HL A2.2 Multicellularity

Multicellularity is the condition where organisms consist of many interdependent cells with specialized functions.

Some prokaryotes form colonies with specialized cells (e.g. heterocysts in cyanobacteria for nitrogen fixation).

Advantages include division of labour, increased size (reduced predation), and more efficient functioning.

Multicellularity evolved multiple times independently, showing it provides strong selective advantages.

Some unicellular eukaryotes (e.g. Dictyostelium) aggregate temporarily to behave as a multicellular organism.

Volvox shows simple multicellularity with somatic cells for movement and reproductive cells for reproduction.