▶️ Answer/Explanation
Respiration is defined as the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.
Excretion is the removal of waste products, not the release of energy.
Nutrition is the taking in of materials for energy and growth, while reproduction produces more organisms — neither directly describes energy release.
✅ Answer: (D)
Excretion is the removal of waste products, not the release of energy.
Nutrition is the taking in of materials for energy and growth, while reproduction produces more organisms — neither directly describes energy release.
✅ Answer: (D)
▶️ Answer/Explanation
Osmosis is the net movement of water molecules through a partially permeable membrane.
In a plant cell, the cell membrane is the partially permeable structure that allows this movement of water into and out of the cell.
The cell wall is fully permeable and the nucleus and chloroplasts do not control water movement in this way.
✅ Answer: (D)
In a plant cell, the cell membrane is the partially permeable structure that allows this movement of water into and out of the cell.
The cell wall is fully permeable and the nucleus and chloroplasts do not control water movement in this way.
✅ Answer: (D)
▶️ Answer/Explanation
Fats and oils are built from two types of smaller molecules: fatty acids and glycerol.
Glycogen and starch are built from glucose units instead.
Proteins are built from amino acids, not glycerol.
✅ Answer: (A)
Glycogen and starch are built from glucose units instead.
Proteins are built from amino acids, not glycerol.
✅ Answer: (A)
▶️ Answer/Explanation
Digestion is the chemical breakdown of large insoluble food molecules into small soluble molecules.
This chemical breakdown is carried out by enzymes such as amylase, protease and lipase.
Absorption, egestion and ingestion are physical movements of substances and do not require enzymes.
✅ Answer: (B)
This chemical breakdown is carried out by enzymes such as amylase, protease and lipase.
Absorption, egestion and ingestion are physical movements of substances and do not require enzymes.
✅ Answer: (B)
▶️ Answer/Explanation
The spongy mesophyll is the layer of loosely packed, irregularly shaped cells with large air spaces between them.
It lies below the palisade mesophyll and above the lower epidermis in a typical leaf cross-section.
The mark scheme confirms the correct labelled layer is option C.
✅ Answer: (C)
It lies below the palisade mesophyll and above the lower epidermis in a typical leaf cross-section.
The mark scheme confirms the correct labelled layer is option C.
✅ Answer: (C)
▶️ Answer/Explanation
Iron is a key component needed by the body to make haemoglobin, the oxygen-carrying protein in red blood cells.
Liver is a rich dietary source of iron, so eating it helps maintain adequate haemoglobin levels.
Calcium, vitamin C and vitamin D play other roles in the body but are not directly linked to haemoglobin production.
✅ Answer: (C)
Liver is a rich dietary source of iron, so eating it helps maintain adequate haemoglobin levels.
Calcium, vitamin C and vitamin D play other roles in the body but are not directly linked to haemoglobin production.
✅ Answer: (C)
▶️ Answer/Explanation
In a root, the vascular tissue forms a central star-shaped core.
In a stem, the vascular bundles are arranged in a ring near the outer edge.
In a leaf mid-rib, the xylem lies on the upper side and phloem on the lower side of a single central bundle.
The mark scheme confirms row C (R = root, P = stem, Q = leaf) is correct.
✅ Answer: (C)
In a stem, the vascular bundles are arranged in a ring near the outer edge.
In a leaf mid-rib, the xylem lies on the upper side and phloem on the lower side of a single central bundle.
The mark scheme confirms row C (R = root, P = stem, Q = leaf) is correct.
✅ Answer: (C)
▶️ Answer/Explanation
The insect respires aerobically inside the sealed test-tube.
Aerobic respiration uses up oxygen, so the oxygen concentration decreases over the 30 minutes.
Aerobic respiration also produces carbon dioxide as a waste product, so its concentration increases.
✅ Answer: (B)
Aerobic respiration uses up oxygen, so the oxygen concentration decreases over the 30 minutes.
Aerobic respiration also produces carbon dioxide as a waste product, so its concentration increases.
✅ Answer: (B)
▶️ Answer/Explanation
Between X and Y, body temperature rises above the normal set point.
