Question 1 (B1.1)
Which characteristic of living things is described as the removal of toxic materials and substances in excess of requirements?
A. excretion
B. homeostasis
C. nutrition
D. respiration
▶️Answer/Explanation
Answer: A
Explanation: Excretion is the process by which living organisms remove toxic materials and waste products of metabolism (like urea and carbon dioxide) that are in excess of requirements. Homeostasis refers to maintaining internal balance, nutrition involves obtaining food, and respiration is the release of energy from food.
Question 2 (B2.1)
What is not in contact with cytoplasm?
A. cellulose cell wall
B. cell membrane
C. chloroplast
D. nucleus
▶️Answer/Explanation
Answer: A
Explanation: The cellulose cell wall is an outer layer found in plant cells that provides structural support but is not part of the living cell contents. The cytoplasm (gel-like substance inside the cell) is in direct contact with the cell membrane, chloroplasts, and nucleus.
Question 3 (B4.1)
A food contains reducing sugar, but no starch. What colours will be obtained if samples of the food are tested with Benedict’s solution and with iodine solution?
| Benedict’s test | iodine test | |
|---|---|---|
| A | blue | blue-black |
| B | blue | brown |
| C | red-orange | blue-black |
| D | red-orange | brown |
▶️Answer/Explanation
Answer: D
Explanation: Benedict’s solution turns from blue to red-orange in the presence of reducing sugars. Iodine solution remains brown when no starch is present (it only turns blue-black if starch is present). Therefore, the correct combination is red-orange (Benedict’s) and brown (iodine).
Question 4 (B5.1)
Why do cells contain many different types of enzymes?
A. Enzymes are affected by substrate concentration.
B. Enzymes are affected by temperature.
C. Enzymes have an active site complementary to a specific substrate.
D. Enzymes work at different pH values.
▶️Answer/Explanation
Answer: C
Explanation: Each enzyme has a unique active site shape that is complementary to a specific substrate (lock-and-key model). Since cells need to catalyze many different biochemical reactions, they require many different enzymes, each specialized for a particular substrate.
Question 5 (B6.1)
In photosynthesis, how many molecules of glucose will be produced from twelve molecules of carbon dioxide?
A. 2
B. 6
C. 12
D. 24
▶️Answer/Explanation
Answer: A
Explanation: The balanced equation for photosynthesis is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. This shows that 6 molecules of CO₂ are needed to produce 1 molecule of glucose. Therefore, 12 CO₂ molecules (double the amount) would produce 2 glucose molecules.
Question 6 (B7.1)
Why is calcium needed in the diet?
A. to make carbohydrates
B. to make teeth
C. to make enzymes
D. to make protein
▶️Answer/Explanation
Answer: B
Explanation: Calcium is essential for the formation and maintenance of strong bones and teeth. It combines with phosphorus to form calcium phosphate, which gives hardness to bones and teeth. Calcium is not directly involved in making carbohydrates, enzymes, or proteins.
Question 7 (B9.2)
Which is not a risk factor in coronary heart disease?
A. diet high in fat
B. low blood pressure
C. smoking
D. stress
▶️Answer/Explanation
Answer: B
Explanation: Low blood pressure is not a risk factor for coronary heart disease. In fact, high blood pressure is a risk factor. The other options (high-fat diet, smoking, and stress) are all known risk factors that can lead to atherosclerosis and coronary heart disease.
Question 8 (B11.1)
Which cells produce mucus in the human breathing system?
A. alveoli cells
B. capillary cells
C. ciliated cells
D. goblet cells
▶️Answer/Explanation
Answer: D
Explanation: Goblet cells are specialized epithelial cells that secrete mucus in the respiratory tract. This mucus traps dust and pathogens. Ciliated cells move the mucus upward, while alveoli and capillary cells are involved in gas exchange.
Question 9 (B13.3)
What happens when the body temperature falls below normal?
A. Arterioles supplying the skin constrict.
B. Arterioles supplying the skin dilate.
C. Capillaries move towards the skin surface.
D. Capillaries move away from the skin surface.
▶️Answer/Explanation
Answer: A
Explanation: When body temperature drops, arterioles in the skin constrict (vasoconstriction) to reduce blood flow to the skin surface, minimizing heat loss. This is part of the body’s thermoregulatory mechanism to conserve heat.
