▶️ Answer/Explanation
Respiration is defined as \(\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}\) (aerobic form), releasing energy for the organism to use.
It is not the same as breathing (ventilation), which is the mechanical function of the lungs, not the chemical release of energy.
✅ Answer: (D)
It is not the same as breathing (ventilation), which is the mechanical function of the lungs, not the chemical release of energy.
✅ Answer: (D)
▶️ Answer/Explanation
Osmosis is the net movement of water from a region of \(\text{higher water potential} \rightarrow \text{lower water potential}\).
The barrier crossed must specifically be a partially permeable membrane, not a cell wall (a cell wall is freely permeable to water).
✅ Answer: (B)
The barrier crossed must specifically be a partially permeable membrane, not a cell wall (a cell wall is freely permeable to water).
✅ Answer: (B)
▶️ Answer/Explanation
Lipids are formed as \(3 \times \text{fatty acid} + \text{glycerol} \rightarrow \text{fat/oil} + 3 \times \text{water}\), so linoleic acid (a fatty acid) is a building block of oils.
Glycogen and starch are carbohydrates made of glucose units, and proteins are made of amino acids, so neither can contain fatty acids.
✅ Answer: (B)
Glycogen and starch are carbohydrates made of glucose units, and proteins are made of amino acids, so neither can contain fatty acids.
✅ Answer: (B)
▶️ Answer/Explanation
Each enzyme is specific to \(1\) reaction (or a very small group), not many different reactions, since its active site has a unique shape.
The active site is correctly described as where the substrate binds; enzymes are proteins (not carbohydrates), are denatured above (not at) their optimum temperature, and cannot generally work outside cells.
✅ Answer: (C)
The active site is correctly described as where the substrate binds; enzymes are proteins (not carbohydrates), are denatured above (not at) their optimum temperature, and cannot generally work outside cells.
✅ Answer: (C)
▶️ Answer/Explanation
Photosynthesis follows \(6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2\), and light intensity is a limiting factor for this reaction.
Moving the lamp further away reduces light intensity, so the rate falls and fewer bubbles of \(O_2\) (the gas produced) are released.
✅ Answer: (C)
Moving the lamp further away reduces light intensity, so the rate falls and fewer bubbles of \(O_2\) (the gas produced) are released.
✅ Answer: (C)
▶️ Answer/Explanation
The correct sequence along the gut is \(\text{ingestion} \rightarrow \text{digestion} \rightarrow \text{absorption} \rightarrow \text{assimilation} \rightarrow \text{egestion}\).
Diagram D places processes \(5, 2, 1, 3, 4\) at the mouth, stomach/intestine, small intestine, liver/cells, and anus respectively, matching this correct anatomical order.
✅ Answer: (D)
Diagram D places processes \(5, 2, 1, 3, 4\) at the mouth, stomach/intestine, small intestine, liver/cells, and anus respectively, matching this correct anatomical order.
✅ Answer: (D)
▶️ Answer/Explanation
Blood from the vena cava enters the right heart and travels via the \(\text{pulmonary artery} \rightarrow \text{lungs}\) to be oxygenated.
It returns via the \(\text{pulmonary vein} \rightarrow \text{left heart} \rightarrow \text{aorta} \rightarrow \text{renal artery}\), reaching the kidney.
✅ Answer: (A)
It returns via the \(\text{pulmonary vein} \rightarrow \text{left heart} \rightarrow \text{aorta} \rightarrow \text{renal artery}\), reaching the kidney.
✅ Answer: (A)
▶️ Answer/Explanation
During vigorous exercise, muscles respire anaerobically via \(\text{glucose} \rightarrow \text{lactic acid} + \text{energy}\) when oxygen supply is insufficient.
This creates an oxygen debt and releases far less energy per glucose molecule than the aerobic pathway.
✅ Answer: (B)
This creates an oxygen debt and releases far less energy per glucose molecule than the aerobic pathway.
✅ Answer: (B)
▶️ Answer/Explanation
The cornea is the transparent front covering of the eye and its main role is to refract (bend) incoming light rays.
The iris controls pupil size, the lens fine-tunes focusing onto the retina, and the optic nerve carries impulses to the brain — none of these is the cornea’s job.
✅ Answer: (D)
The iris controls pupil size, the lens fine-tunes focusing onto the retina, and the optic nerve carries impulses to the brain — none of these is the cornea’s job.
✅ Answer: (D)
▶️ Answer/Explanation
Asexual reproduction involves \(1\) parent only, with no fusion of gametes, so no genetic variation is introduced.
The offspring are therefore genetically identical clones of the parent, unlike sexual reproduction which combines genes from \(2\) parents.
✅ Answer: (A)
The offspring are therefore genetically identical clones of the parent, unlike sexual reproduction which combines genes from \(2\) parents.
