▶️ Answer/Explanation
Growth requires energy, and this energy is released inside cells through respiration.
Respiration is the breakdown of nutrient molecules such as glucose to release energy for metabolism, including building new cell material for growth.
Excretion, reproduction, and sensitivity do not themselves release energy — they depend on the energy respiration provides.
✅ Answer: (C)
Respiration is the breakdown of nutrient molecules such as glucose to release energy for metabolism, including building new cell material for growth.
Excretion, reproduction, and sensitivity do not themselves release energy — they depend on the energy respiration provides.
✅ Answer: (C)
▶️ Answer/Explanation
The formula for magnification is \( \text{magnification} = \dfrac{\text{image size}}{\text{actual size}} \).
Rearranging gives \( \text{actual size} = \dfrac{\text{image size}}{\text{magnification}} = \dfrac{140}{2} = 70 \) mm.
So the actual length of the chicken’s egg is 70 mm.
✅ Answer: (B)
Rearranging gives \( \text{actual size} = \dfrac{\text{image size}}{\text{magnification}} = \dfrac{140}{2} = 70 \) mm.
So the actual length of the chicken’s egg is 70 mm.
✅ Answer: (B)
▶️ Answer/Explanation
Benedict’s solution is used as a chemical test for reducing sugars such as glucose.
When Benedict’s solution (which is blue) is heated with a reducing sugar, a colour change occurs from blue through green and yellow to an orange/brick-red precipitate.
The intensity and final colour depend on the sugar concentration, but the characteristic positive result is orange.
✅ Answer: (C)
When Benedict’s solution (which is blue) is heated with a reducing sugar, a colour change occurs from blue through green and yellow to an orange/brick-red precipitate.
The intensity and final colour depend on the sugar concentration, but the characteristic positive result is orange.
✅ Answer: (C)
▶️ Answer/Explanation
Enzyme activity increases with rising temperature up to an optimum, because particles move faster and collide more often.
Above the optimum temperature, the enzyme’s active site is denatured and activity falls rapidly to zero.
This gives a curve that rises to a peak and then drops sharply, matching graph D.
✅ Answer: (D)
Above the optimum temperature, the enzyme’s active site is denatured and activity falls rapidly to zero.
This gives a curve that rises to a peak and then drops sharply, matching graph D.
✅ Answer: (D)
▶️ Answer/Explanation
Photosynthesis requires both light energy and carbon dioxide as raw materials.
The rate of photosynthesis increases when light intensity and \(CO_2\) concentration both increase, as neither factor is then limiting.
So the highest rate occurs when both light intensity and carbon dioxide concentration are high.
✅ Answer: (A)
The rate of photosynthesis increases when light intensity and \(CO_2\) concentration both increase, as neither factor is then limiting.
So the highest rate occurs when both light intensity and carbon dioxide concentration are high.
✅ Answer: (A)
▶️ Answer/Explanation
Carbohydrates such as those in bread, pasta and rice are mainly used to provide energy for the body.
Fats provide energy and insulation (not tissue growth), and fibre aids digestion rather than repairing tissue; proteins, from fish, meat and seeds, are for tissue growth and repair.
Only row A correctly matches the food group, its main function and its food sources.
✅ Answer: (A)
Fats provide energy and insulation (not tissue growth), and fibre aids digestion rather than repairing tissue; proteins, from fish, meat and seeds, are for tissue growth and repair.
Only row A correctly matches the food group, its main function and its food sources.
✅ Answer: (A)
▶️ Answer/Explanation
In a dicotyledonous root, the xylem tissue is arranged in a central, star-shaped core at the very centre of the root.
This central position gives the root strength to resist pulling (tension) forces as water is drawn upward.
Diagram C shows the label pointing to this central star-shaped region, which is the xylem.
✅ Answer: (C)
This central position gives the root strength to resist pulling (tension) forces as water is drawn upward.
Diagram C shows the label pointing to this central star-shaped region, which is the xylem.
