skip to primary navigationskip to content

Guidance on essay writing

There are two types of Part II and Part III essay: those written for exam practice and in exams and essays written to assist comprehension and revision. The guidelines below apply to both, with some comments at the end that relate specifically to revision essays.


Read the question carefully so that you are sure you see what it is asking (beware making a reflex response to key words): a lot of thought goes into structuring Part II/III essay titles so be sure you are clear at the outset about the precise areas you are asked to cover. If the question clearly has more than one facet, ensure that your answer reflects this and that you do not write extensively about an area that you are particularly interested in at the expense of other aspects because you will probably be penalized.


There is no unique, ideal form for an essay on a given topic. However, one rule that will stand you in very good stead when writing anything is 'Start by making a plan'.

Begin with headings that indicate the major components of the story. Amplify these with sub-headings that reflect the specific topics you wish to cover under each major category. Consider the best sequence - which may change as you complete the overall design. Under each sub-heading note what you might use as specific examples and how best to convey the information: that is, use sketches/diagrams/graphs/tables, ANYTHING that helps to get facts and concepts across as clearly and succinctly as possible.

This process will really help you to focus on the question, decide what is to be included (and, equally important given the huge amount of information that is usually available), what to leave out, and give you a logical theme and progression to the story (any story). At Part II/III there is the great temptation to stick down everything you can think of that seems dimly relevant: the result is that, rather than producing a structured story that the reader can’t put down, you compile a disparate agglomeration of facts that ends up being confusing. The key thing is to convey understanding and ‘feel’ for the subject, not to catalogue every molecule.

Writing rules

Whilst it is more satisfying to produce polished prose, in Tripos exams in particular the dominant requirement is to convey relevant information and your scientific arguments. Thus:

  • Don’t tell the reader what you’re going to do: just do it.
  • Use the headings and sub-headings to introduce new topics (so you do not start each section with a bit of waffle).
  • If it seems appropriate, use bullet points.
  • Use generally accepted definitions and abbreviations (if you are unsure, write in full the first time and then use your abbreviation).
  • Do not repeat in prose what is in the sketches/diagrams/graphs/tables: just use the text to expand any points arising.

The aim is to tell the reader a factual story in as clear and selectively comprehensive a manner as possible. If you can do this in an exam answer you will appear knowledgeable, critical and thoughtful and it is a well-informed mind at work that the examiners are looking for!

All of the above should have been learned in IA & IB but that practice often seems to have been forgotten by Part II/III. One result of following the above strategies is that what would have been a good basic account in a IB essay can be condensed into the first page or less of a good Part II/III answer (using sketches, etc. to help). This permits the bulk of the essay to be devoted to the science covered in Part II/III lectures and in your reading and to discussion, for example, of the current position, the critical questions and controversies and where the field is going.

Common problems:

  1. How knowledgeable can I assume the reader to be? Don’t think about this problem. Just make the first heading the most direct point of entry to the core of the subject. For example, if the topic is ‘The action of the X family of membrane receptors’ a first heading of ‘The Superfamily of X ligands’ might be fine. Don’t feel you always have to start with Watson and Crick. Even if you omit minor points, as a good essay proceeds it will become evident that this was a rational decision, not ignorance.
  2. Separate sections/sub-headings for everything? The advice above to have lots of sub-headings sometimes raises the problem of ‘should something go in its own section or be intercalated with other parts of the story?’ You have to decide which works best for the particular question. For example, this might arise when trying to relate transgenic mouse studies to in vitro biochemical data and studies of human disease. One basis for decision could be ‘do I just want passing references to transgenics?’ or ‘are they such a major part of the story that they need their own section(s)?’
  3. Experimental evidence and methods. Emphasised in Part II/III: usually the intention is that you grasp the principle of a method, not memorise the molarity of the buffer. In essays this might manifest itself in discussing sets of seemingly conflicting data: why does A bind to B in an immunoprecipitate in one study but not in another? Possible answers include different cell lines used, antibodies of differing specificity, etc., which are only evident if you are aware of the experimental procedures at the relevant level of detail.
  4. How to deal with apparent contradictions in experimental evidence and arising from consideration of the literature. Possible explanations are that comparisons have been made between experimental procedures or systems that are not identical: these differences may be identifiable from scrutiny of the published methods (as in the example above). However, that may not be possible and significant differences may have to be inferred pending further (possible collaborative) experiments. Experimental procedures may be directly comparable but the methods of data analysis may differ – an increasing problem with the expansion of ‘omics methods.
    A different problem may arise when data sets that are perfectly valid in themselves are forced into a general model that may have little physiological relevance (a particular hazard in the cell signalling field). Regardless of the specific nature of the problem, a succinct summary followed by some basic suggestions for its resolution will accrue credit.
  5. Where is the field going? Often the final and most difficult part of an essay. You’re unlikely to win a Nobel prize on the basis of a Part II/III essay but you can identify problems and even rather simple suggestions will bring you credit. For example, would an attempt at an exact replication of an experiment in a second lab be sensible? How relevant are the animal models for human disease and could they be improved?
  6. References: include or omit? Including ‘(Bloggs et al., 2007)’ or ‘the work of Bloggs and his group...’ can help the reader and it does make the point that you’ve actually looked at papers. Don’t include the full reference: if the reader doesn’t know it he can look it up. However, if you include the appropriate information, thoroughly digested, the extent of your knowledge will be very clear, referenced or not.

Writing v. typing

It’s up to you. You have to write in the exam so practising that is obviously useful. However, you can readily amend an electronic version to produce something that is finally very polished. One problem with typing is that folk either assume that sketches/diagrams/graphs/tables are unnecessary or download them: both a mistake. Either leave gaps into which you can insert by hand or include captions and have sketches/diagrams/graphs/tables as separate pages. If you produce it electronically don’t assume the recipient will be happy to receive it by e-mail. Check with them first, and remember that formatting, figures and symbols may be altered when opened on someone else’s computer. Resist the temptation to paste directly: aside from the risk of your plagiarism being detected, you should practise thinking the story through and then formulating it in your own words. If you do generally type, make sure you don’t forget how to write by hand for three hours.

Revision essays

A fairly comprehensive review of a subject will be very useful as the exams approach and, bearing in mind that you do not know what the exam questions are going to be, it should make you better equipped to deal with anything on that topic. However, an alternative is to assemble an integrated version of your notes and the lecture handouts together with additional reading.

Whichever of the above strategies you follow, write also as many timed essays on specific exam questions as you can and get both versions assessed.