▶️ Answer/Explanation
Phototropism is the growth of a plant shoot toward a directional light source.
This response involves growth (the shoot bends and elongates unevenly) and sensitivity (the plant detects and responds to the light stimulus).
It does not involve nutrition or reproduction, since no feeding or gamete-related process occurs.
✅ Answer: (B)
This response involves growth (the shoot bends and elongates unevenly) and sensitivity (the plant detects and responds to the light stimulus).
It does not involve nutrition or reproduction, since no feeding or gamete-related process occurs.
✅ Answer: (B)
▶️ Answer/Explanation
Osmosis specifically refers to the movement of water molecules, not solute (sugar) molecules.
Water moves through a partially permeable membrane from a region of higher water potential (dilute solution) to lower water potential (concentrated solution).
✅ Answer: (D)
Water moves through a partially permeable membrane from a region of higher water potential (dilute solution) to lower water potential (concentrated solution).
✅ Answer: (D)
▶️ Answer/Explanation
A purple biuret result confirms protein is present.
A blue (not brick-red) Benedict’s result shows no reducing sugar is present.
A blue/black iodine result confirms starch is present.
✅ Answer: (C)
A blue (not brick-red) Benedict’s result shows no reducing sugar is present.
A blue/black iodine result confirms starch is present.
✅ Answer: (C)
▶️ Answer/Explanation
Enzymes are biological catalysts made up of long chains of amino acids.
This amino-acid chain structure classifies them as proteins, not carbohydrates, fats or starches.
✅ Answer: (C)
This amino-acid chain structure classifies them as proteins, not carbohydrates, fats or starches.
✅ Answer: (C)
▶️ Answer/Explanation
The overall equation for photosynthesis is \(CO_2 + H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + O_2\).
Carbon dioxide and water are the raw materials; glucose and oxygen are the products.
✅ Answer: (A)
Carbon dioxide and water are the raw materials; glucose and oxygen are the products.
✅ Answer: (A)
▶️ Answer/Explanation
Fibre (roughage) is the nutrient that helps move food through the alimentary canal by aiding peristalsis.
Row C has the highest fibre content (10.9 g per 100 g) compared to the other rows.
✅ Answer: (C)
Row C has the highest fibre content (10.9 g per 100 g) compared to the other rows.
✅ Answer: (C)
▶️ Answer/Explanation
A leaf wilts when water loss (transpiration) exceeds water uptake, causing a net water deficit.
Leaf D is the only one where uptake (15) exceeds loss (10), giving a net water gain.
✅ Answer: (D)
Leaf D is the only one where uptake (15) exceeds loss (10), giving a net water gain.
✅ Answer: (D)
▶️ Answer/Explanation
The insects respire, taking in oxygen and releasing carbon dioxide.
The soda lime absorbs all the carbon dioxide produced, so the overall gas volume in the tube decreases.
This drop in gas volume pulls the coloured liquid up towards the tube, so the level at X goes down.
✅ Answer: (A)
The soda lime absorbs all the carbon dioxide produced, so the overall gas volume in the tube decreases.
This drop in gas volume pulls the coloured liquid up towards the tube, so the level at X goes down.
✅ Answer: (A)
▶️ Answer/Explanation
In dim light, the pupil must widen to let in more light, which needs the radial iris muscles to contract.
Distance from focal length (ciliary muscles/lens) is not relevant here; only the muscle controlling pupil dilation matters.
The radial muscle labelled Q contracts to widen the pupil.
✅ Answer: (D)
Distance from focal length (ciliary muscles/lens) is not relevant here; only the muscle controlling pupil dilation matters.
The radial muscle labelled Q contracts to widen the pupil.
✅ Answer: (D)
▶️ Answer/Explanation
Male gametes (sperm) are made in the testes, structure V.
Female gametes (eggs) are made in the ovary, structure W.
Fertilisation, structure Z, occurs in the oviduct (fallopian tube).
✅ Answer: (C)
Female gametes (eggs) are made in the ovary, structure W.
