The cells are the fundamental unit of all living organisms.
These cells form tissues, tissues form organs, and organs form organ systems that ultimately form a living body. The movement of molecules should maintain this organization, as all the structures are made up of molecules.
Cells to an organism
These maintenance processes are observed in living organisms even when they are at rest (just sitting or during sleep).
The primary functions performed by a living organism to maintain its life are called life processes.
The Life Process
It is the characteristic feature of all living organisms to become bigger, taller and heavier in size over a period of time.
Growth can be defined as the irreversible continual increase in the organism's body size (of a part or even of a single cell) and mass with time.
It is a process that takes place by cell division.
- Growth in plants is an indefinite process as cell division occurs continuously throughout their life span in these organisms.
- In animals, growth is seen only till a particular age. Hence, it is definite.
A video showing the growth seen in Raddish plants
In the biological context. the terms growth and development are related to each other.
- When the organism's body increases in size or mass with time, it is referred to as growth.
- When the organism grows mentally, physically and physiologically, it is known as development.
Growth in plants:
Growth in plants is of four types as follows:
- Primary growth: It is a growth that serves as a result of mitotic divisions. It occurs in the meristematic cells found at the roots and shoots, leading to the increase in the size of the plant lengthwise.
- Secondary growth: Growth is seen in the secondary meristems leading to an increase in the diametral plant size.
- Vegetative growth: The growth and development of the vegetative structures of the plant such as roots, stem and leaves are known as vegetative growth.
- Reproductive growth: It is the stage during which flowers are produced.
Factors that affect growth:
The growth of both plants and animals is influenced by hormones in animals and by growth regulators in plants. On the whole, the factors which affect the growth of living organisms can be divided into two categories such as internal and external factors.
Heredity, enzymes and hormones are considered as internal factors while abiotic elements such as light, water, temperature and minerals, nutrients are considered as external factors.