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KCSE Biology Paper 1 (231/1) Short-Answer Practice
Original CBC Guide questions in the KCSE format, not an official KNEC paper. Checked by the CBC Guides team. Spot an error? Tell us.
Sit an original KCSE Biology Paper 1 (231/1) short-answer practice paper online: 20 concept questions and 5 calculations covering the Form 1–4 syllabus, 50 marks in 60 minutes, auto-marked with explanations. The first five questions are free; Learners unlock all 25, the timer and the full review.
The Three KCSE Biology Papers
| Paper | Date (2026) | Time | Marks | Format |
|---|---|---|---|---|
| 231/1 | Tuesday 10 November, 2.00 p.m. | 2 h | 80 | Short structured questions across the syllabus |
| 231/2 | Thursday 12 November, 8.00 a.m. | 2 h | 80 | Section A structured (40), a compulsory data/graph question (20), and one essay from a choice (20) |
| 231/3 | Friday 13 November, 8.00 a.m. | 1 h 45 min | 40 | Practical: specimens, food tests, experiments |
Dates and times from the KNEC 2026 KCSE timetable.
What This Practice Covers
Like the real Paper 1, our questions sample every major topic: classification and binomial names, cell structure and organelles, osmosis, nutrition and enzymes, photosynthesis, transport in plants and animals, gaseous exchange, respiration, excretion and homeostasis, genetics (monohybrid crosses and sex linkage), ecology and population estimation, reproduction in plants, evidence for evolution, support and coordination. The five calculation questions cover magnification, cell size from the field of view, capture–recapture, the respiratory quotient and genetic ratios, which are classic easy marks if the formula is known.
Writing Answers Examiners Accept
Biology marking schemes are strict about scientific terms. “Water moves in by osmosis” scores where “the cell drinks water” does not. Spell technical words correctly, because a misspelling that changes the word (for example “ureter” for “urethra”) loses the mark. When a question says “explain”, give the process and the reason: “the cell bursts because water enters by osmosis from a hypotonic solution”. For “name” questions, one correct word is enough, and adding a wrong second answer can cancel the right one.
Formulas And Facts To Memorise
- Magnification = drawing size ÷ actual size (same units).
- Population estimate = (first catch × second catch) ÷ marked in second catch.
- Cell size = field diameter ÷ number of cells across, with 1 mm = 1,000 µm.
- RQ = CO₂ produced ÷ O₂ used: about 1.0 for carbohydrates, about 0.7 for fats.
- Tt × Tt gives 3 : 1; Tt × tt gives 1 : 1.
Preparing For Paper 2 And The Practical
Paper 2 always includes a compulsory question built on a table of data. You will usually be asked to plot a graph, read values from it and explain the trend. Practise choosing a sensible scale, labelling both axes with units, plotting accurately and joining the points as the question asks. The essay is marked by points, so plan five or six clear points before writing. For the practical, revise the food tests, how to cut and draw specimens with a magnification, and how to identify adaptations of plant and animal specimens to their habitats.
Common Mistakes
- Mixing up the pulmonary artery and the pulmonary vein.
- Saying plants respire only at night.
- Writing the genus in lower case or the species with a capital letter.
- Forgetting units in magnification and cell-size answers.
More practice: KCSE Chemistry, KCSE Mathematics, and the KCSE past papers hub.
Original CBC Guide questions in the KCSE format, not an official KNEC paper. KCSE follows the KNEC 8-4-4 syllabus; checked by the CBC Guides team. Spot an error? Tell us.