IB Biology HL C1.2.6 Variables Affecting Rate Questions

Practise IB Biology HL 1.2.6 by evaluating how conditions, oxygen supply and apparatus design affect measured respiration or fermentation rates.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Relate temperature, oxygen availability, substrate concentration, pH, organism size and metabolic demand to measured respiration or fermentation rate in a named context.
  • Design and evaluate rate experiments using respirometers, fermenters or sensors, including apparatus suitability, controls, calibration and time-based measurements.
  • Interpret respiration-rate data to calculate or compare changes, identify optima or limiting conditions, and distinguish respiration measurements from photosynthesis or ventilation confounds.

IB Biology HL C1.2.6 Variables Affecting Rate Questions question 1

[Maximum number: 1]

Proteasomes are a group of proteins that destroy unwanted proteins in the cell, thereby maintaining cell health. However, chemical inhibitors can block the action of proteasomes, resulting in a build up of unwanted proteins with negative consequences for the cell.

Rat heart cells were incubated at different concentrations of a proteasome inhibitor in order to test its toxicity. The bar graph shows the percentage survival of these cells compared to untreated control cells.

Figure for Question IB Biology HL C1.2.6 Variables Affecting Rate Questions question 1 — IB Biology HL

Anticancer Therapeutic Agent Bortezomib', with permission from Elsevier.]

Describe the effect of the two treatments with proteasome inhibitor on mean oxygen consumption.

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