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Building Blocks

From a single cell to a whole organism: the levels of organisation — with a real named example at every step.

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What you'll cover

Building Blocks 🧱

A single cell is tiny — yet a whole human is built from trillions of them, organised into **levels**. This module climbs that ladder: **cell → tissue → organ → organ system → organism** — and, the bit that wins marks, a **real named example** at every rung.

Cells and tissues 🔬

**Cells** are the basic building blocks of all living things. A **tissue** is a group of cells with **similar structure and function**, working together. For example, **muscular tissue** is made of many muscle cells that contract together.

Organs, systems and organisms 🫀

Climb higher: • An **organ** is a group of **different tissues** working together to perform a **specific function** (the stomach, the heart). • An **organ system** is a group of **organs** working together (the digestive system). • Organ systems work together to make a whole **organism** (a human).

Climb the ladder

An interactive activity.

Match the definitions

  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
  • The basic building block of living things
  • A group of cells with similar structure and function
  • Different tissues working together for a function
  • A group of organs working together
  • All the organ systems working together

Define a tissue

Which is the best definition of a **tissue**?

  • A group of cells with similar structure and function
  • A group of different tissues working together
  • A single specialised cell
  • A group of organs working together

A real example: digestion 🍽️

Abstract chains lose marks — examiners want a **named example at each level**. Follow one up the digestive system: • **Cell** — a gland cell that makes enzymes • **Tissue** — glandular tissue • **Organ** — the stomach (muscular + glandular + epithelial tissue) • **Organ system** — the digestive system • **Organism** — a human

Name it at each level

  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
  • A gland cell that makes enzymes
  • Glandular tissue
  • The stomach
  • The digestive system
  • A human

What level is it?

The stomach is made of muscular tissue, glandular tissue and epithelial tissue all working together. What level of organisation is the stomach?

  • An organ
  • A tissue
  • An organ system
  • A cell

Complete the chain

Similar cells form a _____; different tissues form an _____; a group of organs forms an organ _____.

tissue organ system cell

In the exam 🎓

Ladder climbed. Grade-9 habits for organisation: • Know the order cold: **cell → tissue → organ → organ system → organism**. • Get the definitions precise — a **tissue** is *similar* cells; an **organ** is *different* tissues. • Always give a **named example at every level** (gland cell → glandular tissue → stomach → digestive system → human), not just the abstract chain.