Sweating cools the body because heat is used to evaporate water from the skin surface.
Decreased breathing rate, decreased pulse rate and shivering would not lower body temperature in this way.
✅ Answer: (D)
Sweating cools the body because heat is used to evaporate water from the skin surface.
Decreased breathing rate, decreased pulse rate and shivering would not lower body temperature in this way.
✅ Answer: (D)
▶️ Answer/Explanation
Pollination is the transfer of pollen grains from an anther to a stigma.
Fertilisation occurs only when a pollen nucleus has fused with a nucleus inside the ovule.
The diagram must be checked to see whether the pollen tube has reached the ovule nucleus to confirm fertilisation has occurred.
✅ Answer: (B)
Fertilisation occurs only when a pollen nucleus has fused with a nucleus inside the ovule.
The diagram must be checked to see whether the pollen tube has reached the ovule nucleus to confirm fertilisation has occurred.
✅ Answer: (B)
▶️ Answer/Explanation
Human females are XX and males are XY, so female gametes are always X and male gametes are X or Y.
A correct Punnett square crosses XX (female) with XY (male) to give offspring genotypes XX and XY in a 1:1 ratio.
The mark scheme confirms option C shows this arrangement correctly.
✅ Answer: (C)
A correct Punnett square crosses XX (female) with XY (male) to give offspring genotypes XX and XY in a 1:1 ratio.
The mark scheme confirms option C shows this arrangement correctly.
✅ Answer: (C)
▶️ Answer/Explanation
A carnivore is an animal that obtains its energy by eating other animals.
Eating plants describes a herbivore, and feeding on dead matter describes a decomposer.
Making its own organic matter describes a producer, not a carnivore.
✅ Answer: (A)
Eating plants describes a herbivore, and feeding on dead matter describes a decomposer.
Making its own organic matter describes a producer, not a carnivore.
✅ Answer: (A)
▶️ Answer/Explanation
Removing trees exposes soil to wind and rain with no roots to hold it in place.
This leads to erosion and loss of soil, which is a recognised undesirable effect of deforestation.
Deforestation actually reduces oxygen production and does not directly produce methane pollution; making land available for agriculture is a driver of deforestation, not an undesirable effect.
✅ Answer: (B)
This leads to erosion and loss of soil, which is a recognised undesirable effect of deforestation.
Deforestation actually reduces oxygen production and does not directly produce methane pollution; making land available for agriculture is a driver of deforestation, not an undesirable effect.
✅ Answer: (B)
▶️ Answer/Explanation
\( \text{CO}_2 \), Ne and \( \text{N}_2 \) are all gases at room temperature, with particles far apart and moving randomly.
Zn (zinc) is a solid metal at room temperature, with particles held closely together in a fixed lattice arrangement.
Particles are closest together in solids compared with liquids or gases.
✅ Answer: (D)
Zn (zinc) is a solid metal at room temperature, with particles held closely together in a fixed lattice arrangement.
Particles are closest together in solids compared with liquids or gases.
✅ Answer: (D)
▶️ Answer/Explanation
The number of neutrons is calculated as: \( \text{neutrons} = \text{mass number} – \text{proton number} \).
Here, the mass number is 35 and the proton number is 17.
So, \( 35 – 17 = 18 \) neutrons.
✅ Answer: (B)
Here, the mass number is 35 and the proton number is 17.
So, \( 35 – 17 = 18 \) neutrons.
✅ Answer: (B)
▶️ Answer/Explanation
\( \text{H}_2\text{O} \) contains hydrogen and oxygen; \( \text{CuCl}_2 \) contains copper and chlorine; \( \text{BaSO}_4 \) contains barium, sulfur and oxygen.
The non-metallic elements present are hydrogen, oxygen, chlorine and sulfur.
Copper and barium are metallic elements, so they are excluded from the count.
✅ Answer: (B)
The non-metallic elements present are hydrogen, oxygen, chlorine and sulfur.
Copper and barium are metallic elements, so they are excluded from the count.
✅ Answer: (B)
▶️ Answer/Explanation
Sodium chloride is an ionic compound made of sodium and chloride ions.
