Question 1 (Subtopic: B1.1)
Which characteristic of living organisms is described as the chemical reactions in cells that break down nutrient molecules and release energy?
A. excretion
B. nutrition
C. photosynthesis
D. respiration
▶️Answer/Explanation
Answer: D. respiration
Explanation: Respiration is the process by which cells break down nutrient molecules to release energy. This is a key characteristic of living organisms, as it provides the energy needed for various cellular activities.
Question 2 (Subtopic: B3.1)
What is the net movement of molecules during diffusion?
A. from a higher concentration to a lower concentration down a concentration gradient
B. from a higher concentration to a lower concentration up a concentration gradient
C. from a lower concentration to a higher concentration down a concentration gradient
D. from a lower concentration to a higher concentration up a concentration gradient
▶️Answer/Explanation
Answer: A. from a higher concentration to a lower concentration down a concentration gradient
Explanation: Diffusion is the net movement of molecules from an area of higher concentration to an area of lower concentration, down a concentration gradient. This process occurs due to the random motion of particles.
Question 3 (Subtopic: 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. red-orange, brown
Explanation: Benedict’s solution turns red-orange in the presence of reducing sugars, while iodine solution remains brown in the absence of starch. Therefore, the correct answer is D.
Question 4 (Subtopic: B5.1)
Which graph shows the effect of temperature on the activity of a mammalian enzyme?
▶️Answer/Explanation
Answer: C. Graph C
Explanation: The activity of enzymes increases with temperature up to an optimum point, after which the enzyme denatures and activity decreases. Graph C correctly shows this relationship.
Question 5 (Subtopic: B6.1)
A farmer observes that his field of grass is not looking as green as it should be. Which substance is likely to be in short supply?
A. carbon dioxide in the air
B. magnesium in the soil
C. nitrogen in the air
D. water in the soil
▶️Answer/Explanation
Answer: B. magnesium in the soil
Explanation: Magnesium is a key component of chlorophyll, the green pigment in plants. A deficiency in magnesium would lead to chlorosis, causing the grass to appear less green.
Question 6 (Subtopic: 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. to make teeth
Explanation: Calcium is essential for the formation and maintenance of strong bones and teeth. It is a key mineral in the structure of these tissues.
Question 7 (Subtopic: B9.4)
What is transported by red blood cells?
A. glucose
B. insulin
C. oxygen
D. urea
▶️Answer/Explanation
Answer: C. oxygen
Explanation: Red blood cells contain hemoglobin, which binds to oxygen in the lungs and transports it to tissues throughout the body.
Question 8 (Subtopic: B11.1)
As a molecule of carbon dioxide is removed from the body, in which order does it pass through these structures?
A. pulmonary artery → capillary → alveolus → bronchiole
B. pulmonary artery → capillary → bronchiole → alveolus
C. pulmonary vein → capillary → alveolus → bronchiole
D. pulmonary vein → capillary → bronchiole → alveolus
▶️Answer/Explanation
Answer: A. pulmonary artery → capillary → alveolus → bronchiole
Explanation: Carbon dioxide is carried in the blood to the lungs via the pulmonary artery. It diffuses from the capillaries into the alveoli and is then exhaled through the bronchioles.
Question 9 (Subtopic: B13.3)
What is the definition of homeostasis?
A. controlling body temperature
B. controlling responses to stimuli
C. maintaining a constant external environment
D. maintaining a constant internal environment
▶️Answer/Explanation
Answer: D. maintaining a constant internal environment
Explanation: Homeostasis is the process by which the body maintains a stable internal environment, despite changes in external conditions.
Question 10 (Subtopic: B12.1)
An experiment using germinating seeds is set up as shown, and left at room temperature for 12 hours.
The pump is then switched on and air is drawn through the apparatus for 2 minutes.
