CAIE A-Level Biology AS 8.3.3 Cardiac Cycle and Valves Questions
Explain the cardiac cycle and valve roles in one-way blood flow using evidence from each question and mark scheme.
- Syllabus
- 2028–2030
- Course
- Biology 9700
- Level
- AS
Exam points
- Explain the cardiac cycle and the role of valves in maintaining one-way blood flow.
CAIE A-Level Biology AS 8.3.3 Cardiac Cycle and Valves Questions question 1
[Maximum number: 4]
During one cardiac cycle:
- blood enters the heart from the lungs and from the rest of the body
- blood leaves the heart to be transported to the lungs and to the rest of the body.
One phase of the cardiac cycle is ventricular diastole (ventricular relaxation). A number of events occur in the heart during this phase.
Outline and explain the events that occur in the heart during ventricular diastole.
Blood arriving in the lungs from the heart is oxygenated as it passes through the pulmonary capillaries.
Sickle-shaped red blood cells are present in a person with sickle cell anaemia. These cells have a very high quantity of abnormal (sickle cell) haemoglobin and take up and transport less oxygen than red blood cells containing normal haemoglobin.
any four from:
1 pressure in ventricles decreases (in context of relaxation) ;
2 semilunar valves close ;
3 atria filling with blood / blood entering atria
4 bicuspid and tricuspid / left and right atrioventricular, valves open ;
A mitral for bicuspid
5 blood enters ventricles (passively) ;
allow once only (either marking point 5 or 8)
6 atria contract / atrial systole ;
7 pressure in atria exceeds pressure in ventricles ;
8 (so) blood enters ventricles (from atria) ;
allow once only (either marking point 5 or 8)
9 AVP ;
e.g. ref. to heart sounds (from valve closure)
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