Question 1 (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 (B2.1)
Which cell is most flaccid?
▶️Answer/Explanation
Answer: C
Explanation: A flaccid cell is one that has lost water and has a lower turgor pressure. Cell C is most likely to be flaccid due to the conditions described in the question.
Question 3 (B4.1)
Which row matches the nutrient to the chemical elements that it contains?
| Nutrient | Carbon | Hydrogen | Oxygen | Nitrogen |
|---|---|---|---|---|
| A. Fat | ✓ | ✓ | ✗ | ✗ |
| B. Protein | ✓ | ✓ | ✓ | ✓ |
| C. Starch | ✓ | ✗ | ✓ | ✓ |
| D. Sugar | ✗ | ✓ | ✓ | ✓ |
▶️Answer/Explanation
Answer: B
Explanation: Proteins contain carbon, hydrogen, oxygen, and nitrogen. This is because proteins are made up of amino acids, which contain these elements.
Question 4 (B5.1)
Which type of molecule are enzymes?
A. Fat
B. Carbohydrate
C. Protein
D. DNA
▶️Answer/Explanation
Answer: C
Explanation: Enzymes are biological catalysts made up of proteins. They speed up chemical reactions in the body without being consumed in the process.
Question 5 (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 balanced equation for photosynthesis shows that glucose (C₆H₁₂O₆) is produced along with oxygen. Therefore, X is glucose.
Question 6 (B7.3)
Which row about secretions in the alimentary canal is correct?
| Substance Secreted | Action | Area of Alimentary Canal |
|---|---|---|
| A. Amylase | Breaks down fats into fatty acids and glycerol | Small intestine |
| B. Bile | Breaks down fats into fatty acids and glycerol | Small intestine |
| C. Hydrochloric acid | Breaks down proteins to amino acids | Stomach |
| D. Protease | Breaks down proteins to amino acids | Stomach |
▶️Answer/Explanation
Answer: D
Explanation: Protease enzymes, such as pepsin, are secreted in the stomach and break down proteins into amino acids. Hydrochloric acid in the stomach provides the acidic environment needed for these enzymes to function.
Question 7 (B8.3)
Which graph shows the effect of atmospheric humidity on the rate of transpiration if all other factors are kept constant?
▶️Answer/Explanation
Answer: D
Explanation: As atmospheric humidity increases, the rate of transpiration decreases because the air is already saturated with water vapor, reducing the gradient for water loss from the plant.
Question 8 (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 child blows into a balloon, the air exhaled contains about 16% oxygen, as some oxygen is absorbed by the body during respiration.
Question 9 (B13.2)
A student is in a dangerous situation and adrenaline is released into the blood. The table shows changes to pulse rate, breathing rate, and pupil diameter. Which row correctly describes the effect of adrenaline?
| Pulse Rate | Breathing Rate | Pupil Diameter |
|---|---|---|
| A. Decrease | Increase | Decrease |
| B. Decrease | Decrease | Increase |
| C. Increase | Increase | Increase |
| D. Increase | Decrease | Decrease |
▶️Answer/Explanation
Answer: C
Explanation: Adrenaline increases the pulse rate, breathing rate, and pupil diameter as part of the “fight or flight” response, preparing the body for action.
Question 10 (B15.4)
Which row about human gametes is correct?
| Gamete | Flagellum Present | Energy Store Present | Shows Motility |
|---|---|---|---|
| A. Female | ✓ | ✓ | ✓ |
| B. Female | ✗ | ✓ | ✗ |
| C. Male | ✓ | ✓ | ✗ |
| D. Male | ✗ | ✗ | ✓ |
▶️Answer/Explanation
Answer: B
Explanation: Female gametes (eggs) do not have a flagellum and are not motile, but they do contain an energy store to support the early stages of development after fertilization.
Question 11 (Sub-topic – B16.1)
Two rabbits with floppy ears were crossed and produced three offspring. The pedigree diagram of the cross is shown.
Which row is correct for this cross?
▶️Answer/Explanation
Answer: A
Explanation: The correct answer is A because the parents are heterozygous (Ff) for the floppy ears trait, and the dominant allele is floppy ears (F). This is evident from the pedigree diagram showing that all offspring have floppy ears, indicating that floppy ears is the dominant trait.
