Wednesday, 26 September 2007

S204: Revision day

A day of revision to prepare for that dreaded exam...

It started off gently enough with PP giving a general talk on exams and how to revise for them. He looked at various strategies and what was useful and what wasn't. He was against question spotting, meaning revising answers to specific questions that seem to come up - as you get that sinking feeling when they don't. Rather revise common themes that come up. He also told us to make revision fun - so I started a quiz on the FC forum.

Then it was into S204 revision class with CM, which went well, but I think a number of us came out realising we knew less than we thought we did! We covered long questions, data interpretation, and enzyme/membrane kinetics. Another graph drawn helped lock in the v/S stuff a little more.

Over lunch it was back to PP and how to deal with data interpretation questions. You can't revise for these, you have to know how to use the skills you've learnt. Anyay we tried a couple of examples, and learnt to use the clues in the questions.

After this, back to more S204 specifics with GL. He had a few tricks to share with us, things like learning certain diagrams that were adaptable to multiple questions. Also learning specific organisms that could be trotted out as examples. Then we went through a number of example short answer questions and discussed answers and where the marks might be.

All in all very useful. Not exactly feeling confident about the exam, but feeling it is possible.

Thursday, 20 September 2007

A251: TMA-1

Its onwards to the first TMA.

We have on the way to this event an e-tutorial. This is a tutorial conducted online. The tutor suggests a topic, and we are to each write about 100 words on it. In this case it was what theory do you think started agriculture, and why.
I didn't spend too long on this, despite being the first to post. I see the evidence as not very conclusive as given in the course, and suspect the reasons are probably many and varied. Besides I need to revise for an exam, so I rather skim it.

Then the TMA - it is in three parts.

Part 1 you need to write 500 words on the agricultural development in SE Asia, and describe the main theories.

Part 2 you write 500 words on agricultural development in either SW Asia, Mesoamerica or North America based on the book text and how the theories might apply. I picked North America.

Finally part 3 requires a compare and contrast 500 words on part1/part2.

Lots of references are required to support the arguments. Now I'd been struggling with bibus as referencing software, and in many of the S204 essays I'd just hand typed references eventually as I had a few problems with bibus locking up. I did take a look at the software (as its open source) wondering if I could upgrade it, but decided I didn't really have the time. I looked around for alternatives. I came across zotero which blew me away! It integrates directly with firefox, will pick up references directly from things like wikipedia, amazon, pubmed and so on with a single click. It has a word plugin to export references and bibliographies directly to word.
You can even drag and drop wiki format references into wiki-pages. It's just brilliant. It needs some work to support other reference styles, and a way of sharing data - but that is being worked on. Its the future I tell you!
Anyway, its my new best friend for these TMA's.

This course uses the eTMA system, so I will be uploading the written document using it.

Thursday, 13 September 2007

S204: TMA-7

The last TMA, and the good news is there is NO essay question!

Its designed as a bit of preparation for that ex*m that is coming up, so it's got a similar structure to some parts of the exam.

The first question is a graph giving infection rates from Schistosoma mansoni - a blood fluke. In this case you have to answer a number of sub questions about possible infections and how the data is interpreted. There is 15 marks in all for this question. Some of the parts a little ambiguous about what is being compared with what but its not too bad.

The next one is a similar sort of question, some graphs relating female dominance in red deer to their propensity to produce offspring and survive the winter. Another 15 marks.

Question 3 is only four marks, and you have to compare and contrast smell and taste organs. Then a quick sentence on how sight works.

Question 4 asks you to give four differences between the structural organisation of sponges and cnidarians for four marks. Not too bad again, but I had to go back to the book to tease them all out.

Question 5 is two questions about insects and spiders and crustaceans - another 4 marks.

Question 6 is another 4 pointer about oxygen dissociation in haemoglobin.

Question 7 asks for four features essential for flight. Another 4 points.

Next you get a choice. Question 8 and 9 are both worth 50 points, and involve sketching from the digital microscope. Question 8 is about plant tissues and 9 about animal tissues. For some reason I seem to have been drawn into the plant side of things, which is not what I had planned at the start of the course. Anyway, I go with the plant question, and have to draw and label low and high power sketches of a vascular bundle and a phloem sieve plate and surrounds.
This is followed up by a number of questions about phloem and apoplastic and symplastic flow.

