Today we’ll be going over some interesting questions from the most recent Solympiad.
- There are two amino acids which are especially rare in alpha helices, Proline and glycine. Proline has a rigid ring preventing rotation into optimal alpha helix form, while glycine has too much conformational freedom and bends the helix. The other options are fine in an alpha helix, so A, Glycine is the answer.
- The purpose of hemoglobin is to pick up oxygen when in an oxygen rich place near the lungs, and to release the oxygen in places lacking oxygen; if you want hemoglobin to be able to release oxygen well, it needs to have a low affinity. Assuming that hemoglobin is quite optimized for its purpose, we would think that large animals need more oxygen, so they would have hemoglobin with lower oxygen affinity. Similarly, warm blooded animals need more oxygen than cold blooded, as do high altitude animals compared to low altitude ones, so A, B, D are false and E is true. At high temperatures one acts more, so I suppose more oxygen would be desired at high temperatures, so B is also false. Therefore, E is the only true answer.
- Our dear Peter would use his lymphatic system in digestion with the lacteals being used for lipids, so we want to find the most lipid-y food. Upon seeing the “nachos and cheese” I thought of them as quite lipid-y and the answer is indeed A. One could perhaps remember this from thinking of lacteals, which would be used to help digest whole fat milk.
- Looking at the picture, one can see faint bands of lighter color in the NE – SW direction, so the picture shows a muscle. They do not look very orderly, so they are not skeletal. They are also not especially tapered and spindle shaped, so they are not smooth muscle. Therefore, they are cardiac muscle. If you look closely I think you can see intercalated disks, which confirms this conclusion. Thus, the answer is B.
- When I think of the vitamins, which is not too often, first I think that there are two main classes, fat soluble and water soluble. I remember the fat soluble ones, A,D,E,K by rearranging them to DAKE which means “only” in Japanese, as only DAKE are fat soluble. Then I think of how pregnant women take Vitamin B9 supplements to lessen the risk of neural tube defects, and how Vitamin B9, folic acid, is quite similar to Vitamin B12, cobalamin, in that both of them are used in nucleic acid metabolism. As Abijihit does not have a B9 deficiency, he could possibly have a B12 deficiency, and indeed the answer is A.
- Nervous tissue related things are made up of ectoderm, so it seems reasonable that the lens, which has a vaguely nervous related function would be made of ectoderm. Therefore, the correct answer is C.
- If in AP Euro one sets next to someone taking Anatomy and Physiology, invariably the subject of the humerus-scapula joint being of ball-and-socket type arises; one could also tell this from observing the existence of the arm-circle stretch. One’s arms about the elbow appear to be like hinges, so A seems true. Vertebrae do not resemble hinges, and neither do pelvises.
- The action potential propagates with a refractory period behind it, so if two action potentials meet, then there will be refractory periods on both sides, so the AP could not propagate any further in either direction. Therefore, the answer is B.
- Brown fat is used for non-shivering thermogenesis; one would expect hibernating animals to want to keep warm without shivering constantly, so it makes sense for them to have much brown fat. The energy of the heat takes away from the energy, which is the proton motive force, a force in the same way that EMF is, that could have been used to make ATP, so fewer ATP are produced. One would expect the intermembrane space to have fewer protons, and a higher pH. However, since the intermembrane space is essentially continuous through the cytosol (through protein channels such as porins), the pH will remain more or less constant. Therefore, the correct answer is D.
- Upon seeing a mention of smooth ER, which is indeed in the liver, one may be tempted towards the wrong answer, but smooth ER is also prevalent in lipid producing regions, such as the gonads (testosterone and estrogen and relatives are lipids); macrophages would not be expected to produce much proteins (with rough ER), but pancreatic cells would, so to produce insulin. Therefore, the correct answer is D.
- Using my “Calc 3 Guest Lecturer” skills, I can see that is related to the growth of prey, and thatis coefficient of xy, so it must have some relation to y, the number of predators. Furthermore, is positive so would show growth of predators, and when x = 0, dy/dt = –y, which shows that shows the decrease in predators, so D is the answer.
- Keystone species are important for having a large number of species, which means that they are essential for creating balance between species, and ensuring that one species does not dominate over the others, so D is true.
-Varkey Alumootil
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