Question 21M.1A.HL.TZ1.29
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.1A.HL.TZ1.29 |
| Level | HL | Paper | 1A | Time zone | TZ1 |
| Command term | Question number | 29 | Adapted from | N/A |
What blood flow does the right semilunar valve prevent?
A. Backflow of blood to the right atrium during ventricular contraction
B. Blood flowing from the aorta back into the heart when the ventricle is filling
C. Blood flowing from the pulmonary artery to the right ventricle when the heart is relaxing
D. Blood flowing from the right atrium to the vena cava when the right atrium contracts
[1]
C
Knowledge of the structure and functioning of the heart is normally strong so it was surprising that this proved to be the second most difficult question on the paper. All four possible answers attracted substantial numbers of candidates, suggesting that many were guessing. The percentage answering correctly was only a little above the 25 % guess-level. Many candidates were confused about whether arteries always carry oxygenated blood or where the right semilunar valve is located.
