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प्रश्न
Who proposed the Cell theory? Explain the main points of this theory.
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
Make a comparison and write down ways in which plant cells are different from animal cells.
Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
- Keep cup A empty
- Put one teaspoon of sugar in cup B
- Put one teaspoon salt in cup C
- Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then, observe the four potato cups and answer the following:
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- Why is potato A necessary for this experiment?
- Explain why water does not gather in the hollowed-out portions of A and D.
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the question has four options. Choose the correct answer:
Chromosomes are made up of
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