Question 1 (Subtopic: B1.1)
What is respiration?
A. breakdown of food by enzymes in the alimentary canal
B. breathing to supply oxygen to cells
C. release of carbon dioxide from the lungs
D. release of energy for body activities
▶️Answer/Explanation
Answer: D
Explanation: Respiration is the process by which cells break down glucose to release energy for body activities. This process occurs in the mitochondria of cells and is essential for all living organisms to function.
Question 2 (Subtopic: B15.4)
Which row is correct for a human sperm cell?
| flagellum | nucleus | presence of enzymes | |
|---|---|---|---|
| A | no | diploid | yes |
| B | no | haploid | no |
| C | yes | diploid | no |
| D | yes | haploid | yes |
▶️Answer/Explanation
Answer: D
Explanation: A human sperm cell has a flagellum for movement, a haploid nucleus (containing half the genetic material), and enzymes in the acrosome to help penetrate the egg during fertilization.
Question 3 (Subtopic: B4.1)
What is the test for the presence of protein in a food sample?
A. Benedict’s solution
B. biuret reagent
C. ethanol emulsion
D. iodine solution
▶️Answer/Explanation
Answer: B
Explanation: The biuret reagent is used to test for the presence of proteins. When the reagent is added to a solution containing proteins, it turns from blue to purple, indicating the presence of peptide bonds in the proteins.
Question 4 (Subtopic: B5.1)
Which graph shows the effect of temperature on the rate of an enzyme-controlled reaction?
▶️Answer/Explanation
Answer: C
Explanation: The rate of an enzyme-controlled reaction increases with temperature up to an optimum point, after which the enzyme denatures and the reaction rate drops sharply. Graph C correctly shows this trend.
Question 5 (Subtopic: B6.1)
The balanced equation for photosynthesis is shown.
What is X?
A. C6H12O6
B. C6H12O12
C. C12H6O6
D. C12H12O2
▶️Answer/Explanation
Answer: A
Explanation: The product of photosynthesis is glucose, which has the chemical formula C6H12O6. This is the sugar that plants produce and use for energy.
Question 6 (Subtopic: B3.2)
A mixture of starch suspension and saliva is placed inside a bag with a partially permeable membrane. The bag is placed into a test-tube filled with distilled water, as shown.
After one hour, the water is found to contain glucose.
Which row explains this result?
| type of digestion | movement of glucose through partially permeable membrane | |
|---|---|---|
| A | chemical | diffusion |
| B | chemical | osmosis |
| C | mechanical | diffusion |
| D | mechanical | osmosis |
▶️Answer/Explanation
Answer: A
Explanation: Saliva contains the enzyme amylase, which chemically digests starch into glucose. The glucose then diffuses through the partially permeable membrane into the distilled water.
Question 7 (Subtopic: B9.2)
What happens to the valves in the heart when the ventricles contract?
| valves between atria and ventricles | valves between ventricles and arteries | |
|---|---|---|
| A | close | close |
| B | close | open |
| C | open | close |
| D | open | open |
▶️Answer/Explanation
Answer: B
Explanation: When the ventricles contract, the atrioventricular valves (between the atria and ventricles) close to prevent backflow of blood into the atria, and the semilunar valves (between the ventricles and arteries) open to allow blood to be pumped out of the heart.
Question 8 (Subtopic: B11.1)
A child blows into a rubber balloon. What is the percentage of oxygen inside the balloon?
A. 0%
B. 4%
C. 16%
D. 21%
▶️Answer/Explanation
Answer: C
Explanation: When a person exhales, the percentage of oxygen in the breath is around 16%, as some oxygen is absorbed by the body during respiration.
Question 9 (Subtopic: B13.1)
A plant was placed horizontally in complete darkness. The diagram shows how the plant had grown after one week.
Which response has the shoot made?
A. gravitropism away from gravity
B. gravitropism towards gravity
C. phototropism away from light
D. phototropism towards light
▶️Answer/Explanation
Answer: A
Explanation: In the absence of light, the plant exhibits gravitropism, where the shoot grows away from the direction of gravity, while the roots grow towards gravity.
Question 10 (Subtopic: B15.3)
The diagram shows a flower.
