STRUCTURAL ORGANIZATION OF LIFE

IMPORTANT QUESTIONS   

Q.1: How was cell discovered? 

ANS: DISCOVERY OF CELL:

In 1610. Galileo, an Italian astronomer and physicist developed a microscope to observe small organisms.

• In 1665, Robert Hook made a compound microscope by combining lenses. It was a better microscope. Robert Hook examined a slice of cork under it. The cork was made from the bark of Oak. He found small honey comb like chambers and called them cells. 
• In 1842, Dutrochet boiled some plant material in nitric acid and examined it under a microscope. It consisted of cells.
• In 1831. Robert Brown discovered a spherical body, the nucleus, in the cells of orchids.
• In 1838, a German. botanist. Schleiden suggested that all plants are made of cells. 
• In 1839, Schwann, a German zoologist. suggested that all animals are made of cells.

Q.2: What are the three principles of the cell theory? 

ANS: CELL THEORY: 

The cell theory was formulated separately by a German botanist, Schleiden, in 1838 and a German zoologist, Schwann, in 1839. The salient features or three principles of this theory are as under:

• All organisms are composed of one or more cells. 
• All cells arise from pre-existing cells. 
• The cell is the structural and functional unit of all organisms.