Checkpoint: the breathing path, the chest and villi

Which part of the air path traps dust with hairs and mucus?

• The nasal passages
• The alveoli
• The windpipe

You breathe in. What does the diaphragm do?

• It stays still
• It moves up
• It moves down

The ribs move up and out. What happens to the space in the chest?

• It grows
• It stays the same
• It shrinks

Which gas passes from the blood into the air at the alveoli?

• Dust
• Oxygen
• Carbon dioxide

Why does the small intestine have finger-like villi?

• To stop the food from moving on
• To give a big surface for absorbing food
• To churn and crush the food until it is soft