KCSE Biology Paper 1 (231/1): Revision Guide and Questions

Last reviewed: 31 October 2026

Updated October 2026. KCSE Biology Paper 1 (231/1, Biology Paper 1 (Theory)) is a 2 hours paper. Short-answer questions, all compulsory, 80 marks. On the KNEC 2026 timetable it is on Tuesday 10 November 2026, 2.00 to 4.00 pm. Below: what the paper covers, how to answer for marks, original practice questions with answers, and a timed KCSE Biology Paper 1 challenge you can try free.

What is in KCSE Biology Paper 1?

Short-answer questions, all compulsory, 80 marks. Always follow the instructions printed on your own paper; layouts can change.

Topics that come up most in Biology Paper 1

• Cell biology and cell physiology
• Nutrition in plants and animals
• Transport, gaseous exchange and respiration
• Classification
• Excretion, homeostasis and ecology

How to answer Biology Paper 1 for marks

1. Use correct biological terms and spell them right.
2. Give one point per mark.
3. Labelled diagrams must have ruled label lines.
4. Read every question twice and underline the command word (state, explain, describe, calculate).
5. Budget time by marks: roughly one minute per mark, plus checking time.

Topic weighting: where the marks are in Biology Paper 1

Short compulsory questions sample every Form 1 to 4 topic. Cell physiology, nutrition, transport and ecology are consistent sources of marks.

Common mistakes in KCSE Biology Paper 1

• Vague answers like ‘it helps the plant’ without the function
• Misspelt terms (for example ‘photosythesis’)
• Mixing up diffusion and osmosis
• Giving two points where one is asked and the second is wrong (it can cancel the mark)

Examiner-style tips for Biology Paper 1

• Use precise verbs: absorbs, secretes, transports.
• Learn adaptations as structure plus function pairs.
• When asked to ‘name’, a single correct term is enough.

KCSE Biology Paper 1 questions and answers (practice)

These are original practice questions written for revision, not KNEC papers.

Question 1

State two functions of the cell membrane.

Answer: It controls movement of substances into and out of the cell and protects the cell contents.

Question 2

Name the process by which plants lose water through leaves.

Answer: Transpiration.

Question 3

Name the organelle where aerobic respiration takes place.

Answer: Mitochondrion.

Question 4

State two adaptations of the leaf for photosynthesis.

Answer: Broad, flat lamina for a large surface area, and many chloroplasts in the palisade layer.

Question 5

What is a food chain?

Answer: A feeding sequence showing the transfer of energy from producers to consumers.

Biology Paper 1 revision checklist

Tick each line only when you can do it from memory, under time:

• I can answer an exam-style question on cell biology and cell physiology without notes.
• I can answer an exam-style question on nutrition in plants and animals without notes.
• I can answer an exam-style question on transport, gaseous exchange and respiration without notes.
• I can answer an exam-style question on classification without notes.
• I can answer an exam-style question on excretion, homeostasis and ecology without notes.
• I have done at least one full 2 hours practice paper and marked it.
• I have listed my last five mistakes and redone them correctly.

On the day of Biology Paper 1

Tuesday 10 November 2026, 2.00 to 4.00 pm. Be seated 15 minutes early. Carry blue or black pens, a pencil, a ruler and a rubber, a mathematical set and an approved non-programmable calculator. Read the whole paper in the first five minutes and mark the questions you will answer first. Leave the last ten minutes to check your answers and that your index number is on every page you hand in.

Three-day plan for Biology Paper 1

Practise Biology Paper 1 online

The KCSE Biology Paper 1 challenge gives timed questions with a score, a leaderboard rank and a share card. For full papers with worked answers see KCSE practice papers, the KCSE Biology revision quiz and this related guide. Check dates in the KCSE 2026 timetable and use the last-minute revision plan.

How this guide differs from past-paper sites

The top Google results for KCSE Biology Paper 1 are mostly PDF downloads of old papers and marking schemes. Those are useful, but they rarely explain where the marks sit, what candidates get wrong or how to practise under time. This guide adds that, with original questions and a timed online challenge with instant marking.

Frequently asked questions

How many marks is KCSE Biology Paper 1?

80 marks in short-answer questions, 2 hours.

Where can I get the KCSE Biology Paper 1 marking scheme?

Official marking schemes are not published by KNEC for sale. Use practice papers with worked answers and the answers on this page, and be wary of anyone selling ‘marking schemes’ for the coming exam.

Are KCSE Biology Paper 1 leaked papers real?

No. Papers sold online before the exam are scams, and holding them is an exam irregularity that can lead to cancelled results (see KCSE exam rules).

How long is KCSE Biology Paper 1?

2 hours on the 2026 timetable.

Can I download the KCSE Biology Paper 1 2025 PDF here?

We do not host KNEC papers. Practise with original papers in the same format, with worked answers, in KCSE practice papers; schools keep past KNEC papers for their candidates.

Is there a KCSE Biology Paper 1 prediction for 2026?

Prediction papers are teachers’ practice papers, not the real exam. Use them like any past paper and focus on the topics listed above.

Want marked practice? Try the first questions free. A Day Pass (KSh 20) or Weekly Pass unlocks full papers with worked answers, paid once by M-Pesa, no auto-renewal. See all passes.

Keep revising with these: KCSE 2026 Paper-by-Paper Revision Challenges.