Cells, tissues and organ systems
Learn Cells, tissues and organ systems for Year 9 pupils (ages 13–14). Free practice questions, lessons and worked examples — aligned to the UK National Curriculum.
What you'll learn
- 1
Living things are organised in levels: cells → tissues → organs → organ systems → organism.
- 2
The heart is an organ. It contains muscle tissue to contract, nerve tissue to control the rhythm, and blood vessels to feed itself.
- 3
Which level comes directly above "tissue"?
- 4
Common error: calling blood a tissue "because it is liquid". Blood IS a tissue — a tissue is defined by cells working together, not by being solid.
- 5
Why is blood classed as a tissue?
- 6
Apply it: the lungs are an organ in the respiratory system. Alveoli give a huge surface area, are one cell thick, and are surrounded by capillaries — all three features speed up diffusion.
- 7
Why are alveoli only one cell thick?
Practise Cells, tissues and organ systems with Whizlo
Free AI-tutored lessons, unlimited practice questions, and progress tracking for ages 13–14. Aligned to the UK National Curriculum.