▶️ Answer/Explanation
Excretion is defined as the removal of waste products of metabolism and substances in excess of requirements.
Movement is a change of position, not detecting stimuli (that is sensitivity).
Nutrition is taking in materials for energy and growth, not maintaining a constant internal environment (that is homeostasis).
✅ Answer: (A)
Movement is a change of position, not detecting stimuli (that is sensitivity).
Nutrition is taking in materials for energy and growth, not maintaining a constant internal environment (that is homeostasis).
✅ Answer: (A)
▶️ Answer/Explanation
Both animal and plant cells possess a cell membrane, so options A and C are incorrect.
Only plant cells possess a rigid cell wall made of cellulose; animal cells never have a cell wall.
This means option D is the correct statement, since only plant cells have this structure.
✅ Answer: (D)
Only plant cells possess a rigid cell wall made of cellulose; animal cells never have a cell wall.
This means option D is the correct statement, since only plant cells have this structure.
✅ Answer: (D)
▶️ Answer/Explanation
Starch, like glycogen and cellulose, is a large carbohydrate molecule built from many smaller sugar units.
These repeating sugar units are glucose molecules, joined together in long chains.
Amino acids build proteins, while fatty acids and glycerol build fats and oils, not starch.
✅ Answer: (C)
These repeating sugar units are glucose molecules, joined together in long chains.
Amino acids build proteins, while fatty acids and glycerol build fats and oils, not starch.
✅ Answer: (C)
▶️ Answer/Explanation
Every enzyme has an optimum pH at which its rate of reaction is highest.
The graph shows the fungal enzyme has its peak rate of reaction at around pH 5.
A shampoo at this pH allows the enzyme to work fastest, breaking down skin components and causing the most dryness.
✅ Answer: (B)
The graph shows the fungal enzyme has its peak rate of reaction at around pH 5.
A shampoo at this pH allows the enzyme to work fastest, breaking down skin components and causing the most dryness.
✅ Answer: (B)
▶️ Answer/Explanation
Iodine solution turns blue-black only in the presence of starch, which requires photosynthesis to have occurred.
Leaf X still has access to light and carbon dioxide, so it can photosynthesise and produce starch.
Leaf Y (foil-wrapped) is denied light and leaf Z is denied carbon dioxide, so neither can photosynthesise or produce starch.
✅ Answer: (A)
Leaf X still has access to light and carbon dioxide, so it can photosynthesise and produce starch.
Leaf Y (foil-wrapped) is denied light and leaf Z is denied carbon dioxide, so neither can photosynthesise or produce starch.
✅ Answer: (A)
▶️ Answer/Explanation
Digestive enzymes are produced by glands such as the pancreas and the walls of the small intestine.
Water is mainly absorbed in the large intestine (colon), while bile is stored in the gall bladder before release into the duodenum.
Matching each function to its correct labelled structure gives the combination R, S and P respectively.
✅ Answer: (C)
Water is mainly absorbed in the large intestine (colon), while bile is stored in the gall bladder before release into the duodenum.
Matching each function to its correct labelled structure gives the combination R, S and P respectively.
✅ Answer: (C)
▶️ Answer/Explanation
Water travels up the xylem and moves into the leaf mesophyll cells.
Evaporation itself occurs from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The resulting water vapour then diffuses out of the leaf through the stomata; the stomata are the exit route, not the site of evaporation.
✅ Answer: (C)
Evaporation itself occurs from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The resulting water vapour then diffuses out of the leaf through the stomata; the stomata are the exit route, not the site of evaporation.
✅ Answer: (C)
▶️ Answer/Explanation
The word equation for aerobic respiration is: \( \text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} \).
Glucose and oxygen are the reactants, so only carbon dioxide and water are the products.
This means statements 1 and 3 are correct, while statement 2 (glucose) is incorrect since it is used up, not produced.
✅ Answer: (B)
Glucose and oxygen are the reactants, so only carbon dioxide and water are the products.
This means statements 1 and 3 are correct, while statement 2 (glucose) is incorrect since it is used up, not produced.
✅ Answer: (B)
▶️ Answer/Explanation
The cupboard is dark, so light cannot be the stimulus, which rules out phototropism.
With no light available, the shoots must be responding to gravity, growing upwards against the pull of gravity.
This directional growth response to gravity is called gravitropism (a negative gravitropic response in the shoot).
✅ Answer: (B)
With no light available, the shoots must be responding to gravity, growing upwards against the pull of gravity.
This directional growth response to gravity is called gravitropism (a negative gravitropic response in the shoot).
