▶️ Answer/Explanation
Respiration is the life process in which nutrient molecules (e.g. glucose) are broken down by chemical reactions inside cells to release energy.
Excretion removes waste, nutrition takes in food, and reproduction produces offspring — none of these describe energy release.
✅ Answer: (D)
Excretion removes waste, nutrition takes in food, and reproduction produces offspring — none of these describe energy release.
✅ Answer: (D)
▶️ Answer/Explanation
Cell membrane, nucleus and cytoplasm are present in both plant and animal cells.
The cell wall is a rigid structure made of cellulose that surrounds plant cells only, giving them shape and support.
✅ Answer: (B)
The cell wall is a rigid structure made of cellulose that surrounds plant cells only, giving them shape and support.
✅ Answer: (B)
▶️ Answer/Explanation
Fats and oils are large molecules built from smaller building-block molecules: fatty acids and glycerol.
Glycogen and starch are made from glucose units, and proteins are made from amino acids — neither contains glycerol.
✅ Answer: (A)
Glycogen and starch are made from glucose units, and proteins are made from amino acids — neither contains glycerol.
✅ Answer: (A)
▶️ Answer/Explanation
Enzymes are biological catalysts, meaning they speed up the rate of chemical reactions.
They are proteins (not fats), are not used up or changed permanently by the reaction, and are strongly affected by temperature.
✅ Answer: (C)
They are proteins (not fats), are not used up or changed permanently by the reaction, and are strongly affected by temperature.
✅ Answer: (C)
▶️ Answer/Explanation
Starch (which stains blue-black with iodine) can only form where chlorophyll is present AND light reaches the leaf.
Area 2 is green and in the light, so it photosynthesises and stains blue-black; area 1 is green but covered, area 3 is white (no chlorophyll) and in the light, area 4 is white and covered — none of these turn blue-black.
✅ Answer: (D)
Area 2 is green and in the light, so it photosynthesises and stains blue-black; area 1 is green but covered, area 3 is white (no chlorophyll) and in the light, area 4 is white and covered — none of these turn blue-black.
✅ Answer: (D)
▶️ Answer/Explanation
Following the alimentary canal in order from the mouth: food passes down the oesophagus (P), into the coiled small intestine (Q), and finally the large intestine (R) before the anus.
This sequence and structure shape matches row D.
✅ Answer: (D)
This sequence and structure shape matches row D.
✅ Answer: (D)
▶️ Answer/Explanation
In a root, the vascular tissue forms a central star-shaped core; in a stem, vascular bundles are arranged in a ring near the edge; in a leaf mid-rib, the vein sits centrally with xylem on top and phloem below.
Matching each diagram to its correct tissue arrangement gives row C.
✅ Answer: (C)
Matching each diagram to its correct tissue arrangement gives row C.
✅ Answer: (C)
▶️ Answer/Explanation
Aerobic respiration is summarised by \( \text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy} \).
So glucose and oxygen must move into the cell, while carbon dioxide and water move out — this is the arrangement shown in diagram C.
✅ Answer: (C)
So glucose and oxygen must move into the cell, while carbon dioxide and water move out — this is the arrangement shown in diagram C.
✅ Answer: (C)
▶️ Answer/Explanation
In a ‘fight or flight’ response, adrenaline increases both breathing rate and pulse rate above their resting values to prepare the body for action.
A normal resting breathing rate is around 12–18 breaths/min and pulse around 70 beats/min, so both values must rise well above these — matching row D (18 and 140).
✅ Answer: (D)
A normal resting breathing rate is around 12–18 breaths/min and pulse around 70 beats/min, so both values must rise well above these — matching row D (18 and 140).
✅ Answer: (D)
▶️ Answer/Explanation
Stage 1 involves reproduction “without fertilisation”, which is the definition of asexual reproduction.
Stage 2 involves fusion of sperm and egg (“fertilised”), which is the definition of sexual reproduction.
✅ Answer: (B)
Stage 2 involves fusion of sperm and egg (“fertilised”), which is the definition of sexual reproduction.
✅ Answer: (B)
▶️ Answer/Explanation
A characteristic with a full range of values between two extremes (such as size or height) is continuous variation.
Discontinuous variation instead produces distinct, separate categories (e.g. blood group), which does not match “a range between two extremes”.
