Breathing, gas exchange and smoking
The dark areas on this X-ray are your lungs, full of air. Inside them, about 300 million tiny air sacs called alveoli swap oxygen for carbon dioxide with your blood, every breath. Breathing moves the air; gas exchange is the swap.
By the end of this page you can
- Compare gas exchange surfaces in fish, plants and people, and the damage smoking does
- Name the parts of the breathing system and what each does
- Put the steps of breathing in, in order
- Define ventilation, gaseous exchange and alveolus
- Explain the effects of smoking on the body
Goals tick themselves off as you try the activities below.
Photo: Mikael Häggström, CC0, via Wikimedia Commons. Side markers cropped off, resized onto black.
A normal chest X-ray. Air shows dark; bone shows white. Note the ribs and the dome of the diaphragm below the lungs.
How often it shows up in past papers
Paper 1 counts come from our past-paper bank of CSEC Biology Paper 1s. Paper 2 is not included yet.
Same rules, different organisms
Every gas exchange surface is large, thin and moist, with a supply that keeps the gases moving. Tap each card.
From nose to alveolus
Air travels down a branching tree of tubes; muscles move it in and out. Tap each part.
What does it do?
Tap a part on the list to see its job.
Breathing is not respiration: breathing moves air; respiration releases energy in cells. After hard exercise you keep panting to repay the oxygen debt and break down lactic acid.
Breathing in
Put the steps of breathing in (inhaling) in order. Drag or tap each card into its slot.
What do the muscles do first?
Seven terms to know cold
Say what each term means before you flip the card. Keep breathing and respiration apart.
Six quick questions, then a real one
Pick an answer to see why it’s right or wrong.
When you breathe in, the diaphragm
Which is NOT a feature of a gas exchange surface?
Carbon monoxide in cigarette smoke
Gases enter and leave a leaf mainly through
Why do the cilia in the trachea matter?
Emphysema reduces a person’s fitness because
exam style · 3 marks
Explain how smoking reduces a person’s ability to exercise.
Sign in to have your answer marked, or check it against the mark scheme. Sign in
Practice questions are written by My V.I.P. Academy. They are not official CXC papers.