Question 10 (B16.3)
Which statements about individuals in a large population of birds are correct?
- All individuals are diploid.
- Some individuals may have the same allele combination as both of their parents.
- Some individuals will be better adapted to their environment than others.
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2 and 3
▶️Answer/Explanation
Ans: B
Question 11 (B17.2)
A farmer wants to breed sheep that will produce a high yield of milk.
What is required for breeding these sheep?
| genetic variation | selective breeding | natural selection | |
|---|---|---|---|
| A | ✓ | ✓ | ✗ |
| B | ✓ | ✗ | ✓ |
| C | ✗ | ✓ | ✗ |
| D | ✗ | ✗ | ✓ |
key: ✓ = yes, ✗ = no
▶️Answer/Explanation
Answer: A
Explanation: Selective breeding requires both genetic variation (to have different traits to select from) and the process of selective breeding itself (choosing individuals with desired traits to reproduce). Natural selection is not involved as this is an artificial selection process controlled by the farmer.
Question 12 (B18.2)
The diagram shows a food web.
Which statement is correct?
A. The fox is a secondary consumer only.
B. The mouse is a primary consumer only.
C. The owl is a tertiary consumer only.
D. The snake is a tertiary consumer only.
▶️Answer/Explanation
Answer: D
Explanation: In a typical food web, snakes often occupy the tertiary consumer level as they feed on secondary consumers (like mice or frogs). The other options are incorrect because foxes, mice, and owls can occupy multiple trophic levels depending on what they’re eating in a particular food chain within the web.
Question 13 (C10.2)
Which line shows how the oxygen concentration of the water changes after excess fertilizer has entered a stream?
▶️Answer/Explanation
Answer: B
Explanation: Excess fertilizer causes algal blooms which initially increase oxygen production through photosynthesis. When the algae die, decomposition by bacteria uses up oxygen, causing a sharp decrease. As the organic matter is fully decomposed, oxygen levels gradually recover downstream.
Question 14 (C2.2)
Which statement about atoms and molecules is correct?
A. All molecules are gases at room temperature and pressure.
B. An atom is the smallest part of an element.
C. Atoms of the same element all have the same mass.
D. Molecules always contain atoms of more than one element.
▶️Answer/Explanation
Answer: B
Explanation: An atom is indeed the smallest unit of an element that retains its properties. Option A is incorrect as molecules can be solids, liquids or gases. Option C is wrong because isotopes exist. Option D is incorrect as elements like O2 are molecules of a single element.
Question 15 (C2.4)
What happens to rubidium atoms and to oxygen atoms when they form rubidium oxide, Rb2O?
| rubidium atoms | oxygen atoms | |
|---|---|---|
| A | gain one electron each | lose one electron each |
| B | gain one electron each | lose two electrons each |
| C | lose one electron each | gain one electron each |
| D | lose one electron each | gain two electrons each |
▶️Answer/Explanation
Answer: D
Explanation: Rubidium (Group I) loses one electron to form Rb+, while oxygen (Group VI) gains two electrons to form O2-. The formula Rb2O shows two Rb+ ions are needed to balance one O2- ion.
Question 16 (C2.5)
Which dot-and-cross diagram represents the bonding in a molecule of carbon dioxide?
▶️Answer/Explanation
Answer: A
Explanation: CO2 has two double covalent bonds between carbon and each oxygen atom. Each double bond is represented by two shared electron pairs (::). Carbon shares 4 electrons total (its outer shell) and each oxygen shares 2 electrons to complete their outer shells.
Question 17 (C4.1)
The diagram shows the electrolysis of lead(II) bromide using inert electrodes.
Which statement about this experiment is correct?
A. Electrode X is positively charged.
B. The colored fumes are produced at the negative electrode.
C. The electrolyte is lead(II) bromide.
D. The grey solid is lead(II) bromide.
▶️Answer/Explanation
Answer: C
Explanation: The electrolyte is indeed molten lead(II) bromide. Electrode X is the cathode (negative) where lead metal (grey solid) forms. Bromine gas (colored fumes) forms at the anode (positive electrode). The grey solid is lead metal, not lead(II) bromide.
Question 18 (C6.3)
The ionic equation for the formation of chromium(III) ions is shown:
Cr → Cr3+ + 3e–
Which statement about chromium atoms is correct?
