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S4 Biology: Human Transport System (Paper 3)
S4 Biology: Human Transport System (Paper 3)
The third paper links transport to health: anaemia, white cell and platelet function, blood groups, donation volume and oxygen carriage during exercise.
Direct answer Compare any blood value with its normal range before judging, and for blood groups remember cells carry the antigen while plasma carries the opposite antibody.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: S4 Biology: Human Transport System |
| Level | Four basic, three advanced, two challenge and one error-repair item |
02 Questions (10 items)
- FoundationA long-term lack of iron in the diet most likely causes which condition?
- FoundationWhat is the main function of white blood cells?
- FoundationWhat do platelets do in the body?
- FoundationA person with group A blood has which antigen and which antibody?
- IntermediateNormal adult male haemoglobin is about 13 to 18 g/dL. What does a result of 8 g/dL indicate?
- IntermediateAn adult holds about 5 litres of blood. What percentage is a 450 mL donation?
- IntermediateNormal platelets are about 150 000 to 400 000 per mm3. What risk comes with a count of 50 000?
- ChallengeHaemoglobin is 15 g/dL and each gram binds 1.34 mL of oxygen. How much oxygen can 100 mL of blood carry?
- ChallengeDuring hard exercise cardiac output can rise from 5 to 20 litres a minute. What is the increase and how is it achieved?
- Error redoA student says white cells carry oxygen to muscles. What actually carries oxygen, and what do white cells do?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Iron-deficiency anaemia | Iron is part of haemoglobin, so a shortage lowers haemoglobin and the blood carries less oxygen. |
| 2 | Defence against pathogens, by engulfing microbes or making antibodies | White cells squeeze out of capillaries to infection sites, and a raised count usually signals a fight against infection. |
| 3 | They cause clotting to seal damaged blood vessels | Platelets stick to the damaged wall and trigger the clotting cascade that plugs the wound. |
| 4 | A antigen on the red cells and anti-B antibody in the plasma | Blood group is set by red cell antigens while plasma carries the opposite antibody, so a mismatched transfusion agglutinates. |
| 5 | It is clearly low, indicating anaemia | A value below the normal range means anaemia, commonly from iron deficiency, blood loss or chronic illness. |
| 6 | 9 per cent | 450 out of 5 000 is 9 per cent, and the body replaces it within a few weeks. |
| 7 | It is low, so the person bruises and bleeds easily | Too few platelets slow clotting, so even minor knocks can leave bruises. |
| 8 | About 20.1 mL | Fifteen times 1.34 is about 20.1 mL, so five litres of blood carries around 1 000 mL of oxygen. |
| 9 | A fourfold rise, achieved by a faster heart rate and a larger stroke volume | Twenty divided by five is four, driven by a faster rate and stronger contraction, helped by greater venous return. |
| 10 | Haemoglobin in red blood cells carries oxygen; white cells provide immune defence | The division is clear: red cells carry gases while white cells engulf pathogens or make antibodies. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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