Question 1 (Subtopic: B12.1 Respiration)
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: B2.2 Size of specimens)
The photograph shows a bumble bee at a magnification of ×6. The line shows the length of the bumble bee. What is the actual length of the bumble bee?
A. 0.05 mm
B. 20 mm
C. 126 mm
D. 720 mm
▶️Answer/Explanation
Answer: B
Explanation: To find the actual length, divide the magnified length by the magnification factor. If the magnified length is 120 mm, then the actual length is 120 mm / 6 = 20 mm.
Question 3 (Subtopic: B4.1 Biological molecules)
Three food tests are carried out on a sample of food. The results are shown in the table.
| Food Test | Final Colour |
|---|---|
| Benedict’s | Blue |
| Biuret | Blue |
| Iodine | Blue-black |
From these results, which nutrient is in the food?
A. reducing sugar
B. protein
C. starch
D. vitamin C
▶️Answer/Explanation
Answer: C
Explanation: The iodine test turning blue-black indicates the presence of starch. Benedict’s test for reducing sugars and Biuret test for proteins both resulted in blue, indicating no reducing sugars or proteins were present.
Question 4 (Subtopic: B5.1 Enzymes)
What is an enzyme?
A. a carbohydrate that speeds up the rate of a reaction
B. a carbohydrate that alters the activity of a target organ
C. a protein that alters the activity of a target organ
D. a protein that speeds up the rate of a reaction
▶️Answer/Explanation
Answer: D
Explanation: Enzymes are biological catalysts made of proteins that speed up chemical reactions in the body without being consumed in the process.
Question 5 (Subtopic: B6.1 Photosynthesis)
Four test-tubes were set up as shown. Which test-tube will contain the most dissolved oxygen after 24 hours?
▶️Answer/Explanation
Answer: A
Explanation: The aquatic plant will produce oxygen through photosynthesis in the presence of light, leading to the highest concentration of dissolved oxygen in test-tube A.
Question 6 (Subtopic: B7.2 Digestive system)
Which term is defined as the movement of digested food molecules into the cells of the body where they are used?
A. assimilation
B. absorption
C. egestion
D. ingestion
▶️Answer/Explanation
Answer: A
Explanation: Assimilation is the process by which digested food molecules are taken up by cells and used for energy, growth, and repair.
Question 7 (Subtopic: B8.1 Xylem and phloem)
Which graph shows the concentration of sugar solution found in phloem and xylem?
▶️Answer/Explanation
Answer: B
Explanation: The phloem transports sugars from the leaves to other parts of the plant, so the concentration of sugar in the phloem is higher than in the xylem, which primarily transports water and minerals.
Question 8 (Subtopic: B11.1 Gas exchange in humans)
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 oxygen content in the breath is reduced from 21% (inhaled air) to around 16% (exhaled air), as some oxygen is absorbed by the body.
Question 9 (Subtopic: B13.3 Homeostasis)
What is homeostasis?
A. keeping internal conditions constant
B. keeping the body at the same temperature as the environment
C. sweating to keep the body warm
D. vasoconstriction of arterioles to increase heat loss
▶️Answer/Explanation
Answer: A
Explanation: Homeostasis is the process by which the body maintains a stable internal environment, such as constant temperature, pH, and glucose levels, despite changes in external conditions.
Question 10 (Subtopic: B15.4 Sexual reproduction in humans)
The diagram shows the female reproductive system. Where does fertilisation usually occur?
A. A
B. B
C. C
D. D
▶️Answer/Explanation
Answer: A
Explanation: Fertilisation typically occurs in the fallopian tube (oviduct), which is labeled as A in the diagram.
Question 11 (Subtopic: B16.1 Chromosomes and genes)
Cystic fibrosis is an inherited condition caused by a recessive allele. A man and woman have a child who has cystic fibrosis. Neither parent has the condition. What is the probability of their next child also having cystic fibrosis?
A. 0%
B. 25%
C. 50%
D. 75%
▶️Answer/Explanation
Answer: B
Explanation: Since both parents are carriers (heterozygous) of the recessive allele, there is a 25% chance that their next child will inherit two recessive alleles and thus have cystic fibrosis.