Which row identifies solutions P and Q and the results obtained?
| solution P | solution P results | solution Q | solution Q results | |
|---|---|---|---|---|
| A | ethanol | remains colourless | ethanol | turns milky |
| B | ethanol | turns milky | limewater | remains colourless |
| C | limewater | remains colourless | limewater | turns milky |
| D | limewater | turns milky | ethanol | remains colourless |
▶️Answer/Explanation
Answer: C. limewater remains colourless, limewater turns milky
Explanation: Limewater turns milky in the presence of carbon dioxide, indicating that the germinating seeds are respiring and producing CO₂. Ethanol would not react with CO₂, so it remains colorless.
Question 11 (Subtopic: B16.3)
In some plants, the red flower allele is dominant to the yellow flower allele. Two heterozygous red-flowered plants are crossed. Which statement about the offspring produced is correct?
A. 25% of plants will have red flowers, 75% will have yellow flowers.
B. 50% of plants will have red flowers, 50% will have yellow flowers.
C. 75% of plants will have red flowers, 25% will have yellow flowers.
D. 100% of plants will have red flowers.
▶️Answer/Explanation
Answer: C. 75% of plants will have red flowers, 25% will have yellow flowers.
Explanation: When two heterozygous red-flowered plants (Rr) are crossed, the offspring will have a genotypic ratio of 1 RR : 2 Rr : 1 rr. Since red (R) is dominant over yellow (r), 75% of the offspring will have red flowers, and 25% will have yellow flowers.
Question 12 (Subtopic: B18.2)
The flow chart shows part of a food chain: grass → rabbit → fox. What describes the rabbit?
A. consumer and carnivore
B. consumer and herbivore
C. producer and carnivore
D. producer and herbivore
▶️Answer/Explanation
Answer: B. consumer and herbivore
Explanation: The rabbit is a consumer because it eats grass (a producer). It is also a herbivore because it feeds on plants.
Question 13 (Subtopic: B19.1)
What could deforestation cause?
A. a decrease in carbon dioxide levels and a decrease in flooding
B. a decrease in carbon dioxide levels and an increase in flooding
C. an increase in carbon dioxide levels and a decrease in flooding
D. an increase in carbon dioxide levels and an increase in flooding
▶️Answer/Explanation
Answer: D. an increase in carbon dioxide levels and an increase in flooding
Explanation: Deforestation leads to an increase in carbon dioxide levels because trees absorb CO₂ during photosynthesis. It also increases the risk of flooding because trees help absorb rainwater and reduce runoff.
Question 14 (Subtopic: 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. An atom is the smallest part of an element.
Explanation: An atom is the smallest unit of an element that retains its chemical properties. Molecules can be made up of atoms of the same or different elements, and not all molecules are gases at room temperature.
Question 15 (Subtopic: C2.3)
One atom of an isotope of fluorine is represented by \( ^{19}_{9}F \). How many neutrons does this atom have?
A. 6
B. 9
C. 10
D. 15
▶️Answer/Explanation
Answer: C. 10
Explanation: The number of neutrons is calculated by subtracting the atomic number (protons) from the mass number. For \( ^{19}_{9}F \), the number of neutrons is \( 19 – 9 = 10 \).
Question 16 (Subtopic: C2.6)
Which row describes the volatility and electrical conductivity of liquid covalent compounds?
| volatility | electrical conductivity | |
|---|---|---|
| A | high | high |
| B | high | low |
| C | low | high |
| D | low | low |
▶️Answer/Explanation
Answer: B. high, low
Explanation: Liquid covalent compounds are generally volatile (high volatility) because they have weak intermolecular forces. They also have low electrical conductivity because they do not contain free ions or electrons to carry charge.
Question 17 (Subtopic: 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 coloured 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. The electrolyte is lead(II) bromide.
Explanation: In the electrolysis of lead(II) bromide, the electrolyte is lead(II) bromide (PbBr₂). Lead is deposited at the cathode (negative electrode), and bromine gas (coloured fumes) is produced at the anode (positive electrode).
