National 4 Biology: the units, the assignment and practice questions

There's no National 4 exam to sit a prelim for, so use the National 4 daily paper as practice for your unit tests, and the National 5 paper to see what comes next.

How National 4 Biology is assessed

The course specification sets out four units, each worth 6 SCQF credit points at level 4, making 24 in all.

The three units

Each unit has two outcomes (unit specification):

• An experiment or practical investigation. You plan it, follow it safely, record observations, present the results, draw a conclusion and suggest an improvement.
• Knowledge and problem solving. You make accurate statements across the unit and solve problems: predicting, selecting information and processing it. When this is one combined test, you need at least 50% to pass.

The National 4 Biology assignment

For the added value unit, you choose a topical issue from one of the units with your teacher, and justify the choice: for example, stem cell treatments or the effect of fertilisers on a loch. You research it, process and present the information, apply your biology to it and communicate what you found. It's done in class under some supervision, with no more than 8 hours on the whole assignment. Your teacher marks it, and you need at least 50% (7 marks or more) to pass.

• Assessed in school. Your teachers mark every unit, and Qualifications Scotland checks schools' standards.
• Not graded. You must pass all four units, including the assignment. There are no A to D grades at National 4.
• No exam date. National 4 courses aren't in the 2027 exam timetable.

Qualifications Scotland replaced SQA on 1 February 2026 and says these documents remain current.

From National 4 to National 5 Biology

Each National 4 unit leads into the matching area of National 5 Biology, which is assessed by an exam and an assignment and graded A to D. In 2027 the National 5 Biology exam is on Wednesday 12 May, 13:00 to 15:00.

National 4 Biology practice questions

We wrote these for this guide. Answer in full sentences, using the key words.

Question 1 (Cell Biology): what kind of cell division makes new cells for growth and repair, and how do the new cells compare with the original? Answer: mitosis. The two daughter cells are genetically identical to the parent cell, with a matching chromosome count. Try naming the stages of mitosis in our Cell Biology course and press Mark.

Question 2 (Cell Biology): an enzyme works best at 37 °C. What happens to its activity at 60 °C, and why? Answer: activity falls. Heat alters the active site, so the substrate can no longer bind to it. The enzyme is denatured.

Question 3 (Cell Biology): name three factors that can limit the rate of photosynthesis. Answer: light intensity, carbon dioxide concentration and temperature.

Question 4 (Life on Earth): a survey counts 40 song thrushes in a wood one year and 50 the next. Find the percentage increase. Answer: the increase is 10, and 10 ÷ 40 × 100 = 25%. Always divide by the starting number.

Common mistakes

• Saying enzymes are killed. Enzymes aren't alive: they're denatured.
• Dividing by the new number in a percentage change, instead of the starting number.
• Vague variables: in your experiment, name exactly what you changed, what you measured and what you kept the same.
• Copying sources in the assignment instead of explaining the biology in your own words.

Practise with a daily paper

Today's National 4 Biology paper covers cells, photosynthesis, respiration, inheritance and variation, ecosystems and food chains, and human impact on the environment, which match much of the course. It also includes the heart, digestion and disease, and it doesn't cover enzymes and microorganisms in industry, growing plants, the nitrogen cycle or learned behaviour. It can't practise your experiment or assignment. When you're ready for more, try the National 5 Biology paper.

Read next

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