Biology · Plant Growth and Development · NEET
| Meaning | Meristematic cell matures into a permanent cell | Mature cell regains the power to divide |
| Direction of change | Divides -> stops dividing (differentiation) | Stops -> divides again (dedifferentiation) |
| Power to divide at end | Lost (differentiation / redifferentiation) | Regained (dedifferentiation only) |
| Classic example | Meristem forms tracheid / xylem vessel (differentiation) | Parenchyma forms interfascicular & cork cambium (dedifferentiation) |
| Redifferentiation | Dedifferentiated cambium matures into secondary xylem/phloem | End cells again lose the power to divide |
Differentiation = meristematic cell becomes a mature cell (loses power to divide). Dedifferentiation = mature cell regains power to divide. Redifferentiation = the cell made by dedifferentiation matures again and once more loses power to divide. So it is a cycle: divide -> stop -> divide -> stop.
Differentiation comes first. A cell must first mature (differentiate) and lose the capacity to divide before it can later regain that capacity (dedifferentiate). You cannot dedifferentiate a cell that never differentiated. This order is a common NEET trick point.
It is dedifferentiation. Fully mature parenchyma cells (which had stopped dividing) regain the power to divide and form the interfascicular cambium. Cork cambium (phellogen) forms the same way. This is the single most-asked NEET example, so memorise it.
Yes. In tissue culture, mature leaf mesophyll cells are placed in a medium and start dividing to form a callus (a mass of dividing cells). Since mature, non-dividing cells regain division power, this is dedifferentiation. NEET has asked exactly this.
No. Redifferentiation means the dividing (dedifferentiated) cells mature into specific tissues and once again lose the power to divide. For example, the interfascicular cambium (dedifferentiated) later produces secondary xylem and secondary phloem - those mature cells are redifferentiated and do not divide.
Formation of interfascicular cambium from fully developed parenchyma cells is an example for
In tissue culture experiments, leaf mesophyll cells are put in a culture medium to form callus. This phenomenon may be called as:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Differentiation: a meristematic cell matures into a tracheid or xylem vessel. Dedifferentiation: mature parenchyma forms interfascicular cambium or cork cambium. Redifferentiation: that interfascicular cambium then produces secondary xylem and phloem, which are again mature, non-dividing cells.
During differentiation, cells lose their protoplasm and gain special features (like thick lignified walls in tracheids) to do a fixed job. Once a cell is fully specialised this way, it normally cannot go back. Dedifferentiation is the special exception where living mature cells (like parenchyma) regain division power.
No. Only living cells that still have a nucleus and protoplasm (like parenchyma) can dedifferentiate. Dead cells such as mature tracheids or xylem vessels cannot dedifferentiate because they have no living contents.
NEET repeats the interfascicular cambium and cork cambium example for dedifferentiation almost every year, and callus formation too. Learn the direction: differentiation and redifferentiation END in non-dividing mature cells; only dedifferentiation GAINS division power.
