Combined Science Practice Questions.

Combined Science practice questions for Zimsec O’level Students. I have divided them into sections in which they belong. I will upadate the answers and explanations later on.

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Biology Section questions

  1. Why is photosynthesis an important process to all living organisms?
  2. Write a word equation to summarise the process of photosynthesis.
  3. By means of a simple labelled diagram and full experimental details, describe an experiment to show one of the conditions necessary for photosynthesis to occur.
  4. State five ways in which a leaf is adapted for photosynthesis.
  5. Draw a simple diagram showing a transverse section through a leaf and label the following parts:
  • Epidermis layer
  • Stomata
  • Vascular tissue
  • Mesophyll
  1. Draw a fully labelled diagram of the alimentary canal and state the functions of five of the labelled parts.
  2. Copy and complete table 2.6, on products of digestion and their use.
NutrientEnd product of digestionUse
  1. Distinguish between absorption and assimilation.
  2. How is the gut adapted to facilitate absorbtion?
  3. Tabulate the differences between inhaled and exhaled air.
  4. How is the alveolus adapted for gaseous exchange?
  5. Why is respiration important to all living organisms?
  6. Which gas is used as evidence that respiration has occurred. Describe a test for the gas you named.
  7. Describe an experiment to show either production of carbon dioxide or energy by one of the following: green plants, germinating seeds or small animal.
  8. State the functions of any five of the human respiratory organs.
  9. Distinguish between diffusion and osmosis. Which process facilitates mineral ion uptake into the plant?
  10. Why is transpiration an important process in plants?
  11. What conditions can favour an increase in the rate of transpiration?
  12. Explain how the plant leaves are adapted to reduce water loss.
  13. State four characteristics of wind pollinated flowers.
  14. State the functions of the following parts of a seed:
  • Testa
  • Micropyle
  • Radicle
  • Plumule
  1. State the conditions necessary for germination.
  2. What do you understand by the term variation?
  3. Distinguish between continuous and discontinuous variation, giving two examples of each in plants and animals.
  4. When determining water content in soil a sample, why is the soil dried over a hot water bath than directly over the burner?
  5. The following are results from the experiment on heating the soil directly over a burner.
  • Mass of container = 60g
  • Mass of container + fresh soil = 100g
  • Mass of container + soil after heating over water bath = 96,5g
  • Mass of container + soil after direct heating = 83,5g

Calculate the percentage of water and the percentage of humus in the soil sample.
27. State the importance of each physical and biological component of soil.
28. Define a balanced diet.
29. List the components of a balanced diet and for each state its use(s) and two food sources.
30. State the importance of breast-feeding.
31. Copy and complete table

NutrientReagent(s)ObservationsIs nutrient present or absent
Reducing sugarpresent
  1. Describe the types of teeth and their functions of teeth.
  2. Describe the proper care of teeth.
  3. What causes malaria?
  4. Describe the main symptoms of malaria.
  5. How can malaria be controlled and treated?
  6. What is the causative agent for cholera?
  7. State the symptoms of cholera.
  8. How can cholera be controlled and treated?
  9. What are the body’s defence mechanisms?
  10. Distinguish between:
  • HIV and AIDS.
  • Active and passive immunity.
  • Naturally and artificially acquired immunity.
  1. How does an infant acquire immunity?
  2. Draw a fully labelled diagram of either the human male or female reproductive system and state the functions of the five labelled parts.
  3. What are the differences and similarities between the sperm and the ovum?
  4. Where in humans does fertilisation occur?
  5. Where does ovulation occur in humans?
  6. What is implantation?
  7. What is the purpose of the menstrual cycle in women and why does it stop during pregnancy?
  8. State four methods of contraception and for each method, give three advantages and three disadvantages.
  9. For any three sexually transmitted diseases (STIs) you have studied, state the causative agent, signs and symptoms, treatment, prevention and control.
  10. In what ways does AIDS differ from Syphilis?