Fertilisation, structure Z, occurs in the oviduct (fallopian tube).
✅ Answer: (C)
▶️ Answer/Explanation
Discontinuous variation (e.g. blood group, eye colour) is controlled by a single gene, so it results only from genetic differences.
Continuous variation (e.g. height, mass) results from an interaction of both genetic and environmental factors, so options A and B are incorrect.
✅ Answer: (D)
Continuous variation (e.g. height, mass) results from an interaction of both genetic and environmental factors, so options A and B are incorrect.
✅ Answer: (D)
▶️ Answer/Explanation
A primary consumer eats producers directly, and a secondary consumer eats primary consumers.
The squirrel eats the beech tree/berries directly (primary consumer role) and is also eaten as prey by other consumers while itself preying on lower-level organisms in some food webs of this type.
Based on the food web links, the squirrel is the organism that occupies both feeding levels.
✅ Answer: (D)
The squirrel eats the beech tree/berries directly (primary consumer role) and is also eaten as prey by other consumers while itself preying on lower-level organisms in some food webs of this type.
Based on the food web links, the squirrel is the organism that occupies both feeding levels.
✅ Answer: (D)
▶️ Answer/Explanation
Burning forests (deforestation) releases stored carbon as CO2 and removes trees that would otherwise absorb \(CO_2\) through photosynthesis.
Planting more crops or using fewer fossil fuels would decrease, not increase, atmospheric \(CO_2\), and pesticide use is unrelated.
✅ Answer: (A)
Planting more crops or using fewer fossil fuels would decrease, not increase, atmospheric \(CO_2\), and pesticide use is unrelated.
✅ Answer: (A)
▶️ Answer/Explanation
Filtration separates the insoluble solid chalk from the liquid, leaving a filtrate containing the dissolved salt and water.
Crystallisation is then used to separate the dissolved soluble salt from the water by evaporating the solvent.
✅ Answer: (D)
Crystallisation is then used to separate the dissolved soluble salt from the water by evaporating the solvent.
✅ Answer: (D)
▶️ Answer/Explanation
Isotopes are atoms of the same element, so they must have the same number of protons (and electrons, if neutral).
They differ in mass number because they have different numbers of neutrons in the nucleus.
✅ Answer: (B)
They differ in mass number because they have different numbers of neutrons in the nucleus.
✅ Answer: (B)
▶️ Answer/Explanation
A correct ionic equation removes spectator ions (\(Na^+\) and \(SO_4^{2-}\)) that do not take part in forming the precipitate.
Only \(Fe^{2+}\) and \(OH^-\) combine to form the insoluble precipitate \(Fe(OH)_2\).
This gives \(Fe^{2+}(aq) + 2OH^-(aq) \rightarrow Fe(OH)_2(s)\).
✅ Answer: (A)
Only \(Fe^{2+}\) and \(OH^-\) combine to form the insoluble precipitate \(Fe(OH)_2\).
This gives \(Fe^{2+}(aq) + 2OH^-(aq) \rightarrow Fe(OH)_2(s)\).
✅ Answer: (A)
▶️ Answer/Explanation
At the cathode, water is preferentially discharged (not \(Na^+\)), producing hydrogen gas, so the number of sodium ions stays the same.
At the anode, chloride ions (\(Cl^-\)) are discharged to form chlorine gas, so the number of chloride ions decreases.
✅ Answer: (C)
At the anode, chloride ions (\(Cl^-\)) are discharged to form chlorine gas, so the number of chloride ions decreases.
✅ Answer: (C)
▶️ Answer/Explanation
Using larger pieces of a solid reactant reduces the exposed surface area for a given mass.
A smaller surface area means fewer particles are available for collisions, decreasing collision frequency and reaction rate.
All the other options increase collision frequency by increasing particle concentration or energy.
✅ Answer: (D)
A smaller surface area means fewer particles are available for collisions, decreasing collision frequency and reaction rate.
All the other options increase collision frequency by increasing particle concentration or energy.