✅ Answer: (C)
▶️ Answer/Explanation
The insects respire, using up oxygen from the air in the tube and releasing carbon dioxide.
The sodium hydroxide absorbs this carbon dioxide as it is produced, so the overall gas volume inside the tube decreases.
This drop in volume causes the coloured oil droplet to move to the left, towards the insects.
✅ Answer: (B)
The sodium hydroxide absorbs this carbon dioxide as it is produced, so the overall gas volume inside the tube decreases.
This drop in volume causes the coloured oil droplet to move to the left, towards the insects.
✅ Answer: (B)
▶️ Answer/Explanation
Adrenaline is a hormone, not an enzyme, so it is secreted by a gland (the adrenal gland) rather than being produced by an organ as an enzyme.
Hormones travel to their target organs in the bloodstream rather than along nerves.
Adrenaline travels in the blood to the heart, where it increases heart rate.
✅ Answer: (C)
Hormones travel to their target organs in the bloodstream rather than along nerves.
Adrenaline travels in the blood to the heart, where it increases heart rate.
✅ Answer: (C)
▶️ Answer/Explanation
The scrotum is the sac that holds the testes outside the main body cavity, where the temperature is slightly lower and more suitable for sperm production.
The prostate gland (not sperm ducts) adds fluid to semen, the testes produce sperm and testosterone (fluid is from other glands), and the urethra carries semen out through the penis, not to an ovary.
Only row B correctly matches a structure with its true function.
✅ Answer: (B)
The prostate gland (not sperm ducts) adds fluid to semen, the testes produce sperm and testosterone (fluid is from other glands), and the urethra carries semen out through the penis, not to an ovary.
Only row B correctly matches a structure with its true function.
✅ Answer: (B)
▶️ Answer/Explanation
Continuous variation describes characteristics, such as height, that can take any value across a range rather than falling into distinct categories.
This range extends between two extreme values, with every intermediate value possible, unlike discontinuous variation which has no intermediates.
So the correct definition is a range of phenotypes between two extremes.
✅ Answer: (C)
This range extends between two extreme values, with every intermediate value possible, unlike discontinuous variation which has no intermediates.
So the correct definition is a range of phenotypes between two extremes.
✅ Answer: (C)
▶️ Answer/Explanation
Every organism in a food chain requires a continuous supply of energy to carry out life processes such as movement, growth and repair.
This energy is obtained by feeding on other organisms, since energy is passed along the food chain from producers to consumers.
Water, oxygen and disease protection are not the universal reason all organisms in a food chain feed; energy is.
✅ Answer: (D)
This energy is obtained by feeding on other organisms, since energy is passed along the food chain from producers to consumers.
Water, oxygen and disease protection are not the universal reason all organisms in a food chain feed; energy is.
✅ Answer: (D)
▶️ Answer/Explanation
Burning trees during deforestation releases the carbon stored in the wood as carbon dioxide gas through combustion.
Fewer trees also means less carbon dioxide is removed from the air by photosynthesis, adding to the increase.
Together, these effects raise the concentration of carbon dioxide in the atmosphere.
✅ Answer: (A)
Fewer trees also means less carbon dioxide is removed from the air by photosynthesis, adding to the increase.
Together, these effects raise the concentration of carbon dioxide in the atmosphere.
✅ Answer: (A)
▶️ Answer/Explanation
A mixture is judged to contain dye X if it produces spots on the chromatogram that match the position (and hence the \(R_f\) value) of every spot seen for X.
Comparing the spot patterns, only mixture P shows spots in exactly the same positions as dye X.
So dye X is present only in mixture P.
✅ Answer: (C)
Comparing the spot patterns, only mixture P shows spots in exactly the same positions as dye X.
So dye X is present only in mixture P.
✅ Answer: (C)
▶️ Answer/Explanation
\(N_2\) is nitrogen gas, made of two nitrogen atoms joined together, so it is an element, not a compound.
Ni is the symbol for nickel, a metal made of only one type of atom, so it is also an element.
Both symbols represent elements, since a compound must contain atoms of at least two different elements chemically combined.
