A Level Biology exam technique: where students lose marks

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A Level biology is full of challenges. There’s the volume of content, the biological vocabulary, and the complex topics, but one of the hardest lessons that students learn when they embark on their A Level biology studies is that knowledge alone is not enough to score the highest marks; it is possible to know everything, but still fail to achieve your goals in exams.

In this article I will be drawing on years of teaching and examining experience to discuss a few of the areas where students often fall down in exams. Read on to discover some of the ways that you can improve your exam technique; I will address:

  • command words
  • precise terminology
  • data handling
  • answering the question
  • misconceptions

Pay attention to command words

Command words are the words in exam questions that tell us the type of response an examiner is looking for, e.g. whether you should describe, explain or suggest. The command word gives you crucial information, such as how you should structure your answer, how much you should know about a context already, and what type of content you need to include.

Failing to pay attention to the command word will mean that you will be unable to tailor your response to the demands of the question, and may cause you to miss out on marks even when you know the answer.

Some common command word mistakes include:

An empty classroom with arranged desks, exam papers, and pencils ready for students.
  • confusing describe and explain: students often describe when they should explain, explain when they should describe, or fail to do both in a question that requires both; remember that describe = a clear account of features or processes, while explain = scientific reasons
  • failing to compare and contrast: questions that require students to compare and contrast between two objects or processes require both similarities (comparisons) and differences (contrasts), and each sentence must contain a reference to both items, e.g. a comparison of starch and glycogen should contain a reference to both molecules in every sentence, not a paragraph about starch and then a paragraph about glycogen
  • panicking about suggest: this type of question often presents an unfamiliar context and then asks students to ‘suggest’ an explanation for a feature or observation; it can be easy to panic when something seems unfamiliar, but remember that questions like this will always link back to a topic you know
  • failing to evaluate: questions requiring evaluation require a balanced argument, so be sure to give arguments both for and against; it is often also a good idea to refer to any data, or any methodology information that has been provided

Be precise

Never assume that an examiner will know what you mean; you need to say precisely what you intend to say at all times. This includes:

  • correct use of A Level biological terminology: don’t use a generic term when there is a biology key term that you could use instead
  • describing practical work and data using words with the correct meaning

See the table below for some common examples of imprecise writing that causes students to lose marks in exams.

Topic Common precision mistakes
The nervous system Referring to signals or messages instead of nerve impulses
Protein synthesis Using the terms base and amino acid interchangeably; bases make up the rungs of the DNA double helix while amino acids are the monomers in proteins.
Biological molecules Using generic language for the breakdown of molecules, rather than using the term hydrolysis
Genetics / natural selection Using the terms gene and allele interchangeably; a gene is a section of DNA that codes for a polypeptide, while an allele is a version of a gene.

E.g. 'in natural selection it is a new allele (not a gene) that arises by mutation.
Respiration Energy is released or transferred, it is not created or produced.
Cell communication Referring to the "active sites" of antibodies or hormone receptors; these structures have binding sites while active sites are specific to enzymes.
Disease and immunity Using the terms immune and resistant interchangeably; immunity is to do with lymphocytes in the immune system, while resistance is the ability of some bacteria to survive treatment with an antibiotic.
Practical work Describing a measurement as an "amount" rather than a volume, mass or concentration.

Using terms such as accurate, precise, reliable and valid interchangeably.

Take care when handling data

Biology exams will often contain around 10 % of marks that require mathematical calculations or other forms of data handling, and marks are frequently lost in questions with these types of demands.

Avoid losing marks in maths and data questions by:

  • noting the number of decimal places or significant figures required, and rounding answers carefully
  • converting units consistently
  • noticing logarithmic scales
  • avoiding the phrase “the results are significant” in statistics questions; examiners require “the difference between the means is significant” or “the correlation is significant“
  • learning which statistical test should be used in different situations
  • interpreting P-values correctly; the P-value shows the probability of a difference being due to chance, not the probability of a specific outcome occurring
  • interpreting standard deviations correctly: overlapping standard deviations indicate that a difference may not be significant, but this is just an indication, not a statistical test
  • plotting graphs carefully, with axes the right way around, clearly labelled with units, and that have consistent scales

Keep answers focused

A Level mark schemes have strict requirements, and marks can only be awarded if the criteria are met, so it is essential that you read questions carefully, and that your answers are focused entirely on meeting the demands of the question.

  • Take time to determine exactly what a question is about; examiners note that students can sometimes get ‘keyword tunnel vision’, i.e. they spot a keyword and assume that a question is about one thing, but actually it is about something else.
  • Answers should be specific to the question asked, and not rote-learned statements, info-dumps, or references to closely related topics
  • Avoid statements that just repeat the question stem without adding anything
Close-up portrait of a woman winking and holding a magnifying glass against a white background.
  • Follow instructions in the question carefully; if a question includes a phrase such as “apart from” or “do not include…” then no credit will be available for discussing these examples, and if a question only refers to a specific part of a process, then no credit will be given for references to other parts of the process
  • Don’t lose time writing lengthy introductions or conclusions for your answers, but get straight to the point and move on to the next question

Avoid biology misconceptions

Hopefully by the time you get to exams, your understanding of the A level syllabus will be solid, but even when you know a course well, it is possible for small misconceptions to creep in unnoticed. Watch out for the common misconceptions described below.

Topic Common misconception
Genetics and evolution Believing that antibiotics and selective breeding cause mutations to occur. Mutations arise randomly during DNA replication; selective pressures such as antibiotics simply favour individuals that already carry an advantageous allele.
Bioenergetics and respiration Describing the electron transport chain proteins as pumping protons into the intermembrane space by "active transport." This isn't accurate, since active transport specifically requires ATP hydrolysis; the pumping is instead powered directly by the energy released as electrons pass along the chain.
Cell transport Stating that a "thin membrane" is an adaptation for a short diffusion pathway, rather than recognising that membranes are of similar thickness and the short pathway usually comes from a single layer of cells.

Confusing villi (finger-like projections made of many cells) with microvilli (foldings of a single cell's membrane).
Nervous coordination and muscles Describing a "weak" or "strong" nerve impulse. Impulses are all-or-nothing; stimulus intensity is instead encoded by impulse frequency.

Believing that ATP is needed for the power stroke in muscle contraction, rather than to break the cross-bridges afterwards.
Plant biology Believing that plants cannot carry out sexual reproduction or produce gametes.

Describing glucose as moving through the phloem, when the main transport sugar is sucrose.
Homeostasis Locating vasoconstriction in the capillaries rather than the arterioles, which contain the smooth muscle needed to constrict or dilate.
Biotechnology Describing viruses as replicating via binary fission or mitosis, rather than hijacking host cell machinery to assemble new virus particles.

Stating that DNA polymerase forms the hydrogen bonds between bases, rather than catalysing the phosphodiester bonds between nucleotides.

In conclusion

Most of the pitfalls discussed here have little to do with a lack of knowledge; they are the result applying this knowledge incorrectly under exam conditions. Paying close attention to command words, precise terminology, data handling, and the specific demands of each question will help you turn what you know into the marks you deserve.