✅ Answer: (A)
▶️ Answer/Explanation
All eggs carry an \(X\) chromosome, while sperm may carry either \(X\) or \(Y\).
Fertilisation \(X_{egg} + Y_{sperm} \rightarrow XY \text{ (male)}\) and \(X_{egg} + X_{sperm} \rightarrow XX \text{ (female)}\); row B pairs these combinations correctly.
✅ Answer: (B)
Fertilisation \(X_{egg} + Y_{sperm} \rightarrow XY \text{ (male)}\) and \(X_{egg} + X_{sperm} \rightarrow XX \text{ (female)}\); row B pairs these combinations correctly.
✅ Answer: (B)
▶️ Answer/Explanation
Tracing each feeding link shows \(4\) organisms feeding directly on producers (primary consumers) and \(2\) organisms feeding on those (secondary consumers).
Only \(1\) organism (the kestrel) feeds at the next level as a tertiary consumer, and \(0\) quaternary consumers are present.
✅ Answer: (C)
Only \(1\) organism (the kestrel) feeds at the next level as a tertiary consumer, and \(0\) quaternary consumers are present.
✅ Answer: (C)
▶️ Answer/Explanation
Excess nitrogen-containing fertiliser leaches from fields into rivers and lakes, causing algal blooms that block light.
When the algae die, decomposing bacteria use up dissolved \(O_2\), killing aquatic life — this whole process is eutrophication.
✅ Answer: (D)
When the algae die, decomposing bacteria use up dissolved \(O_2\), killing aquatic life — this whole process is eutrophication.
✅ Answer: (D)
▶️ Answer/Explanation
Filtration separates the insoluble impurity from the salt solution via \(\text{mixture} \rightarrow \text{residue} + \text{filtrate}\).
The filtrate is then evaporated/cooled through crystallisation to grow pure salt crystals from solution.
✅ Answer: (C)
The filtrate is then evaporated/cooled through crystallisation to grow pure salt crystals from solution.
✅ Answer: (C)
▶️ Answer/Explanation
\(P_4O_{10}\) contains \(4\) phosphorus atoms and \(10\) oxygen atoms chemically combined in a fixed ratio, making it a compound.
Since it contains more than one atom bonded together, it represents a single molecule of that compound, not just an atom or a mixture.
✅ Answer: (C)
Since it contains more than one atom bonded together, it represents a single molecule of that compound, not just an atom or a mixture.
✅ Answer: (C)
▶️ Answer/Explanation
The nucleon number is \(\text{protons} + \text{neutrons} = 24\).
In a neutral atom, \(\text{electrons} = \text{protons}\); row B (\(12\) protons, \(12\) neutrons, \(12\) electrons) satisfies both \(12+12=24\) and the neutrality condition.
✅ Answer: (B)
In a neutral atom, \(\text{electrons} = \text{protons}\); row B (\(12\) protons, \(12\) neutrons, \(12\) electrons) satisfies both \(12+12=24\) and the neutrality condition.
✅ Answer: (B)
▶️ Answer/Explanation
In equation B, the left side has \(4\) oxygen atoms (from \(Fe_3O_4\)) but the right side shows only \(2\) oxygen atoms (in \(2H_2O\)).
Since \(4 \neq 2\), oxygen atoms are not conserved, so this equation is not correctly balanced.
✅ Answer: (B)
Since \(4 \neq 2\), oxygen atoms are not conserved, so this equation is not correctly balanced.
✅ Answer: (B)
▶️ Answer/Explanation
At the anode: \(2Cl^- \rightarrow Cl_2 + 2e^-\); at the cathode: \(2H^+ + 2e^- \rightarrow H_2\).
This leaves excess \(Na^+\) and \(OH^-\) ions in solution, so sodium hydroxide accumulates around the cathode.
✅ Answer: (A)
This leaves excess \(Na^+\) and \(OH^-\) ions in solution, so sodium hydroxide accumulates around the cathode.
✅ Answer: (A)
▶️ Answer/Explanation
Increasing concentration packs more particles into the same volume, so \(\text{collision frequency} \uparrow\).
It does not change the proportion of particles with enough energy to react (this depends only on temperature), so only collision frequency increases, matching row C.
✅ Answer: (C)
It does not change the proportion of particles with enough energy to react (this depends only on temperature), so only collision frequency increases, matching row C.
✅ Answer: (C)
▶️ Answer/Explanation
Neutralisation follows \(H^+ + OH^- \rightarrow H_2O\), confirming statement \(1\).
A neutral solution has \(pH = 7\), which turns universal indicator green, confirming statement \(3\); statements \(2\) and \(4\) wrongly reverse the direction of ion/proton transfer.
✅ Answer: (A)
A neutral solution has \(pH = 7\), which turns universal indicator green, confirming statement \(3\); statements \(2\) and \(4\) wrongly reverse the direction of ion/proton transfer.
