• Growth in an organism consists of a permanent and an irreversible increase in
size, commonly accompanied by an increase in solid matter, dry mass and amount
of cytoplasm. Growth in living beings is intrinsic or internal in contrast to extrinsic
growth observed in non-living objects.
• Plant growth is generally indeterminate i.e., continued throughout life. In lower
plants, growth is diffused i.e., every cell can divide and enlarge but in higher plants,
special body regions called meristems cause body growth.
• Plant growth takes place in three phases – formative, enlargement and
differentiation.
(i) Formative phase: It is the phase of cell division. As the formation of new
cells requires biosynthetic activity, the respiration rate of cells is high in this
phase.
(ii) Phase of enlargement: In it, the newly formed cells produced in formative
phase undergo enlargement. In many parts cell enlargement may occur
in all directions, e.g., isodiametric parenchymatous cells. In many parts, cell
enlargement takes place prominently in the linear direction, so much so that
this phase is also called phase of cell elongation.
(iii) Phase of differentiation or maturation: In this phase the enlarged cells
develop into special or particular type of cells by undergoing structural and
physiological differentiation.
• Growth can be arithmetic (cells divide in such a fashion that one daughter cell
divides again while the other cell differentiates) or geometric (each daughter
cell divides). Geometric growth causes rapid increase in size, weight, etc. and is
generally observed in unicellular organisms or at early embryonic stage.FACTS
HGH
YIELD
Class XI
Primary and Secondary
Growth in Plants
Analysis of various PMTs from 2011-201520112012201320142015AIPMT/NEET1131AIIMS11AMU121Kerala11K.CET1122J & K1