About Lesson
Primary Growth
It results into an increase in the length of shoots and roots.
It occurs at the tips of roots and shoots due to the activity of apical meristems.
Apical meristems originate from embryonic tissues.
In primary growth, there are three distinctive zones;
- Zone of cell division,
- Zone of cell elongation
- Zone of cell differentiation.
Zone of cell division is an area of actively dividing meristematic cells. The cells are have thin cell walls, dense cytoplasm and no vacuoles.
Zone of cell elongation consists of cells that become enlarged to their maximum size by stretching of their walls. Vacuoles start forming and enlarging.
Zone of cell differentiation; cells attain their permanent size, have large vacuoles and thickened cell walls. The cells differentiate into tissues specialized for specific functions.
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