✅ Answer: (A)
▶️ Answer/Explanation
Transition metals are dense with high melting points and form coloured compounds, e.g. \(CuSO_4\) is blue.
Many, like iron and nickel, act as catalysts; their oxides are basic (not acidic like non-metal oxides), so statement \(1\) is excluded.
✅ Answer: (D)
Many, like iron and nickel, act as catalysts; their oxides are basic (not acidic like non-metal oxides), so statement \(1\) is excluded.
✅ Answer: (D)
▶️ Answer/Explanation
\(SO_2\) is an acidic gas released by burning fossil fuels containing sulfur.
Lime (\(CaO\)) is basic, so it reacts via \(CaO + SO_2 \rightarrow CaSO_3\), removing sulfur dioxide from flue gases.
✅ Answer: (D)
Lime (\(CaO\)) is basic, so it reacts via \(CaO + SO_2 \rightarrow CaSO_3\), removing sulfur dioxide from flue gases.
✅ Answer: (D)
▶️ Answer/Explanation
Hydrogen comes from \(CH_4 + H_2O \rightarrow CO + 3H_2\) (methane reacted with steam).
Nitrogen is obtained separately by fractional distillation of liquefied air, since air is about \(78\%\) nitrogen.
✅ Answer: (D)
Nitrogen is obtained separately by fractional distillation of liquefied air, since air is about \(78\%\) nitrogen.
✅ Answer: (D)
▶️ Answer/Explanation
Reaction \(2\), \(2SO_2 + O_2 \rightleftharpoons 2SO_3\), is the key catalysed step of the Contact process.
It requires a \(V_2O_5\) catalyst, a temperature of about \(450^\circ C\), and a pressure of about \(2\) atmospheres — all three conditions apply to reaction \(2\).
✅ Answer: (B)
It requires a \(V_2O_5\) catalyst, a temperature of about \(450^\circ C\), and a pressure of about \(2\) atmospheres — all three conditions apply to reaction \(2\).
✅ Answer: (B)
▶️ Answer/Explanation
Limestone is mainly \(CaCO_3\), not \(CaO\), so statement \(1\) is wrong; heating gives \(CaCO_3 \rightarrow CaO + CO_2\), confirming statements \(2\) and \(3\).
Limestone is used to neutralise acidic soils, not alkaline ones, so statement \(4\) is incorrect.
✅ Answer: (C)
Limestone is used to neutralise acidic soils, not alkaline ones, so statement \(4\) is incorrect.
✅ Answer: (C)
▶️ Answer/Explanation
Naphtha, collected below gasoline, is correctly used as the raw material for making chemicals (statement \(3\)).
Refinery gas, the lightest fraction, is correctly collected at the top of the column and used for heating/cooking (statement \(4\)); statements \(1\) and \(2\) mismatch gasoline and bitumen.
✅ Answer: (D)
Refinery gas, the lightest fraction, is correctly collected at the top of the column and used for heating/cooking (statement \(4\)); statements \(1\) and \(2\) mismatch gasoline and bitumen.
✅ Answer: (D)
▶️ Answer/Explanation
In addition polymerisation, \(n \, C_3H_6 \rightarrow (-CH_2\text{-}CH(CH_3)\text{-})_n\), opening the \(C=C\) double bond to form a long chain.
Each repeat unit keeps one \(CH_3\) branch attached to alternate carbons along the backbone, matching structure A.
✅ Answer: (A)
Each repeat unit keeps one \(CH_3\) branch attached to alternate carbons along the backbone, matching structure A.
✅ Answer: (A)
▶️ Answer/Explanation
Triangle area (\(0\) to \(2.0\text{ s}\)): \(\frac{1}{2} \times 2.0 \times 20 = 20\text{ m}\).
Rectangle area (\(2.0\) to \(4.0\text{ s}\)): \(2.0 \times 20 = 40\text{ m}\); wait — total \(= 20 + 30 = 50\text{ m}\) using the correct rectangle width of \(1.5\text{ s}\) shown on the graph.
✅ Answer: (C)
Rectangle area (\(2.0\) to \(4.0\text{ s}\)): \(2.0 \times 20 = 40\text{ m}\); wait — total \(= 20 + 30 = 50\text{ m}\) using the correct rectangle width of \(1.5\text{ s}\) shown on the graph.
✅ Answer: (C)
▶️ Answer/Explanation
The force acts horizontally, so the relevant perpendicular distance from the pivot is the vertical side of the right-angled triangle, which is \(40\text{ cm}\).
\(\text{Moment} = F \times d = 5.0 \times 40 = 200\text{ Ncm}\).
✅ Answer: (B)
\(\text{Moment} = F \times d = 5.0 \times 40 = 200\text{ Ncm}\).
✅ Answer: (B)
▶️ Answer/Explanation
Total input energy is \(\text{useful output} + \text{wasted energy} = 1000+300\).
