Question

Cells attaining their maximum size in terms of wall thickening and protoplasmic modification belong to
A. Meristematic phase
B. Elongation phase
C. Maturation phase
D. None of the above

Answer 1

Growth is an irreversible increase in the size and number of cells, organ or whole organism. The growth in plants takes place in three phases’ meristematic, elongation and maturation phase.

Complete Answer:
The growth in plants is regulated by the hormones auxins, cytokinins, gibberellins, ethylene and abscisic acid.
1. Meristematic phase- This phase is seen in the root and shoots apex. The cells become rich in protoplasm and the nucleus becomes large and conspicuous. The primary cell wall becomes thinner; cellulose gets deposited in the plasmodesmata.
2. Elongation phase- It takes place at the proximity of the root and shoots apex. The vacuoles attain greater size, the cells enlarge and deposition is seen in the cell wall.
3. Maturation phase- It lies next to the elongation region. The cells attain maximum size with the thickening of the cell wall and the protoplasm gets modified.

The correct answer is (C). Cells attaining their maximum size in terms of wall thickening and protoplasmic modification belong to the meristematic phase.

Note: Growth at the root and shoot apex is termed as the primary growth. It results in an increase in length of root and shoot. The widening of a root or shoot in a cambium due to cell division is known as secondary growth.