Red blood cells transport oxygen around the body.
Explain how two features of a red blood cell adapt it for transporting oxygen.
The air at high altitude contains less oxygen than the air at sea level. People who live at high altitude have more red blood cells in each mm3\text{mm}^3mm3 of blood than people who live at sea level.
Explain how having more red blood cells helps these people.
A 1 mm3 sample of blood contains 5 000 000 5\,000\,000\,5000000 red blood cells.
Give this number in standard form.
42 exam-style questions on Edexcel GCSE Biology 8.2 Blood and circulation, covering 8.2.1 Structure and function of the blood, 8.2.2 Structure of blood vessels, 8.2.3 Structure of the heart and circulatory system, and 8.2.4 Cardiac output. Each one has a worked solution and a mark scheme showing where the marks go.