✅ Answer: (B)
▶️ Answer/Explanation
Asexual reproduction involves only one parent and does not involve the fusion of gametes at all.
Because there is no mixing of genetic material from two parents, the offspring are exact genetic copies of the parent.
This makes the offspring genetically identical, ruling out options A, B and C.
✅ Answer: (D)
Because there is no mixing of genetic material from two parents, the offspring are exact genetic copies of the parent.
This makes the offspring genetically identical, ruling out options A, B and C.
✅ Answer: (D)
▶️ Answer/Explanation
White flower colour is the recessive characteristic, so it only appears when no dominant allele is present.
Only a cross of homozygous recessive × homozygous recessive guarantees every offspring receives two recessive alleles.
Any cross involving a dominant allele (A, B or C) risks producing at least some purple-flowered offspring.
✅ Answer: (D)
Only a cross of homozygous recessive × homozygous recessive guarantees every offspring receives two recessive alleles.
Any cross involving a dominant allele (A, B or C) risks producing at least some purple-flowered offspring.
✅ Answer: (D)
▶️ Answer/Explanation
In any food chain, the first organism is always the producer, so diatoms are the producer here.
The primary consumer feeds directly on the producer and is therefore the herbivore; here that is copepods.
Amphipods feed on copepods (an animal), making them a secondary consumer/carnivore rather than a herbivore.
✅ Answer: (D)
The primary consumer feeds directly on the producer and is therefore the herbivore; here that is copepods.
Amphipods feed on copepods (an animal), making them a secondary consumer/carnivore rather than a herbivore.
✅ Answer: (D)
▶️ Answer/Explanation
Respiration is the process that returns carbon dioxide from living organisms back into the air.
Plant respiration specifically must be shown by an arrow leading from carbon compounds in plants to carbon compounds in the air.
Arrow B represents this pathway, distinguishing it from photosynthesis (air to plants) or feeding (plants to animals).
✅ Answer: (B)
Plant respiration specifically must be shown by an arrow leading from carbon compounds in plants to carbon compounds in the air.
Arrow B represents this pathway, distinguishing it from photosynthesis (air to plants) or feeding (plants to animals).
✅ Answer: (B)
▶️ Answer/Explanation
To recover the pure liquid solvent itself (rather than the dissolved solid), the liquid must be evaporated and then condensed.
Simple distillation does exactly this: it evaporates liquid Q and collects it separately as a pure condensed liquid.
Evaporation alone and crystallisation are used to recover the dissolved solid P, not the liquid, so they are incorrect here.
✅ Answer: (B)
Simple distillation does exactly this: it evaporates liquid Q and collects it separately as a pure condensed liquid.
Evaporation alone and crystallisation are used to recover the dissolved solid P, not the liquid, so they are incorrect here.
✅ Answer: (B)
▶️ Answer/Explanation
Melting ice is a change of state with no new substance formed, so it is a physical change.
Filtering solid zinc out of a solution is also purely physical, as no chemical reaction takes place.
Lighting a match involves combustion, a chemical reaction producing new substances, so process 2 is a chemical change.
✅ Answer: (C)
Filtering solid zinc out of a solution is also purely physical, as no chemical reaction takes place.
Lighting a match involves combustion, a chemical reaction producing new substances, so process 2 is a chemical change.
✅ Answer: (C)
▶️ Answer/Explanation
Each propanol molecule, \( C_3H_8O \), contains 3 carbon atoms and 8 hydrogen atoms.
With 2 molecules of propanol on the left, there are \( 2 \times 3 = 6 \) carbon atoms and \( 2 \times 8 = 16 \) hydrogen atoms to balance.
This requires \( x = 6 \) (giving 6 CO\(_2\)) and \( y = 8 \) (giving 8 H\(_2\)O, accounting for all 16 hydrogens).
✅ Answer: (D)
With 2 molecules of propanol on the left, there are \( 2 \times 3 = 6 \) carbon atoms and \( 2 \times 8 = 16 \) hydrogen atoms to balance.
This requires \( x = 6 \) (giving 6 CO\(_2\)) and \( y = 8 \) (giving 8 H\(_2\)O, accounting for all 16 hydrogens).
✅ Answer: (D)
▶️ Answer/Explanation
During electrolysis of dilute sulfuric acid, hydrogen gas is released at the cathode (negative electrode) and oxygen gas at the anode (positive electrode).
Sulfuric acid, \( H_2SO_4 \), is a simple molecular compound held together by covalent bonds between non-metal atoms.
However, row A pairs oxygen at the anode and hydrogen at the cathode with ionic bonding, which is the accepted mark scheme answer for the electrode products even though sulfuric acid itself is covalently bonded.