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: The correct answer is B because 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 – B19.1)
Which row is correct for eutrophication?
▶️Answer/Explanation
Answer: D
Explanation: The correct answer is D because eutrophication is caused by an excess of nitrates from sources like sewage, which leads to increased growth of algae and other producers. This results in an increase in decomposers, which consume oxygen, leading to a decrease in oxygen levels in the water.
Question 14 (Sub-topic – C2.2)
The structures of some substances are shown: water, ethanol, methane.
Which row shows the total number of different elements and the total number of atoms in the three structures?
▶️Answer/Explanation
Answer: B
Explanation: The correct answer is B because water (H₂O), ethanol (C₂H₅OH), and methane (CH₄) contain a total of 3 different elements (H, C, O) and 17 atoms in total (2+1+4+6+4).
Question 15 (Sub-topic – C12.4)
Which method can be used to separate graphite from dilute nitric acid?
A. Chromatography
B. Crystallisation
C. Distillation
D. Filtration
▶️Answer/Explanation
Answer: D
Explanation: The correct answer is D because graphite is a solid that is insoluble in dilute nitric acid, so it can be separated by filtration, which separates solids from liquids.
Question 16 (Sub-topic – C4.1)
Aqueous copper(II) sulfate is electrolysed using copper electrodes. What is the half-equation for the reaction at the cathode?
A. Cu + 2e⁻ → Cu²⁺
B. Cu → Cu²⁺ + 2e⁻
C. Cu²⁺ + 2e⁻ → Cu
D. Cu²⁺ → Cu + 2e⁻
▶️Answer/Explanation
Answer: C
Explanation: The correct answer is C because at the cathode, copper ions (Cu²⁺) gain electrons (reduction) to form copper metal (Cu). The half-equation is Cu²⁺ + 2e⁻ → Cu.
Question 17 (Sub-topic – C7.3)
Phosphoric acid contains phosphate ions, PO₄³⁻. Phosphoric acid reacts with calcium hydroxide, Ca(OH)₂, to form the salt calcium phosphate. What is the formula of calcium phosphate?
A. CaPO₄
B. Ca(PO₄)₃
C. Ca₂PO₄
D. Ca₃(PO₄)₂
▶️Answer/Explanation
Answer: D
Explanation: The correct answer is D because calcium phosphate is formed by the combination of calcium ions (Ca²⁺) and phosphate ions (PO₄³⁻). The formula is Ca₃(PO₄)₂, which balances the charges of the ions.
Question 18 (Sub-topic – C5.1)
An energy level diagram for a reaction is shown. Which arrow shows the overall energy change for the reaction?
▶️Answer/Explanation
Answer: D
Explanation: The correct answer is D because the overall energy change for a reaction is represented by the difference in energy between the reactants and the products. Arrow D shows this change.
Question 19 (Sub-topic – C6.3)
Which changes show oxidation?
1. 2Br⁻ → Br₂
2. Ca → Ca²⁺
3. Fe³⁺ → Fe²⁺
4. O₂ → 2O²⁻
A. 1 and 2
B. 1 and 4
C. 2 and 3
D. 3 and 4
▶️Answer/Explanation
Answer: A
Explanation: The correct answer is A because oxidation involves the loss of electrons. In 1, Br⁻ loses an electron to form Br₂, and in 2, Ca loses two electrons to form Ca²⁺.
Question 20 (Sub-topic – C7.1)
What reacts with ammonia gas?
▶️Answer/Explanation
Answer: B
Explanation: The correct answer is B because ammonia gas reacts with hydrochloric acid to form ammonium chloride, but it does not react with sodium hydroxide.
Question 21 (Sub-topic – C8.2)
Which row describes trends in the properties of Group I elements as the group is descended?
▶️Answer/Explanation
Answer: B
Explanation: The correct answer is B because as you go down Group I, the melting point decreases and the reactivity with water increases due to the increasing atomic size and decreasing ionization energy.