✅ Answer: (D)
▶️ Answer/Explanation
Iron (Fe) loses electrons to form \(Fe^{2+}\), so iron is oxidised.
A substance that is oxidised (loses electrons) is the reducing agent, since it causes another species to be reduced.
Here, Fe reduces \(Cu^{2+}\) to Cu, so Fe is the reducing agent.
✅ Answer: (C)
A substance that is oxidised (loses electrons) is the reducing agent, since it causes another species to be reduced.
Here, Fe reduces \(Cu^{2+}\) to Cu, so Fe is the reducing agent.
✅ Answer: (C)
▶️ Answer/Explanation
The pH of the indicator solution decreasing shows that carbon dioxide gas is being produced and dissolving in it, forming carbonic acid.
Only a reaction between hydrochloric acid and a carbonate releases \(CO_2\) gas as a product.
Zinc carbonate is the solid that reacts with the acid to release \(CO_2\).
✅ Answer: (B)
Only a reaction between hydrochloric acid and a carbonate releases \(CO_2\) gas as a product.
Zinc carbonate is the solid that reacts with the acid to release \(CO_2\).
✅ Answer: (B)
▶️ Answer/Explanation
Halogens are diatomic non-metals, not metals, so statement 1 is incorrect.
Their atoms have seven outer-shell electrons, so statement 2 is correct.
Going down the group they change from gas to liquid to solid (not solid to liquid to gas), so statement 3 is incorrect.
Going down the group they get darker in colour, so statement 4 is correct.
✅ Answer: (C)
Their atoms have seven outer-shell electrons, so statement 2 is correct.
Going down the group they change from gas to liquid to solid (not solid to liquid to gas), so statement 3 is incorrect.
Going down the group they get darker in colour, so statement 4 is correct.
✅ Answer: (C)
▶️ Answer/Explanation
Argon is used to fill lamps because it is unreactive and will not react with the hot filament.
An unreactive gas prevents the filament from oxidising and burning out quickly.
✅ Answer: (D)
An unreactive gas prevents the filament from oxidising and burning out quickly.
✅ Answer: (D)
▶️ Answer/Explanation
Statement 1 shows W is more reactive than X (W reduces X’s oxide).
Statement 2 shows Z is less reactive than W, but more reactive than X and Y.
Statement 3 shows X is more reactive than Y, giving the overall order W > Z > X > Y.
✅ Answer: (B)
Statement 2 shows Z is less reactive than W, but more reactive than X and Y.
Statement 3 shows X is more reactive than Y, giving the overall order W > Z > X > Y.
✅ Answer: (B)
▶️ Answer/Explanation
The graph shows rising atmospheric \(CO_2\) concentration since 1900, driven mainly by combustion of fossil fuels such as gasoline.
Increased atmospheric \(CO_2\) traps more heat (the greenhouse effect), leading to climate change as the environmental problem.
Sulfur combustion causes acid rain, not this \(CO_2\)-driven trend, ruling out options A and C.
✅ Answer: (B)
Increased atmospheric \(CO_2\) traps more heat (the greenhouse effect), leading to climate change as the environmental problem.
Sulfur combustion causes acid rain, not this \(CO_2\)-driven trend, ruling out options A and C.
✅ Answer: (B)
▶️ Answer/Explanation
The Contact process stages are: burning sulfur to form \(SO_2\), oxidising \(SO_2\) to \(SO_3\), dissolving \(SO_3\) in sulfuric acid to form oleum (\(H_2S_2O_7\)), then diluting with water to give \(H_2SO_4\).
The reaction \(CaO + SO_2 \rightarrow CaSO_3\) describes flue-gas desulfurisation (removing sulfur pollutants), not a step of the Contact process itself.
✅ Answer: (A)
The reaction \(CaO + SO_2 \rightarrow CaSO_3\) describes flue-gas desulfurisation (removing sulfur pollutants), not a step of the Contact process itself.
