The principles of organisation

Cells are the basic building blocks of all living organisms.

Prokaryotic organisms (e.g., bacteria) are made of just one cell.

Eukaryotic organisms:

• Some are single-celled (e.g., yeast and some algae).

• Many are multicellular, with cells working together.

Organisation in multicellular organisms

Specialised Cells:

• In multicellular organisms, cells often specialise for specific functions.

• Examples:

  • Epithelial cells: Line the lungs.

  • Palisade cells: Found in plant leaves for photosynthesis.

Tissues:

• A group of cells with similar structure and function.

• Examples:

  • Muscle tissue in animals.

  • Xylem tissue in plants (for water transport).

Organs:

• Aggregations (groups) of tissues performing specific functions.

• Examples:

  • Lungs: For gas exchange in animals.

  • Leaves: For photosynthesis in plants.

Organ Systems:

• Groups of organs working together to perform complex functions.

• Examples:

  • Digestive system: Includes the stomach, intestines, and liver, working together to digest and absorb food.

  • Plant transport system: Includes roots, stem, and leaves for moving water, minerals, and sugars.

Organisation in a typical plant

Additional maths skills