9.1

Circulatory systems

Cambridge IGCSE Biology (0610)  · Unit 9: Transport in animals  · 11 flashcards

Circulatory systems is topic 9.1 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 9 — Transport in animals , alongside Heart, Blood vessels and Blood.  In one line: The primary function is to transport substances (oxygen, nutrients, hormones, waste) throughout the body.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).

The deck below contains 11 flashcards — 3 definitions, 5 key concepts and 3 process cards — covering the precise wording mark schemes reward.  Use the 3 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

The primary function of a circulatory system

The primary function is to transport substances (oxygen, nutrients, hormones, waste) throughout the body.

Example: the circulatory system transports oxygen from the lungs to muscle cells for respiration.

What the Cambridge 0610 syllabus says

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. Describe Describe the circulatory system as a system of blood vessels with a pump and valves to ensure one-way flow of blood
  2. Describe Describe the single circulation of a fish Supplement
  3. Describe Describe the double circulation of a mammal Supplement
  4. Explain Explain the advantages of a double circulation Supplement
Definition Flip

What is the primary function of a circulatory system?

Answer Flip

The primary function is to transport substances (oxygen, nutrients, hormones, waste) throughout the body.

Example: the circulatory system transports oxygen from the lungs to muscle cells for respiration.
Key Concept Flip

Describe the basic components of a circulatory system.

Answer Flip

A circulatory system consists of blood vessels (arteries, veins, capillaries), a pump (the heart), and valves. Valves ensure blood flows in one direction to prevent backflow, like in the veins of the human leg.

Definition Flip

What is single circulation?

Answer Flip

Single circulation is a circulatory system where blood passes through the heart only once in each complete circuit of the body. An example is seen in fish, where blood flows from the heart to the gills, then to the body, and back to the heart.

Key Concept Flip

Describe the pathway of blood in a fish's single circulatory system.

Answer Flip

Blood flows from the heart to the gills where it picks up oxygen, then to the body to deliver oxygen to cells, and back to the heart. This is a less efficient system for delivering oxygen to active tissues.

Definition Flip

What is double circulation?

Answer Flip

Double circulation is a circulatory system where blood passes through the heart twice in each complete circuit of the body. Mammals, like humans, have this system.

Key Concept Flip

Describe the two circuits in a mammal's double circulatory system.

Answer Flip

The two circuits are the pulmonary circuit (heart to lungs and back) and the systemic circuit (heart to body and back). The pulmonary circuit oxygenates the blood and the systemic circuit delivers oxygen to the body's tissues.

Key Concept Flip

What are the advantages of a double circulatory system?

Answer Flip

Double circulation allows for higher blood pressure and more efficient oxygen delivery to tissues. The heart pumps blood twice, increasing pressure after the pulmonary circuit, crucial for active organisms like mammals.

Key Concept Flip

Explain how valves ensure one-way flow of blood in the heart.

Answer Flip

Valves open and close in response to pressure changes in the heart chambers.

Example: the atrioventricular valves (between atria and ventricles) prevent backflow of blood into the atria when the ventricles contract.
Key Concept Flip

Where does the pulmonary artery transport blood to?

Answer Flip

The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs. This is part of the pulmonary circulation, where blood gets oxygenated.

Key Concept Flip

Where does the pulmonary vein transport blood to?

Answer Flip

The pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart. This completes the pulmonary circulation, returning oxygen-rich blood to the heart.

Key Concept Flip

Explain the role of the aorta in the circulatory system.

Answer Flip

The aorta is the largest artery in the body and carries oxygenated blood from the left ventricle to the systemic circulation. It branches into smaller arteries that supply blood to all parts of the body, such as the brain and muscles.

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Key Questions: Circulatory systems

What is the primary function of a circulatory system?

The primary function is to transport substances (oxygen, nutrients, hormones, waste) throughout the body.

Example: the circulatory system transports oxygen from the lungs to muscle cells for respiration.
What is single circulation?

Single circulation is a circulatory system where blood passes through the heart only once in each complete circuit of the body. An example is seen in fish, where blood flows from the heart to the gills, then to the body, and back to the heart.

What is double circulation?

Double circulation is a circulatory system where blood passes through the heart twice in each complete circuit of the body. Mammals, like humans, have this system.

More topics in Unit 9 — Transport in animals

Circulatory systems sits alongside these Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0610 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

circulatory system blood heart blood vessel artery vein capillary double circulation pulmonary systemic oxygenated deoxygenated

Key terms covered in this Circulatory systems deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

The primary function of a circulatory system
Single circulation
Double circulation

Related Biology guides

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