That seems a bit picky to me
. Are you talking about the June 2015 AQA P3 paper?
If you take a look at a mark scheme for the advice on a six mark question, the awards are given in levels (1, 2 and 3). A level one response (1-2 marks) shows basic knowledge, a level two response (3-4 marks) shows accurate knowledge, and a level three response (5-6 marks) shows accurate knowledge
appropriately contextualised. In most cases, this means they want you to link every point you make with
a reason. So for the June 2015 question, they want a use, the risk
and an associated precaution; the main difference between level 2 and 3 is the ability to expand on the point. (If your school uses PEE, it's a bit like 1 = P, 2 = PE, and 3 =PEE).
Then, below the section where the minimum requirements for each level is laid out, theres a list of
example points. These are the ideal points to make because they'll be the ones an examiner's looking for, but there are other correct responses and examiners are encouraged to award marks for these, too. The mark scheme for this particular question (not sure if it's the one you have in mind) states 'Imaging (a named body part)' and has no guidelines for points to specifically ignore, so I see no reason why it wouldn't have been allowed (however I am not an examiner so I suppose the teacher knows more!).
So my tips for 6 mark questions would be to put down as much as you know, but recognise that what they expect you to write is usually far less than you realise - for this June 2015 question, the guideline for a 6 mark response was, 'At least one medical use is given for both types of wave linked to the risks and any precautions necessary'. It is always important to expand upon each statement if you're aiming for a top band response, giving reasons why if nothing is explicitly stated as expansion. You should never need to use the extra space provided to gain full marks, so don't overly focus on creating a well-worded response, as a Level 3 response is simply 'coherent and in an organised, logical sequence', with 'almost faultless spelling'.
It may be that your teacher felt you hadn't used enough 'relevant specialist terms' required for a six mark response by using 'creates'? Anyway, I hope this helps
I'm doing GCSEs myself and just posted a question about how mark schemes work, so I might not be the best source, but working on these tips has gotten me 6 marks in the past. Don't overthink it, I'm sure you'll do great