What makes a definition mark-worthy

IGCSE Biology definitions have specific required elements. For example, the definition of osmosis must include:

  • "net movement of water molecules"
  • "from a region of higher water potential / dilute solution"
  • "to a region of lower water potential / more concentrated solution"
  • "through a partially permeable membrane"

Missing any one of these elements means losing the mark, even if your general idea is correct.

How to learn definitions

Do not memorise full sentences: memorise the required components. Write each definition as a checklist of elements. Then practise writing the definition from memory and checking it against your list.

The syllabus glossary contains the definitions Cambridge expects. Use it as your primary reference.

Common definition mistakes

Being vague: "movement of water": missing "net", missing "through a partially permeable membrane".

Using "it": "It moves from high to low concentration": name the substance (water molecules, ions, etc.).

Confusing similar terms: mixing up diffusion, osmosis, and active transport definitions.