A free printable respiratory system worksheet for Grade 11 biology.
This free respiratory system worksheet follows a breath of air from the nose to the alveoli and back out again. Students label ten parts of the respiratory system, compare what the diaphragm and rib cage do when inhaling and exhaling, and explain why exhaled air has less oxygen and more carbon dioxide.
They then read a spirometer graph to find tidal volume, vital capacity, breathing rate and minute ventilation, trace an oxygen molecule into a red blood cell, and match four respiratory disorders to their causes.
| Part | Skill practised | Marks |
|---|---|---|
| A | Label the respiratory system (10 parts) | 5 |
| B | Inhaling vs exhaling | 4 |
| C | Inhaled vs exhaled air | 4 |
| D | Reading a spirometer graph | 5 |
| E | Gas exchange | 4 |
| F | Respiratory disorders | 2 |
| G | Spot the mistake | 2 |
It supports the Ontario Grade 11 biology curriculum expectations in the Animals: Structure and Function unit.
Air enters through the nasal cavity, where it is warmed, moistened and filtered, then passes the pharynx and larynx. The epiglottis folds over the larynx when you swallow so food goes down the esophagus instead. The trachea, held open by C-shaped rings of cartilage, splits into two bronchi, which branch into thousands of bronchioles and end at the alveoli. Part A of the respiratory system worksheet asks students to label all ten structures. For more detail, see the respiratory system on Wikipedia.
| Feature | Inhaling | Exhaling |
|---|---|---|
| Diaphragm | Contracts and flattens (moves down) | Relaxes and domes up |
| Rib cage (intercostal muscles) | Moves up and out | Moves down and in |
| Volume of the chest cavity | Increases | Decreases |
| Air pressure in the lungs | Drops below outside air pressure | Rises above outside air pressure |
On a respiratory system worksheet, breathing is all about pressure. The lungs have no muscles of their own, so the diaphragm and intercostal muscles change the size of the chest. A bigger chest means lower pressure inside the lungs, and air rushes in. Part C of the respiratory system worksheet then compares the air going in and out:
| Gas | Inhaled air | Exhaled air |
|---|---|---|
| Oxygen | 21% | 16% |
| Carbon dioxide | 0.04% | 4% |
| Nitrogen | 78% | 78% |
Exhaled air has less oxygen because some diffuses into the blood, and far more carbon dioxide because cells release it during cellular respiration. Only about 24% of the oxygen in each breath is absorbed.
A spirometer records how much air moves in and out of the lungs. In the graph from Part D of the respiratory system worksheet, a student breathes normally, then takes the deepest breath in and out that they can:
Each normal breath moves 0.5 L of air (the tidal volume). The deepest breath in reaches 6 L and the deepest breath out drops to 1.5 L, so the vital capacity is 4.5 L. The 1.5 L that can never be breathed out is the residual volume, which keeps the alveoli open. With 5 breaths in 20 seconds, the breathing rate is 15 breaths per minute, so minute ventilation is 0.5 × 15 = 7.5 L/min.
About 480 million alveoli give the lungs a surface area of roughly 70 m². Their walls are one cell thick, moist and wrapped in capillaries, so oxygen diffuses into the blood and carbon dioxide diffuses out. That oxygen then travels around the body, which is covered in the circulatory system worksheet. Damage to any part of the system affects breathing:
| Disorder | What happens |
|---|---|
| Asthma | Airways become inflamed and narrow, causing wheezing |
| Emphysema | Alveolus walls break down, so the lungs have less surface area |
| Pneumonia | Alveoli fill with fluid because of a bacterial or viral infection |
| Lung cancer | Uncontrolled cell growth in lung tissue, strongly linked to smoking |
Part F of the respiratory system worksheet matches these four disorders. Emphysema shows why surface area matters: as the alveolus walls break down, there is less area for diffusion, and people feel short of breath even at rest.
These questions match the respiratory system worksheet PDF, which has the full-size diagram, tables, spirometer graph and ruled answer space.
Questions 1–10: label the ten numbered parts of the diagram above.
Questions 11–14: complete what the diaphragm, rib cage, chest volume and lung pressure do during each phase.
Open each part of the respiratory system worksheet answers to check your work. The printable key is at the end of the PDF.
Review with the cellular respiration quiz, which explains what cells do with the oxygen.
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
Air travels through the nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles, and finally reaches the alveoli, where gas exchange happens.
When the diaphragm contracts, it flattens and moves down, making the chest cavity larger. Pressure in the lungs drops below outside air pressure, so air flows in. When it relaxes, the chest gets smaller and air is pushed out.
Tidal volume is the air moved in a normal breath, about 0.5 L. Vital capacity is the most air you can breathe out after the deepest possible breath in, usually 4 to 5 L in an adult.
Only part of the oxygen in each breath diffuses into the blood. Exhaled air still contains about 16% oxygen, which is why rescue breathing works.
Ready to start? Download the free respiratory system worksheet PDF (use the Download button above), print it double-sided and keep the key for marking.