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O-Level Combined Science (Phy/Bio) Topical Practice Questions & Answers

Practise O-Level Combined Science (Phy/Bio) multiple-choice questions aligned to the Singapore-Cambridge GCE O-Level examination. WeloScholars covers all 36 topics — including PHYSICS: Measurement, PHYSICS: Newtonian Mechanics, PHYSICS: Thermal Physics, PHYSICS: Waves — with curriculum-aligned MCQs, an AI tutor that explains every concept step by step, and analytics that show exactly where to focus next. Every question includes a clear explanation of the correct answer and why each distractor is wrong, building real conceptual understanding. Start free: no credit card needed, and your first practice session takes under a minute to set up.

All 36 O-Level Combined Science (Phy/Bio) topics

PHYSICS: Measurement

Physical Quantities, Units and Measurement

PHYSICS: Newtonian Mechanics

Kinematics
Dynamics
Mass, Weight and Density
Turning Effect of Forces
Pressure
Energy, Work and Power

PHYSICS: Thermal Physics

Kinetic Model of Matter
Transfer of Thermal Energy
Thermal Properties of Matter

PHYSICS: Waves

General Wave Properties
Light
Electromagnetic Spectrum
Sound

PHYSICS: Electricity and Magnetism

Static Electricity
Current Electricity
D.C. Circuits
Practical Electricity
Magnetism and Electromagnetism

BIOLOGY: Principles of Biology

Cell Structure and Organisation
Movement of Substances
Biological Molecules

BIOLOGY: Maintenance and Regulation of Life Processes

Nutrition in Humans
Nutrition in Plants
Transport in Flowering Plants
Transport in Humans
Respiration in Humans
Excretion in Humans
Homeostasis
Coordination and Response in Humans

BIOLOGY: Continuity of Life

Reproduction in Plants
Reproduction in Humans
Cell Division
Molecular Genetics
Inheritance

BIOLOGY: Man and His Environment

Organisms and their Environment

Try 5 O-Level Combined Science (Phy/Bio) practice questions with answers

Which of the following is a characteristic of enzymes?

A. They are specific in their action.
B. They are consumed during the reaction.
C. They increase the activation energy of a reaction.
D. They are always composed of lipids.

✅ Answer: A

Enzymes are highly specific, meaning each enzyme typically catalyses only one or a few specific reactions. They are not consumed, they lower activation energy, and are composed of proteins. Option B describes reactants, option C is incorrect as enzymes lower activation energy, and option D is incorrect as enzymes are proteins.

An organism's somatic cells each contain 30 chromosomes. How many chromosomes would be expected in its gametes?

A. 60
B. Any number between 15 and 30
C. 30
D. 15

✅ Answer: D

Somatic cells are diploid (2n), while gametes are haploid (n). Meiosis reduces the chromosome number by half. Therefore, if somatic cells have 30 chromosomes, gametes will have 30 ÷ 2 = 15 chromosomes. Option C is incorrect as it represents the diploid number. Option A is a doubled diploid number. Option B is incorrect as the number is specific.

A student observed a cell under a microscope and noted the presence of a cell wall, chloroplasts, and a large central vacuole. Which type of cell was most likely observed?

A. Fungal cell
B. Animal cell
C. Bacterial cell
D. Plant cell

✅ Answer: D

The presence of a cell wall, chloroplasts, and a large central vacuole are distinguishing features of a plant cell. Animal cells lack these structures, while bacterial and fungal cells have cell walls but lack chloroplasts and a large central vacuole.

A rocket is launched upwards. According to Newton's Third Law of Motion, the force that propels the rocket upwards is due to:

A. The exhaust gases pushing on the rocket.
B. The Earth's gravitational pull on the rocket.
C. The air pushing on the rocket's fins.
D. The rocket pushing on the Earth.

✅ Answer: A

Newton's Third Law states that for every action, there is an equal and opposite reaction. The rocket expels hot gases downwards (action), and in reaction, the gases exert an equal and opposite force upwards on the rocket (reaction), propelling it. Option B is the weight of the rocket, not the propelling force.

Which of the following molecules stores the greatest amount of energy per unit mass?

A. Fat
B. Glucose
C. Protein
D. Glycogen

✅ Answer: A

Fats (lipids) store approximately twice as much energy per unit mass compared to carbohydrates (like glucose and glycogen) or proteins due to their higher proportion of carbon-hydrogen bonds. Glucose is a monosaccharide, glycogen is a polysaccharide, and protein serves structural and enzymatic roles.

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Frequently asked questions

Is this aligned to the current Singapore MOE syllabus?

Yes. WeloScholars maps every O-Level Combined Science (Phy/Bio) question to the official syllabus, topic by topic, and updates when the syllabus changes. Off-syllabus content is excluded.

How many O-Level Combined Science (Phy/Bio) topics are covered?

All 36 topics in the O-Level Combined Science (Phy/Bio) curriculum, each with its own question pool, learning objectives and AI tutor support.

Can my child practise O-Level Combined Science (Phy/Bio) for free?

Yes. The free plan includes practice questions every month plus a demo you can try without creating an account. Premium unlocks unlimited practice and full explanations.

Related practice

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