✅ Answer: (A)
▶️ Answer/Explanation
Lime (calcium oxide) is manufactured by heating limestone (calcium carbonate) strongly, a thermal decomposition reaction.
This releases carbon dioxide gas, leaving calcium oxide (lime) as the solid product.
✅ Answer: (B)
This releases carbon dioxide gas, leaving calcium oxide (lime) as the solid product.
✅ Answer: (B)
▶️ Answer/Explanation
Condensation polymerisation uses two different monomers, unlike addition polymerisation which uses one monomer containing a C=C bond.
Condensation polymerisation also produces a small molecule (such as water) alongside the polymer.
✅ Answer: (D)
Condensation polymerisation also produces a small molecule (such as water) alongside the polymer.
✅ Answer: (D)
▶️ Answer/Explanation
The springs are in series, so the full 1.0 N load acts on each individual spring.
Using the spring constant from \(k = \frac{3.0\text{ N}}{3.0\text{ cm}} = 1.0\text{ N/cm}\), each spring extends by \(\frac{1.0\text{ N}}{1.0\text{ N/cm}} = 1.0\) cm.
With three springs each extending 1.0 cm, the total extension is \(3 \times 1.0 = 3.0\) cm.
✅ Answer: (B)
Using the spring constant from \(k = \frac{3.0\text{ N}}{3.0\text{ cm}} = 1.0\text{ N/cm}\), each spring extends by \(\frac{1.0\text{ N}}{1.0\text{ N/cm}} = 1.0\) cm.
With three springs each extending 1.0 cm, the total extension is \(3 \times 1.0 = 3.0\) cm.
✅ Answer: (B)
▶️ Answer/Explanation
The weight of the concrete block is \(10\,000\text{ kg} \times 10\text{ N/kg} = 100\,000\) N.
At balance, the clockwise moment equals the anticlockwise moment: \(6000 \times x = 100\,000 \times 2.0\).
Solving gives \(x = \frac{200\,000}{6000} \approx 33\) m.
✅ Answer: (D)
At balance, the clockwise moment equals the anticlockwise moment: \(6000 \times x = 100\,000 \times 2.0\).
Solving gives \(x = \frac{200\,000}{6000} \approx 33\) m.
✅ Answer: (D)
▶️ Answer/Explanation
Minimum pressure occurs when the block rests on its face with the largest area, since \(P = \frac{F}{A}\) and pressure is inversely proportional to area.
The largest face has dimensions \(15\text{ cm} \times 10\text{ cm} = 150\text{ cm}^2\).
So the minimum pressure is \(\frac{1200\text{ N}}{150\text{ cm}^2} = 8.0\) N/cm².
✅ Answer: (B)
The largest face has dimensions \(15\text{ cm} \times 10\text{ cm} = 150\text{ cm}^2\).
So the minimum pressure is \(\frac{1200\text{ N}}{150\text{ cm}^2} = 8.0\) N/cm².
✅ Answer: (B)
▶️ Answer/Explanation
Using \(v^2 = u^2 + 2as\) with \(u = 0\), \(a = 10\text{ m/s}^2\) and \(s = 45\) m.
\(v^2 = 0 + 2 \times 10 \times 45 = 900\), so \(v = \sqrt{900} = 30\) m/s.
✅ Answer: (C)
\(v^2 = 0 + 2 \times 10 \times 45 = 900\), so \(v = \sqrt{900} = 30\) m/s.
✅ Answer: (C)
▶️ Answer/Explanation
Wind is generated by the uneven heating of the Earth’s atmosphere by the Sun, so all wind energy ultimately originates from solar energy.
Geothermal energy comes from radioactive decay in the Earth’s core, tidal energy comes mainly from the Moon’s gravity, and nuclear fission uses stored nuclear energy in atoms — none of these originate solely from the Sun.
✅ Answer: (D)
Geothermal energy comes from radioactive decay in the Earth’s core, tidal energy comes mainly from the Moon’s gravity, and nuclear fission uses stored nuclear energy in atoms — none of these originate solely from the Sun.
