Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate.
(a) Growth:
It is an irreversible and permanent process, accomplished by an increase in the size of an organ or organ parts or even of an individual cell.
(b) Differentiation:
It is a process in which the cells derived from the apical meristem (root and shoot apex) and the cambium undergo structural changes in the cell wall and the protoplasm, becoming mature to perform specific functions.
(c) Development:
It refers to the various changes occurring in an organism during its life cycle – from the germination of seeds to senescence.
(d) De-differentiation:
It is the process in which permanent plant cells regain the power to divide under certain conditions.
(e) Re-differentiation: It is the process in which de-differentiated cells become mature again and lose their capacity to divide.
(f) Determinate growth: It refers to limited growth. For example, animals and plant leaves stop growing after having reached maturity.
(g) Meristem: In plants, growth is restricted to specialised regions where active cell divisions take place. Such a region is called meristem. There are three types of meristems – apical meristem, lateral meristem, and intercalary meristem.
(h) Growth rate: It can be defined as the increased growth in plants per unit time.