Biology · Form and function

B2.3 — Cell specialization

Biology · SL / HL · syllabus-mapped notes

1. B2.3.1

   Production of unspecialized cells following fertilization and their development into specialized cells by differentiation

   Explain differentiation, and how gradients of signalling chemicals control gene expression in the embryo.

2. B2.3.2

   Properties of stem cells

   State the two properties of stem cells: endless division, and differentiation along different pathways.

3. B2.3.3

   Location and function of stem cell niches in adult humans

   Describe two stem cell niches in adults, and how a niche either maintains or activates the cells.

4. B2.3.4

   Differences between totipotent, pluripotent and multipotent stem cells

   Distinguish totipotent, pluripotent and multipotent stem cells.

5. B2.3.5

   Cell size as an aspect of specialization

   Explain how the size of a human cell is itself an adaptation to its function.

6. B2.3.6

   Surface area-to-volume ratios and constraints on cell size

   Explain why exchange depends on surface area while the need for it depends on volume.

7. B2.3.7

   Adaptations to increase surface area-to-volume ratios of cells

   Explain flattening, microvilli and invagination, using erythrocytes and proximal tubule cells.

8. B2.3.8

   Adaptations of type I and type II pneumocytes in alveoli

   Contrast type I pneumocytes (thinness) with type II (surfactant), in one tissue with two cell types.

9. B2.3.9

   Adaptations of cardiac muscle cells and striated muscle fibres

   Contrast cardiac and striated muscle by branching, length and nuclei; discuss whether a fibre is a cell.

10. B2.3.10

    Adaptations of sperm and egg cells

    Explain the adaptations of human sperm and egg cells.