Question 12 (Subtopic: B18.2 Food chains and food webs)
Dung beetles lay their eggs in the faeces of plant-eating mammals like buffalo. Both the adult beetles and their young stages eat the undigested food in the faeces. Which diagram shows this food relationship?
▶️Answer/Explanation
Answer: D
Explanation: The correct food relationship is grass (producer) → buffalo (primary consumer) → dung beetles (secondary consumer). The dung beetles feed on the undigested food in the buffalo’s faeces.
Question 13 (Subtopic: B18.3 Carbon cycle)
What does not contribute to the carbon cycle?
A. combustion
B. deforestation
C. transpiration
D. photosynthesis
▶️Answer/Explanation
Answer: C
Explanation: Transpiration is the process by which water is lost from plants through evaporation and does not directly involve the carbon cycle. Combustion, deforestation, and photosynthesis all play roles in the carbon cycle.
Question 14 (Subtopic: C2.2 Atomic structure and the Periodic Table)
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?
| Option | 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: The three substances contain 3 different elements (H, C, O) and a total of 17 atoms (2 in H₂O, 9 in C₂H₅OH, and 6 in CH₄).
Question 15 (Subtopic: C3.1 Formulas)
Pure substance X has a melting point of 110°C. The melting point ranges of four impure samples of substance X are measured. What is the melting point range of the most impure sample of substance X?
| Option | Melting Point Range (°C) |
|---|---|
| A | 81–85 |
| B | 86–92 |
| C | 98–99 |
| D | 102–110 |
▶️Answer/Explanation
Answer: A
Explanation: The most impure sample will have the widest and lowest melting point range, as impurities disrupt the crystal lattice, lowering and broadening the melting point.
Question 16 (Subtopic: C2.5 Simple molecules and covalent bonds)
Which statement about a carbon dioxide molecule is correct?
A. It is composed of metallic elements, which are covalently bonded.
B. It is composed of metallic elements, which are ionically bonded.
C. It is composed of non-metallic elements, which are covalently bonded.
D. It is composed of non-metallic elements, which are ionically bonded.
▶️Answer/Explanation
Answer: C
Explanation: Carbon dioxide (CO₂) is composed of non-metallic elements (carbon and oxygen) that are covalently bonded, sharing electrons to form a stable molecule.
Question 17 (Subtopic: C4.1 Electrolysis)
Apparatus used for electrolysis is shown. Which label identifies the electrolyte?
▶️Answer/Explanation
Answer: D
Explanation: The electrolyte is the substance that undergoes electrolysis, typically a molten or aqueous ionic compound, and is labeled as D in the diagram.
Question 18 (Subtopic: C6.3 Redox)
The catalytic converter in the exhaust of a car brings about the reaction shown.
2NO + 2CO → 2CO₂ + N₂
Which row about this reaction is correct?
| Option | Oxidation | Reduction |
|---|---|---|
| A | ✓ | ✓ |
| B | ✓ | ✗ |
| C | ✗ | ✓ |
| D | ✗ | ✗ |
▶️Answer/Explanation
Answer: A
Explanation: In this reaction, CO is oxidized to CO₂, and NO is reduced to N₂. Therefore, both oxidation and reduction occur.
Question 19 (Subtopic: C12.5 Identification of ions and gases)
Three different tests are carried out on an aqueous solution of substance X. The results are shown.
| Test | Result |
|---|---|
| Add a few drops of aqueous sodium hydroxide | Blue precipitate |
| Add acidified aqueous silver nitrate | No precipitate |
| Add acidified aqueous barium nitrate | White precipitate |
What is X?
A. copper(II) chloride
B. copper(II) sulfate
C. iron(II) chloride
D. iron(II) sulfate
▶️Answer/Explanation
Answer: B
Explanation: The blue precipitate with sodium hydroxide indicates the presence of copper(II) ions. The white precipitate with barium nitrate indicates the presence of sulfate ions. Therefore, X is copper(II) sulfate.