✅ Answer: (A)
Discontinuous variation instead produces distinct, separate categories (e.g. blood group), which does not match “a range between two extremes”.
✅ Answer: (A)
▶️ Answer/Explanation
A producer is an organism, typically a green plant or alga, that makes its own organic food using light energy through photosynthesis.
Organisms that digest plants or animals are consumers, and those feeding on dead matter are decomposers — neither is a producer.
✅ Answer: (B)
Organisms that digest plants or animals are consumers, and those feeding on dead matter are decomposers — neither is a producer.
✅ Answer: (B)
▶️ Answer/Explanation
Removing trees exposes soil directly to wind and rain, since roots no longer bind it together, leading to erosion and loss of fertile soil.
The other options describe either false effects (increased oxygen) or effects that are advantages, not problems, of deforestation.
✅ Answer: (B)
The other options describe either false effects (increased oxygen) or effects that are advantages, not problems, of deforestation.
✅ Answer: (B)
▶️ Answer/Explanation
The diagram shows particles spreading out from a small concentrated region into the surrounding space, without any change of state.
This random spreading from high to low concentration is the definition of diffusion, not a state change like evaporation or condensation.
✅ Answer: (B)
This random spreading from high to low concentration is the definition of diffusion, not a state change like evaporation or condensation.
✅ Answer: (B)
▶️ Answer/Explanation
The nucleon (mass) number is the total number of protons and neutrons in the nucleus: \( \text{nucleon number} = \text{protons} + \text{neutrons} \).
Substituting the given values: \( 9 + 10 = 19 \).
✅ Answer: (C)
Substituting the given values: \( 9 + 10 = 19 \).
✅ Answer: (C)
▶️ Answer/Explanation
A hydrocarbon contains only carbon and hydrogen, which rules out option D since it contains oxygen.
The ratio of H atoms to C atoms must be exactly 3:1; checking each remaining formula, only \(C_2H_6\) gives \( \frac{6}{2} = 3 \).
✅ Answer: (C)
The ratio of H atoms to C atoms must be exactly 3:1; checking each remaining formula, only \(C_2H_6\) gives \( \frac{6}{2} = 3 \).
✅ Answer: (C)
▶️ Answer/Explanation
Electrolysis is the decomposition of an ionic compound, when molten or in solution, by passing an electric current through it.
Molten sodium chloride is electrolysed to give sodium metal at the cathode and chlorine gas at the anode; chromatography, cracking and distillation do not break down compounds this way.
✅ Answer: (D)
Molten sodium chloride is electrolysed to give sodium metal at the cathode and chlorine gas at the anode; chromatography, cracking and distillation do not break down compounds this way.
✅ Answer: (D)
▶️ Answer/Explanation
An exothermic reaction releases heat energy to the surroundings, so the temperature increases; an endothermic reaction absorbs heat, so the temperature decreases.
This means row 1 (decrease, endothermic) and row 3 (increase, exothermic) are correctly matched.
✅ Answer: (A)
This means row 1 (decrease, endothermic) and row 3 (increase, exothermic) are correctly matched.
✅ Answer: (A)
▶️ Answer/Explanation
Since equal masses of calcium carbonate are used in both experiments, the same final volume of gas is eventually produced, but X reacts faster (steeper initial slope) than Y.
A faster reaction happening in X, with the same total amount of gas released, is best explained by X using a more concentrated acid, which increases collision frequency.
✅ Answer: (D)
A faster reaction happening in X, with the same total amount of gas released, is best explained by X using a more concentrated acid, which increases collision frequency.
✅ Answer: (D)
▶️ Answer/Explanation
Neutralising excess stomach acid requires a base (an alkali or other substance with pH above 7).
Vinegar (pH 4) and orange juice (pH 6) are themselves acidic, and water (pH 7) is neutral so cannot neutralise anything; baking powder (pH 9) is basic and will react with and neutralise the acid.
✅ Answer: (D)
Vinegar (pH 4) and orange juice (pH 6) are themselves acidic, and water (pH 7) is neutral so cannot neutralise anything; baking powder (pH 9) is basic and will react with and neutralise the acid.
✅ Answer: (D)
▶️ Answer/Explanation
Bromine is the only Group VII element that is liquid at room temperature, so statement 1 is correct.