Which row shows the correct names for the structures labelled P, Q and R?
| P | Q | R | |
|---|---|---|---|
| A | anther | ovary | sepal |
| B | anther | style | carpel |
| C | filament | ovary | carpel |
| D | filament | style | sepal |
▶️Answer/Explanation
Answer: A
Explanation: The anther is the part of the stamen that produces pollen, the ovary contains the ovules, and the sepal is the outer part of the flower that protects the bud before it opens.
Question 11 (Sub-topic – B16.2)
Which row about cell division is correct?
| Type of cell division | Cell chromosome number at start | Number of cells produced | Cell chromosome number at end | |
|---|---|---|---|---|
| A | meiosis | diploid | 2 | haploid |
| B | meiosis | haploid | 4 | diploid |
| C | mitosis | diploid | 2 | diploid |
| D | mitosis | haploid | 4 | haploid |
▶️Answer/Explanation
Answer: C
Explanation: Mitosis is a type of cell division that results in two daughter cells, each having the same number of chromosomes as the parent cell (diploid). Therefore, the correct row is C, where the cell starts as diploid and ends as diploid after producing 2 cells.
Question 12 (Sub-topic – B18.2)
Why do food chains usually have fewer than five trophic levels?
A) All the carnivores consume herbivores.
B) The energy passed on reduces from one trophic level to the next.
C) There is less protein in each individual higher up the chain.
D) There is only one producer in each chain.
▶️Answer/Explanation
Answer: B
Explanation: Energy is lost at each trophic level due to metabolic processes, heat loss, and incomplete digestion. This energy loss limits the number of trophic levels in a food chain, typically to fewer than five.
Question 13 (Sub-topic – C10.2)
Putting too much fertiliser on soil can lead to eutrophication in water. Which substance, dissolved in water, is reduced in concentration as a result of eutrophication?
A) carbon dioxide
B) ions
C) nitrogen
D) oxygen
▶️Answer/Explanation
Answer: D
Explanation: Eutrophication leads to excessive growth of algae, which depletes oxygen levels in the water as the algae decompose. This reduction in oxygen concentration can harm aquatic life.
Question 14 (Sub-topic – C2.1)
The structures of some substances are shown.
Which row shows the total number of different elements and the total number of atoms in the three structures?
| Total number of different elements | Total number of atoms | |
|---|---|---|
| A | 3 | 9 |
| B | 3 | 17 |
| C | 7 | 9 |
| D | 7 | 17 |
▶️Answer/Explanation
Answer: B
Explanation: Water (H2O), ethanol (C2H6O), and methane (CH4) contain a total of 3 different elements (H, C, O) and 17 atoms in total (2+6+4=12 for H, 2+1=3 for C, and 1+1=2 for O).
Question 15 (Sub-topic – C12.3)
A chromatogram of four different inks, W, X, Y and Z, is shown.
How many inks contain a dye with an Rf value of 0.7?
A) 0
B) 1
C) 2
D) 3
▶️Answer/Explanation
Answer: C
Explanation: The Rf value is calculated as the distance travelled by the substance divided by the distance travelled by the solvent. If two inks have the same Rf value of 0.7, it means they contain a dye with that Rf value.
Question 16 (Sub-topic – C2.5)
Which dot-and-cross diagram represents a molecule of carbon dioxide?
▶️Answer/Explanation
Answer: C
Explanation: Carbon dioxide (CO2) is a linear molecule with double bonds between the carbon atom and each oxygen atom. The correct dot-and-cross diagram shows two double bonds, with carbon sharing four electrons with each oxygen atom.
Question 17 (Sub-topic – C3.3)
Which quantity contains one mole of the substance?
A) 6 g of carbon atoms, C
B) 12 dm3 of hydrogen gas, H2, at room temperature and pressure
C) 32 g of oxygen atoms, O
D) 44 g of carbon dioxide gas, CO2
▶️Answer/Explanation
Answer: D) 44 g of carbon dioxide gas, CO2
Explanation: The molar mass of CO2 is 44 g/mol (12 g/mol for carbon and 32 g/mol for oxygen). Therefore, 44 g of CO2 contains one mole of the substance.
