Sunday, 1 April 2007

S103: Block 9 - Continuity and Change, TMA-7

Onwards to block 9 - and its more biology.

The fact that block 8 is encouraged to be read kicks in straight away. There is a fair bit of biochemistry in the early chapters as they discuss biological polymers like proteins, nucleic acids and lipids.

Then it is off into the rather complex TCA cycle, also known as the Krebs cycle, or vitamin-C cycle. This is how nearly all living things make energy. It covers this material in reasonable depth, and has a very nice animation and explanation in an accompanying computer program.
This gets a little confusing for me, because at a similar time studying S204 it also starts to cover the same material and in even more detail.

After that, its into the other end of energy mechanisms, where the photosynthetic reactions are covered.
Then, the next collection of chapters is all about DNA and genetics, and then leads into evolution and a bit about speciation.

Now the TMA on this block.
The first question is a nice easy one. Its just a paragraph about Lynn Margulis and her theory of the symbiotic relationship between mitochondria and the eukaryotic cell. You have to fill in the blanks from the given words. Its a nice and easy 8 marks.

Question 2 is about lactose, and starts off by getting you to show how the molecule is built up from glucose and galactose. Then it considers the effects of lactose (in)tolerance and how it might have come about by an evolutionary path. It also involves a genetic mating diagram, a bit of DNA decoding and a short essay. There are 7 sub-parts to the question, with 31 marks available here.

Question 3 looks at two genes and considers linkage between them. You have to draw diagrams of the chromosomes and how they might possibly split when meiosis occurs. 14 marks.

Question 4 and there are 7 marks for explaining the term regulating mortality factor as it applies to holly leaf miners.

Question 5 - they saved the biggy for last. 40 marks for a 700-800 word essay on the subject of "The metabolism of green plant cells in relation to energy exchange processes". Wow - this is a big subject. You have to cover both respiration and photosynthesis and the energy exchanges that are undertaken - all in 700-800 words. I draw a rather fine diagram in word covering the whole glucose oxidation and electron transport chain, and then rereading the question find that all diagrams must be hand drawn. After spending over an hour tweaking this diagram I am more than a little miffed I didn't notice these instructions earlier. I contacted my tutor to see if there was any way to salvage this. It seems silly to print it out and then trace over it or similar. I can't see why they insist on it being hand drawn either. I was in two minds, just delete the whole thing or include it and hope I only loose 1 mark, but gain a couple for the detail.
In the end I kept the diagram in, as my tutor didn't seem too concerned about it. However my planned diagram on photosynthesis never sees the light of day!
I lost a mark or two on this essay for not including any chemical equations - but otherwise I get a pretty good mark for it.

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