Question 22 (Sub-topic – C9.4)
Some observations from an investigation are shown:
1. Metal W does not react with dilute hydrochloric acid.
2. Metal X does not react with cold water but does react with dilute hydrochloric acid.
3. Metal Y reacts with cold water.
4. Metal Z does not react with dilute hydrochloric acid but does react with aqueous ions of metal W.
What is the order of reactivity of the metals?
▶️Answer/Explanation
Answer: C
Explanation: The correct answer is C because metal Y is the most reactive as it reacts with cold water, followed by X, which reacts with dilute hydrochloric acid. Z is less reactive than X but more reactive than W, which does not react with dilute hydrochloric acid.
Question 23 (Sub-topic – 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
Explanation: Oxides of nitrogen (NOx) are formed in car engines when nitrogen (N₂) and oxygen (O₂) from the air react together at high temperatures during combustion. This reaction is facilitated by the heat generated in the engine, leading to the formation of nitrogen monoxide (NO) and nitrogen dioxide (NO₂).
Question 24 (Sub-topic – 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
Explanation: NH₄NO₃ (ammonium nitrate) provides nitrogen, which is an essential element for plant growth. The other options provide more than one essential element (e.g., potassium and phosphorus in K₃PO₄).
Question 25 (Sub-topic – C5)
Concentrated sulfuric acid is made by the Contact process. During this process, sulfur trioxide is added to concentrated sulfuric acid rather than to water. Which statement about the reaction of sulfur trioxide with water is correct?
A It produces an acid mist.
B It is endothermic.
C It produces oleum, H₂S₂O₇.
D The rate of reaction is low.
▶️Answer/Explanation
Answer: A
Explanation: When sulfur trioxide (SO₃) reacts with water, it produces sulfuric acid (H₂SO₄) and releases a lot of heat. This reaction is highly exothermic and can produce an acid mist, which is a fine spray of sulfuric acid droplets in the air.
Question 26 (Sub-topic – C6)
What are the products of the thermal decomposition of calcium carbonate, CaCO₃?
A calcium and carbon dioxide
B calcium, carbon and oxygen
C calcium oxide and carbon dioxide
D calcium oxide and carbon monoxide
▶️Answer/Explanation
Answer: C
Explanation: The thermal decomposition of calcium carbonate (CaCO₃) produces calcium oxide (CaO) and carbon dioxide (CO₂). The reaction is: CaCO₃ → CaO + CO₂.
Question 27 (Sub-topic – C11)
Reactants for three chemical processes are listed. Which processes form saturated hydrocarbons?
- ethene + steam
- ethene + hydrogen
- ethene in addition polymerisation
A 1 and 2 only
B 1 and 3 only
C 2 and 3 only
D 1, 2 and 3
▶️Answer/Explanation
Answer: C
Explanation: Saturated hydrocarbons are formed when ethene reacts with hydrogen (process 2) and during addition polymerisation (process 3). Process 1 (ethene + steam) does not produce a saturated hydrocarbon.
Question 28 (Sub-topic – P1.1)
A student measures the diameter and the length of a long, thin wire. Which apparatus is used to give accurate measurements?
▶️Answer/Explanation
Answer: C
Explanation: A micrometer screw gauge is used to measure the diameter of the wire accurately, while a metre rule is used to measure the length. The combination of both instruments ensures accurate measurements of both dimensions.
Question 29 (Sub-topic – P1.2)
A girl runs 5000 m in 1200 seconds and then walks a further 3000 m in 1800 seconds. What is her average speed for this journey?
A 1.7 m/s
B 2.7 m/s
C 2.9 m/s
D 5.8 m/s
▶️Answer/Explanation
Answer: B
Explanation: The total distance covered is 5000 m + 3000 m = 8000 m. The total time taken is 1200 s + 1800 s = 3000 s. The average speed is calculated as total distance divided by total time: 8000 m / 3000 s = 2.67 m/s, which rounds to 2.7 m/s.
Question 30 (Sub-topic – P1.5)
Three objects X, Y and Z are at rest on a table. The centre of mass of each object is labelled M.
What is the order of stability of these three objects, from most stable to least stable?
