Structure fits function at every scale. This SL lesson covers B1.1 Carbohydrates & lipids, B1.2 Proteins, B2.1 Membranes & transport, B2.2 Organelles and B2.3 Cell specialisation.
You will link biomolecule shape to role, the fluid mosaic membrane, and how organelles and specialised cells are adapted.
Work through each screen, answer the questions as you go (some are wordy, some are calculations) and collect ⭐ stars. Press Start when you are ready.
Carbohydrates are built from monosaccharides (e.g. glucose) joined by glycosidic bonds in condensation reactions. Polysaccharides include starch and glycogen (energy stores) and cellulose (structural cell walls).
Lipids include triglycerides (glycerol + 3 fatty acids, joined by condensation) and phospholipids. Triglycerides are compact, insoluble, high-energy stores.
Form & function: the same glucose monomer builds starch (coiled, easily digested store) and cellulose (straight chains, strong fibres) — shape sets the job.
Proteins are polymers of amino acids joined by peptide bonds. The 20 amino acids differ in their R groups.
The precise fold gives each protein its function; heat or extreme pH can denature it.
Cell membranes are a phospholipid bilayer: hydrophilic phosphate heads face the water, hydrophobic tails face inward. Proteins, cholesterol and glycoproteins are embedded — the fluid mosaic model.
Transport across membranes:
Sort each biomolecule into the correct group.
Eukaryotic organelles are each adapted for a task:
Large surface areas (cristae, thylakoids, microvilli) recur wherever fast exchange or reaction is needed.
Cells become specialised by differentiation — expressing only some of their genes. A red blood cell loses its nucleus and fills with haemoglobin; a root hair cell has a long extension for absorption.
Stem cells are unspecialised and can divide and differentiate, giving rise to the specialised cells a tissue needs.
Match each transport process to its correct description.
B1.1: glycosidic bonds build carbohydrates; triglycerides are compact energy stores
B1.2: amino acids and peptide bonds; primary to quaternary structure and denaturation
B2.1: fluid mosaic membrane; passive vs active transport
B2.2-B2.3: organelles and specialised cells show form fitting function
Press Finish to see your score.
You have worked through Theme B: Form & Function — Molecules & Cells for IB Diploma Biology. 🎉
Your stars: 0 / 0
Next: test yourself in the Evaluate stage Confidence Quiz, then lock it in with Verify.