IGCSE Biology glossary
Red blood cell
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Definition
A biconcave disc-shaped blood cell that contains haemoglobin and transports oxygen from the lungs to body tissues. Red blood cells have no nucleus, which maximises space for haemoglobin, and their biconcave shape increases surface area for oxygen absorption.
What to include in an exam answer
Three adaptations for carrying oxygen: biconcave disc shape (large surface area), no nucleus (more space for haemoglobin), contains haemoglobin (binds to oxygen). These three points appear repeatedly.
Example in context
Explain two ways in which red blood cells are adapted to carry oxygen (2 marks): They contain haemoglobin which binds reversibly to oxygen. They have a biconcave disc shape which gives a large surface area to volume ratio for faster oxygen absorption.
Related syllabus topic
Transport in animals