Circulatory System Worksheet with Answers (Grade 11 Biology)
A free printable circulatory and respiratory systems worksheet for Grade 11 biology.
This free circulatory system worksheet covers the heart, blood and blood vessels, and links them to breathing and gas exchange. Students label a colour-coded heart diagram, put the path of blood in order, and compare arteries, veins and capillaries.
The second half adds the parts of blood, cardiac output and blood pressure, the path of air into the lungs, and how the diaphragm and alveoli work. The answer key has every label, sequence, calculation and model answer.
- Grade 11 Biology
- 27 marks
- 45–60 minutes
- Full answer key
What's in This Circulatory System Worksheet
| Part | Skill practised | Marks |
|---|---|---|
| A | Label the heart (8 parts) | 4 |
| B | The path of blood and heart structure | 5 |
| C | Parts of the blood | 2 |
| D | Arteries, veins and capillaries | 3 |
| E | Cardiac output and blood pressure | 4 |
| F | Breathing and gas exchange | 7 |
| G | Spot the mistake | 2 |
It supports the Ontario Grade 11 biology curriculum expectations in the Animals: Structure and Function unit.
Parts of the Heart
The human heart has four chambers: two atria that receive blood and two ventricles that pump it out. A wall of muscle called the septum keeps oxygen-poor blood on the right side apart from oxygen-rich blood on the left. This is the diagram from Part A of the circulatory system worksheet:
1 superior vena cava · 2 aorta · 3 pulmonary artery · 4 left atrium · 5 left ventricle · 6 septum · 7 right ventricle · 8 right atrium
Blue shows deoxygenated blood and red shows oxygenated blood. Like every heart diagram, the one on this circulatory system worksheet is drawn as if you are facing the person, so the heart's left side is on your right. The thick wall of the left ventricle (part 5) is easy to compare with the thinner right ventricle (part 7).
The Path of Blood Through the Heart
Humans have a double circulation. Blood passes through the heart twice on each full trip around the body:
- Body → vena cava → right atrium
- → right ventricle → pulmonary artery → lungs (picks up oxygen)
- → pulmonary vein → left atrium → left ventricle
- → aorta → body
The left ventricle has the thickest wall because it pumps blood around the whole body. For a detailed overview, see the circulatory system on Wikipedia.
Arteries, Veins and Capillaries
| Vessel | Wall structure | Direction of flow | Key feature |
|---|---|---|---|
| Artery | Thick, muscular, elastic wall | Away from the heart | High pressure; pulses with each heartbeat |
| Vein | Thin wall, wide lumen | Toward the heart | Valves stop backflow; low pressure |
| Capillary | Wall one cell thick | From arterioles to venules | Where gases, nutrients and wastes are exchanged |
A useful rule on any circulatory system worksheet: arteries carry blood away from the heart. It's about direction, not oxygen, which is why the pulmonary artery carries deoxygenated blood.
Cardiac output (heart rate × stroke volume) shows how much blood the heart pumps each minute: 72 beats/min × 70 mL = 5.04 L/min for a typical teenager at rest. Blood type genetics are covered in the codominance and incomplete dominance worksheet.
The Respiratory System and Gas Exchange
Air travels: nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli. When the diaphragm contracts and moves down, chest volume increases and pressure drops, so air flows in. In the alveoli, oxygen diffuses into the capillaries and carbon dioxide diffuses out. Alveoli are ideal for this because they have a huge surface area, walls one cell thick, a moist lining and a dense network of capillaries.
Circulatory System Worksheet Practice Questions
These questions match the circulatory system worksheet PDF, which has the full-size heart diagram, word bank and ruled answer space.
Part A – Label the Heart
Questions 1–8: label the eight numbered parts of the heart diagram above.
Part B – The Path of Blood
Question 9: put these in order, starting from the vena cava: P right ventricle, Q aorta, R left atrium, S right atrium, T lungs, U left ventricle.
- Look at parts 5 and 7 on the diagram. Why is the wall of the left ventricle much thicker than the wall of the right ventricle?
- Name the only artery that carries deoxygenated blood, and the only vein that carries oxygenated blood.
- What is the job of the valves between the atria and the ventricles?
Part C – Parts of the Blood
Questions 13–16 of the circulatory system worksheet: match plasma, red blood cells, white blood cells and platelets to their functions.
Part D – Blood Vessels
Questions 17–19: describe the wall, direction of flow and key feature of arteries, veins and capillaries.
Part E – Heart Calculations
- Cardiac output = heart rate × stroke volume. A student’s heart rate is 72 beats/min and stroke volume is 70 mL/beat. Find the cardiac output in L/min.
- A blood pressure reading is 120/80 mmHg. What do the two numbers mean?
