Circulatory systemIB MYP Biology: Subtopic test

1. 1
   A cardiologist in Singapore is teaching trainee nurses how blood flows through the heart. Blood from the body returns to the right atrium and is pumped through the heart in a set order. She explains that one of her patients has a faulty valve that lets some blood leak backwards after each beat.

   (a)

   What is the function of the valves in the heart?

   [1 mark]

   • ATo stop blood flowing backwards
   • BTo pump blood around the body
   • CTo supply the heart muscle with oxygen
   • DTo remove carbon dioxide from the blood

   (b)

   Which type of blood vessel has walls only one cell thick, so substances can pass between the blood and the body cells?

   [1 mark]

   • AArtery
   • BVein
   • CCapillary
   • DAorta

   (c)

   Explain why a person with a leaking valve may feel tired.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student in Auckland investigates how exercise affects her pulse rate. She counts her pulse for 30 seconds and doubles it to find the rate in beats per minute. She records it at rest and after 2, 4 and 6 minutes of running on the spot. Her results are 72, 104, 128 and 141 beats per minute.

   (a)

   Which of these is a testable hypothesis for this investigation?

   [1 mark]

   • AExercise makes people healthy.
   • BThe longer a person exercises, the higher their pulse rate will be, because their muscles need more oxygen.
   • CPulse rate is measured in beats per minute.
   • DDoes exercise change pulse rate?

   (b)

   Which change would make her results more reliable?

   [1 mark]

   • ACounting her pulse for only 5 seconds
   • BUsing a different type of exercise each time
   • CUsing only one exercise time
   • DRepeating the investigation several times and calculating a mean

   (c)

   Describe the trend in her results and explain it.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A teenager in Delhi has iron-deficiency anaemia. Because she lacks iron, her body cannot make enough haemoglobin. She feels tired and becomes breathless when she climbs stairs.

   (a)

   Explain why she feels tired and breathless.

   [3 marks]

   (b)

   Describe how the blood transports oxygen, carbon dioxide, glucose and urea.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A 58-year-old man in Lisbon has coronary heart disease. His doctors say that fatty deposits have narrowed two of his coronary arteries. They offer him either an operation to place a stent (a small mesh tube) that holds an artery open, or medicines to lower his cholesterol together with changes to his diet and exercise.

   (a)

   Explain how narrowed coronary arteries can damage the heart and may lead to a heart attack.

   [6 marks]

   (b)

   Discuss and evaluate the two treatments offered to the man.

   [6 marks]

   Total for question 4: 12 marks

End of questions