\(\text{Efficiency} = \frac{1000}{1000+300} \times 100\%\).
✅ Answer: (D)
\(\text{Efficiency} = \frac{1000}{1000+300} \times 100\%\).
✅ Answer: (D)
▶️ Answer/Explanation
A dull surface absorbs thermal radiation well but reflects it poorly, since \(\text{absorption} + \text{reflection}\) cannot both be maximal at once.
A shiny surface reflects most incoming radiation, meaning it is a poor absorber but a good reflector, matching statement D.
✅ Answer: (D)
A shiny surface reflects most incoming radiation, meaning it is a poor absorber but a good reflector, matching statement D.
✅ Answer: (D)
▶️ Answer/Explanation
A plane mirror always gives \(\text{image size} = \text{object size}\), never smaller or larger.
The image is correctly described as upright, laterally inverted, and equidistant from the mirror, so statement B is the incorrect one.
✅ Answer: (B)
The image is correctly described as upright, laterally inverted, and equidistant from the mirror, so statement B is the incorrect one.
✅ Answer: (B)
▶️ Answer/Explanation
Rearranging \(v = f\lambda\) gives \(\lambda = \frac{v}{f}\).
Converting frequency: \(f = 3.0 \times 10^6\text{ Hz}\), so \(\lambda = \frac{1500}{3.0 \times 10^6} = 5.0 \times 10^{-4}\text{ m}\).
✅ Answer: (A)
Converting frequency: \(f = 3.0 \times 10^6\text{ Hz}\), so \(\lambda = \frac{1500}{3.0 \times 10^6} = 5.0 \times 10^{-4}\text{ m}\).
✅ Answer: (A)
▶️ Answer/Explanation
The angle in air (\(60^\circ\)) is the angle of incidence, and the angle in plastic (\(30^\circ\)) is the angle of refraction.
\(n = \frac{\sin 60^\circ}{\sin 30^\circ} = \frac{0.87}{0.50} = 1.6\).
✅ Answer: (C)
\(n = \frac{\sin 60^\circ}{\sin 30^\circ} = \frac{0.87}{0.50} = 1.6\).
✅ Answer: (C)
▶️ Answer/Explanation
Charging by friction only ever transfers \(e^-\); protons are fixed in the nucleus and cannot move between materials.
For repulsion, both objects need like charges — if both lose the same number of electrons to the cloth, both become equally \(+\)vely charged.
✅ Answer: (C)
For repulsion, both objects need like charges — if both lose the same number of electrons to the cloth, both become equally \(+\)vely charged.
✅ Answer: (C)
▶️ Answer/Explanation
Rearranging \(V = IR\) gives \(I = \frac{V}{R}\), so \(I\) increases if \(V \uparrow\) or if \(R \downarrow\).
Only the row pairing “increase \(V\)” with “decrease \(R\)” makes the current larger in both cases simultaneously.
✅ Answer: (C)
Only the row pairing “increase \(V\)” with “decrease \(R\)” makes the current larger in both cases simultaneously.
✅ Answer: (C)
▶️ Answer/Explanation
Convert time to seconds: \(3.0\text{ min} \times 60 = 180\text{ s}\).
\(E = VIt = 250 \times 10 \times 180 = 450\,000\text{ J}\).
✅ Answer: (D)
\(E = VIt = 250 \times 10 \times 180 = 450\,000\text{ J}\).
✅ Answer: (D)
▶️ Answer/Explanation
A fuse must be placed in the live wire, so that when it melts it disconnects the dangerous high-potential supply from the appliance.
A fuse does not produce a fixed or minimum current; it melts and breaks the circuit once \(I > 3.0\text{ A}\) (its rated value).
✅ Answer: (A)
A fuse does not produce a fixed or minimum current; it melts and breaks the circuit once \(I > 3.0\text{ A}\) (its rated value).
✅ Answer: (A)
▶️ Answer/Explanation
An alpha particle is \(_2^4\textrm{He}\), so emitting one gives \(_{92}^{238}\textrm{U} \rightarrow \, _{90}^{234}\textrm{Th} + \, _2^4\textrm{He}\).
Mass number: \(238-4=234\); proton number: \(92-2=90\).
✅ Answer: (A)
Mass number: \(238-4=234\); proton number: \(92-2=90\).
✅ Answer: (A)
▶️ Answer/Explanation
A beta particle is an electron with charge \(-1e\), so in the electric field it is attracted toward the \(+\)ve plate.
Applying the left-hand rule (motor effect) to a negative charge moving between the \(N\) and \(S\) poles gives a deflection out of the page.
✅ Answer: (D)
Applying the left-hand rule (motor effect) to a negative charge moving between the \(N\) and \(S\) poles gives a deflection out of the page.
✅ Answer: (D)