IB Biology B2.3 Notes

This page contains our IB Biology notes for B2.3. By reading each one of these notes, you will fully cover the content for IB Biology 'Further cell specialisation'.

All Topic 2 Sub-topics (HL)A2.1: Origins of cells A2.2: Cell Structure (HL)A2.2: Further cell structure (HL)A2.3: Viruses B2.1: Membranes And Transport (HL)B2.1: Further membranes and transport B2.2: Organelles & Compartmentalisation (HL)B2.2: Further organelles B2.3: Cell Specialisation (HL)B2.3: Further cell specialisation (HL)C2.1: Chemical signalling C2.2: Neural Signalling (HL)C2.2: Further neural signalling D2.1: Cell Division (HL)D2.1: Cell cycle (HL)D2.2: Gene expression D2.3: Water Potential (HL)D2.3: Further water potential

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Cell adaptations

Now that you know about cell specialization, you are expected to understand the several adaptations cells develop to better perform their function. This begins with adaptations for an increased surface-to-volume ratio. This is typically done by:

Reducing cell diameter
Flattening or elongating the cell
Making large membrane invaginations
Forming hair-like structures called microvilli

Using this, cells shaped like or cylinder with microvilli or invaginations will have a greater surface area than a sphere of the corresponding volume. Two examples you need to remember are:

The microvilli contained in luminal cells of the proximal convoluted tubule. These maximize surface area for efficient diffusion of substances whilst maintaining cell shape to form a tube.
The flattened disc shape of erythrocytes with a large invagination on either side. This increases surface area for oxygen to diffuse and bind to haemoglobin.

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