A. They are oxidized by gaining electrons.
B. They are oxidized by losing electrons.
C. They are reduced by gaining electrons.
D. They are reduced by losing electrons.
▶️Answer/Explanation
Answer: B
Explanation: Oxidation is loss of electrons (OIL RIG). Here chromium loses 3 electrons to form Cr3+, so it’s being oxidized. Reduction would involve gaining electrons, which isn’t happening in this equation.
Question 19 (C7.2)
Aluminium oxide (Al2O3), nitrogen monoxide (NO), and sulfur trioxide (SO3) are each tested with dilute hydrochloric acid and with aqueous sodium hydroxide.
The results are shown.
Which oxides are neutral oxides?
A. Al2O3 and NO
B. Al2O3 and SO3
C. NO only
D. SO3 only
▶️Answer/Explanation
Answer: C
Explanation: NO is a neutral oxide – it doesn’t react with acids or bases. Al2O3 is amphoteric (reacts with both), and SO3 is acidic (reacts with bases only). The table shows NO has no reaction (✗) with either acid or base.
Question 20 (C7.3)
Zinc oxide is an insoluble base. It reacts with dilute hydrochloric acid to produce zinc chloride.
Which statement about the preparation of zinc chloride crystals is correct?
A. Once the reaction is complete there is no need to filter the reaction mixture.
B. The reaction mixture is neutral at the point that no more zinc oxide reacts.
C. Zinc chloride crystals are obtained by evaporation to dryness.
D. Zinc chloride precipitates when the solution becomes neutral.
▶️Answer/Explanation
Answer: B
Explanation: When all zinc oxide has reacted, the solution is neutral (pH 7) as the base and acid have completely neutralized each other. The mixture must be filtered to remove excess zinc oxide (A is wrong). Zinc chloride is water-soluble so won’t precipitate (D wrong). Crystals form by gentle evaporation, not drying (C wrong).
Question 21 (C8.3)
The properties of the elements in Group VII of the Periodic Table change going down the group.
Which change in properties is correct?
A. They become darker in colour.
B. They have lower atomic numbers.
C. They have lower boiling points.
D. They become more reactive.
▶️Answer/Explanation
Answer: A
Explanation: As you go down Group VII (halogens), the elements become darker in color. For example, chlorine is pale yellow-green, bromine is red-brown, and iodine is grey-black. The other options are incorrect because atomic numbers increase down the group, boiling points increase, and reactivity decreases down the group.
Question 22 (C9.3)
Which metal is mixed with copper to make brass?
A. aluminium
B. iron
C. magnesium
D. zinc
▶️Answer/Explanation
Answer: D
Explanation: Brass is an alloy made by mixing copper with zinc. The proportion of zinc can vary to create different types of brass with varying properties.
Question 23 (C9.2)
Which statement is not a reason why aluminium is used in aircraft manufacture?
A. It forms low density alloys.
B. It is malleable.
C. It is more reactive than iron.
D. It is resistant to corrosion.
▶️Answer/Explanation
Answer: C
Explanation: While aluminium is indeed more reactive than iron, this is not a reason for its use in aircraft. Its use is due to its low density (A), malleability (B), and corrosion resistance (D) when it forms a protective oxide layer.
Question 24 (C10.2)
Which reaction does not take place in a catalytic converter?
A. 2CO + O2 → 2CO2
B. 2NO → N2 + O2
C. 2NO + 2CO → N2 + 2CO2
D. 2SO2 + O2 → 2SO3
▶️Answer/Explanation
Answer: D
Explanation: Catalytic converters primarily deal with converting carbon monoxide (CO) and nitrogen oxides (NOx) into less harmful substances. The conversion of sulfur dioxide (SO2) to sulfur trioxide (SO3) is not a function of catalytic converters.
Question 25 (C6.2)
Which statement about calcium carbonate is not correct?
A. It forms carbon dioxide when it is heated.
B. It forms carbon dioxide when it is mixed with dilute hydrochloric acid.
C. It is formed by heating lime.
D. It neutralises acids.
▶️Answer/Explanation
Answer: C
Explanation: Calcium carbonate decomposes when heated to form calcium oxide (lime) and carbon dioxide, not the other way around. All other statements are correct: calcium carbonate reacts with acids to form CO2 (A and B) and it does neutralize acids (D).