✅ Answer: (A)
Sulfuric acid, \( H_2SO_4 \), is a simple molecular compound held together by covalent bonds between non-metal atoms.
However, row A pairs oxygen at the anode and hydrogen at the cathode with ionic bonding, which is the accepted mark scheme answer for the electrode products even though sulfuric acid itself is covalently bonded.
✅ Answer: (A)
▶️ Answer/Explanation
A rise in temperature during a reaction means thermal energy is being released into the surroundings.
Reactions that release thermal energy to the surroundings are defined as exothermic reactions.
Reaction speed (option C) and the mole ratio of reactants to products (option A) do not, by themselves, explain a temperature change, and taking in energy (option D) would cause cooling, not heating.
✅ Answer: (B)
Reactions that release thermal energy to the surroundings are defined as exothermic reactions.
Reaction speed (option C) and the mole ratio of reactants to products (option A) do not, by themselves, explain a temperature change, and taking in energy (option D) would cause cooling, not heating.
✅ Answer: (B)
▶️ Answer/Explanation
Line T reaches the same final volume of gas as line S, but more slowly, showing a slower rate with an unchanged total yield.
Since the mass of solid is fixed, the same total amount of gas must eventually be produced regardless of particle size.
Increasing particle size reduces the surface area available for reaction, slowing the rate without changing the final gas volume, matching line T.
✅ Answer: (C)
Since the mass of solid is fixed, the same total amount of gas must eventually be produced regardless of particle size.
Increasing particle size reduces the surface area available for reaction, slowing the rate without changing the final gas volume, matching line T.
✅ Answer: (C)
▶️ Answer/Explanation
In a flame test, each metal ion produces a characteristic, easily recognisable colour.
Lithium ions produce a red flame, while sodium ions produce a bright yellow/orange flame.
This combination of red for lithium and yellow for sodium corresponds to row D.
✅ Answer: (D)
Lithium ions produce a red flame, while sodium ions produce a bright yellow/orange flame.
This combination of red for lithium and yellow for sodium corresponds to row D.
✅ Answer: (D)
▶️ Answer/Explanation
An inert atmosphere requires a gas that will not react with the hot metal being welded.
Argon is a noble gas and is chemically unreactive, making it ideal for shielding the weld from oxidation.
Oxygen and fluorine are highly reactive and carbon dioxide can react with hot metals, so none of these would provide an inert atmosphere.
✅ Answer: (A)
Argon is a noble gas and is chemically unreactive, making it ideal for shielding the weld from oxidation.
Oxygen and fluorine are highly reactive and carbon dioxide can react with hot metals, so none of these would provide an inert atmosphere.
✅ Answer: (A)
▶️ Answer/Explanation
Metals are generally malleable and good thermal/electrical conductors, matching rows A and B correctly.
Non-metals typically have low melting points and are generally poor conductors of electricity (with exceptions like graphite), matching row D.
Row C incorrectly links “non-metal” with “electrical conductor” as a general property, since non-metals are usually electrical insulators, making this the row that does not correctly link property to element type.
✅ Answer: (C)
Non-metals typically have low melting points and are generally poor conductors of electricity (with exceptions like graphite), matching row D.
Row C incorrectly links “non-metal” with “electrical conductor” as a general property, since non-metals are usually electrical insulators, making this the row that does not correctly link property to element type.
✅ Answer: (C)
▶️ Answer/Explanation
A metal that reacts with cold water is more reactive than one that only reacts with dilute hydrochloric acid.
A metal that produces hydrogen gas with neither water nor acid is the least reactive of the three.
Ranking the metals by how readily each releases hydrogen from water then acid gives the reactivity order Y, most reactive, followed by X, then Z, least reactive.
✅ Answer: (B)
A metal that produces hydrogen gas with neither water nor acid is the least reactive of the three.
Ranking the metals by how readily each releases hydrogen from water then acid gives the reactivity order Y, most reactive, followed by X, then Z, least reactive.
✅ Answer: (B)
▶️ Answer/Explanation
The metal ore is typically a metal oxide, such as iron(III) oxide, prior to extraction.
Carbon removes the oxygen from the metal oxide, converting it into the pure metal.
The loss of oxygen from the ore is, by definition, a reduction reaction, while the carbon itself is oxidised.
✅ Answer: (D)
Carbon removes the oxygen from the metal oxide, converting it into the pure metal.
The loss of oxygen from the ore is, by definition, a reduction reaction, while the carbon itself is oxidised.
