Building Blocks
From a single cell to a whole organism: the levels of organisation, with a real named example at every step.
Get the method right under pressure
Free interactive practice on the steps that lose marks under exam pressure.
Start revising freeWhat 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.
The five levels
Each rung of the ladder has a definition the examiner wants word for word:
Climb the ladder
Put the levels of organisation in order, from the smallest building block to the whole living thing.
- Cell
- Tissue
- Organ
- Organ system
- Organism
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 _____.
Climb a new ladder
Nobody has shown you the circulatory system in this module. Place three of its parts on the same ladder, using the definitions rather than a memorised chain.
- Cardiac muscle is made of many similar cells that contract together. Which level is it?
- The heart is built from muscular, nervous and epithelial tissue, working together to pump blood. Which level is it?
- The heart, the blood vessels and the blood work together to move substances around the body. Which level is that?
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.