Question 26 (C11.3)
The diagram represents the fractional distillation of petroleum. Four fractions, W, X, Y and Z, are produced.
Which statement about fraction Y is correct?
A. The forces of attraction between molecules in Y are smaller than those in W.
B. The molecules in Y are smaller than the molecules in Z.
C. Y has a lower boiling point than X.
D. Y vaporizes more readily at room temperature than W and X, but less readily than Z.
▶️Answer/Explanation
Answer: B
Explanation: In fractional distillation, fractions with lower boiling points (and smaller molecules) are collected higher up the fractionating column. Therefore, fraction Y (being between X and Z) would have molecules smaller than Z but larger than X. The forces between molecules increase with molecular size (making A incorrect).
Question 27 (C11.5)
Which row describes properties of alkenes?
| structure of molecules | products of complete combustion | |
|---|---|---|
| A | contain only carbon and hydrogen | CO2 and H2O |
| B | contain only carbon and hydrogen | CO and H2O |
| C | contain only single bonds | CO and H2O |
| D | contain only single bonds | CO2 and H2O |
▶️Answer/Explanation
Answer: A
Explanation: Alkenes are hydrocarbons (contain only carbon and hydrogen) with at least one carbon-carbon double bond. When they undergo complete combustion (with sufficient oxygen), they produce only carbon dioxide and water. Incomplete combustion (option B) can occur with limited oxygen.
Question 28 (P1.4)
A metal has a density of 20 g/cm3. A bar made of this metal has a volume of 50 cm3. What is the mass of the bar?
A. 0.40 g
B. 2.5 g
C. 70 g
D. 1000 g
▶️Answer/Explanation
Answer: D
Explanation: Using the formula: density = mass/volume. Rearranged: mass = density × volume = 20 g/cm3 × 50 cm3 = 1000 g.
Question 29 (P1.6.1)
An object of mass m moving with speed v has kinetic energy E. A second object, also of mass m, moves with speed v/2. What is the kinetic energy of the second object?
A. E/4
B. E/2
C. E
D. 2E
▶️Answer/Explanation
Answer: A
Explanation: Kinetic energy is given by E = ½mv2. For the second object with speed v/2: E’ = ½m(v/2)2 = ½mv2/4 = E/4.
Question 30 (P1.6.3)
Which energy resource does not have the Sun as its source of energy?
A. coal
B. geothermal
C. hydroelectric
D. waves
▶️Answer/Explanation
Answer: B
Explanation: Geothermal energy comes from heat within the Earth’s core, not from the Sun. All other options (coal, hydroelectric, waves) are ultimately powered by solar energy (coal comes from ancient plant matter, hydroelectric relies on water cycle driven by sun, waves are caused by wind which is driven by solar heating).
Question 31 (P2.3.2)
A hot water tank is fitted with two identical heaters P and Q. Heater P is fitted above heater Q as shown. The tank is full of cold water.
When only heater Q is switched on, it takes a long time to heat the tank of water to 60°C.
What happens to the cold water when only heater P is switched on?
A. All the water reaches 60°C in less time.
B. All the water reaches 60°C in the same time.
C. The water below heater P reaches 60°C in less time.
D. The water above heater P reaches 60°C in less time.
▶️Answer/Explanation
Answer: D
Explanation: When heater P (at the top) is used, convection currents are established where heated water rises and stays at the top, while colder water remains below. This means the upper portion heats faster while the lower portion remains relatively cold. The setup with heater Q at the bottom creates more effective convection currents that circulate heat throughout the entire tank.
Question 32 (P3.1)
‘The maximum distance a particle on the surface of deep water moves from its rest position when a wave passes it.’
Which property of a wave does this describe?
A. amplitude
B. frequency
C. speed
D. wavelength
▶️Answer/Explanation
Answer: A
Explanation: The amplitude of a wave is defined as the maximum displacement of particles from their rest position as the wave passes. This matches exactly with the description given in the question. Frequency relates to how often waves pass a point, speed is how fast the wave travels, and wavelength is the distance between successive wave crests.
Question 33 (P3.2.2)
The diagram shows light passing through a plastic block.
What is the refractive index of the plastic?
