How do i approach a long answer question in order to gain full marks?

My approach is to break down the question. In the case of long answer- questions, examiners want to firstly know that you understand a question before answering.  Let's use the following example:

Explain how a DNA mutation can result in a nonfunctioning enzyme

Your introduction should show your understanding of the terminology included in this question. Start by defining the key terms and relating them to each other.

a) Define: DNA

b) Define: enzyme

c) How do the two terms relate to each other: e.g. DNA sequence acts as a template for the primary structure of the amino acid sequence of the protein which affecting the intermolecular attractions within the enzyme, that will allow the enzyme to form into a particular three dimensional structure.

Your main body should be then answering the question directly. Consider how many marks are provided and try to include the same number of points. Remember to use appropriate terminology. Think about what keywords an examiner would be looking out for, and make sure that you include those key words. Since ths question asks you to talk about DNA and ezymes the examiners will be looking out for the following keyterms: biolgical catalyst, primary sequence, translation (translation of DNA sequence into a n amino acid sequence), 3D-folding and active site . It's also good to give brief examples of types of mutation (depending on the examining body. Some examining bodies will not include this in the syllabus)

Your conclusion should then be a very brief overview that highlights the main concept.