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Zimsec Combined Science Revision Questions with Answers

This is an interactive revision session. It is a sample of the combined science paper 1 issued by Zimsec in 2018.

1 Which instrument is most suitable for observing specialised cells?
A microscope
B telescope
C bioviewer
D magnifying lens

2 The diagram shows a specialised cell.
What is the name of the cell?
A muscle cell
B palisade cell
C root hair cell
D red blood cell

3 Which adaptation of a leaf does not increase the rate of photosynthesis?
A air spaces
B thick cuticle
C numerous stomata
D large surface area

4 Which atmospheric condition reduces the rate of water uptake in plants?
A high humidity
B high wind speed
C high temperature
D high light intensity

high humidity
5 A wind pollinated flower
A has short filaments.
B has large petals.
C has numerous pollen grains.
D produces nectar.

6 Ebola is caused by a
A bacterium.
B fungus.
C protozoan.
D virus.

7 Excessive consumption of alcohol leads to
A emphysema.
B hallucinations.
C lung cancer.
D liver cirrhosis.

8 Which deficiency disease is caused by lack of Vitamin C?
A goitre
B scurvy
C anaemia
D rickets

9 A student carried out a test on a food substance using the Biuret solution and a purple
colour was observed.
Which nutrient was present in the food substance?
A fats
B proteins
C vitamins
D carbohydrates

10 Which is a function of the white blood cells?
A defence
B excretion
C transport
D homeostasis

11 Which contraceptive method prevents ovulation?
A pill
B spermicides
C sterilization
D intra uterine device

12 Which event will result in a child acquiring active immunity?
A keeping the child away from sick people
B injection the child with artificial hormones
C injection the child with a vaccine
D breastfeeding the child for at least six months

13 What happens to most of the energy as it flows through an ecosystem?
A It is recycled.
B It is lost as heat.
C It is used in digestion.
D It is stored as carbohydrates.

14 The physical property used in fractional distillation is the difference in
A densities of the liquids.
B boiling points of the liquids.
C melting points of the liquids.
D heat capacities of the liquids.

15 17Cl35 17Cl37  are called
A isomers.
B isotopes.
C monomers.
D polymers.

16 The diagram show the outermost shell of element Z.

Z forms an ion with a charge of

17 Sulphuric acid and calcium hydroxide reacts as shown by the equation:
H2SO4(aq)+Ca(OH)2(aq) → CaSO4(aq)+2H2O(l)
If 0.1 moles of sulphuric acid are used, how many moles of water are produced?
A 0.1
B 0.2
C 1.0
D 2.0

18 An organic compound contains 84 % carbon(C) and 16 % hydrogen (H) by mass.
[atomic mass of C is 12 and that of H is 1]
What is the empirical formula of the organic compound?
D C2H4

19 Which substance, in exhaust fumes, causes global warming?
A carbon soot
B carbon dioxide
C water vapour
D carbon monoxide

20 What is the use of limestone in the blast furnace?
A to produce slag
B to act as a fuel
C to produce carbon monoxide
D to reduce iron (III) oxide to iron

21 Which diagram, A, B, C, or D, shows the structure of ethane?

22 The list shows part of the reactivity series of metals:
What is the position of a metal that reacts vigorously with cold water?
A below copper
B above calcium
C between zinc and copper
D between magnesium and zinc

23 Which temperature is used in the Haber process?
A 200 oC
B 300 oC
C 450 oC
D 800 oC

24 The equation shows the reaction between iron oxide and carbon monoxide.
iron oxide + carbon monoxide iron + carbon dioxide
Which is the oxidising agent?
A iron
B iron oxide
C carbon dioxide
D carbon monoxide

25 The flow diagram shows the manufacture of sulphuric acid.
What is X?
A water
B vanadium pentoxide
C dilute sulphuric acid
D concentrated sulphuric acid

26 The diagram shows the structure of an organic molecule.

To which homologous series does the molecule belong?
A alcohols
B aldehydes
C alkanes
D alkenes

27 Which instrument would be used to accurately measure the internal diameter of
a glass bottle?
A metre rule
B vernier callipers
C tape measure
D micrometer screw gauge

28 Weight can be calculated by multiplying acceleration due to gravity by
A mass.
B velocity.
C time.
D distance.

29 The diagram shows a pulley system.
What is the velocity ratio (VR) of the pulley system?
A 1
B 2
C 3
D 4

30 The diagrams show the four strokes of a petrol engine.
Which diagram, A, B, C or D, shows the inlet stroke?

31 The diagram shows a simple direct current (d.c) electric motor.
Which part, A, B, C or D, is the commutator?

32 Which circuit diagram, A, B, C or D, can be used to determine the resistance of a
resistor, R?

33 The pie chart shows components X, Y and Z which are in a mixture.
What is the percentage of Z in the mixture?
A 8%
B 16%
C 25%
D 75%

34 A wind blows with a force of 200 N against a wall of height 2 m and length 5 m.
What is the pressure exerted on the wall by the wind?
A 20 N/m2
B 40 N/m2
C 100 N/m2
D 200 N/m2

35 The diagram shows a manometer used to measure gas pressure.
[Acceleration due to gravity is g, density of liquid is 휌.]
Which expression gives the gas pressure, G?
A G = P − 휌gh
B G = P + 휌gh
C G = 휌gh−P
D G = 휌gh

36 Why does a solar cooker have a shiny surface?
A to reflect heat
B to conduct heat
C to absorb heat
D to concentrate heat

37 Which media of communication is used to share pictures using cell phones?
A coaxial cable
B optic fibre
C sheathed pair cables
D wi-fi

38 The diagram shows a 3-pin plug.
What is the standard colour of wire Y?
A green-yellow
B blue
C black
D brown

39 What is the energy conversion in a generator?
A electrical energy kinetic energy
B electrical energy mechanical energy
C mechanical energy electrical energy
D mechanical energy potential energy

40 Electricity costs 10 cents per kilowatt hour (kWh).
How much does it cost to run a 0.75 kw machine for 20 hours?
A $0.375
B $1.50
C $7.50
D $15.00


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