Phases Of Growth In Plants - Practice Questions & MCQ

Characteristics of Growth:

1. Plant Growth is generally Indeterminate – Plants possess the ability of growth throughout their life. This is due to the presence of meristems at certain locations in their body and these meristems have the ability to divide and self –perpetuate. This form of growth wherein new cells are always being added to the plant body by the activity of the meristem is called the open form of growth.

2. Growth is Measurable – At the cellular level, Growth is the consequence of an increase in protoplasm and this increase is difficult to measure. Growth, in plants, is measured via different methods like increase in dry weight, volume, cell number, volume or increase in fresh weight. One single maize root apical meristem can give rise to more than 17,500 new cells per hour. This is called hyperplasia. The cells in watermelon may increase in size by up to 3,50,000 times. This is called hypertrophy.

Phases of Plant Growth:

1. Formative Phase:

• Cell division is the basic event in the growth of the plant.
• All cells are the result of the division of pre-existing cells.
• Mitosis is the type of cell division that happens during growth and includes both quantitative and qualitative division of cells. 
• This division is carried out in two steps – Division of Nucleus, which is referred to as Karyokinesis and division of cytoplasm referred to as Cytokinesis.
• In case of higher plants, an increase of cells is carried out in the meristematic region, whereby some daughter cells retain this meristematic activity while some enter the next phase of growth, i.e. the phase of cell enlargement.

2. Cell Enlargement and Cell Differentiation:

• At this stage, the size of tissues and organs is increased. 
• This enlargement occurs by forming Protoplasm, Hydration (absorbing water), developing vacuoles and then adding new cell wall to make it permanent and thicker.

3. Cell Maturation:

• At this stage, the enlarged cells acquire specific size and forms as per their location and role. 
• Several cells are differentiated from simple and complex tissues which perform different functions.