The halogens are non-metals (not metallic), so statement 4 is false; melting/boiling points actually increase down the group, so statement 3 is also false.
✅ Answer: (B)
The halogens are non-metals (not metallic), so statement 4 is false; melting/boiling points actually increase down the group, so statement 3 is also false.
✅ Answer: (B)
▶️ Answer/Explanation
Filament lamps are filled with an unreactive (noble) gas to stop the hot filament reacting with oxygen and burning out.
Argon is the noble gas commonly used for this purpose, being cheap and abundant, unlike helium which is not used industrially for this.
✅ Answer: (A)
Argon is the noble gas commonly used for this purpose, being cheap and abundant, unlike helium which is not used industrially for this.
✅ Answer: (A)
▶️ Answer/Explanation
An alloy is a mixture (not a chemical compound) of a metal with one or more other elements, since the components are not chemically bonded in fixed proportions.
Because alloys are still made of metal atoms, they all retain metallic bonding and therefore all conduct electricity.
✅ Answer: (C)
Because alloys are still made of metal atoms, they all retain metallic bonding and therefore all conduct electricity.
✅ Answer: (C)
▶️ Answer/Explanation
Carbon can only displace and extract a metal from its ore if carbon is more reactive than that metal.
A more reactive element displaces a less reactive one from its compound, so metal X must be less reactive than carbon for this method to work.
✅ Answer: (B)
A more reactive element displaces a less reactive one from its compound, so metal X must be less reactive than carbon for this method to work.
✅ Answer: (B)
▶️ Answer/Explanation
Clean, dry air is approximately 78% nitrogen and 21% oxygen, with much smaller amounts of other gases such as argon and carbon dioxide.
So nitrogen must be the most abundant gas and oxygen the next most abundant, matching row B.
✅ Answer: (B)
So nitrogen must be the most abundant gas and oxygen the next most abundant, matching row B.
✅ Answer: (B)
▶️ Answer/Explanation
Limestone is used to manufacture calcium oxide (by heating), to neutralise acidic industrial waste, and to treat acidic soils — all common applications.
Purifying water is not a recognised use of limestone; water purification instead uses methods like filtration, chlorination or sedimentation.
✅ Answer: (C)
Purifying water is not a recognised use of limestone; water purification instead uses methods like filtration, chlorination or sedimentation.
✅ Answer: (C)
▶️ Answer/Explanation
Refinery gas, gasoline (petrol) and diesel oil are all flammable fractions burned as fuels in heating, cooking or vehicle engines.
Bitumen is a thick, viscous fraction used for surfacing roads and roofing, not as a fuel.
✅ Answer: (D)
Bitumen is a thick, viscous fraction used for surfacing roads and roofing, not as a fuel.
✅ Answer: (D)
▶️ Answer/Explanation
Acceleration is the gradient of a speed–time graph; a straight, sloped line therefore means the acceleration has a constant, non-zero value.
The graph shows a straight line rising steadily, so the gradient (acceleration) stays the same positive value throughout — it neither increases nor decreases.
✅ Answer: (C)
The graph shows a straight line rising steadily, so the gradient (acceleration) stays the same positive value throughout — it neither increases nor decreases.
✅ Answer: (C)
▶️ Answer/Explanation
The volume of the cuboid is \( 10 \times 5.0 \times 2.0 = 100 \, \text{cm}^3 \).
Using \( \text{mass} = \text{density} \times \text{volume} \), the mass is \( 10 \times 100 = 1000 \, \text{g} \).
✅ Answer: (D)
Using \( \text{mass} = \text{density} \times \text{volume} \), the mass is \( 10 \times 100 = 1000 \, \text{g} \).
✅ Answer: (D)
▶️ Answer/Explanation
With no resultant force acting, an object’s velocity (speed and direction) does not change — this is Newton’s First Law.
Since the object was already moving at constant speed in a straight line, it simply continues to do so unchanged.
✅ Answer: (B)
Since the object was already moving at constant speed in a straight line, it simply continues to do so unchanged.
✅ Answer: (B)
▶️ Answer/Explanation
Since both trucks lift identical loads through the same height, they do the same amount of work — so options A and C are wrong.
Power is calculated as \( P = \frac{W}{t} \); since truck Q does the same work in less time, it produces more power than truck P.