Question 18 (Subtopic: C5.1)
A student investigates temperature changes in four chemical reactions, as shown. Which reactions are endothermic?
| reaction | initial temperature /°C | final temperature /°C |
|---|---|---|
| 1 | 22 | 16 |
| 2 | 22 | 27 |
| 3 | 20 | 28 |
| 4 | 20 | 18 |
A. 1 and 3
B. 1 and 4
C. 2 and 3
D. 2 and 4
▶️Answer/Explanation
Answer: B. 1 and 4
Explanation: Endothermic reactions absorb heat, causing the temperature to decrease. Reactions 1 and 4 show a decrease in temperature, indicating they are endothermic.
Question 19 (Subtopic: C6.3)
Which reaction involves both oxidation and reduction?
A. calcium carbonate → calcium oxide + carbon dioxide
B. copper oxide + carbon → copper + carbon dioxide
C. silver nitrate + potassium chloride → silver chloride + potassium nitrate
D. sulfuric acid + sodium hydroxide → sodium sulfate + water
▶️Answer/Explanation
Answer: B. copper oxide + carbon → copper + carbon dioxide
Explanation: This is a redox reaction. Copper oxide is reduced to copper, and carbon is oxidized to carbon dioxide.
Question 20 (Subtopic: C7.3)
Copper sulfate is made by adding an excess of copper carbonate to dilute sulfuric acid and stirring. The excess solid is removed. Most of the water is then removed. The solution is left for solid copper sulfate to form. In which order is apparatus used?
A. Bunsen burner, tripod and flask → filter funnel → crystallising dish
B. Bunsen burner, tripod and flask → crystallising dish → filter funnel
C. filter funnel → crystallising dish → Bunsen burner, tripod and flask
D. filter funnel → Bunsen burner, tripod and flask → crystallising dish
▶️Answer/Explanation
Answer: D. filter funnel → Bunsen burner, tripod and flask → crystallising dish
Explanation: First, the mixture is filtered to remove excess copper carbonate. Then, the solution is heated to remove most of the water. Finally, the solution is left in a crystallising dish to allow copper sulfate crystals to form.
Question 21 (Subtopic: C7.1)
Which gas turns damp red litmus paper blue?
A. ammonia
B. carbon dioxide
C. chlorine
D. hydrogen
▶️Answer/Explanation
Answer: A. ammonia
Explanation: Ammonia is an alkaline gas, and it turns damp red litmus paper blue. Carbon dioxide and chlorine are acidic gases, while hydrogen is neutral.
Question 22 (Subtopic: C8.4)
What is a property of transition elements?
A. They form coloured compounds.
B. They form diatomic molecules.
C. They have low densities.
D. They have low melting points.
▶️Answer/Explanation
Answer: A. They form coloured compounds.
Explanation: Transition elements are known for forming coloured compounds due to the presence of partially filled d-orbitals, which allow for the absorption of specific wavelengths of light.
Question 23 (Subtopic: 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. It is more reactive than iron.
Explanation: Aluminium is used in aircraft manufacture because it forms low-density alloys, is malleable, and is resistant to corrosion. Its reactivity is not a factor in its use for this purpose.
Question 24 (Subtopic: C10.1)
Why do farmers treat their fields with fertilisers?
A. to decrease the acidity of the soil
B. to increase the oxygen content of the soil
C. to increase the water content of the soil
D. to increase the yield of crops
▶️Answer/Explanation
Answer: D. to increase the yield of crops
Explanation: Fertilisers provide essential nutrients like nitrogen, phosphorus, and potassium to the soil, which helps increase the yield of crops by promoting healthy plant growth.
Question 25 (Subtopic: C10.2)
Limestone is converted to lime in process 1. Limestone is used to treat industrial waste in process 2. What are processes 1 and 2?
| process 1 | process 2 | |
|---|---|---|
| A | decomposition | dissolving |
| B | decomposition | neutralisation |
| C | oxidation | dissolving |
| D | oxidation | neutralisation |
▶️Answer/Explanation
Answer: B. decomposition, neutralisation
Explanation: Process 1 is the thermal decomposition of limestone (CaCO₃) to produce lime (CaO). Process 2 involves using lime to neutralise acidic industrial waste.