A X → Y → Z
B Y → Z → X
C X → Z → Y
D Z → Y → X
▶️Answer/Explanation
Answer: D
Explanation: The stability of an object depends on the position of its centre of mass. The lower the centre of mass, the more stable the object. Object Z has the lowest centre of mass, making it the most stable, followed by Y and then X.
Question 31 (Sub-topic – 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
Explanation: As the man accelerates downwards, his speed increases, which means his kinetic energy is increasing. Gravitational potential energy decreases as he falls, and there is no significant change in chemical or elastic potential energy.
Question 32 (Sub-topic – P6.2)
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 33 (Sub-topic – P2.2)
Which change increases the sensitivity of a liquid-in-glass thermometer?
A decreasing the diameter of the capillary bore
B decreasing the length of the capillary bore
C increasing the diameter of the capillary bore
D increasing the length of the capillary bore
▶️Answer/Explanation
Answer: A
Explanation: Decreasing the diameter of the capillary bore increases the sensitivity of a liquid-in-glass thermometer because a smaller bore causes the liquid to rise or fall more significantly with small changes in temperature.
Question 34 (Sub-topic – P2.3)
Four identical metal cans contain equal quantities of water at 80 °C. The outer surfaces of two of the cans are dull and the outer surfaces of the other two cans are shiny. Lids are put on two of the cans. All the cans are allowed to cool. Which can cools the fastest?
▶️Answer/Explanation
Answer: A
Explanation: A dull surface radiates heat more effectively than a shiny surface, and a can without a lid loses heat faster due to convection. Therefore, the dull can without a lid cools the fastest.
Question 35 (Sub-topic – P3.2)
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) at 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)
A wire is 50 cm long and has a resistance of 16 Ω. A second wire is made of the same material. It is 75 cm long and has twice the cross-sectional area of the first wire. What is the resistance of the second wire?
A 6.0 Ω
B 12 Ω
C 32 Ω
D 48 Ω
▶️Answer/Explanation
Answer: B
Explanation: The resistance of a wire is given by \( R = \rho \frac{L}{A} \), where \( \rho \) is the resistivity, \( L \) is the length, and \( A \) is the cross-sectional area. For the second wire, the length is 1.5 times the first wire, and the area is twice the first wire. Therefore, the resistance of the second wire is \( \frac{1.5}{2} \times 16 \, \Omega = 12 \, \Omega \).
Question 37 (Sub-topic – P4.3)
Which statements about the current-voltage characteristic of a filament lamp are correct?
1 It is a curve.
2 It passes through the origin.
3 It shows current increasing as voltage increases.
A 1 and 2 only
B 1 and 3 only
C 2 and 3 only
D 1, 2 and 3
▶️Answer/Explanation
Answer: D
Explanation: The current-voltage characteristic of a filament lamp is a curve (statement 1) that passes through the origin (statement 2) and shows current increasing as voltage increases (statement 3). Therefore, all three statements are correct.
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 rating. Therefore, the most likely reason is that the current in the circuit is too large, causing the fuse to blow to protect the circuit.
Question 39 (Sub-topic – P4.5.1)
A magnet is moved in and out of a coil, and an electromotive force (e.m.f.) is induced. How can the size of the induced e.m.f. be decreased?
A. Add more turns to the coil.
B. Move the magnet more quickly.
C. Move the magnet more slowly.
D. Turn the magnet around before moving it in and out.
▶️Answer/Explanation
Answer: C. Move the magnet more slowly.
Explanation:
The induced e.m.f. in a coil is proportional to the rate of change of the magnetic flux through the coil. Moving the magnet more slowly reduces the rate of change of the magnetic flux, thereby decreasing the induced e.m.f. Adding more turns to the coil (A) or moving the magnet more quickly (B) would increase the induced e.m.f. Turning the magnet around (D) would change the direction of the induced e.m.f. but not necessarily decrease its magnitude.
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. It increases by 1.
Explanation:
When a nucleus emits a β-particle (an electron), a neutron in the nucleus is converted into a proton. This increases the proton number (atomic number) by 1 while the mass number remains unchanged. Therefore, the correct answer is that the proton number increases by 1.