i just did some work on this today, so its fresh in my head.
but from what i can see of the syllabus you have to be able to distinguish between Archaea and Bacteria.
This is pretty easy, your text book will probably have a table of differences between them.
Both are prokaryotes (no nuclear membrane or membrane enclosed organelles, one circular chromosome)
Generally, Archaea are extremophiles, (phile means you like/love something) so Archaea love extreme conditions, this can either mean extreme temperatures, extreme salinity, anoxic enviroments or other extreme conditions depending on what type of Archaea it is. Archaea are generally not pathogens and do not respond do antibiotics. They do not contain chlorophyll and cannot photosynthesise, but can use chemical energy instead in chemosynthesis. Also contain more complex RNA.
Bacteria are commonly thought of as pathogens, although some are, many are useful and essential to human survival. They can photosynthesise and chemosynthesise. Some bacteria fix nitrogen. Live in a variety of enviroments and conditions.
then you have to 'Use available evidence to outline similarities in the environments, past and present for a group of organisms within one of the following: Archaea and Bacteria.'
i did methanogens, which are a type of archaea. Wikipedia should tell you about those.
and you also have to 'Describe the main features of the environment of an organism from one of the following groups and identify its role in that environment: Archaea and Bacteria.'
i did nitrogen-fixing bacteria. Again, use wikipedia.
Hope that helps a little