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IB Biology HL B1.1.12 Phospholipid Bilayers Questions

Practise IB Biology HL B1.1.12 by explaining how amphipathic phospholipids orient in bilayers and alveolar surface films.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Identify the hydrophilic phosphate head and hydrophobic fatty-acid tails that make a phospholipid amphipathic.
  • Explain how amphipathic phospholipids orient heads toward water and tails away from water to form bilayers or surface films.

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Study B1.1.12—Phospholipid bilayers conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL B1.1.12 Phospholipid Bilayers Questions 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 IB Biology HL B1.1.12 Phospholipid Bilayers Questions 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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