All in all its not a bad TMA. As you are answering specific questions, I feel there is a lot less to get wrong or forget to cover. However time, and my tutor will tell how well I've done. In the meantime its a bit of a wake up about how little I know in detail without the books.
I mean, I know most of the way that phloem and stuff works, but without the books I can't recall which is the one that is apoplastic and which symplastic. I think its stuff like this that I will get unstuck on in the ex*m.

Monday, 10 September 2007

A251: Week One

Its week one in the A251 world, so time to open the enormous book and try and get to grips with it.

Its made somewhat easier by there being a course guide that leads you through it, actaully what am I saying, it makes it much easier. If you follow the course guide, it tells you what chapters or part of chapters to read. It discusses the information, and also tells you what to make notes on, and when to listen to the CD tracks.
Some of the exercises are a little tedious, and the first one which includes categorising the timeline events I skipped over mostly. I figured I can understand it just by reading through it.

I did go to the A251 website, and I added a few more events onto their dynamic timeline. The break up of the landbridge from the UK to continental Europe for instance I felt was a useful landmark (or is that timemark?).

With the course you get the text to all the TMAs and the ECA, so you can know what you have to do right from the start if you wish. It does help modify your study a little.

Anyway, the first week is all about the rise of agriculture, and the reasons for it. The take away message is basically no-one knows why agriculture came about, there are 4-5 theories, but none of them conclusive. Agriculture takes more work per person than the hunter/gatherer lifestyle, although it does produce more food.
However its a one way gate, very few civilisations that have adopted agriculture can revert back to other forms of living, as the amount of population it supports can't be sustained in any other way.

So that's the news from the cutting face of A251!

Tuesday, 4 September 2007

S204: TMA-6 / Experimental Week 2

Back to the potatoes!

Oh yes - the potatoes have their revenge. In this combined experimental week and TMA you have to do a new experiment of your own devising on the poor potato homogenate and then write it up fully as TMA-6. This is very similar to TMA-2 except you have about twice the word limit, and you have to write much more about everything, but particularly on the biological mechanisms that you are investigating. On the plus side, this is all you have to do for this TMA!

After a few flights of fancy, I decided to follow the advice and stick to something reasonably simple. A couple of options were to vary the temperature or pH of the solution and see if there was any discernible difference in results. I figured that what they were looking for in this exercise was producing some results and analysing them. They were not looking for new contributions to science.

Its a lesson I've found rather hard to come to terms with in this and other courses. For instance the whole purpose of catalase in the potato homogenate is to break down H2O2. Now why would you have H2O2 present? It turns out this is how free radicals, those rather dangerous reactive molecules are flushed out of the system. They are converted into hydrogen peroxide to partially neutralise them. However should H2O2 come into contact with Fe ions, you suddenly have a worse problem than before as it will make very very reactive free radicals, as opposed to just reactive free radicals. If you follow this through, you find all sorts of interesting avenues, such as oxidative stress, mitochondrial errors, apoptosis signals and so on. Although some of this can go into the report, you have to curb your enthusiasm and write down only what the mark scheme is likely to be looking for. This does mean somewhat that you have to try and stick to the course materials as if you find new discoveries since they were written, or more advanced descriptions of mechanisms, no matter how right they are, they are unlikely to get you marks.

Anyway, I settle for two temperatures and attempt to see if there is a difference in reaction rate. This is actually more chemistry than biology, heat increases all reactions. The only biology that comes in is that most catalysts are rather fragile enzymes that will fall to bits if you heat them too much. So I pick two temperatures that are likely to work. A temperature of 0°C is easy to maintain with ice-cubes, a warmer temperature is more difficult. Without some sort of heating, it will tend to cool, so I pick a temperature about 10°C above room, and hope that a large enough water bath won't cool too quickly to affect things. I know catalase works in animals up to 37°C so I don't think potato catalase will fall apart at 28°C or so, so I should be OK.

It would be interesting to look at a whole range of temperatures and see where its peak rate was, and where it started to denature and so on. But ambition must be curbed, and if you've spent a few hours counting drips from mashed up potato juice, this is actually surprisingly easy to temper! Plus you can only do a t-test on two sets of results, so that's all you really need.

After about 4 hours or so, I've been through the experiments, which include a couple of pilot experiments to work out appropriate concentrations and drip rates.

The write up is much easier than the last TMA, although it takes a while to get it all formatted and the biological data into place, run the t-test software on the results and so on. Ultimately though, it is just a question of doing the time and formatting the results. None of the cold hand of fear from the last TMA! Some faith restored. I struggle to reach close to the 2000 word limit, and a certain amount of revision is required to get not too far away.