Transport in the bodyIB MYP Sciences: Subtopic test

1. 1
   A cardiology nurse in Dubai is explaining the structure of the human heart to a patient. The heart has four chambers and several valves, and it pumps blood both to the lungs and around the rest of the body.

   (a)

   Which chamber of the heart pumps oxygenated blood out to the body through the aorta?

   [1 mark]

   • ARight atrium
   • BRight ventricle
   • CLeft atrium
   • DLeft ventricle

   (b)

   What is the function of the valves in the heart?

   [1 mark]

   • ATo pump the blood with more force
   • BTo stop blood flowing backwards
   • CTo add oxygen to the blood
   • DTo carry blood to the lungs

   (c)

   Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A fish has a heart with two chambers, and its blood passes through the heart once on each complete circuit of the body. A human has a heart with four chambers, and the blood passes through the heart twice on each complete circuit of the body: once on the way to the lungs and once on the way to the body.

   (a)

   What is the name of the type of circulation found in humans, where blood passes through the heart twice on each circuit?

   [1 mark]

   • ASingle circulation
   • BOpen circulation
   • CDouble circulation
   • DPulmonary circulation only

   (b)

   Which is an advantage of double circulation over single circulation?

   [1 mark]

   • ABlood returns to the heart after the lungs, so it can be pumped to the body at high pressure
   • BOxygenated and deoxygenated blood mix in the heart, which lowers the pressure
   • CBlood does not need to pass through the lungs
   • DThe heart does not need any valves

   (c)

   Describe the path taken by blood from the right ventricle of the human heart to the left atrium.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student in Nairobi measures her pulse at her wrist by counting the beats for 15 seconds. At rest she counts 18 beats. She then runs on the spot for three minutes and immediately counts 33 beats in 15 seconds. Her teacher explains that the pulse is the stretching of an artery wall each time the heart pumps blood into it.

   (a)

   Calculate the student's heart rate at rest and after exercise, in beats per minute, and the increase in heart rate caused by exercise.

   [3 marks]

   (b)

   Explain why a pulse can be felt in an artery but not in a vein, and why the heart rate increases during exercise.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A hospital blood bank in Manila collects donated blood and separates each donation into red blood cells, platelets and plasma, which can be given to different patients. Donated red cells can be stored for about 42 days, but platelets can be stored for only five to seven days.

   (a)

   Describe the functions of the four components of blood: red blood cells, white blood cells, platelets and plasma.

   [6 marks]

   (b)

   Discuss the social, economic and ethical implications of encouraging people to donate blood, and justify a conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions