories brought a smile to my face this afternoon when I walked home today... Let's leave it at that for now to fulfil the promise I made.

Today I finally finished marking the Resp tutorials. Hipee! It was actuallly quite tough trying to overcome the inertia of starting to mark right after the completion of Science Camp because once again, I was suffering from another round of sleep deficiency starting from CCAL camp on the plate. But I did anyway despite languishing in serious dream-state on Thursday (the first day after the finale) so that I may make it today to ensure enough buffer time for students to review. Now I can finally sleep/rest with ease. =)



Resp tutorial: general debrief

Overall, there appears to be good understanding of the topic. Putting concepts down in words hopefully helps to distinguish it from photosynthesis.


1) should always try to relate 'oxidative phosphorylation' to the 'formation of ATP'; to say that electrons move down ETC so that oxidative phosphorylation can take place is correct but somewhat lacking.

2) For anaerobic R, some are unclear in their description. you need to realise that while pyruvate/ethanal is the final electron acceptor but being that does not guarantee a regeneration of NAD+. It is the reduction of pyruvate/ethanal in the subsequent step that regenerates NAD+.

3)why do we adopt anaerobic R? It is not to generate more ATP. If it is, I rather generate more with oxidative phosphorylation. Anaerobic Resp is really a backup plan to ensure that we still have a small but sufficient supply of ATP to sustain muscle contraction even when we are out of oxygen. Imagine running away from a bear. Yup, you need it.

4) Quite a handful did not mention the formation of proton gradient in order to generate ATP.

5) students needs to relate answers to the diagram/visual aids given e.g. Question 2; make reference to the molecules given e.g. phosphorylation of glucose!
Question 4d) students only needs to talk about how ATP can affect the enzyme although it was well-written. This is partly an enzyme question so need to mention: end-pdt inhibition/ binding to allosteric site / altering the 3-D conformation at active site; there is no need to talk about AMP/ADP and citrate.

6) Question 7 as well. Pls note that there is no competitive inhibition even though PKF reaches max activity at substrate concentration. The shape is wrong.
You also know it as an allosteric enzyme.
The management of PKF is actually very complex so I will leave it out here for now.

I will go through the answers properly when school reopens. Conceptually, things are fine so I will just round up the points you need to take note of.

For DNA genomics, there will be no answers given to be fair to all classes. However, I would recommend you to do MCQs to test your understanding of the topic itself.

To top it off:
Respiration MCQs










Cheers!! Happy Mugging!