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IB Biology HL 2.1.15 Sodium-Potassium Pumps Question Bank

Practise IB Biology HL 2.1.15 through exact HL questions on ATP-powered ion gradients, resting-potential recovery and sodium-potassium pump evidence.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse how ATP-powered sodium export and potassium import maintain electrochemical gradients.
  • Explain how pump activity restores resting potential after neuronal or muscle stimulation.
  • Interpret concentration, inhibitor and timing data to evaluate sodium-potassium pump function.

B2.1.15 (HL)—Sodium-potassium pumps question 1

[Maximum number: 1]

Hypertension (blood pressure exceeding 140 mmHg ) affects millions of people worldwide. Many modern societies consume more sodium in the form of salt (NaCl) than is required for normal physiology. The effect of changing the levels of dietary sodium has been studied in various organisms.

Scientists recorded the blood pressure changes in chimpanzees (Pan troglodytes) fed a diet without added sodium (control) or a sodium supplemented diet (experimental) as follows
- 5 grams of salt per day from December 1991 until May 1992
- 10 grams of salt per day until June 1992
- 15 grams of salt per day until August 1993
after which no more salt was added to the diet until the experiment ended.

Figure for Question B2.1.15 (HL)—Sodium-potassium pumps question 1 — IB Biology HL

Suggest how sodium-potassium pumps in the membranes of nephron cells in the kidney could allow blood sodium concentrations to be reduced, if there is sufficient potassium in the diet.

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