Tag: biology

Growth is an irreversible process. It refers to a positive change in size, often over a long period of time. It can occur as a stage of maturation or a process toward fullness or fulfillment.

Growth can be defined as an irreversible permanent increase in size of an organ or its parts or even of an individual cell. Generally, growth is accompanied by metabolic processes (both anabolic and catabolic), that occur at the expense of energy. Therefore, for example, expansion of a leaf is growth. Plant growth is unique because plants retain the capacity for unlimited growth throughout their life. This ability of the plants is due to the presence of meristems at certain locations in their body. The cells of such meristems have the capacity to divide and self-perpetuate. The product, however,soon loses the capacity to divide and such cells make up the plant body.This form of growth where in new cells are always being added to the plant body by the activity of the meristem is called the open form of growth.

There are various plant hormones which regulate plant growth. Hormones like auxin, gibberellin, cytokinin promotes growth whereas hormones like ethylene and abscisic acid inhibits growth. Plant growth is also regulated by the climate or atmosphere. Various climatic factors like rainfall, light, temperature, humidity, etc regulates plant growth and development.

Growth is defined as the positive and irreversible change in size and mass over the period of time. It is shown by all living organisms. It occurs by an increase in cell size or number. In animals, growth is observed up to certain period of time only whereas plants shows continuous growth throughout the lifetime. 

Classical growth experiments were conducted by Darwin, Boysen-Jensen paved path to refute ancient misconceptions on plant growth. Boysen and Jensen conducted some experiments, which provided more direct evidence that transmissible substance produced in the tip participates in the response. Charles Darwin explored the inductive nature and mechanistic connection between phototropism and gravitropism.

Auxanometer are simple instruments that measure growth, as increase in axis length, which includes both increase in protoplasm mass as well as expansion, due to water absorption.

Classical experiments on growth were performed by Boysen - Jennsen and Darwin. The existence of first plant growth hormone came from the work of Darwin. They found that bending movement of coleoptile of canary grass was due to exposure of tip to unilateral light. Boysen - Jennsen found that the tip produces a chemical which was later named auxin. Darwin's findings on plants have been published as a book in the name of 'The power of movements in plants.

Eduard Adolf Strasburger was a Polish - German professor who has one of the most famous botanists of the 19th century. He had contributed a lot towards the field of botany. He explained about the distribution of growth in a root by marking it at equal intervals with Indian ink.

Plants respond to their environment to ensure their survival. Plants response to environment is mainly through growth, either towards or away from stimuli. This type of response is called as tropism. It is brought about by hormones, which control plant growth and development.