Well, my worst TMA of the series (so far). One stupid mistake which probably accounts for a couple of lost points, and several questions where I miss the point.
Question 1: This is about 17O and 18O ratios, and what they say about stars. You have to calculate a few quantities and the rest is interpreting the results.
Question 2: Is about geochemical data for asteroids, and looks at rare earth element ratios. You have to calculate some data in a spread sheet for 3 different sample, and then plot it on a graph. You also have to do the same thing with δ17O and δ18O ratios. Then armed with this data make a case for the origins of the various samples.
Question 3: This looks at possible biological molecules, asks you to identify the general type of molecule, its use as a biomarker. Then you have to draw the chiral equivalents of them in a chemistry program.
Question 4: This asks you to discuss the habitable zone around a star, and also looks at habitable zones around larger planets and similar.
Question 5: This is about the martian meteorite ALH 84001 and the possibility that it shows evidence of microbial life on Mars. You have to discuss the evidence for and against. Finally it asks you to critically evaluate the evidence for the emergence of life on earth, but says you should do it in 50-100 words - which to be indicates a short answer. The sample answer contains a number of points that I missed.
Anyway, there it goes, hope to do better in the next one.