✅ Answer: (D)
Ni is the symbol for nickel, a metal made of only one type of atom, so it is also an element.
Both symbols represent elements, since a compound must contain atoms of at least two different elements chemically combined.
✅ Answer: (D)
▶️ Answer/Explanation
The nucleon (mass) number of 1 means the nucleus contains a total of only 1 proton and neutron combined.
Hydrogen’s proton number is 1, so this single nucleon must be a proton, leaving no neutrons in the nucleus.
Electrons orbit outside the nucleus and are not part of it, so the nucleus contains one proton only.
✅ Answer: (C)
Hydrogen’s proton number is 1, so this single nucleon must be a proton, leaving no neutrons in the nucleus.
Electrons orbit outside the nucleus and are not part of it, so the nucleus contains one proton only.
✅ Answer: (C)
▶️ Answer/Explanation
The diagram shows the ratio of sodium, sulfur and oxygen atoms/ions present in the compound.
Counting the particles shown gives 2 sodium atoms, 1 sulfur atom and 4 oxygen atoms in the correct ratio for sodium sulfate.
Writing this ratio as a formula, with elements in the conventional order, gives \(Na_2SO_4\).
✅ Answer: (C)
Counting the particles shown gives 2 sodium atoms, 1 sulfur atom and 4 oxygen atoms in the correct ratio for sodium sulfate.
Writing this ratio as a formula, with elements in the conventional order, gives \(Na_2SO_4\).
✅ Answer: (C)
▶️ Answer/Explanation
In dilute sulfuric acid, the ions present are \(H^+\), \(SO_4^{2-}\) and \(OH^-\) (from water).
At the negative electrode (cathode), positive hydrogen ions are attracted and gain electrons (are reduced) to form hydrogen gas.
Oxygen is produced at the positive electrode instead, so the gas released at the negative electrode is hydrogen.
✅ Answer: (A)
At the negative electrode (cathode), positive hydrogen ions are attracted and gain electrons (are reduced) to form hydrogen gas.
Oxygen is produced at the positive electrode instead, so the gas released at the negative electrode is hydrogen.
✅ Answer: (A)
▶️ Answer/Explanation
Carbon monoxide gains oxygen to form carbon dioxide, so it is oxidised, and nitrogen monoxide loses oxygen to form nitrogen, so it is reduced — both correct statements.
Nitrogen from the air is oxidised at the high temperatures inside the engine to form nitrogen monoxide, which is also correct.
However, carbon monoxide is actually a product of the incomplete combustion of petrol (not complete combustion), so that statement is the one that is not correct.
✅ Answer: (B)
Nitrogen from the air is oxidised at the high temperatures inside the engine to form nitrogen monoxide, which is also correct.
However, carbon monoxide is actually a product of the incomplete combustion of petrol (not complete combustion), so that statement is the one that is not correct.
✅ Answer: (B)
▶️ Answer/Explanation
Calcium and lithium are metals, and metal oxides are generally basic, so calcium oxide and lithium oxide are basic, not acidic.
Nitrogen and phosphorus are non-metals, and non-metal oxides are generally acidic.
So the acidic oxides are nitrogen oxide and phosphorus oxide, which are oxides 3 and 4.
✅ Answer: (D)
Nitrogen and phosphorus are non-metals, and non-metal oxides are generally acidic.
So the acidic oxides are nitrogen oxide and phosphorus oxide, which are oxides 3 and 4.
✅ Answer: (D)
▶️ Answer/Explanation
Adding aqueous sodium hydroxide to a solution containing metal ions produces an insoluble metal hydroxide precipitate whose colour identifies the metal ion.
\(Cu^{2+}\) gives a blue precipitate, \(Fe^{3+}\) gives a reddish-brown precipitate, and \(Zn^{2+}\) gives a white precipitate that redissolves in excess.
\(Fe^{2+}\) is the ion that gives the characteristic green precipitate, so substance X contains \(Fe^{2+}\).