- A trained athlete has the same cardiac output (5.0 L/min) but a resting heart rate of only 50 beats/min. Find the stroke volume, and explain why it is larger. (2 marks)
Part F – The Respiratory System
Question 23: put these in order: P bronchioles, Q trachea, R nasal cavity, S alveoli, T larynx, U bronchi, V pharynx.
- Explain how the diaphragm causes you to inhale. (2 marks)
- Give two features of alveoli that make them good at gas exchange. (2 marks)
- Minute ventilation = tidal volume × breathing rate. Find the minute ventilation for a tidal volume of 500 mL and 12 breaths/min, in L/min.
Part G – Spot the Mistake
- A student writes: “All arteries carry oxygenated blood.” Explain the error and correct it.
- A student writes: “When you inhale, air rushes in and pushes the diaphragm down.” Explain the error and correct it.
Circulatory System Worksheet Answer Key
Open each part of the circulatory system worksheet answers to check your work. The printable key is at the end of the PDF.
Part A answers (Q1–8)
- Superior vena cava
- Aorta
- Pulmonary artery
- Left atrium
- Left ventricle
- Septum
- Right ventricle
- Right atrium
Part B answers (Q9–12)
- S (right atrium) → P (right ventricle) → T (lungs) → R (left atrium) → U (left ventricle) → Q (aorta)
- The left ventricle pumps blood to the whole body at high pressure; the right ventricle only pumps to the nearby lungs.
- Pulmonary artery (heart → lungs) and pulmonary vein (lungs → heart)
- They stop blood flowing backwards into the atria when the ventricles contract.
Part C answers (Q13–16)
- Plasma: c
- Red blood cells: b
- White blood cells: d
- Platelets: a
Part D answers (Q17–19)
- Artery: Thick, muscular, elastic wall; away from the heart; high pressure; pulses with each heartbeat
- Vein: Thin wall, wide lumen; toward the heart; valves stop backflow; low pressure
- Capillary: Wall one cell thick; from arterioles to venules; where gases, nutrients and wastes are exchanged
Part E answers (Q20–22)
- 72 × 70 = 5,040 mL/min = 5.04 L/min
- 120 = systolic pressure (ventricles contracting); 80 = diastolic pressure (heart relaxing between beats).
- 5000 ÷ 50 = 100 mL/beat. Training makes the heart muscle stronger, so it pumps more blood per beat.
Part F answers (Q23–26)
- R (nasal cavity) → V (pharynx) → T (larynx) → Q (trachea) → U (bronchi) → P (bronchioles) → S (alveoli)
- The diaphragm contracts and moves down (and the rib muscles lift the ribs), so chest volume increases and air pressure in the lungs drops below outside pressure. Air flows in.
- Any two: huge total surface area; walls one cell thick; moist lining; surrounded by many capillaries.
- 500 × 12 = 6,000 mL/min = 6.0 L/min
Part G answers (Q27–28)
- Arteries carry blood away from the heart. The pulmonary artery carries deoxygenated blood to the lungs.
- It is the other way around: the diaphragm contracts first, lowering lung pressure, and then air flows in.
5 Common Circulatory System Mistakes
- Mixing up left and right on the diagram. The heart's left side is on the viewer's right.
- "Arteries carry oxygenated blood." Arteries carry blood away from the heart; the pulmonary artery is deoxygenated.
- Skipping the lungs. Blood from the right ventricle goes to the lungs before it reaches the left side.
- Mixing up stroke volume and cardiac output. Stroke volume is per beat; cardiac output is per minute.
- Getting breathing backwards. The diaphragm moves first; air flows in because of the pressure drop.
How to Use This Circulatory System Worksheet in Class
- Lesson 1: Parts A–D, ideally alongside a heart dissection or 3D model.
- Lesson 2: Parts E–G of the circulatory system worksheet. Have students measure their own pulse to calculate cardiac output.
- Lab link: Measure breathing rate at rest and after exercise to calculate minute ventilation.
For review, use the circulatory system quiz and the respiratory system quiz. To see what cells do with the oxygen, try the cellular respiration quiz.
Frequently Asked Questions
Is this circulatory system worksheet free?
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
What is the path of blood through the heart?
Body → vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta → body.
Why is the left side of the heart drawn on the right?
Heart diagrams are drawn as if you are facing the person, so the heart's left side appears on your right.
How are the circulatory and respiratory systems connected?
The respiratory system brings oxygen into the alveoli, where it diffuses into capillaries. The circulatory system then carries that oxygen to every cell and brings carbon dioxide back to the lungs to be exhaled.
What grade is this circulatory system worksheet for?
It is written for Grade 11 biology (the Animals: Structure and Function unit) and also works for Grades 9–10 review.
More Free Grade 11 Biology Resources
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