中文（繁體）
中文（简体）
English
S4 Biology: Human Transport System (Paper 2)
S4 Biology: Human Transport System (Paper 2)
The second paper focuses on the cardiac cycle, valves, coronary arteries and blood pressure, using before and after exercise data to work out changes in cardiac output.
Direct answer Remember the cycle as atria, ventricles, relaxation; for blood pressure separate systolic from diastolic, and pulse pressure is simply the difference.
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)
- FoundationWhat is the order of the three stages in one cardiac cycle?
- FoundationWhich vessels supply blood to the heart muscle itself?
- FoundationWhat values describe normal adult blood pressure?
- FoundationWhat is the main job of the atrioventricular valves?
- IntermediateThe heart beats 75 times a minute. How long does one cardiac cycle take?
- IntermediateCardiac output is 4.5 litres a minute at 75 beats a minute. What is the stroke volume?
- IntermediateWhat happens when a coronary artery is badly blocked?
- ChallengeDuring exercise heart rate goes from 70 to 140 and stroke volume from 70 to 100 mL. By what factor does cardiac output rise?
- ChallengeBlood pressure is 140 over 90. What is the pulse pressure, and how much higher is it than at 120 over 80?
- Error redoA student says veins return blood by the heart sucking it back. What is the main driving force?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Atrial contraction, then ventricular contraction, then complete relaxation | The atria push blood into the ventricles, the ventricles pump it into the arteries, then the whole heart relaxes and refills. |
| 2 | The coronary arteries | The coronary arteries branch from the base of the aorta and feed the heart muscle, so a blockage starves it of oxygen. |
| 3 | About 120 over 80 mmHg, systolic over diastolic | Systolic pressure is the peak during ventricular contraction and diastolic the trough during relaxation. |
| 4 | To stop blood flowing backwards from the ventricles into the atria | Valves open one way only and shut during ventricular contraction so blood can leave only towards the arteries. |
| 5 | 0.8 seconds | Sixty seconds divided by seventy-five beats gives 0.8 seconds, and a faster rate shortens each cycle. |
| 6 | 60 mL | 4 500 millilitres divided by seventy-five gives 60 mL, converting litres to millilitres first. |
| 7 | The heart muscle is starved of oxygen, causing angina and possibly a heart attack | Heart muscle cannot rest, so once its oxygen supply stops the cells die quickly. |
| 8 | About 2.9 times, from 4.9 to 14 litres a minute | Output rises from 4 900 to 14 000 mL a minute, about 2.9 times, using both a faster rate and a bigger stroke volume. |
| 9 | 50 mmHg, ten millimetres higher than the 40 mmHg at 120 over 80 | Pulse pressure is systolic minus diastolic, so 50 against 40 mmHg, a difference of ten. |
| 10 | Contraction of skeletal muscles squeezing the veins, with valves preventing backflow | Vein pressure is very low, so limb veins rely on the muscle pump and one-way valves, helped by negative chest pressure on inhalation. |
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.
Book an S4 Biology tutorTutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