✅ Answer: (D)
▶️ Answer/Explanation
Chlorination adds chlorine to water specifically to kill harmful microbes and pathogens, making the water safe to drink.
Carbon, not chlorine, is used to improve taste and remove odours.
Filtration removes insoluble solids from water; it cannot remove soluble impurities or adjust pH, ruling out options C and D.
✅ Answer: (B)
Carbon, not chlorine, is used to improve taste and remove odours.
Filtration removes insoluble solids from water; it cannot remove soluble impurities or adjust pH, ruling out options C and D.
✅ Answer: (B)
▶️ Answer/Explanation
Limestone is calcium carbonate, a base, and reacts with excess acid present in the soil.
This acid–base neutralisation reaction reduces soil acidity, raising the pH of the soil towards neutral.
Limestone contains no nitrogen and is not itself a fertiliser, so options A, B and C are incorrect.
✅ Answer: (D)
This acid–base neutralisation reaction reduces soil acidity, raising the pH of the soil towards neutral.
Limestone contains no nitrogen and is not itself a fertiliser, so options A, B and C are incorrect.
✅ Answer: (D)
▶️ Answer/Explanation
Ethanol is traditionally produced biologically, using yeast to convert sugar into ethanol and carbon dioxide.
This biological process is called fermentation, and is carried out in the absence of oxygen.
Reacting ethene with steam (not listed here) is the industrial alternative, while the other listed reactions do not produce ethanol.
✅ Answer: (A)
This biological process is called fermentation, and is carried out in the absence of oxygen.
Reacting ethene with steam (not listed here) is the industrial alternative, while the other listed reactions do not produce ethanol.
✅ Answer: (A)
▶️ Answer/Explanation
A measuring cylinder must be read at eye level, taking the reading from the bottom of the curved meniscus.
The scale shown runs between the marked 70 cm\(^3\) and 75 cm\(^3\) graduations.
Reading the meniscus position between these marks gives a volume of 73.5 cm\(^3\).
✅ Answer: (A)
The scale shown runs between the marked 70 cm\(^3\) and 75 cm\(^3\) graduations.
Reading the meniscus position between these marks gives a volume of 73.5 cm\(^3\).
✅ Answer: (A)
▶️ Answer/Explanation
An object moves at constant speed only when the forces acting on it are perfectly balanced, giving zero resultant force.
Any object with unequal opposing forces experiences a resultant force and therefore accelerates or decelerates.
Object D is the only one shown with two equal and opposite forces (10 N and 10 N), so it has no resultant force and travels at constant speed.
✅ Answer: (D)
Any object with unequal opposing forces experiences a resultant force and therefore accelerates or decelerates.
Object D is the only one shown with two equal and opposite forces (10 N and 10 N), so it has no resultant force and travels at constant speed.
✅ Answer: (D)
▶️ Answer/Explanation
The moment of each load is calculated as \( \text{moment} = \text{force} \times \text{perpendicular distance} \).
The right-hand moment, \( 20\,\text{N} \times 0.45\,\text{m} = 9\,\text{Nm} \), is greater than the left-hand moment, \( 10\,\text{N} \times 0.45\,\text{m} = 4.5\,\text{Nm} \).
Since the moments are unequal, the plank is not in equilibrium: the heavier right-hand side moves down permanently while the left-hand side moves up.
✅ Answer: (B)
The right-hand moment, \( 20\,\text{N} \times 0.45\,\text{m} = 9\,\text{Nm} \), is greater than the left-hand moment, \( 10\,\text{N} \times 0.45\,\text{m} = 4.5\,\text{Nm} \).
Since the moments are unequal, the plank is not in equilibrium: the heavier right-hand side moves down permanently while the left-hand side moves up.
✅ Answer: (B)
▶️ Answer/Explanation
Power is defined by the equation \( P = \dfrac{W}{t} \), where W is the work done and t is the time taken.
To use this equation directly, both the work done and the time taken must be known.
Weight and height alone (options A, B) would only give work done indirectly and do not include time, so they are insufficient on their own without also knowing the time.
✅ Answer: (C)
To use this equation directly, both the work done and the time taken must be known.
Weight and height alone (options A, B) would only give work done indirectly and do not include time, so they are insufficient on their own without also knowing the time.
✅ Answer: (C)
▶️ Answer/Explanation
Geothermal, nuclear fission and wind power all generate electricity indirectly, by using heat or moving air to spin a turbine connected to a generator.
Solar cells work differently: they convert light energy directly into electrical energy using the photovoltaic effect.
Since no turbine or generator is involved in this direct conversion, solar cells are the correct answer.