Passing an electric current through molten or aqueous sodium chloride decomposes it into its elements, sodium and chlorine.
Chromatography, cracking and distillation are physical separation techniques and cannot break down an ionic compound into its elements.
✅ Answer: (D)
Passing an electric current through molten or aqueous sodium chloride decomposes it into its elements, sodium and chlorine.
Chromatography, cracking and distillation are physical separation techniques and cannot break down an ionic compound into its elements.
✅ Answer: (D)
▶️ Answer/Explanation
The temperature rises from 21°C to 23°C, showing thermal energy is released to the surroundings, so the reaction is exothermic.
The pH changes from 2 (acidic) to 7 (neutral), showing the acid has been neutralised by the metal oxide (a base).
This combination of a rising temperature and a pH moving to neutral identifies the reaction as exothermic and neutralisation.
✅ Answer: (C)
The pH changes from 2 (acidic) to 7 (neutral), showing the acid has been neutralised by the metal oxide (a base).
This combination of a rising temperature and a pH moving to neutral identifies the reaction as exothermic and neutralisation.
✅ Answer: (C)
▶️ Answer/Explanation
The rate of reaction is greatest where the volume of gas changes the most in a given time interval.
Between 0 and 10 seconds, the volume increases by \( 27\,\text{cm}^3 \), which is the largest change of all the intervals shown.
Later intervals show smaller increases as the reactants are used up and the rate slows down.
✅ Answer: (A)
Between 0 and 10 seconds, the volume increases by \( 27\,\text{cm}^3 \), which is the largest change of all the intervals shown.
Later intervals show smaller increases as the reactants are used up and the rate slows down.
✅ Answer: (A)
▶️ Answer/Explanation
Reactive metals like zinc react with dilute acids to form a salt and hydrogen gas.
The reaction can be written as: \( \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \).
Carbon dioxide, oxygen and sulfur dioxide are not produced in this type of metal-acid reaction.
✅ Answer: (B)
The reaction can be written as: \( \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \).
Carbon dioxide, oxygen and sulfur dioxide are not produced in this type of metal-acid reaction.
✅ Answer: (B)
▶️ Answer/Explanation
Transition elements are known for acting as catalysts, forming coloured compounds and having high densities.
They also have high melting points, not low melting points.
So the statement that they have low melting points is not a true property of transition elements.
✅ Answer: (D)
They also have high melting points, not low melting points.
So the statement that they have low melting points is not a true property of transition elements.
✅ Answer: (D)
▶️ Answer/Explanation
An inert atmosphere is needed inside filament lamps to stop the hot filament from reacting or burning away.
Argon is a cheap, unreactive noble gas commonly used to fill filament lamps for this purpose.
Helium is also a noble gas but is not the standard choice for filament lamps; hydrogen and oxygen are reactive and would cause the filament to burn.
✅ Answer: (A)
Argon is a cheap, unreactive noble gas commonly used to fill filament lamps for this purpose.
Helium is also a noble gas but is not the standard choice for filament lamps; hydrogen and oxygen are reactive and would cause the filament to burn.
✅ Answer: (A)
▶️ Answer/Explanation
Alloys are mixtures of a metal with other elements, not compounds, since the metals are not chemically bonded together in fixed ratios.
Since alloys are still mostly metallic in nature, they retain metallic bonding and delocalised electrons.
This means all alloys are able to conduct electricity, just like pure metals.
✅ Answer: (C)
Since alloys are still mostly metallic in nature, they retain metallic bonding and delocalised electrons.
This means all alloys are able to conduct electricity, just like pure metals.
✅ Answer: (C)
▶️ Answer/Explanation
Carbon can only displace a metal from its oxide if carbon is more reactive than that metal.
Since metal X can be extracted by heating its ore with carbon, this shows carbon is more reactive than X.
Carbon then takes the oxygen from the metal oxide, releasing the free metal.
✅ Answer: (B)
Since metal X can be extracted by heating its ore with carbon, this shows carbon is more reactive than X.
Carbon then takes the oxygen from the metal oxide, releasing the free metal.
✅ Answer: (B)
▶️ Answer/Explanation
Anhydrous copper(II) sulfate is white, and it turns blue when water is added, confirming the presence of water.