Question 20 (Subtopic: C7.1 The characteristic properties of acids and bases)
What reacts with ammonia gas?
| Option | Hydrochloric Acid | Sodium Hydroxide |
|---|---|---|
| A | ✓ | ✓ |
| B | ✓ | ✗ |
| C | ✗ | ✓ |
| D | ✗ | ✗ |
▶️Answer/Explanation
Answer: B
Explanation: Ammonia gas reacts with hydrochloric acid to form ammonium chloride, but it does not react with sodium hydroxide.
Question 21 (Subtopic: C9.1 Properties of metals)
Substance Q is added to cold water. It floats on the water and hydrogen gas is made. What is Q?
A. iodine
B. lithium
C. magnesium
D. zinc
▶️Answer/Explanation
Answer: B
Explanation: Lithium is a highly reactive metal that floats on water and reacts with it to produce hydrogen gas. The reaction is: 2Li + 2H₂O → 2LiOH + H₂.
Question 22 (Subtopic: C2.6 Giant covalent structures)
Which statements describe carbon?
1. It forms basic oxides.
2. It is used as an electrode in electrolysis.
3. It is used to extract iron from its ore.
A. 1, 2 and 3
B. 1 and 2 only
C. 1 and 3 only
D. 2 and 3 only
▶️Answer/Explanation
Answer: D
Explanation: Carbon is used as an electrode in electrolysis (statement 2) and is used in the extraction of iron from its ore (statement 3). However, carbon does not form basic oxides (statement 1 is incorrect).
Question 23 (Subtopic: C5.1 Exothermic and endothermic reactions)
The apparatus used to investigate the combustion of ethanol is shown.
The products of combustion are passed over anhydrous cobalt(II) chloride.
How does the colour of the cobalt(II) chloride change during the investigation?
A. blue to pink
B. blue to white
C. pink to blue
D. white to blue
▶️Answer/Explanation
Answer: A
Explanation: Anhydrous cobalt(II) chloride is blue, but it turns pink when it absorbs water. During the combustion of ethanol, water is produced, causing the cobalt(II) chloride to change from blue to pink.
Question 24 (Subtopic: C10.1 Water)
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
Explanation: NH₄NO₃ (ammonium nitrate) provides nitrogen, which is an essential element for plant growth. The other substances provide multiple elements (e.g., potassium, phosphorus).
Question 25 (Subtopic: C7.3 Preparation of salts)
What is the chemical name for lime?
A. calcium carbonate
B. calcium hydroxide
C. calcium oxide
D. calcium sulfate
▶️Answer/Explanation
Answer: C
Explanation: Lime is the common name for calcium oxide (CaO). It is produced by heating limestone (calcium carbonate) in a process called calcination.
Question 26 (Subtopic: C11.3 Fuels)
What is the main constituent of natural gas?
A. ethane
B. ethanol
C. ethene
D. methane
▶️Answer/Explanation
Answer: D
Explanation: The main constituent of natural gas is methane (CH₄), which makes up the majority of its composition.
Question 27 (Subtopic: C11.7 Polymers)
Which row shows the structure of the monomer used to make poly(ethene) and the structure of a section of poly(ethene)?
▶️Answer/Explanation
Answer: C
Explanation: The monomer for poly(ethene) is ethene (H₂C=CH₂), and the polymer structure is a repeating unit of (-CH₂-CH₂-)ₙ.
Question 28 (Subtopic: P1.2 Motion)
Which distance–time graph represents an object that is decelerating?
▶️Answer/Explanation
Answer: A
Explanation: A decelerating object will have a decreasing slope on a distance-time graph, indicating that its speed is decreasing over time.
Question 29 (Subtopic: P1.2 Motion)
A vehicle moves a total distance of 300 m in 40 seconds. What is its average speed?
A. 0.13 m/s
B. 7.5 m/s
C. 340 m/s
D. 12,000 m/s
▶️Answer/Explanation
Answer: B
Explanation: Average speed is calculated as total distance divided by total time. Therefore, 300 m / 40 s = 7.5 m/s.