✅ Answer: (D)
Power is calculated as \( P = \frac{W}{t} \); since truck Q does the same work in less time, it produces more power than truck P.
✅ Answer: (D)
▶️ Answer/Explanation
Water stored at a height behind a dam has gravitational potential energy due to its position.
As the water falls, this gravitational potential energy is transferred into kinetic energy, which turns turbines to generate electrical energy.
✅ Answer: (C)
As the water falls, this gravitational potential energy is transferred into kinetic energy, which turns turbines to generate electrical energy.
✅ Answer: (C)
▶️ Answer/Explanation
Wood is a poor conductor, so very little heat travels sideways through it to either thermometer by conduction.
Instead, the air around the hot ball is heated, becomes less dense, and rises by convection, so the thermometer positioned above (Q) records the higher reading.
✅ Answer: (C)
Instead, the air around the hot ball is heated, becomes less dense, and rises by convection, so the thermometer positioned above (Q) records the higher reading.
✅ Answer: (C)
▶️ Answer/Explanation
When an object is placed further than \(2F\) from a converging lens, the rays converge to form a real image between \(F\) and \(2F\) on the other side.
This image is always smaller than the object (diminished) and inverted (upside down) compared with the object.
✅ Answer: (A)
This image is always smaller than the object (diminished) and inverted (upside down) compared with the object.
✅ Answer: (A)
▶️ Answer/Explanation
The electromagnetic spectrum, from lowest to highest frequency, runs: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
Checking option B: microwaves come before infrared, and infrared comes before gamma-rays, so this sequence is correctly increasing in frequency.
✅ Answer: (B)
Checking option B: microwaves come before infrared, and infrared comes before gamma-rays, so this sequence is correctly increasing in frequency.
✅ Answer: (B)
▶️ Answer/Explanation
An electromagnet’s magnetism depends entirely on an electric current flowing through its coil, so it can be turned on and off simply by switching the current.
A permanent magnet’s magnetism is fixed in the material itself and cannot be switched on or off at all, let alone rapidly.
✅ Answer: (A)
A permanent magnet’s magnetism is fixed in the material itself and cannot be switched on or off at all, let alone rapidly.
✅ Answer: (A)
▶️ Answer/Explanation
When two insulators are rubbed together, electrons transfer from one to the other; the object gaining electrons becomes negatively charged, and the one losing electrons becomes positively charged.
Since the rod becomes negative, it must have gained electrons (statement 1 correct); those electrons came from the cloth, so the cloth loses electrons (statement 2) and becomes positively charged (statement 3).
✅ Answer: (D)
Since the rod becomes negative, it must have gained electrons (statement 1 correct); those electrons came from the cloth, so the cloth loses electrons (statement 2) and becomes positively charged (statement 3).
✅ Answer: (D)
▶️ Answer/Explanation
Resistors connected in series add together to give the largest total resistance, while resistors connected in parallel give a smaller combined resistance than any single resistor.
Comparing the three arrangements shown, the fully-series combination Y has the highest resistance, the fully-parallel combination has the lowest, giving the order Y → X → Z.
✅ Answer: (A)
Comparing the three arrangements shown, the fully-series combination Y has the highest resistance, the fully-parallel combination has the lowest, giving the order Y → X → Z.
✅ Answer: (A)
▶️ Answer/Explanation
A fuse must have a rating just above the normal operating current, so it does not blow during ordinary use but still trips quickly if the current becomes dangerously high.
A 1 A fuse would blow immediately since 3.1 A exceeds it, while 8 A is too high to protect the mixer promptly; the closest rating above 3.1 A is 5 A.
✅ Answer: (C)
A 1 A fuse would blow immediately since 3.1 A exceeds it, while 8 A is too high to protect the mixer promptly; the closest rating above 3.1 A is 5 A.
✅ Answer: (C)
▶️ Answer/Explanation
Isotopes of the same element must have identical proton numbers (same number of protons in each nucleus of the pair) but different neutron numbers.
Checking each pair of diagrams for equal proton counts but differing neutron counts identifies pair B as the correct match.
✅ Answer: (B)
Checking each pair of diagrams for equal proton counts but differing neutron counts identifies pair B as the correct match.
✅ Answer: (B)