CourseCourseConceptConceptDocsDocuments

IB Biology HL B2.1.5 Osmosis and Aquaporins Questions

Analyse water-potential and solute gradients, predict net osmotic movement and explain how aquaporin pores change membrane permeability in IB Biology HL B2.1.5.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Define osmosis as passive net movement of water across a partially permeable membrane from lower solute concentration or higher water potential toward higher solute concentration.
  • Use solute or water-potential differences to predict the direction and net amount of water movement until equilibrium.
  • Explain that aquaporin protein pores increase membrane permeability and the rate of water movement by osmosis.

Learn this topic

Study B2.1.5—Osmosis and aquaporins conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL B2.1.5 Osmosis and Aquaporins Questions question 1

[Maximum number: 3]

In the early 1990s, investigations involving egg cells from the African clawed frog (Xenopus laevis) led to the discovery of membrane channel proteins called aquaporins.

In one investigation, scientists injected 10 frog egg cells with a solution containing mRNA encoding for an aquaporin, and another 10 frog egg cells with distilled water (control cells). All the frog egg cells were then incubated in a hypotonic solution. The volume of the frog egg cells was then measured during a period of five minutes.

The graph shows the mean results of the investigation.

Figure for Question IB Biology HL B2.1.5 Osmosis and Aquaporins Questions question 1 — IB Biology HL

Question (a)

(a)

State the direction of net movement of water across the plasma membrane of all the frog egg cells between 0 and 3 minutes.

[ 1 ]

Question (b)

(b)

Explain the reasons for the different results obtained for the frog egg cells with aquaporin mRNA and the control frog egg cells.

[ 2 ]
All question bank results loaded