A laboratory measures the red blood cells in samples of blood from three people.
| Person | Number of red blood cells per mm³ of blood | Mean mass of haemoglobin in each red blood cell in pg |
|---|---|---|
| A | 3.8 × 10⁶ | 30 |
| B | 5.2 × 10⁶ | 20 |
| C | 4.2 × 10⁶ | 22 |
Which person is likely to have the least oxygen carried to their respiring cells, and why?
Person B, because each of their red blood cells contains the least haemoglobin
Person A, because they have the fewest red blood cells
Person B, because they have the most red blood cells, leaving less plasma to carry oxygen
Person C, because their blood contains the least haemoglobin per mm³
304 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.