NCERT Solutions for Class 11 Biology Chapter 13 Plant Growth and Development

Short Note:

• Growth is an irreversible, permanent increase in size, and is one of the most conspicuous features of living organisms, generally measured quantitatively (e.g., increase in size, mass, or cell number).

• Growth follows a characteristic sigmoid (S-shaped) curve, comprising lag, exponential (log), and stationary phases when plotted over time.

Short Note:

• Auxins: promote cell elongation, apical dominance, and root initiation. Gibberellins: promote stem elongation, bolting, and seed germination.

• Cytokinins: promote cell division, delay senescence. Ethylene: promotes fruit ripening, senescence, and abscission. Abscisic Acid (ABA): the 'stress hormone', induces dormancy and stomatal closure, generally growth-inhibitory.

Short Note:

• Development includes both growth and differentiation, integrating internal and external signals into a coordinated growth pattern.

• Seed germination is the process by which a seed develops into a seedling, usually triggered by water absorption (imbibition), followed by enzyme activation and mobilisation of stored food reserves.