Question

The cell is the basic structural unit of living organisms. What does the statement mean?

Answer 1

Hint: A living organism exhibits growth, development, responsiveness, adaptation, and reproduction which is the result of various reactions among molecules. The word ‘cell’ originated from a Latin word ‘cellula’ which means little room.

Complete answer:
All living organisms begin their life as a cell. This cell further divides or performs all the functions alone for the rest of their life. The cells are capable of independent existence because they represent a miniature version of all the essential activities in an organism’s lifetime.
- The activities of an organism are actually the aggregate of activities of its cells.
- Depending upon the complexity, an organism is of two types - unicellular and multicellular organisms. - The complexity of an organism is synonymous with the type and range of tissues present in it.
- A unicellular organism has only one cell to perform all sets of functions such as digestion, excretion, reproduction, etc.
 - In a multicellular organism, the division of labor can be observed wherein different sets of functions are performed by separate cells. The cells which have a similar origin, appearance, dimension, and perform identical functions together form tissues. Combination of tissues working as a unit to perform a specific function or a series of related functions form an organ. Further, several organs constitute an organ-system.

Note:In higher organisms, the following sets of tissues are observed:
Epithelial tissue lines body cavities and forms glands. They occur on external and internal exposed surfaces of the body parts where they form a protective covering.
Connective tissue is the most abundant and distributed widely in the body. Its function is to bind together different tissues or organs and support various structures of the animal body.
Muscular tissue brings about movements of the body parts and locomotion of an organism through their special property of contractility.
Nervous tissue helps in the control and coordination of various body parts through their unique property of excitability and conductivity.