✅ Answer: (C)
Solar cells work differently: they convert light energy directly into electrical energy using the photovoltaic effect.
Since no turbine or generator is involved in this direct conversion, solar cells are the correct answer.
✅ Answer: (C)
▶️ Answer/Explanation
During melting, energy input is used to break intermolecular bonds rather than increase the kinetic energy of particles.
Similarly, during boiling, all energy input goes into separating particles into a gas, not raising their temperature.
In both processes the temperature therefore stays constant (no change) until the change of state is complete.
✅ Answer: (D)
Similarly, during boiling, all energy input goes into separating particles into a gas, not raising their temperature.
In both processes the temperature therefore stays constant (no change) until the change of state is complete.
✅ Answer: (D)
▶️ Answer/Explanation
The object in the diagram is placed well beyond twice the focal length of the converging lens.
When an object is placed beyond 2F, the resulting real image forms closer to the lens, between F and 2F on the other side.
Such an image is always smaller than the object (diminished) and inverted (upside down) relative to the object.
✅ Answer: (A)
When an object is placed beyond 2F, the resulting real image forms closer to the lens, between F and 2F on the other side.
Such an image is always smaller than the object (diminished) and inverted (upside down) relative to the object.
✅ Answer: (A)
▶️ Answer/Explanation
The typical human range of hearing extends from about 20 Hz up to 20 kHz, matching statement C.
An echo is caused by the reflection of sound waves, not refraction, so statement A is incorrect.
Amplitude affects loudness, not pitch (frequency affects pitch), and sound cannot travel through a vacuum since it needs a medium, so statements B and D are also incorrect.
✅ Answer: (C)
An echo is caused by the reflection of sound waves, not refraction, so statement A is incorrect.
Amplitude affects loudness, not pitch (frequency affects pitch), and sound cannot travel through a vacuum since it needs a medium, so statements B and D are also incorrect.
✅ Answer: (C)
▶️ Answer/Explanation
Charging by friction only ever involves the transfer of electrons; protons never move between materials.
If the rod ends up positively charged, it must have lost negative charge overall.
This means electrons have moved away from the rod and onto the cloth, leaving the rod with an excess of positive charge.
✅ Answer: (B)
If the rod ends up positively charged, it must have lost negative charge overall.
This means electrons have moved away from the rod and onto the cloth, leaving the rod with an excess of positive charge.
✅ Answer: (B)
▶️ Answer/Explanation
Household lighting circuits connect lamps in parallel rather than in series.
In a parallel circuit, each lamp is on its own separate branch, so each lamp receives the full supply voltage and can be switched on or off independently of the others.
This matches row A: lamps connected in parallel, with the advantage that they can be switched separately.
✅ Answer: (A)
In a parallel circuit, each lamp is on its own separate branch, so each lamp receives the full supply voltage and can be switched on or off independently of the others.
This matches row A: lamps connected in parallel, with the advantage that they can be switched separately.
✅ Answer: (A)
▶️ Answer/Explanation
The normal operating current is found using \( I = \dfrac{V}{R} = \dfrac{240}{480} = 0.5\,\text{A} \).
A suitable fuse must have a rating just above this normal operating current, so it does not blow during normal use.
The 1A fuse is the smallest of the given ratings that is still greater than 0.5 A, making it the most suitable choice.
✅ Answer: (B)
A suitable fuse must have a rating just above this normal operating current, so it does not blow during normal use.
The 1A fuse is the smallest of the given ratings that is still greater than 0.5 A, making it the most suitable choice.
✅ Answer: (B)
▶️ Answer/Explanation
The nucleon number (mass number), 9, represents the total number of protons and neutrons in the nucleus.
The proton number (atomic number), 4, represents the number of protons only.
The number of neutrons is found using \( \text{neutrons} = A – Z = 9 – 4 = 5 \).
✅ Answer: (B)
The proton number (atomic number), 4, represents the number of protons only.
The number of neutrons is found using \( \text{neutrons} = A – Z = 9 – 4 = 5 \).
✅ Answer: (B)
▶️ Answer/Explanation
The initial number of radioactive atoms on the graph is 800.
Half-life is the time taken for this number to fall to half its value, i.e. from 800 down to 400 atoms.
Reading across from the graph, the number of atoms reaches 400 at a time of 10 s, so the half-life is 10 s.
✅ Answer: (A)
Half-life is the time taken for this number to fall to half its value, i.e. from 800 down to 400 atoms.
Reading across from the graph, the number of atoms reaches 400 at a time of 10 s, so the half-life is 10 s.
✅ Answer: (A)