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प्रश्न
Who proposed the Cell theory? Explain the main points of this theory.
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उत्तर
In 1839, M.J. Schleiden and T. Schwann proposed the cell theory. This was further expanded by Virchow in 1858.
The main features of the cell theory as known at present are:
(i) All living organisms are composed of cells. Hence cell is the structural unit of living organisms.
(ii) All cells arise from pre-existing cells of a similar kind by cell division.
(iii) The chemical composition and metabolism of all cells are basically alike.
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संबंधित प्रश्न
Give a brief account of discovery of the cell.
A plant cell has a cell wall made of :
What is the cell theory? Who propounded it and when?
Write a short answer.
Why are mitochondria called the powerhouse of the cell?
Justify the statement "cell is the basic unit of life"
Match the items in column A with the appropriate items in column B:
| column A | column B |
| 1. Platform or workplace for the synthesis of proteins | a. Golgi complex |
| 2. A powerhouse of cells | b. Ribosomes |
| 3. Help in the formation of cell plate during cell division | c. Chloroplast |
| 4. Site for photosynthesis | d. Mitochondria |
| 5. Control tower of cell | e. Chromosomes |
| 6. A structure bearing genes | f. Nucleus |
Answer the following question.
Who discovered cells, and how?
Under the microscope, Priya observes a cell that has a cell wall and distinct nucleus. The cell that she observed is
Write about the contribution of Robert Hooke in cell biology.
Matching:
| 1. | Discovery of cell | a. | Nerve cell |
| 2. | Unicellular organism | b. | spirogyra |
| 3. | Multicellular organism | c. | Robert Hooke |
| 4. | Longest cell | d. | Cyanobacteria |
| 5. | Prokaryotic cell | e. | Amoeba |
