IB Biology HL 2.4.5 Osmosis, haemolysis and cell damage Question Bank
Practise IB Biology HL 2.4.5 by analysing osmotic effects on red blood cells and other animal cells.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Practise IB Biology HL 2.4.5 by analysing osmotic effects on red blood cells and other animal cells.
Data was collected on rabbit red blood cells that were exposed to sodium chloride (NaCl) and scorpion venom. Under some osmotic conditions red blood cells swell and burst, releasing hemoglobin (hemolysis). The graph shows the response of red blood cells to different concentrations of sodium chloride, with and without scorpion venom.

Outline the effect of the venom on the hemolysis of red blood cells.
a. in NaCl concentrations between 0.3 to 0.5 % venom increases the percentage of hemolysis/more cells lyse
b. venom has no effect below 0.3 % and above 0.55 % NaCl OR
Venom has no effect at very low or very high NaCl concentrations