Question 18 (Sub-topic – C4.1)
What are the electrode products when aqueous copper(II) sulfate is electrolysed using inert electrodes?
▶️Answer/Explanation
Answer: C) Oxygen at the anode and copper at the cathode
Explanation: During the electrolysis of aqueous copper(II) sulfate, copper ions (Cu2+) are reduced at the cathode to form copper metal, while water is oxidized at the anode to produce oxygen gas.
Question 19 (Sub-topic – C6.3)
Chlorine displaces iodine from a solution of sodium iodide in a redox reaction. The equation for this reaction is shown.
Cl2 + 2NaI → 2NaCl + I2
Which statement about this reaction is correct?
A) Chlorine is the oxidising agent and it oxidises iodide ions.
B) Chlorine is the oxidising agent and it reduces iodide ions.
C) Chlorine is the reducing agent and it oxidises iodide ions.
D) Chlorine is the reducing agent and it reduces iodide ions.
▶️Answer/Explanation
Answer: A) Chlorine is the oxidising agent and it oxidises iodide ions.
Explanation: In this reaction, chlorine gains electrons (reduction) and oxidises iodide ions (I–) to iodine (I2). Therefore, chlorine acts as the oxidising agent.
Question 20 (Sub-topic – C7.1)
What reacts with ammonia gas?
A) Hydrochloric acid and sodium hydroxide
B) Hydrochloric acid only
C) Sodium hydroxide only
D) Neither hydrochloric acid nor sodium hydroxide
▶️Answer/Explanation
Answer: B) Hydrochloric acid only
Explanation: Ammonia gas reacts with hydrochloric acid to form ammonium chloride, but it does not react with sodium hydroxide.
Question 21 (Subtopic – C8.3)
Which element has similar chemical properties to chlorine?
A. argon
B. bromine
C. oxygen
D. sulfur
▶️Answer/Explanation
Answer: B. bromine
Explanation: Chlorine and bromine are both halogens (Group VII elements) and have similar chemical properties due to having the same number of valence electrons. They both form diatomic molecules and have similar reactivity patterns.
Question 22 (Subtopic – C9.4)
An experiment is carried out to investigate the reactions of four metals M, N, O and P with solutions of their sulfates. The results of the experiment are listed.
metal N + metal O sulfate = reacts
metal N + metal P sulfate = reacts
metal O + metal M sulfate = no reaction
metal M + metal P sulfate = reacts
What is the order of the reactivity of these metals, from most to least reactive?
A. N → M → P → O
B. N → P → M → O
C. O → M → P → N
D. O → P → M → N
▶️Answer/Explanation
Answer: A. N → M → P → O
Explanation: The reactivity series can be deduced from the reactions. Metal N reacts with both O and P sulfates, indicating it is more reactive than both O and P. Metal M reacts with P sulfate but not with O sulfate, placing it between N and P. Metal O does not react with M sulfate, making it the least reactive.
Question 23 (Subtopic – C10.2)
Which statement explains how oxides of nitrogen are formed in a car engine?
A. Nitrogen from the air reacts with the fuel.
B. Oxygen and nitrogen from the air react together.
C. Oxygen from the air reacts with sulfur impurities in the fuel.
D. Oxygen from the air reacts with the fuel.
▶️Answer/Explanation
Answer: B. Oxygen and nitrogen from the air react together.
Explanation: Oxides of nitrogen (NOx) are formed in car engines when nitrogen and oxygen from the air react at high temperatures during combustion.
Question 24 (Subtopic – B6.1)
Other than hydrogen and oxygen, which substance provides only one of the essential elements for plant growth?
A. K₃PO₄
B. KNO₃
C. (NH₄)₃PO₄
D. NH₄NO₃
▶️Answer/Explanation
Answer: D. NH₄NO₃
Explanation: NH₄NO₃ provides nitrogen, which is essential for plant growth, but it does not provide phosphorus or potassium, which are also essential elements.
Question 25 (Subtopic – C6.2)
Which row about the Contact process is correct?
| catalyst | pressure / atm | |
|---|---|---|
| A | iron | 2 |
| B | iron | 200 |
| C | vanadium(V) oxide | 2 |
| D | vanadium(V) oxide | 200 |
▶️Answer/Explanation
Answer: C. vanadium(V) oxide, 2
Explanation: The Contact process for the production of sulfuric acid uses vanadium(V) oxide as a catalyst and operates at a pressure of around 2 atm.
