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IB Biology SL B1.1 Carbohydrates and Lipids Questions

Compare carbohydrate and lipid structures, then connect condensation, hydrolysis, solubility and molecular organisation to energy storage, membranes and recognition.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Explain how carbon’s four covalent bonds and self-bonding create diverse biological compounds and carbon skeletons.
  • Explain condensation and hydrolysis in biological molecules, identify reaction products and digestive enzymes, and relate hydrolysis products to absorption.
  • Identify glucose, fructose, galactose and ribose from structures, distinguish alpha- and beta-D-glucose, and relate monosaccharide solubility to biological use.
  • Describe starch and glycogen as alpha-glucose polymers and explain how compact, insoluble stores provide glucose energy.
  • Describe cellulose as unbranched beta-glucose chains with 1–4 bonds, hydrogen-bonded microfibrils and plant cell-wall strength.
  • Identify cell-surface glycoproteins as mediators of cell adhesion.
  • Identify non-polar lipids and explain how hydrophobic structure relates to insolubility in water.
  • Identify glycerol, fatty acids, ester bonds and phosphate groups when distinguishing triglyceride and phospholipid structures.
  • Classify fatty acids as saturated, mono- or polyunsaturated, and distinguish cis and trans isomers from double-bond geometry.
  • Identify amphipathic phospholipid heads and tails and explain their orientation in bilayers or surface films.

Covered syllabus points

B1.1.1—Carbon atom propertiesB1.1.2—Macromolecules by condensationB1.1.3—Digestion by hydrolysisB1.1.4—Form and function of monosaccharidesB1.1.5—Polysaccharides as energy storageB1.1.6—Cellulose structure and functionB1.1.7—Glycoproteins in cell-cell recognitionB1.1.8—Hydrophobic properties of lipidsB1.1.9—Formation of triglycerides and phospholipidsB1.1.10—Fatty acidsB1.1.11—Triglycerides functionsB1.1.12—Phospholipid bilayersB1.1.13—Non-polar steroids

Question 1

[Maximum number: 4]

Carbon is an essential element for life on Earth and must be distributed and recycled within ecosystems.

Outline the chemical properties of carbon that allow it to form diverse compounds.

Question 2

[Maximum number: 1]

The diagram shows some of the metabolic processes taking place in a plant cell.

Figure for Question 2 — IB Biology SL

State the type of reaction which converts excess monosaccharides to polysaccharides.

Question 3

[Maximum number: 1]

Explain why digestion of large food molecules is essential.

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