7 Command Terms used in IB Biology and Chemistry

By Luke Palmer

(Head of Math and Sciences, Biology, Chemistry, Environmental Science and ESS tutor at The Edge Learning Center)

With this years IB exams coming up soon in May, students are busy taking mocks and doing practice questions. From experience over the years students are not always doing as well as they can on these tests. It not a lack of understanding concepts or knowledge of the topic, it can simply the fact they are not answering the question. They can give a great detailed and true answer but if it does not address the question it will not score the marks.

Reading the questions and understanding what the examiner wants is an essential skill to achieve the marks and get the top grades. Everybody has the potential to make mistakes or errors, but this blog aims to reduce this by discussing 7 of the major command terms students find tricky.

Science Terms

1) Define

This term wants the student to give a precise meaning of the given word, phrase or concept. Seems simple at first glance, but it how they want it given and often their details that guide this.

E.g.      define oxidation in terms of change in oxidation state

A student could say, “oxidation is the loss of electrons” and they would be correct but did not answer the question. A right answer would be, “ oxidation is when the oxidation state of the element increases”. The answer used the details from the question and defined it how the examiner wanted it.

2) Describe

Again this seems to be an easy term, the examiner wants you to give a detailed account. This can be easier said than done, students could write long answers but never actually convey the point of what they need to describe. The first thing to check is the marks for the question. If it only 2 marks they are looking for specific points and a 3 mark would want more depth in the detail. Students should construct concise sentences to address details for each mark.

3) Outline

The way this trips up students is they end up describing the concept or ideas in detail and wasting time. The idea of this term is to give a basic or brief summary of the concept and again marks are an important indicator of work needed. A common way this comes up in Chemistry and Biology is with experiment or data questions, both of which will be in Paper 2 and Paper 3. With data, the graph or table trends must be given and manipulation of data or ranges can score good points.

4) Analyse

This is another term used in data questions, students have to break down and bring out essential points from the source or concept. Most likely the question will want the detail or essential points from more than one data source given. With concepts to analyse it will be referring to ideas from previous questions, and how that concept relates to the ideas.


5) Compare and Contrast

With this term the similarities and differences between two (or more) items or concepts. When giving the similarities or differences the items have to be referred to throughout.

E.g.      Voltaic cells convert chemical energy to electrical energy, were Electrolytic cells convert electrical energy into chemical energy.

This had the difference between the two types of electrochemical cells outlined and referring to both of them, making it clear how they differ.

Another way students fail to score marks is they give just differences or similarities. If they do not give both ideas, full marks will never be scored. If there were just similarities the term would be compared only. Both of the ideas must be given, yet they do not have to be used to equal amounts, especially in a 3 marks question.

6) Suggest

This term wants the student to give a solution, hypothesis or a possible answer. Students get stumped on this, as it can be very open to possibilities, yet a sensible answer is likely to get a mark.

7) Justify

Simply put the student must give a valid reason or evidence to support their answer. This can be from the data given, a trend in the graph or concept knowledge. Yet this term can vital in scoring marks, regularly it found in 1-mark questions. That means even if the answer correct, if it not justified or supported the mark will not be given.

These are the main terms I have seen students go wrong on and lose marks. The important thing to take away from this blog is that to take time reading question and be sure you are addressing the question with a valid answer. With the exams only being a couple of months away we offer comprehensive lessons that can cover the full range of topic areas with practice in all styles of question. There is also the possibility to do full mocks with a detailed review of areas that need improvement. If you have questions about IB Chemistry or IB Biology just contact us and sure we will be able to help.

About The Edge

The Edge Learning Center is Hong Kong’s premier Test Preparation, Academic Tutoring, and Admissions Consulting services provider. Founded in 2008, The Edge has helped thousands of students improve their ACT and SAT scores as well as their IB and AP grades. The AC team has just finished off another successful period in which student gained acceptance to schools such as Columbia, MIT, University of Chicago, and more! Check out the rest of our 2018-9 Admissions Results!