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IB Biology HL D2.3.4 Changes in Plant Tissue Questions

Control plant-tissue osmosis experiments and interpret percentage-mass graphs to estimate osmolarity and explain tissue responses in IB Biology HL D2.3.4.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Describe controlled variables for estimating plant-tissue osmolarity, including tissue mass or dimensions, temperature, immersion time, solution conditions and blotting method.
  • Explain why percentage mass change is calculated so water gain or loss can be compared fairly across tissue samples with different starting masses.
  • Outline how to plot percentage mass change against solution concentration and use the zero-change intercept to estimate plant-tissue osmolarity.
  • Estimate the solute concentration of plant tissue from the isotonic point in the experiment data.
  • Interpret a potato-cylinder graph relative to its isotonic concentration to count solutions in which tissue loses mass.

Learn this topic

Study D2.3.4—Changes in plant tissue conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL D2.3.4 Changes in Plant Tissue Questions question 1

[Maximum number: 3]

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.

Figure for Question IB Biology HL D2.3.4 Changes in Plant Tissue Questions question 1 — IB Biology HL

Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.

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