Question 26 (Subtopic: C11.1)
The structures of three organic compounds are shown.
Which statement about these three compounds is correct?
A. They are alcohols.
B. They are alkenes.
C. They are saturated.
D. They do not burn.
▶️Answer/Explanation
Answer: C. They are saturated.
Explanation: The compounds shown are alkanes, which are saturated hydrocarbons. They contain only single bonds between carbon atoms and can burn in the presence of oxygen.
Question 27 (Subtopic: C11.7)
Which statement about the manufacture of polymers is correct?
A. Polymers are made by breaking long-chain molecules into shorter chain ones.
B. Polymers are made by joining polymers together.
C. Polymers are made by fractional distillation of petroleum.
D. Polymers are made by joining short-chain molecules together.
▶️Answer/Explanation
Answer: D. Polymers are made by joining short-chain molecules together.
Explanation: Polymers are formed by joining monomers (short-chain molecules) together through a process called polymerisation. This can occur via addition or condensation reactions.
Question 28 (Subtopic: P1.6.1)
Which is a unit of energy?
A. J
B. kg
C. N
D. W
▶️Answer/Explanation
Answer: A. J
Explanation: The unit of energy is the joule (J). Kilograms (kg) measure mass, newtons (N) measure force, and watts (W) measure power.
Question 29 (Subtopic: P1.4)
A solid cube of metal of side 2.0 cm has a mass of 400 g.
What is the density of the metal?
A. 0.020 g/cm³
B. 50 g/cm³
C. 100 g/cm³
D. 200 g/cm³
▶️Answer/Explanation
Answer: B. 50 g/cm³
Explanation: Density is calculated as mass divided by volume. The volume of the cube is \( 2.0 \, \text{cm} \times 2.0 \, \text{cm} \times 2.0 \, \text{cm} = 8.0 \, \text{cm}^3 \). Therefore, the density is \( \frac{400 \, \text{g}}{8.0 \, \text{cm}^3} = 50 \, \text{g/cm}^3 \).
Question 30 (Subtopic: P1.5.1)
Two children X and Y pull on a rope in opposite directions.
The diagram shows the size of each force and its direction.
What is the resultant force on the rope?
A. 50 N towards X
B. 50 N towards Y
C. 950 N towards X
D. 950 N towards Y
▶️Answer/Explanation
Answer: A. 50 N towards X
Explanation: The resultant force is calculated by subtracting the smaller force from the larger force. If X pulls with 500 N and Y pulls with 450 N, the resultant force is \( 500 \, \text{N} – 450 \, \text{N} = 50 \, \text{N} \) towards X.
Question 31 (Subtopic: P1.6.3)
Which statement describes the production of electricity from a renewable energy source?
A. Coal is burnt to release energy to make steam that turns a generator.
B. Moving air passes over blades that rotate and turn a generator.
C. Nuclear fission releases energy to make steam that turns a generator.
D. Oil is burnt to release energy to make steam that turns a generator.
▶️Answer/Explanation
Answer: B. Moving air passes over blades that rotate and turn a generator.
Explanation: This describes wind energy, which is a renewable energy source. Coal, nuclear fission, and oil are non-renewable energy sources.
Question 32 (Subtopic: P2.2.2)
A liquid-in-glass thermometer contains mercury. The thermometer is moved from cold water into hot water. What happens to the mercury?
A. It contracts.
B. It expands.
C. It freezes.
D. It melts.
▶️Answer/Explanation
Answer: B. It expands.
Explanation: Mercury expands when heated. When the thermometer is moved from cold water to hot water, the mercury inside the thermometer expands, causing the level to rise.
