Places where we all struggled to some extent were evident throughout the test. This is what I think we need to improve on – see whether you agree with me and of course, comment if you have anything to offer.
1) On the first question there’s a question about resolving power of an electron microscope – you all need to go away and look at how an electron microscope works. The key is that the electrons have a much smaller wavelength than light photons so can fit through smaller gaps.
2) Saturated and unsaturated fatty acids caused us some problems. Visit the information on this website to work out what being saturated and unsaturated means in terms of the structure of lipids.
3) The question ‘suggest why the cholera exotoxin is specific to the epithelial cells of the small intestine,’ requires you to use knowledge from different parts of the specification. Basically it wants to see that you understand that molecules whose shapes compliment each other fit together – like the receptor on the membrane of epithelial cells and the cholera exotoxin.
4) Quite a few missed marks on the question about how ions normally enter the blood. Remember, whenever it’s against a concentration gradient we’re talking about active transport. I’ve posted a video on here for you to watch that explains why you need energy to carry out active transport.
5) I want you all to go away and find out about the symptoms of cholera – why do you get diarrhoea?
6) You all struggled to link the graph showing facilitated diffusion to the explanation of why the rate of diffusion levels off even though the concentration gradient is still rising. Read up on it please.
These are the hot spots that we need to focus our efforts on. I know it’s only a day away but I’ve attached the test (3.1.3 test). Please download it from here and complete the answers to the areas that I’ve outlined above. Use the links to the support material. I hope that it makes answering the questions easier.
We’ll review the test again in our lesson on Thursday morning.
Happy studying. Any problems or comments then please leave a comment on here.