RBSE Class 11 Biology Notes Chapter 15 Plant Growth and Development

These comprehensive RBSE Class 11 Biology Notes Chapter 15 Plant Growth and Development will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 15 Notes Plant Growth and Development

→ The life of any organism starts from a cell. Unicellular organisms perform all the life process in a cell but in multicellular organisms single cell forms many cells, tissue, organ, organ system and body by divisions.

→ Each multicellular organism develops from unicellular zygote. It divides to gives rise to many cells. From their perpetuation and differentiation a body is formed.

→ In higher plants a resting stage is produced after zygote formation, which is called seed. The seed on germination form seedling then growing to form a plant. The mature plant bears reproductive structure. Zygote is reformed by fusion of reproductive gametes. Such a time also comes when the plant dies but it remains some structure to its existance such as seeds, tuber etc.

→ Growth is final result of all metabolic processes. The growth is irreversible quantitative change in size of a cell, organ or whole organism. As a result there is increase in volume, and dry weight of the plant.

 

→ The growth can be decipher as following:

• Growth in size; e.g., length, broadness, volume etc.
• Growth in quantity; e.g., wet weight, dry weight etc.
• Growth in number of cells which occurs due to cell division.

→ Meristems are growing points in plants.

→ Along with root apex and shoot apex meristem many times intercalary meristems take part in long duration growth of plant axis.

→ The growth in higher plants is irregular.

→ The growth can be arithmetic or geometrical observing cell division in root apex and shoot apex.

→ There is no equal growth in whole life in cell/tissue/ organ/organism.

→ The growth has three phases:

1. Lag phase
2. Log phase
3. Senescence. 

→ When the cell loses its division capacity, then it enters in differentiation phase.

→ Qualitative difference between cells, tissues and organs is called differentiation.

→ A differentiated cell can redivide or dedivide.

→ Plant growth and development controlled by both external and internal factors.

→ Intracellular internal factor are chemical, which is called plant growth regulators (PGR).

→ The plant growth regulators are divided into five groups: Auxins, gibberellins, abscisic acid, cytokinins and ethylene.

→ Growth regulators or phytohormones are transported to different parts producing in various parts of the plant.

→ Phytohormones are functional in very little quantity and affect the physiology of the plants.

→ In some plants flowering depends on photoperiodism. On the basis of photoperiodism, plants and divided into three groups: Short day plants, long day plants and day neutral plants.

→ Growth: Increase in size or volume of organisms.

→ Meristems: The tissues present on growing sites of plants.

→ Auxanometer: Plant growth measuring instrument.

→ Differentiation: The cell stops division and turned for a specific function. It is called differentiation.

→ Dedifferentiation: The differentiated cell gains redividation capacity, it is called dedifferentiation.

→ Redifferentiation: The loss of division capacity by the cell produced from tissues.

→ Plant hormones: Natural or synthetic chemicals which control metabolic activities of plants.

→ Basipetal transport: The movement of substances from upward to downward in plants.

→ Parthenocarpy: The process of formation of fruit without seeds.

→ Parthenogenesis: Formation of fruits without fertilization.

→ Cambium: A tissue in plant which has the capacity of division.

→ Apical dominance: The reduction in growth of lateral bud in the presence of apical bud in plants.

→ Photoperiodism: Duration of light required by plants to flowering.

→ Vernalization: Low temperature treatment of plants for flowering.