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IB Biology HL B1.1.12 Phospholipid Bilayers Question Bank

Practise IB Biology HL B1.1.12 through questions that extend amphipathic phospholipids into bilayer, monolayer and membrane-orientation reasoning.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse how hydrophilic heads and hydrophobic tails determine membrane or surfactant orientation.
  • Compare natural and synthetic surfactants using phospholipid composition and alveolar function.

B1.1.12—Phospholipid bilayers question 1

[Maximum number: 4]

Cells in the alveolus wall produce a surfactant. Its function is to prevent alveoli collapse at the end of expiration. Surfactants are used in the treatment of respiratory system disease in premature babies.

The table shows some of the components of different surfactant preparations.

Table for Question B1.1.12—Phospholipid bilayers question 1 — IB Biology HL

Question (a)

(a)

State the surfactant that contains the least amount of phospholipids.

[ 1 ]

Question (b)

(b)

Compare the composition of natural human surfactant with synthetic surfactants.

[ 2 ]

Question (c)

(c)

Phospholipids found in the surfactants form a surface film on the moist lining of the alveoli. Outline how the hydrophilic and hydrophobic parts of the phospholipids in the surfactants are aligned on the alveolar surface.

[ 1 ]
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