Read How Plant Cells Change Their Fate
Plant cells specialise according to developmental signals and position, and some mature cells can regain the ability to divide.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Differentiate by structure and location
Differentiation changes cell walls and protoplasm so cells perform specialised roles. Position and function are linked; descendants of one meristem may become epidermis, cortex, xylem or phloem.
Recognise specialised xylem and renewed division
Tracheary elements lose their protoplasm and develop thick lignified secondary walls. Dedifferentiation occurs when mature cells regain division, as in formation of interfascicular cambium. Bakanae disease of rice led to gibberellin discovery.
Use the auxin-to-cytokinin ratio
In tobacco tissue culture, a high auxin:cytokinin ratio favours roots and a low ratio favours shoots. An intermediate balance maintains undifferentiated callus. Compare each culture set with the callus-producing ratio before predicting its fate: no organised growth, cell enlargement, root, then shoot. Choose B.
OlympIQ exam lens
- ✓Differentiation changes cell structure and contents.
- ✓Tracheary elements: dead at maturity, lignified walls.
- ✓Interfascicular cambium: dedifferentiation.
- ✓High auxin relative to cytokinin favours roots; low auxin relative to cytokinin favours shoots.
Differentiation and dedifferentiation describe opposite shifts in developmental state.
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