Question 26 (Subtopic – C6.1)
Which equation represents a thermal decomposition reaction?
A. CaCO₃ → CaO + CO₂
B. HCl + NaOH → NaCl + H₂O
C. Mg + H₂SO₄ → MgSO₄ + H₂
D. S + O₂ → SO₂
▶️Answer/Explanation
Answer: A. CaCO₃ → CaO + CO₂
Explanation: Thermal decomposition involves breaking down a compound into simpler substances using heat. In this case, calcium carbonate decomposes into calcium oxide and carbon dioxide when heated.
Question 27 (Subtopic – C11.5)
Which substances can be produced by cracking?
A. alkanes only
B. alkenes only
C. alkenes and hydrogen only
D. alkanes, alkenes and hydrogen
▶️Answer/Explanation
Answer: D. alkanes, alkenes and hydrogen
Explanation: Cracking is a process that breaks down larger hydrocarbon molecules into smaller ones, producing alkanes, alkenes, and hydrogen as byproducts.
Question 28 (Subtopic – P1.2)
Which expression defines the acceleration of a moving object?
A. change of velocity × time taken
B. distance travelled × time taken
C. \(\frac{change of velocity}{time taken}\)
D. \( \frac{distance travelled}{time taken}\)
▶️Answer/Explanation
Answer: C. change of velocity / time taken
Explanation: Acceleration is defined as the rate of change of velocity with respect to time, which is mathematically expressed as change in velocity divided by time taken.
Question 29 (Subtopic – P1.5)
Two springs P and Q both obey Hooke’s law. A force of 10 N is applied to spring P and it extends by 2.0 cm. The spring constant of Q is double the spring constant of P. A force of 20 N is applied to spring Q. What is the extension of spring Q?
A. 1.0 cm
B. 2.0 cm
C. 4.0 cm
D. 8.0 cm
▶️Answer/Explanation
Answer: B. 2.0 cm
Explanation: Using Hooke’s law, F = kx, where F is the force, k is the spring constant, and x is the extension. For spring P, k = F/x = 10 N / 2 cm = 5 N/cm. Since the spring constant of Q is double that of P, k_Q = 10 N/cm. Applying a force of 20 N to spring Q, the extension x = F/k = 20 N / 10 N/cm = 2 cm.
Question 30 (Subtopic – P1.6)
The diagram shows a man diving into water.
Which form of energy is increasing as he accelerates downwards through the air?
A. chemical
B. elastic potential (strain)
C. gravitational potential
D. kinetic
▶️Answer/Explanation
Answer: D. kinetic
Explanation: As the man accelerates downwards, his speed increases, which means his kinetic energy is increasing. Gravitational potential energy decreases as he falls.
Question 31 (Sub-topic – P1.6.3)
The Sun is an important energy resource. Which energy source powers the Sun?
A. chemical
B. geothermal
C. nuclear fission
D. nuclear fusion
▶️Answer/Explanation
Answer: D
Explanation: The Sun is powered by nuclear fusion, where hydrogen nuclei combine to form helium, releasing a tremendous amount of energy in the process.
Question 32 (Sub-topic – P2.3.1)
A solid metal transfers energy by thermal conduction. What causes this transfer?
A. molecular vibration and moving electrons
B. molecular vibration only
C. moving electrons only
D. neither molecular vibration nor moving electrons
▶️Answer/Explanation
Answer: A
Explanation: In metals, thermal conduction occurs due to both molecular vibrations (phonons) and the movement of free electrons, which transfer energy through the material.
Question 33 (Sub-topic – P3.1)
Which statement about waves is correct?
A. They do not transfer energy or matter.
B. They transfer energy and matter.
C. They transfer energy but not matter.
D. They transfer matter but not energy.
▶️Answer/Explanation
Answer: C
Explanation: Waves transfer energy from one place to another without transferring matter. For example, light waves transfer energy but do not move matter through space.
Question 34 (Sub-topic – P3.2.1)
A boy stands 3.0 m in front of a plane mirror. He sees his image formed by the mirror. The boy moves 1.0 m closer to the mirror. How much closer is the boy to his image now?