✅ Answer: (B)
\(Cu^{2+}\) gives a blue precipitate, \(Fe^{3+}\) gives a reddish-brown precipitate, and \(Zn^{2+}\) gives a white precipitate that redissolves in excess.
\(Fe^{2+}\) is the ion that gives the characteristic green precipitate, so substance X contains \(Fe^{2+}\).
✅ Answer: (B)
▶️ Answer/Explanation
Group I metals are soft, not hard, and become more reactive going down the group as the outer electron is further from the nucleus and more easily lost.
Density and melting point generally decrease down the group, so potassium is denser than lithium and has a lower melting point than sodium (not higher).
Since potassium is below sodium in Group I, it reacts more vigorously with water than sodium does.
✅ Answer: (D)
Density and melting point generally decrease down the group, so potassium is denser than lithium and has a lower melting point than sodium (not higher).
Since potassium is below sodium in Group I, it reacts more vigorously with water than sodium does.
✅ Answer: (D)
▶️ Answer/Explanation
Argon is a noble gas and is chemically inert, meaning it does not react with the hot filament inside a light bulb.
This makes it ideal for filling filament lamps, providing an unreactive atmosphere that prevents the filament from burning away.
Argon is not used as a catalyst, in alloys, or to neutralise chemical waste, since these uses require reactive or structural properties argon does not have.
✅ Answer: (C)
This makes it ideal for filling filament lamps, providing an unreactive atmosphere that prevents the filament from burning away.
Argon is not used as a catalyst, in alloys, or to neutralise chemical waste, since these uses require reactive or structural properties argon does not have.
✅ Answer: (C)
▶️ Answer/Explanation
Metals high in the reactivity series, such as aluminium, form very stable compounds that cannot be reduced by carbon.
These metals must instead be extracted by electrolysis of their molten ore, which requires large amounts of electrical energy.
Iron is extracted by reduction with carbon, copper can be extracted by reduction or other methods, and gold is unreactive enough to be found native, so aluminium is the one extracted by electrolysis.
✅ Answer: (A)
These metals must instead be extracted by electrolysis of their molten ore, which requires large amounts of electrical energy.
Iron is extracted by reduction with carbon, copper can be extracted by reduction or other methods, and gold is unreactive enough to be found native, so aluminium is the one extracted by electrolysis.
✅ Answer: (A)
▶️ Answer/Explanation
Clean, dry air is made up mainly of nitrogen and oxygen, with small proportions of other naturally occurring gases including carbon dioxide.
Carbon monoxide, nitrogen dioxide and sulfur dioxide are all pollutant gases produced by human activities such as combustion, and are not natural components of clean air.
Carbon dioxide, in contrast, is naturally present in air at a low but constant concentration.
✅ Answer: (A)
Carbon monoxide, nitrogen dioxide and sulfur dioxide are all pollutant gases produced by human activities such as combustion, and are not natural components of clean air.
Carbon dioxide, in contrast, is naturally present in air at a low but constant concentration.
✅ Answer: (A)
▶️ Answer/Explanation
Petroleum (crude oil) is a naturally occurring mixture made up mostly of alkane hydrocarbons of different chain lengths, not alkenes.
It is separated into useful fractions by fractional distillation based on boiling point, whereas cracking is a separate process used to break large hydrocarbons into smaller, more useful ones.
Since it contains many different hydrocarbons rather than one single compound, petroleum is correctly described as a mixture of hydrocarbons.
✅ Answer: (B)
It is separated into useful fractions by fractional distillation based on boiling point, whereas cracking is a separate process used to break large hydrocarbons into smaller, more useful ones.
Since it contains many different hydrocarbons rather than one single compound, petroleum is correctly described as a mixture of hydrocarbons.
✅ Answer: (B)
▶️ Answer/Explanation
Poly(ethene) is an addition polymer made by joining together many ethene monomer molecules.
It is a synthetic (man-made) plastic and does not occur naturally, and its long polymer chains contain far more than 12 carbon atoms.
Since it is formed by polymerising ethene (not ethane), the correct statement is that it is formed from ethene.