✅ Answer: (D)
▶️ Answer/Explanation
Sensitivity means a large movement of liquid along the tube for a small temperature change.
Decreasing the internal diameter of the capillary tube means the same volume of expanding liquid must travel further along the thinner tube, giving a bigger, more visible movement.
✅ Answer: (A)
Decreasing the internal diameter of the capillary tube means the same volume of expanding liquid must travel further along the thinner tube, giving a bigger, more visible movement.
✅ Answer: (A)
▶️ Answer/Explanation
Loudness of a sound is determined by the amplitude of the wave: a larger amplitude means a greater/louder sound.
Pitch is determined by the frequency of the wave: a lower frequency means a lower pitch.
So increased amplitude and decreased frequency give greater loudness and lower pitch.
✅ Answer: (B)
Pitch is determined by the frequency of the wave: a lower frequency means a lower pitch.
So increased amplitude and decreased frequency give greater loudness and lower pitch.
✅ Answer: (B)
▶️ Answer/Explanation
Charging by friction always involves the transfer of electrons, never protons, since protons are fixed in the nucleus.
If the rod becomes positively charged, it must have lost electrons to the cloth, leaving an excess of positive charge on the rod.
✅ Answer: (B)
If the rod becomes positively charged, it must have lost electrons to the cloth, leaving an excess of positive charge on the rod.
✅ Answer: (B)
▶️ Answer/Explanation
As voltage across a filament lamp increases, its temperature rises, which increases its resistance.
This means current increases less than proportionally with voltage, producing a curve that flattens out rather than a straight line.
✅ Answer: (D)
This means current increases less than proportionally with voltage, producing a curve that flattens out rather than a straight line.
✅ Answer: (D)
▶️ Answer/Explanation
Lamp brightness increases with more current through it, which happens when the total circuit resistance is lowest.
Placing resistors in parallel (rather than in series) with the lamp reduces the overall resistance the battery has to drive current through, allowing more current to flow through the lamp.
Circuit D has the arrangement that gives the lowest effective resistance in the lamp’s branch, making the lamp brightest.
✅ Answer: (D)
Placing resistors in parallel (rather than in series) with the lamp reduces the overall resistance the battery has to drive current through, allowing more current to flow through the lamp.
Circuit D has the arrangement that gives the lowest effective resistance in the lamp’s branch, making the lamp brightest.
✅ Answer: (D)
▶️ Answer/Explanation
The lamp lighting briefly then going off, and never lighting again after the switch is reopened and closed, is the classic behaviour of a fuse blowing.
A fuse melts and permanently breaks the circuit once, unlike a switch, resistor or diode, which would not behave this way.
✅ Answer: (A)
A fuse melts and permanently breaks the circuit once, unlike a switch, resistor or diode, which would not behave this way.
✅ Answer: (A)
▶️ Answer/Explanation
The magnetic field around a straight current-carrying wire forms concentric circles centred on the wire.
Using the right-hand grip rule, with the current coming out of the page, the field circles counterclockwise around the wire.
✅ Answer: (D)
Using the right-hand grip rule, with the current coming out of the page, the field circles counterclockwise around the wire.
✅ Answer: (D)
▶️ Answer/Explanation
Alpha particles are positive and beta particles are negative, so in an electric field they are pushed toward opposite plates, deflecting in opposite directions; statement 1 is correct.
In a magnetic field, opposite charges moving in the same direction experience force in opposite directions, so alpha and beta particles deflect in opposite ways, making statement 2 incorrect.
Gamma rays are uncharged electromagnetic radiation, so they are undeflected by both electric and magnetic fields; statement 3 is correct.
✅ Answer: (A)
In a magnetic field, opposite charges moving in the same direction experience force in opposite directions, so alpha and beta particles deflect in opposite ways, making statement 2 incorrect.
Gamma rays are uncharged electromagnetic radiation, so they are undeflected by both electric and magnetic fields; statement 3 is correct.
✅ Answer: (A)