Last reviewed: 25 October 2026
Integrated Science is sat over two days of the 2026 KJSEA. This guide sets out how the two papers work and then revises the topics Grade 9 learners miss most on the science CBC Challenge. At the top of that list are nutrition in plants and nutrition in animals, followed by curved mirrors, the structure of the atom and metals and alloys.
On this page
The two papers
The KNEC 2026 KJSEA timetable schedules:
- 905/1 Integrated Science (theory): Thursday 29 October, 8.30 to 10.10 am (1 hour 40 minutes).
- 905/2 Integrated Science: Friday 30 October, 2.00 to 3.00 pm (1 hour).
Paper 1 has a multiple-choice section followed by structured questions. Paper 2 tests practical skills through written questions on experiments. Our Grade 9 Integrated Science practice papers follow the 905/1 layout. Read each question for its command word: state needs a short fact, explain needs a reason, and describe needs the steps in order.
1. Nutrition in plants
Photosynthesis is the process by which green plants make glucose from carbon dioxide and water, using light energy trapped by chlorophyll, and release oxygen. The word equation is worth memorising: carbon dioxide + water → glucose + oxygen, in the presence of light and chlorophyll. The overview of photosynthesis is a useful refresher. Exam favourites:
- Starch test on a leaf: boil in water, then in alcohol (to remove chlorophyll), rinse, then add iodine. Blue-black means starch is present.
- Leaf adaptations: a broad, thin blade for light and gas exchange, stomata for gas exchange, and veins for transport.
- Destarching a plant by keeping it in the dark for 48 hours before an experiment.
Revise more on our photosynthesis revision page.
2. Nutrition in animals
Know the stages in order: ingestion, digestion, absorption, assimilation and egestion. Then match each part of the gut to its job. The mouth starts starch digestion with saliva. The stomach digests protein in acidic conditions. The small intestine finishes digestion and absorbs food through villi. The large intestine absorbs water. Learners lose marks by mixing up where absorption happens, which is mainly the small intestine. Also revise the types of teeth and their functions. Our digestive system revision has diagrams.
3. Curved mirrors
A concave mirror curves inwards and can form real or virtual images, depending on where the object is. It is used in torches, car headlamps and shaving mirrors. A convex mirror curves outwards and always forms an upright, smaller, virtual image, which is why it is used as a car side mirror and at blind corners. Learn the meaning of principal focus and focal length. The curved mirror reference has clear ray diagrams.
4. Structure of the atom
An atom has a nucleus of protons (positive) and neutrons (no charge), surrounded by electrons (negative) in energy levels. The atomic number is the number of protons. The mass number is protons plus neutrons. For the first 20 elements, the energy levels fill as 2, 8, 8, 2. So sodium (atomic number 11) is 2.8.1. A common error is writing the number of neutrons as the mass number.
5. Metals and alloys
An alloy is a mixture of a metal with other elements, made to improve its properties. Examples include brass (copper and zinc), bronze (copper and tin) and steel (iron and carbon). Link each alloy to a use, and remember the conditions for rusting: iron needs both water and oxygen.
Final-days plan
- Do one Grade 9 science Challenge set and note the “Revise next” topics.
- Revise the first topic using this page, then practise it.
- The night before each paper, read the Day 4 guide and pack pens, pencils, an eraser and a ruler.