✅ Answer: (C)
It is a synthetic (man-made) plastic and does not occur naturally, and its long polymer chains contain far more than 12 carbon atoms.
Since it is formed by polymerising ethene (not ethane), the correct statement is that it is formed from ethene.
✅ Answer: (C)
▶️ Answer/Explanation
The distance travelled is equal to the area under the speed–time graph, which here is a trapezium with parallel sides of speed 10 m/s and 18 m/s over 5 s.
Using the trapezium area formula: \( \text{distance} = \dfrac{1}{2}(10+18)\times 5 = \dfrac{1}{2}\times 28 \times 5 = 70 \) m.
So the car travels 70 m in the time shown.
✅ Answer: (C)
Using the trapezium area formula: \( \text{distance} = \dfrac{1}{2}(10+18)\times 5 = \dfrac{1}{2}\times 28 \times 5 = 70 \) m.
So the car travels 70 m in the time shown.
✅ Answer: (C)
▶️ Answer/Explanation
The mass of the liquid alone is found by subtracting the empty cylinder’s mass from the total: \( 95 – 15 = 80 \) g.
The measuring cylinder reading shows the liquid volume is 56 cm³ (read from the meniscus between the 50 and 60 cm³ marks).
Density is then \( \rho = \dfrac{m}{V} = \dfrac{80}{56} \approx 1.4 \) g/cm³.
✅ Answer: (B)
The measuring cylinder reading shows the liquid volume is 56 cm³ (read from the meniscus between the 50 and 60 cm³ marks).
Density is then \( \rho = \dfrac{m}{V} = \dfrac{80}{56} \approx 1.4 \) g/cm³.
✅ Answer: (B)
▶️ Answer/Explanation
The moment of a force is calculated using \( \text{moment} = \text{force} \times \text{perpendicular distance from the pivot} \).
Substituting the values given: \( \text{moment} = 240 \times 1.6 = 384 \) N m.
The correct unit for a moment is newton-metres (N m), not N/m, so the answer is 384 N m.
✅ Answer: (C)
Substituting the values given: \( \text{moment} = 240 \times 1.6 = 384 \) N m.
The correct unit for a moment is newton-metres (N m), not N/m, so the answer is 384 N m.
✅ Answer: (C)
▶️ Answer/Explanation
Non-renewable energy resources are fossil fuels that formed over millions of years and cannot be replaced within a human lifetime, such as oil and natural gas.
Geothermal resources, tides and wind are all renewable, since they are continuously available from natural ongoing processes.
The only pair that are both non-renewable is oil and natural gas.
✅ Answer: (B)
Geothermal resources, tides and wind are all renewable, since they are continuously available from natural ongoing processes.
The only pair that are both non-renewable is oil and natural gas.
✅ Answer: (B)
▶️ Answer/Explanation
During evaporation, the most energetic water particles escape from the liquid surface as vapour.
These particles take their kinetic energy with them, which is drawn as heat energy from the skin and remaining liquid, lowering their temperature.
Since evaporation takes in heat from its surroundings (the person’s skin), the person feels cold.
✅ Answer: (B)
These particles take their kinetic energy with them, which is drawn as heat energy from the skin and remaining liquid, lowering their temperature.
Since evaporation takes in heat from its surroundings (the person’s skin), the person feels cold.
✅ Answer: (B)
▶️ Answer/Explanation
Conduction requires particles in a solid to transfer vibrations, and convection requires the movement of particles in a liquid or gas — neither is possible in the vacuum of space, since there are no particles present.
Thermal radiation, in contrast, consists of electromagnetic waves that do not need a medium and can travel through empty space.
So thermal energy from the Sun reaches the Earth by radiation only.
✅ Answer: (D)
Thermal radiation, in contrast, consists of electromagnetic waves that do not need a medium and can travel through empty space.
So thermal energy from the Sun reaches the Earth by radiation only.
✅ Answer: (D)
▶️ Answer/Explanation
As the light ray enters the glass block, it bends (refracts) towards the normal because glass is optically denser than air.