Question 30 (Subtopic: P1.5 Forces)
Which statement applies to a system in equilibrium?
A. There is a resultant force and there is a resultant turning effect on the system.
B. There is a resultant force but there is no resultant turning effect on the system.
C. There is no resultant force but there is a resultant turning effect on the system.
D. There is no resultant force and there is no resultant turning effect on the system.
▶️Answer/Explanation
Answer: D
Explanation: In equilibrium, there is no resultant force and no resultant turning effect (moment) acting on the system.
Question 31 (Subtopic: P1.6 Energy, work and power)
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
Explanation: As the man accelerates downwards, his speed increases, leading to an increase in kinetic energy.
Question 32 (Subtopic: P1.6 Energy, work and power)
Which two quantities are used to calculate power?
A. distance moved and time taken
B. speed and distance moved
C. work done and speed
D. work done and time taken
▶️Answer/Explanation
Answer: D
Explanation: Power is calculated as work done divided by time taken (P = W/t).
Question 33 (Subtopic: P2.3 Transfer of thermal energy)
Which row shows a good thermal conductor and a bad thermal conductor?
| Option | Good Conductor | Bad Conductor |
|---|---|---|
| A | copper | air |
| B | copper | silver |
| C | water | air |
| D | water | silver |
▶️Answer/Explanation
Answer: A
Explanation: Copper is a good thermal conductor, while air is a poor thermal conductor (insulator).
Question 34 (Subtopic: P3.2 Light)
The diagram shows a ray of light striking a converging lens.
What happens to the ray after it passes through the lens?
A. It continues in its original direction.
B. It travels away from the principal focus F of the lens.
C. It travels towards the centre X of the lens.
D. It travels towards the principal focus F of the lens.
▶️Answer/Explanation
Answer: D
Explanation: A converging lens causes parallel rays of light to converge at the principal focus (F) after passing through the lens.
Question 35 (Subtopic: P3.1 General properties of waves)
Sound from a loudspeaker at P travels directly to Q. Sound also reaches Q after being reflected from a wall at R.
The speed of sound is 330 m/s.
What is the difference in time for sound to travel from P to Q by the two routes?
A. (6/330) s
B. (16/330) s
C. (6 × 330) s
D. (16 × 330) s
▶️Answer/Explanation
Answer: A
Explanation: The difference in distance between the two routes is 6 m. Using the formula time = distance/speed, the time difference is (6 m) / (330 m/s) = (6/330) s.
Question 36 (Subtopic: P4.3 Electrical circuits)
Which circuit shows an ammeter that measures the current in the lamp and a voltmeter that measures the potential difference (p.d.) across the lamp?
▶️Answer/Explanation
Answer: C
Explanation: In Circuit C, the ammeter is correctly placed in series with the lamp to measure the current, and the voltmeter is correctly placed in parallel with the lamp to measure the potential difference across it.
Question 37 (Subtopic: P4.3 Electrical circuits)
A student connects a circuit as shown. What is the total resistance of the circuit?
A. 5.0 Ω
B. 10 Ω
C. 15 Ω
D. 25 Ω
▶️Answer/Explanation
Answer: D
Explanation: The resistors are connected in series, so the total resistance is the sum of the individual resistances: 10 Ω + 15 Ω = 25 Ω.
Question 38 (Subtopic: P4.4 Electrical safety)
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: If the current in the circuit exceeds the fuse’s rating, the fuse will blow to protect the circuit. This indicates that the current is too large.
Question 39 (Subtopic: P4.5 Electromagnetic effects)
The diagrams each show a wire carrying a current in the direction of the arrow. Which diagram shows the pattern and the direction of the magnetic field around the wire?
▶️Answer/Explanation
Answer: C
Explanation: The magnetic field around a current-carrying wire forms concentric circles, and the direction of the field can be determined using the right-hand rule. Diagram C correctly shows this pattern and direction.
Question 40 (Subtopic: P5.2 Radioactivity)
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 β-particle (electron) is emitted, a neutron in the nucleus is converted into a proton, increasing the atomic number by 1.