Who this is for: Cambridge IGCSE Biology (0610) students who want blood composition — plasma, red cells, white cells and platelets — to become reliable marks instead of a vague “carries things around the body” answer.
What query it owns: how to understand and revise blood in Cambridge IGCSE Biology.
Why this is safe: this page owns the blood revision-guide angle, while Tutopiya’s Blood subtopic page owns the learning resource and the free Blood quiz owns the practice.

Blood is a tissue that transports substances around the body. Cambridge IGCSE Biology (0610) tests whether you can name each component, state its function, and link structure to role — especially red blood cells and their adaptations. This guide covers the syllabus definitions, comparison tables, and the question types that appear every year in Transport in Animals.

Key takeaways

• Blood consists of plasma, red blood cells, white blood cells and platelets — each with a distinct function.
• Red blood cells transport oxygen; adaptations include haemoglobin, no nucleus, biconcave shape.
• White blood cells defend against pathogens; platelets initiate blood clotting.
• Plasma is the liquid that carries dissolved food, CO₂, urea, hormones and heat.
• Exam answers must match component to function — not generic “transport”.

What is blood in Cambridge IGCSE Biology?

Blood is a liquid connective tissue made of cells suspended in plasma. It transports oxygen and carbon dioxide, dissolved nutrients, hormones, urea, antibodies and heat, and plays a role in defence and clotting. In living organisms, blood links gas exchange, digestion and excretion through the circulatory system.

You can read the full explanation, diagrams and notes on Tutopiya’s Blood subtopic page before you attempt questions.

The core components you must master

Component	Structure highlight	Main function
Plasma	Straw-coloured liquid (~55% of blood)	Transports dissolved substances, heat
Red blood cells (erythrocytes)	Biconcave, no nucleus, haemoglobin	Carry oxygen to tissues
White blood cells (phagocytes, lymphocytes)	Larger, have nucleus	Phagocytosis, antibody production
Platelets	Cell fragments	Blood clotting at wounds

Red blood cell adaptations — the high-mark table

Adaptation	How it helps
Haemoglobin	Binds oxygen in lungs, releases in tissues
No nucleus	More space for haemoglobin
Biconcave disc shape	Large surface area for gas exchange
Small size	Fits through narrow capillaries

Blood in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical blood stem
State	Short factual answer	”State the function of platelets.”
Describe	Structure or adaptations	”Describe red blood cells.”
Explain	Link structure to function	”Explain how red blood cells are adapted.”
Compare	Two components contrasted	”Compare red and white blood cells.”
Name	Identify component	”Name the blood component that carries oxygen.”

Worked exam-style stems (how to answer the wording)

1. “State the function of plasma.” Plasma transports dissolved food molecules, carbon dioxide, urea, hormones and heat around the body. Mark-scheme reward: named dissolved substances, not just “liquid”.
2. “Describe how red blood cells are adapted to carry oxygen.” Biconcave shape increases surface area; no nucleus allows more haemoglobin; haemoglobin binds oxygen in lungs and releases it in tissues. Reward: adaptation linked to function.
3. “Compare red blood cells and white blood cells.” Red cells: no nucleus, biconcave, carry oxygen. White cells: have nucleus, larger, defend against disease. Reward: structure and function contrasted.

When you can recognise the wording instantly, work the full set on Transport in Animals topical past paper questions and the Blood quiz to lock the definitions in.

How blood connects to the rest of the syllabus

Blood sits at the centre of Transport in Animals — it flows through arteries, veins and capillaries pumped by the heart. It links to gas exchange (oxygen carriage), digestion (glucose transport) and Diseases and Immunity. Use Blood flashcards for active recall.

Common mistakes students make

• Saying red blood cells “contain oxygen” instead of haemoglobin binds oxygen.
• Confusing platelets with white blood cells (clotting vs defence).
• Describing plasma as “just water” — it carries many dissolved substances.
• Forgetting no nucleus as a red blood cell adaptation.
• Mixing up phagocytes and lymphocytes functions.

When you need more support

If blood component questions keep costing marks — especially compare and explain stems — work through Transport in Animals topical past paper questions and the Blood quiz, then get focused help from a Cambridge IGCSE Biology tutor.

Frequently asked questions

Is blood hard in Cambridge IGCSE Biology? The components are straightforward, but marks are lost when students blur functions or omit adaptations in explain answers.

What is the difference between red and white blood cells? Red cells carry oxygen (haemoglobin, no nucleus); white cells defend against pathogens (have nucleus, larger).

Do platelets carry oxygen? No — platelets are involved in blood clotting at wound sites.

How do I revise blood effectively? Read the subtopic notes, learn the component table, practise adaptations from memory, then take the Blood quiz.

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