A. 0.50 m
B. 1.0 m
C. 2.0 m
D. 4.0 m
▶️Answer/Explanation
Answer: C
Explanation: When the boy moves 1.0 m closer to the mirror, his image also moves 1.0 m closer. Therefore, the total distance between the boy and his image decreases by 2.0 m.
Question 35 (Sub-topic – P3.2.2)
The diagram represents the surface of a transparent liquid. Two rays of light are travelling in the liquid. They both reach the surface. The path of each ray is shown.
What is the critical angle for this liquid?
A. 35°
B. 40°
C. 50°
D. 55°
▶️Answer/Explanation
Answer: A
Explanation: The critical angle is the angle of incidence in the denser medium (liquid) for which the angle of refraction in the less dense medium (air) is 90°. From the diagram, the critical angle is 35°.
Question 36 (Sub-topic – P4.2.4)
Four wires are made of the same material. They have different lengths and different cross-sectional areas. Which row shows the wire with the smallest resistance?
| Length (m) | Cross-sectional area (mm²) |
|---|---|
| A. 20 | 2.0 |
| B. 20 | 4.0 |
| C. 50 | 2.0 |
| D. 50 | 4.0 |
▶️Answer/Explanation
Answer: B
Explanation: Resistance is directly proportional to length and inversely proportional to cross-sectional area. Wire B has the shortest length and the largest cross-sectional area, resulting in the smallest resistance.
Question 37 (Sub-topic – P4.3.2)
A 4.0 Ω resistor and an 8.0 Ω resistor are connected in series with a power supply.
The reading on the voltmeter connected across the 4.0 Ω resistor is 2.0 V. What is the potential difference (p.d.) across the power supply?
A. 2.0 V
B. 4.0 V
C. 6.0 V
D. 12 V
▶️Answer/Explanation
Answer: C
Explanation: In a series circuit, the total resistance is the sum of the individual resistances (4.0 Ω + 8.0 Ω = 12 Ω). The current through the circuit is the same, so the potential difference across the power supply is the sum of the potential differences across each resistor. Since the p.d. across the 4.0 Ω resistor is 2.0 V, the p.d. across the 8.0 Ω resistor is 4.0 V (because V = IR and the current is the same). Therefore, the total p.d. across the power supply is 2.0 V + 4.0 V = 6.0 V.
Question 38 (Sub-topic – P4.4)
A student connects the circuit shown.
When the switch is closed, the fuse blows and stops the current.
What is a possible reason for this?
A. The current rating of the fuse is too high.
B. The current is too large.
C. The lamp is too dim.
D. The voltage is too small.
▶️Answer/Explanation
Answer: B
Explanation: The fuse blows when the current exceeds its rated value. This indicates that the current in the circuit is too large, causing the fuse to melt and break the circuit to prevent damage.
Question 39 (Sub-topic – P4.5.6)
The primary coil of a 100% efficient transformer has \( N_p \) turns and the secondary coil has \( N_s \) turns. The voltage supplied to the primary coil is \( V_p \) and the voltage induced across the secondary coil is \( V_s \). Which equation relates these terms?
A. \(\frac{N_p}{N_s} = \frac{V_p}{V_s}\)
B. \(\frac{N_p}{N_s} = \frac{V_s}{V_p}\)
C. \(N_p \times N_s = V_p \times V_s\)
D. \(N_p \times N_s \times V_p = V_s\)
▶️Answer/Explanation
Answer: A
Explanation: For a transformer, the ratio of the number of turns in the primary coil to the number of turns in the secondary coil is equal to the ratio of the primary voltage to the secondary voltage: \(\frac{N_p}{N_s} = \frac{V_p}{V_s}\).
Question 40 (Sub-topic – P5.2.3)
A radioactive nucleus emits a β-particle. What happens to the proton number (atomic number) of the nucleus?
A. It stays the same.
B. It increases by 1.
C. It decreases by 2.
D. It decreases by 4.
▶️Answer/Explanation
Answer: B
Explanation: When a nucleus emits a β-particle (an electron), a neutron is converted into a proton. This increases the proton number (atomic number) by 1.