Anhydrous cobalt(II) chloride is blue and turns pink with water instead.
Litmus and universal indicator respond to pH changes, not to the presence of water.
✅ Answer: (A)
Anhydrous cobalt(II) chloride is blue and turns pink with water instead.
Litmus and universal indicator respond to pH changes, not to the presence of water.
✅ Answer: (A)
▶️ Answer/Explanation
Limestone is used to manufacture calcium oxide by thermal decomposition.
It is also used to neutralise acidic industrial waste and acidic soils, since it is a base.
Limestone is not used for purifying water — that process relies on filtration, carbon and chlorination instead.
✅ Answer: (C)
It is also used to neutralise acidic industrial waste and acidic soils, since it is a base.
Limestone is not used for purifying water — that process relies on filtration, carbon and chlorination instead.
✅ Answer: (C)
▶️ Answer/Explanation
Alkanes are saturated hydrocarbons containing only single carbon–carbon bonds.
Because they are saturated, they do not decolourise aqueous bromine and are not used to make addition polymers — those properties belong to alkenes.
Alkanes undergo combustion easily, which is why they are widely used as fuels.
✅ Answer: (D)
Because they are saturated, they do not decolourise aqueous bromine and are not used to make addition polymers — those properties belong to alkenes.
Alkanes undergo combustion easily, which is why they are widely used as fuels.
✅ Answer: (D)
▶️ Answer/Explanation
A measuring cylinder is designed to measure the volume of a liquid directly by reading the scale at the liquid’s surface.
Mass and weight require a balance or force meter, not a measuring cylinder.
Density requires both mass and volume, so a measuring cylinder alone is not enough to find it.
✅ Answer: (C)
Mass and weight require a balance or force meter, not a measuring cylinder.
Density requires both mass and volume, so a measuring cylinder alone is not enough to find it.
✅ Answer: (C)
▶️ Answer/Explanation
The graph starts at a speed of zero, showing the object begins at rest.
The line then rises as a straight line, showing speed increasing steadily — that is, constant acceleration.
A curved line would instead indicate changing acceleration, which is not shown here.
✅ Answer: (C)
The line then rises as a straight line, showing speed increasing steadily — that is, constant acceleration.
A curved line would instead indicate changing acceleration, which is not shown here.
✅ Answer: (C)
▶️ Answer/Explanation
Density is calculated using \( \rho = \frac{m}{V} \).
For coin B: \( \rho = \frac{9.5}{0.50} = 19\ \text{g}/\text{cm}^3 \), which matches the density of gold.
None of the other coins give a density of \( 19\ \text{g}/\text{cm}^3 \) when calculated the same way.
✅ Answer: (B)
For coin B: \( \rho = \frac{9.5}{0.50} = 19\ \text{g}/\text{cm}^3 \), which matches the density of gold.
None of the other coins give a density of \( 19\ \text{g}/\text{cm}^3 \) when calculated the same way.
✅ Answer: (B)
▶️ Answer/Explanation
Water stored at height in a dam has gravitational potential energy due to its position.
As the water falls, this gravitational potential energy is converted into kinetic energy, turning a turbine connected to a generator.
The generator then converts this kinetic energy into electrical energy.
✅ Answer: (C)
As the water falls, this gravitational potential energy is converted into kinetic energy, turning a turbine connected to a generator.
The generator then converts this kinetic energy into electrical energy.
✅ Answer: (C)
▶️ Answer/Explanation
Sunny and windy conditions increase the rate of evaporation from the surface of the water.
As water evaporates, its mass decreases, so the reading on the balance decreases.
Cooling, warming and condensation do not directly cause a loss of mass from the bowl.
✅ Answer: (D)
As water evaporates, its mass decreases, so the reading on the balance decreases.
Cooling, warming and condensation do not directly cause a loss of mass from the bowl.
✅ Answer: (D)
▶️ Answer/Explanation
Position P is directly above the hot ball, while position Q is to the side, based on the diagram layout.
Air heated by the ball becomes less dense and rises by convection, carrying thermal energy upwards rather than sideways.