Chemistry Section Revision

  1. Name the three states of matter.
  2. Explain using the kinetic theory, the changes observed when ice is heated to a high temperature.
  3. Describe an atom.
  4. Name the sub-atomic particle that:
  • Has a positive charge.
  • Is found in the shells.
  1. Describe the nucleus of an atom.
  2. Draw an atom show the location of the nucleus, protons, electrons, and neutrons.
  3. Define an element.
  4. Give an example of a metallic element and a non-metallic element.
  5. Give two differences between a compound and a mixture.
  6. Write an equation for the chemical reaction that occurs between magnesium and air to produce magnesium oxide.
  7. State two elements that conduct electricity.
  8. Give one use for each of the elements:
  • Iron
  • Copper
  1. Name the salt formed when iron reacts with sulphuric acid.
  2. Name the metal and acid that react to produce zinc nitrate.
  3. Define oxidation in terms of oxygen gain or loss.
  4. Write equations for the reactions that in the blast furnace and name the substances that are oxidised and reduced.
  5. What is produced when sulphuric acid reacts with ammonia?
  6. What is the function of universal indicator?
  7. What colour is litmus in:
  • Ammonia solution?
  • Sodium hydroxide solution?
  1. Name two alloys of iron and state a use for each.
  2. State two uses of copper and explain why it is preferred over iron.
  3. Name the raw materials for the contact process.
  4. Why is sulphur trioxide not added directly to water in the contact proccess?
  5. State the reactants and products in the Haber process.
  6. Describe an industrial manufacture for one of the reactants in the Haber process.
  7. Draw a labelled diagram for the electrolysis of water.
  8. What substances are removed as solids at -55⁰C during the liquefaction of air?
  9. List the states in which fuel can be found.
  10. State the occurrence of coal in Zimbabwe and name the place where coal is mined.
  11. State the factors affecting:
  • Biogas production
  • Ethanol production
  1. State three uses of each of the following :
  • Ethanol
  • Carbon dioxide
  1. Which fuel between the following pairs produce more energy?
  • Charcoal and coke
  • Diesel and ethanol
  • Biogas and hydrogen
  1. Write word equations to show complete and incomplete combustion when petrol blend (fuel) is burnt in plentiful air and in very limited air.
  2. State the dangers of incomplete combustion.

Physics Section Questions

  1. State the four strokes in a petrol engine and describe the operations of any two of the strokes.
  2. What is the function of the carburettor?
  3. Describe the effects of:
  • Blocked filters.
  • Worn out jets.
  • Sticky choke control.
  1. Give two advantages of multiple cylinders in an engine.
  2. Give the differences between a diesel engine and a petrol engine.
  3. Distinguish between renewable and non-renewable sources of energy.
  4. Give two examples of both renewable and non-renewable sources of energy.
  5. Describe the social and economic implications of using fuels.
  6. Describe how charges are produced.
  7. State the action between like and unlike charges.
  8. State the dangers of lightning.
  9. Explain:
  • The production of lightning.
  • The principle of a lightning conductor.
  1. State precautions one must take against lightning.
  2. Explain what is meant by:
  • Voltage (V)
  • Current (I)
  1. Name the instrument used to measure the following and give the unit for each.
  • Voltage
  • Current
  1. Calculate the current and hence power drawn from a power source where voltage is 210V when passing a current through a resistor of 30Ω.
  2. State Ohm’s Law.
  3. A 12V battery is supplying a current to two resistors in parallel of resistance ⅓ Ω and ⅟2Ω.
  • Draw a fully labelled circuit diagram to show the above connections.
  • Calculate the total current flowing in the circuit.
  1. State the unit of charge.
  2. Explain/Describe the arrangement of cells to give:
  • Higher current
  • Higher voltage
  1. Distinguish between ac and dc.
  2. Give reasons for transmitting electricity as ac.
  3. Draw a fully labelled diagram of a motor.
  4. State energy changes that occur when a motor is used to pump water.
  5. Distinguish between a motor and a generator in terms of energy changes.
  6. Describe and explain how a bicycle dynamo lights the bulb.
  7. Give any two electrical hazards and for each hazard give a corresponding safety precaution.
  8. Describe how a three-pin plug is wired.
  9. State three methods by which heat is transferred.
  10. Describe and explain why:
  • In cold countries, houses are painted dull black.
  • In hot countries, houses are painted white/shiny colours.
  1. Draw a diagram to show convection currents in water in a flask in which a crystal of potassium permanganate is gently heated.
  2. Define a machine.
  3. Give three examples of machines.
  4. A load of 60N is lifted by an effort of 5N over a height of 2m. Calculate:
  • The mechanical advantage of the system.
  • The velocity ratio and hence.
  • The efficiency of the machine.
  1. Describe how energy is lost machines and give two ways of reducing the energy losses.
  2. What is pressure and what are the units of pressure.
  3. Name the instrument used to measure pressure in fluids.
  4. Name two types of pumps.
  5. Draw a fully labelled diagram of a named pump and describe its operation.
  6. What principles of liquid pressure do hydraulic systems use?
  7. Describe how the following simple hydraulic systems function and operate:
  • A siphon used to transfer diesel from a container into the car tank.
  • Car braking system.

To be continued…

Sydney Chako

Mathematics, Chemistry and Physics teacher at Sytech Learning Academy. From Junior Secondary School to Tertiary Level Engineering Mathematics and Engineering Science.


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