๐Ÿ”ฌ Official Revision Pack

KS3 Science
Challenge Quiz

20 exam-style questions across Biology, Chemistry & Physics โ€” timed, graded with full explanations.

20 Questions
25 Minutes
3 Subjects
Cells & Organisation Digestion Ecosystems Atoms & Elements Chemical Reactions Acids & Bases Periodic Table Forces Energy Waves & Light Electricity Space
KS3 Science Revision

Key Concepts & Facts

Tap each unit to expand concepts, key facts, and worked examples.

๐Ÿงฌ
Biology: Cells, Organisms & Ecosystems
Q1โ€“7
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๐Ÿ”‘ Key Facts to Memorise

Animal cell โ€“ cell membrane, cytoplasm, nucleus, mitochondria.
Plant cell โ€“ all the above PLUS cell wall, chloroplasts, large vacuole.
Organ hierarchy: cells โ†’ tissues โ†’ organs โ†’ organ systems โ†’ organism.
Photosynthesis: carbon dioxide + water โ†’ glucose + oxygen (chloroplasts, light needed).
Respiration: glucose + oxygen โ†’ carbon dioxide + water + energy (mitochondria).
Enzymes are biological catalysts made of protein; they have an optimum temperature (~37 ยฐC in humans).
Food chains always begin with a producer (plant). Energy is lost at each trophic level.
Diffusion โ€“ passive movement from high to low concentration. No energy needed.
Photosynthesis: 6COโ‚‚ + 6Hโ‚‚O โ†’ Cโ‚†Hโ‚โ‚‚Oโ‚† + 6Oโ‚‚ (light + chlorophyll)
๐Ÿ“ Worked Example

Q: Why do plant cells have chloroplasts but animal cells do not?
A: Chloroplasts contain chlorophyll, which absorbs light energy for photosynthesis. Animals obtain energy by eating food, so they do not photosynthesise and do not need chloroplasts.

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Chemistry: Atoms, Reactions & the Periodic Table
Q8โ€“14
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๐Ÿ”‘ Key Facts to Memorise

Atom structure: protons & neutrons in nucleus; electrons in shells around nucleus.
Element โ€“ one type of atom. Compound โ€“ two or more elements chemically joined. Mixture โ€“ not chemically joined (can be separated).
Periodic table groups: Group 1 = alkali metals (very reactive); Group 7 = halogens; Group 0 = noble gases (unreactive).
Acid + base โ†’ salt + water (neutralisation). pH < 7 = acid; pH = 7 = neutral; pH > 7 = alkali.
Acid + metal โ†’ salt + hydrogen gas. Test: burning splint โ€“ squeaky "pop" = Hโ‚‚.
Conservation of mass: atoms are neither created nor destroyed in a reaction.
Physical change is reversible (e.g. melting). Chemical change is usually irreversible (new substance formed).
Neutralisation: acid + base โ†’ salt + water Acid + carbonate โ†’ salt + water + COโ‚‚
๐Ÿ“ Worked Example

Q: Hydrochloric acid reacts with sodium hydroxide. Name the salt produced.
A: HCl + NaOH โ†’ NaCl + Hโ‚‚O. The salt is sodium chloride (table salt). The acid provides the 'chloride' part; the metal from the base provides 'sodium'.

โšก
Physics: Forces, Energy, Waves & Electricity
Q15โ€“20
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๐Ÿ”‘ Key Facts to Memorise

Speed = distance รท time (m/s). Force = mass ร— acceleration (N). Weight = mass ร— g (g = 10 N/kg on Earth).
Balanced forces โ†’ no change in motion. Unbalanced forces โ†’ acceleration or deceleration.
Energy stores: kinetic, gravitational potential, elastic potential, thermal, chemical, nuclear.
Law of conservation of energy: energy cannot be created or destroyed, only transferred or transformed.
Waves: frequency ร— wavelength = wave speed. Transverse (light) vs longitudinal (sound).
Ohm's Law: V = I ร— R (voltage = current ร— resistance). Series circuit: current same everywhere. Parallel: voltage same across branches.
Light travels at 3 ร— 10โธ m/s in a vacuum. It travels faster in less dense media.
Speed = distance / time | v = d/t Force = mass ร— acceleration | F = ma V = I ร— R (Ohm's Law) Wave speed = frequency ร— wavelength | v = f ร— ฮป
๐Ÿ“ Worked Example

Q: A car travels 300 m in 15 seconds. What is its speed?
A: Speed = distance รท time = 300 รท 15 = 20 m/s.

Question 1 of 20
โฑ 25:00
Biology Medium
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๐ŸŽ‰
18/20
Excellent โ€“ A* Grade!
18Correct
2Incorrect
00:00Time Used
Score: 90%

๐Ÿ“‹ Full Answer Review & Explanations