9.4

Blood

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

Blood is topic 9.4 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 9 — Transport in animals , alongside Circulatory systems, Heart and Blood vessels.  In one line: The components of blood are: red blood cells, white blood cells, platelets, and plasma. Plasma makes up the majority of blood volume, carrying cells and other substances.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical). Past papers from 2022 to 2025 show this topic across 13 questions worth 186 marks (around 2.8% of all Biology marks in those years).

The deck below contains 11 flashcards — 2 definitions, 7 key concepts and 2 process cards — covering the precise wording mark schemes reward.  Use the 2 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

List the four main components of blood

The components of blood are: red blood cells, white blood cells, platelets, and plasma. Plasma makes up the majority of blood volume, carrying cells and other substances.

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. List List the components of blood as: red blood cells, white blood cells, platelets and plasma
  2. Identify Identify red and white blood cells in photomicrographs and diagrams
  3. State State the functions of the following components of blood: (a) red blood cells in transporting oxygen, including the role of haemoglobin (b) white blood cells in phagocytosis and antibody production (c) platelets in clotting (details are not required) (d) plasma in the transport of blood cells, ions, nutrients, urea, hormones and carbon dioxide
  4. State State the roles of blood clotting as preventing blood loss and the entry of pathogens
  5. Identify Identify lymphocytes and phagocytes in photomicrographs and diagrams Supplement
  6. State State the functions of: (a) lymphocytes – antibody production (b) phagocytes – engulfing pathogens by phagocytosis Supplement
  7. Describe Describe the process of clotting as the conversion of fibrinogen to fibrin to form a mesh Supplement
Definition Flip

List the four main components of blood.

Answer Flip

The components of blood are: red blood cells, white blood cells, platelets, and plasma. Plasma makes up the majority of blood volume, carrying cells and other substances.

Key Concept Flip

What is the primary function of red blood cells?

Answer Flip

The main function of red blood cells is to transport oxygen from the lungs to all respiring cells in the body. They contain haemoglobin, which binds to oxygen.

Example: Oxygen binds to haemoglobin in the lungs to form oxyhemoglobin.
Key Concept Flip

Describe the role of white blood cells in the immune system.

Answer Flip

White blood cells defend the body against pathogens. Some, like phagocytes, engulf pathogens by phagocytosis, while others, like lymphocytes, produce antibodies that target specific pathogens.

Example: Lymphocytes produce antibodies against the measles virus.
Key Concept Flip

What is the function of platelets in the blood?

Answer Flip

Platelets are responsible for blood clotting, which prevents blood loss and the entry of pathogens into the body. They initiate the cascade that forms a blood clot when a blood vessel is damaged.

Key Concept Flip

Describe the role of plasma in the blood.

Answer Flip

Plasma is the liquid component of blood and transports various substances, including blood cells, ions, nutrients (e.g., glucose, amino acids), urea (waste product), hormones (e.g., insulin), and carbon dioxide.

Example: Plasma transports glucose from the small intestine to liver cells.
Key Concept Flip

What are the two main roles of blood clotting?

Answer Flip

Blood clotting prevents excessive blood loss from damaged blood vessels and prevents the entry of pathogens into the body through open wounds.

Example: Clotting prevents blood loss when a cut occurs on the skin.
Key Concept Flip

Describe the function of lymphocytes in antibody production.

Answer Flip

Lymphocytes are a type of white blood cell that produces antibodies. These antibodies are specific to particular antigens found on pathogens, marking them for destruction or neutralizing them.

Example: B-lymphocytes produce antibodies to neutralize the tetanus toxin.
Key Concept Flip

Explain the process of phagocytosis carried out by phagocytes.

Answer Flip

Phagocytosis is the process by which phagocytes engulf and digest pathogens, cellular debris, and foreign particles. The phagocyte extends its cytoplasm to surround and internalize the particle into a vacuole, where it is then broken down by enzymes.

Example: Macrophages in the lungs engulf dust particles.
Key Concept Flip

Outline the process of blood clotting, including the role of fibrinogen.

Answer Flip

Blood clotting begins with platelet activation at the site of injury. This triggers a cascade where soluble fibrinogen is converted into insoluble fibrin. Fibrin forms a mesh that traps blood cells and platelets, forming a clot.

Example: A cut triggers the conversion of fibrinogen to fibrin to stop bleeding.
Key Concept Flip

How does haemoglobin contribute to oxygen transport in the blood?

Answer Flip

Haemoglobin, found in red blood cells, contains iron and binds reversibly to oxygen. It loads oxygen in the lungs, forming oxyhaemoglobin, and then releases oxygen to respiring tissues throughout the body, where oxygen concentration is lower.

Example: Haemoglobin binds to oxygen in capillaries surrounding alveoli.
Definition Flip

State some substances transported by the plasma, besides blood cells.

Answer Flip

Besides blood cells, plasma transports ions (e.g., sodium, potassium), nutrients (e.g., glucose, amino acids), waste products (e.g., urea), hormones (e.g., insulin), and carbon dioxide. These substances are essential for maintaining homeostasis and supporting cellular functions throughout the body.

Example: Hormones are transported from glands to target tissues.

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9.3 Blood vessels 10.1 Diseases and immunity

Key Questions: Blood

List the four main components of blood.

The components of blood are: red blood cells, white blood cells, platelets, and plasma. Plasma makes up the majority of blood volume, carrying cells and other substances.

State some substances transported by the plasma, besides blood cells.

Besides blood cells, plasma transports ions (e.g., sodium, potassium), nutrients (e.g., glucose, amino acids), waste products (e.g., urea), hormones (e.g., insulin), and carbon dioxide. These substances are essential for maintaining homeostasis and supporting cellular functions throughout the body.

Example: Hormones are transported from glands to target tissues.

Tips to avoid common mistakes in Blood

More topics in Unit 9 — Transport in animals

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

9.1 Circulatory systems

11 flashcards
9.2 Heart

12 flashcards
9.3 Blood vessels

12 flashcards

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.

blood red blood cell white blood cell platelet plasma haemoglobin oxygen carbon dioxide phagocyte lymphocyte antibody clotting fibrin biconcave

Key terms covered in this Blood 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.

List the four main components of blood
Some substances transported by the plasma, besides blood cells

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How to study this Blood deck

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