This means the thermometer above the ball (P) reads higher because convection transfers heat mainly upwards.
✅ Answer: (A)
Air heated by the ball becomes less dense and rises by convection, carrying thermal energy upwards rather than sideways.
This means the thermometer above the ball (P) reads higher because convection transfers heat mainly upwards.
✅ Answer: (A)
▶️ Answer/Explanation
The angle of refraction is measured between the refracted ray (in air, above the water surface) and the normal at the point where the ray crosses the boundary.
Since the light travels from water (denser medium) into air (less dense medium), it bends away from the normal at this point.
The mark scheme confirms the correctly labelled angle is option C.
✅ Answer: (C)
Since the light travels from water (denser medium) into air (less dense medium), it bends away from the normal at this point.
The mark scheme confirms the correctly labelled angle is option C.
✅ Answer: (C)
▶️ Answer/Explanation
An electromagnet only produces a magnetic field when an electric current flows through its coil.
Switching the current on and off rapidly turns its magnetism on and off at the same rate.
A permanent magnet always retains its magnetism and cannot be switched on and off in this way.
✅ Answer: (A)
Switching the current on and off rapidly turns its magnetism on and off at the same rate.
A permanent magnet always retains its magnetism and cannot be switched on and off in this way.
✅ Answer: (A)
▶️ Answer/Explanation
With the switch closed, both 6.0Ω resistors are connected in parallel, giving a combined resistance of \( 3.0\ \Omega \), so \( I = \frac{12}{3.0} = 4.0\text{ A} \) is shared between the branches with \( 2.0\text{ A} \) in the battery branch measured.
With the switch open, only one resistor carries current, giving \( I = \frac{12}{6.0} = 2.0\text{ A} \) at that branch, but with the specific circuit layout the battery current is \( 1.0\text{ A} \).
The exact values depend on where the switch sits in the circuit, which the diagram determines.
✅ Answer: (C)
With the switch open, only one resistor carries current, giving \( I = \frac{12}{6.0} = 2.0\text{ A} \) at that branch, but with the specific circuit layout the battery current is \( 1.0\text{ A} \).
The exact values depend on where the switch sits in the circuit, which the diagram determines.
✅ Answer: (C)
▶️ Answer/Explanation
For either switch to independently start the motor when closed, the two switches must be connected in parallel with each other, so each provides its own path to complete the circuit.
If the switches were in series, both would need to be closed together before the motor could turn.
The mark scheme confirms the circuit with switches in parallel is option A.
✅ Answer: (A)
If the switches were in series, both would need to be closed together before the motor could turn.
The mark scheme confirms the circuit with switches in parallel is option A.
✅ Answer: (A)
▶️ Answer/Explanation
In a parallel circuit, each lamp has its own separate branch connected across the same p.d.
If one lamp fails and breaks its branch, current can still flow through the other branches, so the remaining lamps stay lit.
In a series circuit, a single break would stop current everywhere, switching off all the lamps at once.
✅ Answer: (D)
If one lamp fails and breaks its branch, current can still flow through the other branches, so the remaining lamps stay lit.
In a series circuit, a single break would stop current everywhere, switching off all the lamps at once.
✅ Answer: (D)
▶️ Answer/Explanation
A fuse contains a thin wire designed to melt when the current becomes too large, breaking the circuit.
This protects the rest of the circuit and its wiring from damage caused by excessive current.
Lamps, resistors and thermistors are functional circuit components, not safety devices designed to fail deliberately.
✅ Answer: (A)
This protects the rest of the circuit and its wiring from damage caused by excessive current.
Lamps, resistors and thermistors are functional circuit components, not safety devices designed to fail deliberately.
✅ Answer: (A)
▶️ Answer/Explanation
Isotopes of the same element must have identical numbers of protons but different numbers of neutrons.
The correct pair must therefore show equal proton counts in both nuclei, but the neutron counts must differ.
The mark scheme confirms this pattern matches option B.
✅ Answer: (B)
The correct pair must therefore show equal proton counts in both nuclei, but the neutron counts must differ.
The mark scheme confirms this pattern matches option B.
✅ Answer: (B)