Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want movement in and out of cells — diffusion, osmosis and active transport — to become reliable marks instead of definitions they blur together.
What query it owns: how to understand and revise movement in and out of cells in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the movement revision-guide angle, while Tutopiya’s Movement In and Out of Cells subtopic page owns the learning resource and the free Movement quiz owns the practice.

Movement in and out of cells covers the three main ways substances cross cell membranes: diffusion, osmosis and active transport. Cambridge IGCSE Coordinated Science (0654) tests whether you can define each process precisely, explain where they happen in living organisms, and distinguish passive from energy-requiring movement. This guide covers the syllabus definitions, the factors that change rate, and the question types that appear every year.

Key takeaways

• Diffusion is the net movement of particles from high to low concentration — passive, no energy from respiration.
• Osmosis is the net movement of water molecules through a partially permeable membrane — a special case of diffusion.
• Active transport moves substances against a concentration gradient using energy from respiration.
• Rate of diffusion increases with higher temperature, greater concentration difference, larger surface area and shorter distance.
• Exam answers must name what is moving and which direction relative to concentration.

What is movement in and out of cells in Cambridge IGCSE Coordinated Science?

Cells need to take in nutrients and oxygen and remove waste products. Small molecules cross the cell membrane by diffusion (e.g. oxygen into blood at the lungs). Water crosses by osmosis (e.g. water into root hair cells). Ions and glucose can be absorbed against a gradient by active transport (e.g. in the small intestine). Each process has a precise syllabus definition that examiners reward.

You can read the full explanation, worked examples and notes on Tutopiya’s Movement In and Out of Cells subtopic page before you attempt questions.

The three processes you must master

Process	What moves	Direction	Energy needed?
Diffusion	Dissolved substances or gases	High → low concentration	No (passive)
Osmosis	Water molecules only	High → low water potential (dilute → concentrated)	No (passive)
Active transport	Ions, glucose, amino acids	Low → high concentration (against gradient)	Yes (from respiration)

Factors affecting the rate of diffusion

Factor	Effect on rate	Biological example
Temperature	Higher temperature → faster (more kinetic energy)	Warm water vs cold water
Concentration difference	Steeper gradient → faster	Oxygen into blood at lungs
Surface area	Larger area → faster net movement	Alveoli, root hair cells
Distance	Shorter distance → faster	Thin walls of capillaries

Movement in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical movement stem
Define	Precise syllabus definition	”Define the term diffusion.”
State	Short factual answer	”State the direction of net movement.”
Explain	Cause and effect	”Explain how oxygen reaches muscle cells.”
Describe	What happens, step by step	”Describe what happens to a plant cell in strong salt solution.”
Compare	Similarities and differences	”Compare diffusion and active transport.”

Worked exam-style stems (how to answer the wording)

1. “Define the term diffusion.” Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. Mark-scheme reward: net movement, higher to lower concentration.
2. “Explain how oxygen moves from the air in the alveoli into the blood.” Oxygen concentration is higher in the alveolar air than in the blood → net movement down the concentration gradient across the thin alveolar wall. Reward: named locations + gradient direction.
3. “Compare diffusion and active transport.” Both involve movement across membranes; diffusion is passive (down a gradient); active transport requires energy from respiration and moves substances against a gradient. Reward: energy + direction for both.

When you can recognise the wording instantly, work the full set on the Movement In and Out of Cells quiz to lock the definitions in.

How movement connects to the rest of Coordinated Science biology

Movement sits after Cell Structure (the membrane that substances cross) and underpins gas exchange, absorption in the Alimentary Canal, and water uptake in Plant Nutrition. The Cambridge IGCSE Coordinated Science resource hub links every Cells subtopic.

Common mistakes students make

• Defining diffusion as “movement” without net movement or concentration gradient.
• Describing osmosis when the question asks about dissolved glucose or oxygen.
• Saying diffusion requires energy from respiration (that is active transport).
• Ignoring surface area adaptations in explain questions.
• Using “high to low pressure” instead of concentration.

When you need more support

If movement questions keep costing marks — especially compare questions — work through the Movement In and Out of Cells quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is movement in and out of cells hard in Coordinated Science? The ideas are simple, but marks are lost when students blur diffusion with osmosis or omit net movement in definitions.

What is the difference between diffusion and osmosis? Diffusion is net movement of any particles down a concentration gradient; osmosis is the net movement of water molecules through a partially permeable membrane.

Does diffusion need energy? No — it is passive. Active transport moves substances against a gradient and requires energy from respiration.

How do I revise movement effectively? Read the subtopic notes, practise definitions from memory, compare all three processes in a table, then take the Movement quiz.

Ready to master Cambridge IGCSE Coordinated Science movement?

Start with the Movement In and Out of Cells subtopic page, then book a free trial with a Cambridge IGCSE Coordinated Science specialist to turn diffusion, osmosis and active transport into guaranteed marks.

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