A. 0.73
B. 0.78
C. 1.27
D. 1.38
▶️Answer/Explanation
Answer: C
Explanation: Using Snell’s Law: n = sin(i)/sin(r). From the diagram, angle of incidence (i) = 55° and angle of refraction (r) = 40°. Therefore, n = sin(55°)/sin(40°) ≈ 0.819/0.643 ≈ 1.27. This calculation gives the refractive index of the plastic relative to air.
Question 34 (P3.2.3)
Which ray diagram represents the formation of a virtual image I of an object O?
▶️Answer/Explanation
Answer: A
Explanation: A virtual image is formed when diverging rays appear to come from a point behind the lens. In the correct diagram (A), the object is placed between the focal point and the lens, causing the refracted rays to diverge. The virtual image is upright, magnified, and appears on the same side as the object – characteristic of a magnifying glass configuration.
Question 35 (P4.1)
Two unmagnetised iron nails are in contact with the S-pole of a permanent magnet. The heads of the nails X and Y repel each other.
Why do X and Y repel?
A. X becomes an N-pole and Y becomes an S-pole.
B. X becomes an S-pole and Y becomes an N-pole.
C. X and Y both become N-poles.
D. X and Y both become S-poles.
▶️Answer/Explanation
Answer: D
Explanation: When unmagnetized iron nails touch a magnet’s S-pole, they become induced magnets with the end touching the magnet becoming the opposite pole (N-pole) and the far ends becoming S-poles. Thus both X and Y have S-poles at their heads, causing repulsion between them. This demonstrates induced magnetism and the law that like poles repel.
Question 36 (P4.2.4)
Which graph is the current-voltage characteristic of a filament lamp?
▶️Answer/Explanation
Answer: C
Explanation: A filament lamp shows a curved I-V characteristic because as current increases, the filament heats up, increasing its resistance. This produces a graph where the gradient decreases with increasing voltage (curve flattening out), unlike a resistor which would show a straight line. The correct graph shows this non-ohmic behavior due to temperature-dependent resistance.
Question 37 (P4.2.2)
There is a current of 100 mA in a circuit.
How much charge flows through the circuit in 1.5 minutes?
A. 0.15 C
B. 9.0 C
C. 150 C
D. 9000 C
▶️Answer/Explanation
Answer: B
Explanation: Using Q = I × t. First convert units: 100 mA = 0.1 A; 1.5 minutes = 90 seconds. Then Q = 0.1 A × 90 s = 9.0 C. This calculation shows the relationship between current as charge flow per unit time and the total charge transferred over a given period.
Question 38 (P4.4)
A fuse is a safety device for use in an electrical circuit.
The current in the circuit becomes greater than the rated value for the fuse.
What happens?
A. The current decreases to zero.
B. The current decreases to the rated value for the fuse.
C. The thickness of the insulation around the wires increases.
D. The current is sent to the outer case of the appliance.
▶️Answer/Explanation
Answer: A
Explanation: A fuse contains a thin wire that melts when the current exceeds its rating, breaking the circuit and stopping all current flow (reducing it to zero). This prevents damage to the circuit or potential fires. Fuses don’t regulate current to a specific value – they fail completely when overloaded, which is their safety function.
Question 39 (P4.5.2)
What is the purpose of the slip rings in an alternating current (a.c.) generator?
A. to allow each end of the coil to contact each carbon brush alternately
B. to allow each end of the coil to remain in contact with the same carbon brush at all times
C. to maintain a constant voltage in the output circuit while the coil is rotating
D. to remain stationary while the coil rotates between them
▶️Answer/Explanation
Answer: B
Explanation: Slip rings are continuous conducting rings that rotate with the coil, maintaining constant contact with stationary brushes. This allows the coil to rotate continuously while keeping electrical contact, enabling the alternating current to be conducted to the external circuit without twisting wires. They don’t alternate contact or maintain constant voltage directly.
Question 40 (P5.1)
The diagrams represent the nuclei of four different atoms V, W, X and Y.
Which two diagrams represent isotopes of the same element?
A. V and Y
B. W and X
C. X and Y
D. Y and W
▶️Answer/Explanation
Answer: C
Explanation: Isotopes are atoms of the same element (same number of protons) with different numbers of neutrons. The correct pair (X and Y) shows nuclei with identical proton numbers but different neutron numbers, making them isotopes. Other pairs either have different proton numbers (different elements) or identical nucleon numbers (same isotope).