Updated November 2026. These KCSE 2026 Biology Paper 1 (231/1) predicted questions are built from past-paper trends: we ranked the topics that past KCSE Biology Paper 1 papers test most often, then wrote original practice questions on them. They are not leaked, official or guaranteed questions, and this site is not linked to KNEC or KICD. Use them to practise the areas most likely to appear, alongside your full syllabus revision.
KCSE Biology 231/1 prediction: most commonly tested topics
The ranking below comes from the topic coverage of past KCSE papers, as summarised in our paper guides. It is a ranking, not an exact count: exam papers change every year.
| Rank | Topic | How it is usually tested |
|---|---|---|
| 1 | Cell biology and the microscope | Organelles, magnification, preparing slides |
| 2 | Cell physiology | Diffusion, osmosis, active transport |
| 3 | Nutrition in plants | Photosynthesis, leaf structure, limiting factors |
| 4 | Nutrition in animals | Digestion, enzymes, teeth, absorption |
| 5 | Transport in plants and animals | Xylem, phloem, transpiration, the heart, blood vessels, blood |
| 6 | Gaseous exchange | Lungs, gills, stomata, breathing mechanism |
| 7 | Respiration | Aerobic and anaerobic respiration, respiratory quotient |
| 8 | Classification | Kingdoms, binomial naming, dichotomous keys |
Free sample: 3 KCSE 2026 Biology Paper 1 predicted questions
Q1. A cell drawing is 6 cm long. The actual cell is 0.06 mm long. Calculate the magnification.
Marking scheme
6 cm = 60 mm. Magnification = 60/0.06 = ×1,000.
Q2. Explain what happens to a red blood cell placed in distilled water.
Marking scheme
Water enters by osmosis because the cell sap is more concentrated. The cell swells and bursts (haemolysis), since it has no cell wall.
Q3. State three ways a leaf is adapted for photosynthesis.
Marking scheme
Broad and thin for a large surface area and short diffusion distance; many chloroplasts in the palisade layer; stomata for gas exchange; veins with xylem and phloem.
Full set: 16 more predicted questions with marking scheme
16 more predicted questions with full marking schemes are locked. They cover every topic in the table above.
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Frequently asked questions
Are these the real KCSE 2026 Biology Paper 1 questions?
No. Nobody outside KNEC knows the real questions, and any site claiming a leak is lying or breaking the law. These are original practice questions written by the CBC Guide team, predicted from the topics past KCSE papers test most often.
Which topics come up most in KCSE Biology Paper 1 (231/1)?
The most commonly tested areas in past papers are Cell biology and the microscope, Cell physiology, Nutrition in plants, Nutrition in animals. The full ranked list is in the table above.
How do I get the full set of predicted questions?
The first 3 questions are free. The remaining 16, each with a marking scheme, unlock with the KSh 20 Day Pass or the KSh 500 Monthly Pass, paid by M-Pesa. The passes do not auto-renew.
How should I use predicted questions in the last days before the exam?
Answer each question under time, mark it with the scheme, then go back to your notes for any topic you got wrong. Do not skip topics that are not on this list, because KNEC can test any part of the syllabus.
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