Question 33 (Subtopic: P2.3.1)
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. The water above heater P reaches 60°C in less time.
Explanation: When heater P is switched on, it heats the water above it first due to convection currents. The warm water rises, and the cooler water sinks, creating a cycle that heats the water above the heater more quickly.
Question 34 (Subtopic: P3.2.2)
Light passes from air through a solid glass block. Which diagram shows the path of the light?
▶️Answer/Explanation
Answer: A. Diagram A
Explanation: When light passes from air into a glass block, it bends towards the normal (refraction). When it exits the glass block, it bends away from the normal. Diagram A correctly shows this path.
Question 35 (Subtopic: P3.4)
A person stands 80 m from a high wall and claps his hands. He hears an echo 0.50 s later. Using this information, how is the speed of sound in air calculated?
A. \(\frac{(0.50 \times 2)}{80} \, \text{m/s}\)
B. \(\frac{0.50}{(80 \times 2)} \, \text{m/s}\)
C. \(\frac{(80 \times 2)}{0.50} \, \text{m/s}\)
D. \(\frac{80}{0.50} \, \text{m/s}\)
▶️Answer/Explanation
Answer: C. \(\frac{(80 \times 2)}{0.50} \, \text{m/s}\)
Explanation: The sound travels to the wall and back, so the total distance is \( 80 \, \text{m} \times 2 = 160 \, \text{m} \). The speed of sound is calculated as distance divided by time: \( \frac{160 \, \text{m}}{0.50 \, \text{s}} = 320 \, \text{m/s} \).
Question 36 (Subtopic: P4.2.4)
The circuit shown is used when determining the resistance of a lamp.
The ammeter reading is 2.0 A and the voltmeter reading is 6.0 V. What is the resistance of the lamp?
A. 0.33 Ω
B. 3.0 Ω
C. 8.0 Ω
D. 12 Ω
▶️Answer/Explanation
Answer: B. 3.0 Ω
Explanation: Resistance is calculated using Ohm’s Law: \( R = \frac{V}{I} \). Substituting the values, \( R = \frac{6.0 \, \text{V}}{2.0 \, \text{A}} = 3.0 \, \Omega \).
Question 37 (Subtopic: P4.3.2)
The diagram shows a circuit containing two resistors of resistance \( R \) and \( 2R \), and two ammeters \( X \) and \( Y \).
Which ammeter shows the largest reading, and what is the combined resistance of the two resistors?
| ammeter with largest reading | combined resistance | |
|---|---|---|
| A | \( X \) | less than \( R \) |
| B | \( X \) | more than \( 2R \) |
| C | \( Y \) | less than \( R \) |
| D | \( Y \) | more than \( 2R \) |
▶️Answer/Explanation
Answer: C. \( Y \), less than \( R \)
Explanation: In a parallel circuit, the total resistance is less than the smallest individual resistance. Ammeter \( Y \) measures the current through the resistor \( R \), which has a lower resistance than \( 2R \), so it will show a larger current.
Question 38 (Subtopic: 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. The current decreases to zero.
Explanation: A fuse is designed to break the circuit when the current exceeds its rated value. This prevents damage to the circuit and reduces the risk of fire. When the fuse blows, the current drops to zero.
Question 39 (Subtopic: P4.5.5)
Which pair of changes must make the coil of an electric motor rotate more quickly?
| number of turns on the coil | current in the coil | |
|---|---|---|
| A | decreases | decreases |
| B | decreases | increases |
| C | increases | decreases |
| D | increases | increases |
▶️Answer/Explanation
Answer: D. increases, increases
Explanation: Increasing the number of turns on the coil and increasing the current in the coil both increase the magnetic force acting on the coil, causing it to rotate more quickly.
Question 40 (Subtopic: 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. X and Y
Explanation: Isotopes of the same element have the same number of protons but different numbers of neutrons. Diagrams X and Y show nuclei with the same number of protons but different numbers of neutrons, indicating they are isotopes.