Inside a parallel-sided block, the ray travels in a straight line until it reaches the opposite parallel face.
Tracing this straight path from the point of entry shows the ray leaves the block at point B.
✅ Answer: (B)
Inside a parallel-sided block, the ray travels in a straight line until it reaches the opposite parallel face.
Tracing this straight path from the point of entry shows the ray leaves the block at point B.
✅ Answer: (B)
▶️ Answer/Explanation
The loudness of a sound is determined by the amplitude of the sound wave, which relates to how much energy the wave carries.
A larger amplitude means the wave carries more energy, producing a louder sound at the ear.
Wavelength affects the pitch of the sound, not its loudness, so increasing the amplitude is what makes the sound louder.
✅ Answer: (C)
A larger amplitude means the wave carries more energy, producing a louder sound at the ear.
Wavelength affects the pitch of the sound, not its loudness, so increasing the amplitude is what makes the sound louder.
✅ Answer: (C)
▶️ Answer/Explanation
Ball P is negatively charged, and it moves away from ball Q, so like charges must be repelling — meaning ball Q is also negatively charged.
When ball Q is brought close to ball R, the balls move closer together, showing attraction, which only happens between unlike charges.
Since Q is negative, ball R must be positively charged for attraction to occur.
✅ Answer: (B)
When ball Q is brought close to ball R, the balls move closer together, showing attraction, which only happens between unlike charges.
Since Q is negative, ball R must be positively charged for attraction to occur.
✅ Answer: (B)
▶️ Answer/Explanation
Current is measured in amperes and resistance is measured in ohms, so neither shares a unit with potential difference.
Potential difference (p.d.) and electromotive force (e.m.f.) are both types of voltage, since e.m.f. is the voltage of the source and p.d. is the voltage across a component.
Because both describe a form of voltage, they are both measured in volts (V), the same unit.
✅ Answer: (C)
Potential difference (p.d.) and electromotive force (e.m.f.) are both types of voltage, since e.m.f. is the voltage of the source and p.d. is the voltage across a component.
Because both describe a form of voltage, they are both measured in volts (V), the same unit.
✅ Answer: (C)
▶️ Answer/Explanation
The two resistors are connected in parallel, so their combined resistance is always less than the smallest individual resistor, which here is less than 3.0 Ω.
Ammeter Q measures the current in the branch with the smaller 3.0 Ω resistor, which carries a larger share of the current than the 6.0 Ω branch.
So the combined resistance is less than 3.0 Ω, and ammeter Q has the greater reading.
✅ Answer: (B)
Ammeter Q measures the current in the branch with the smaller 3.0 Ω resistor, which carries a larger share of the current than the 6.0 Ω branch.
So the combined resistance is less than 3.0 Ω, and ammeter Q has the greater reading.
✅ Answer: (B)
▶️ Answer/Explanation
A fuse must have a current rating that is higher than the normal operating current of the appliance, so it does not blow during normal use.
The kettle operates at 9.0 A, so fuses rated at 1 A, 3 A or 8 A would all be too low and would melt during normal operation.
The 13 A fuse is the smallest standard rating above 9.0 A, making it the most appropriate choice.
✅ Answer: (D)
The kettle operates at 9.0 A, so fuses rated at 1 A, 3 A or 8 A would all be too low and would melt during normal operation.
The 13 A fuse is the smallest standard rating above 9.0 A, making it the most appropriate choice.
✅ Answer: (D)
▶️ Answer/Explanation
In nuclide notation \( ^{A}_{Z}X \), the bottom number Z is the proton number and the top number A is the nucleon (mass) number.
Here \( Z = 1 \), so there is 1 proton, and \( A = 3 \), so the total number of protons and neutrons is 3.
The number of neutrons is \( A – Z = 3 – 1 = 2 \), giving
Here \( Z = 1 \), so there is 1 proton, and \( A = 3 \), so the total number of protons and neutrons is 3.
The number of neutrons is \( A – Z = 3 – 1 = 2 \), giving