The Heart and Blood Vessels
Recap The Heart and Blood Vessels for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Remember the heart is a double pump, and that arteries carry blood away from the heart, veins carry it back, and capillaries allow exchange with tissues.
Free downloads
These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
The heart is a double pump made of muscle, pumping blood twice around the body in a double circulatory system. One circuit carries blood to the lungs and back; the other carries it to the rest of the body and back.
The right side receives deoxygenated blood from the body and pumps it to the lungs. The left side receives oxygenated blood from the lungs and pumps it around the body. The left ventricle has a thicker muscular wall because it must generate enough pressure to reach the whole body.
Three vessel types serve the system. Arteries carry blood away from the heart under high pressure and have thick elastic walls. Veins carry blood back at low pressure and contain valves. Capillaries are one cell thick, allowing substances to diffuse into and out of the blood.
Revision notes
The double circulatory system
Blood passes through the heart twice for each complete circuit of the body.
The right side pumps deoxygenated blood to the lungs; the left side pumps oxygenated blood to the body. This keeps oxygenated and deoxygenated blood separate and maintains high pressure to the body.
Structure of the heart
The four chambers are the right and left atria (upper) and the right and left ventricles (lower).
The left ventricle wall is thicker because it must pump blood at high pressure all around the body, whereas the right ventricle only pumps to the lungs. Valves prevent backflow.
The blood vessels
Arteries: thick muscular and elastic walls, narrow lumen, carry blood away from the heart at high pressure.
Veins: thinner walls, wider lumen, valves to prevent backflow, carry blood towards the heart at low pressure. Capillaries: one cell thick for short diffusion distance.
Key points
- The heart is a double pump.
- The right side pumps blood to the lungs.
- The left side pumps blood around the body.
- The left ventricle has a thicker wall to generate higher pressure.
- Arteries carry blood away from the heart; veins carry it back.
- Capillaries are one cell thick for efficient exchange.
Worked examples
Example 1
Explain why the wall of the left ventricle is thicker than that of the right ventricle. [2 marks]
Model answer
The left ventricle pumps blood all around the body, whereas the right ventricle only pumps to the lungs (1 mark). It therefore needs a thicker muscular wall to contract more powerfully and generate the higher pressure required (1 mark).
Example 2
Explain why veins contain valves but arteries do not. [2 marks]
Model answer
Blood in the veins is at low pressure (1 mark), so valves are needed to prevent it flowing backwards; blood in arteries is at high pressure and flows in one direction without assistance (1 mark).
Example 3
Describe how capillaries are adapted for the exchange of substances. [2 marks]
Model answer
Their walls are only one cell thick, giving a very short diffusion path (1 mark). They also form dense networks, giving a large surface area for exchange (1 mark).
Common mistakes
Saying arteries carry oxygenated blood.
Usually true, but the pulmonary artery carries deoxygenated blood. Define arteries by direction, not oxygen content.
Confusing atria and ventricles.
Atria are the upper chambers receiving blood; ventricles are the lower chambers pumping it out.
Saying the left ventricle is bigger because it holds more blood.
Both ventricles hold a similar volume. The wall is thicker to generate higher pressure.
Forgetting valves in veins.
They are a key adaptation and frequently examined.
Exam tips
- Define arteries and veins by direction of flow, not oxygen content.
- Link wall thickness to the pressure required.
- Learn the four chambers and which side handles which blood.
- Use short diffusion path when describing capillaries.
Key terms
- Atrium
- An upper chamber of the heart receiving blood.
- Ventricle
- A lower chamber of the heart pumping blood out.
- Double circulatory system
- A system in which blood passes through the heart twice per circuit.
- Lumen
- The internal space within a blood vessel.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.