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.
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