DP Biology (first assessment 2025)
Question 19N.2.SL.TZ0.6a
| Date | November 2019 | Marks available | [Maximum mark: 4] | Reference code | 19N.2.SL.TZ0.6a |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Outline | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 4]
19N.2.SL.TZ0.6a
(a)
Outline how cuts in the skin are sealed to prevent blood loss.
[4]
Markscheme
a. platelets respond to/detect skin/blood vessel damage ✔
b. platelets release clotting factors ✔
c. clotting factors trigger a chain/cascade of reactions ✔
d. «leading to» formation of thrombin ✔
e. thrombin causes fibrinogen conversion into fibrin ✔
f. blood clot seals the wound due to fibrin network of fibres ✔
Accept answers presented as a flow chart.
