Spine

You should know the technical terms which appear in the syllabus. These will certainly be the ones which your notes and text book use. Technical terms are not there to make life difficult. They are a very useful shorthand way of saying exactly what you mean with no possibility of confusion, so they are well worth learning. For example in the case you give in your question "spine" and "vertebrae" are actually quite different things. If the question required the answer vertebrae then it is quite possible that spine would be wrong. It would be the wrong answer that lost the mark rather than the use or otherwise of the technical term.