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प्रश्न
Write short notes on the following.
Nucleus of a cell
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उत्तर
Nucleus of a cell: The nucleus is a spherical structure generally present at the centre of a cell. The nucleus is composed of the following components:
1) Nuclear membrane: It is a double-layered membrane which separates the contents of the nucleus from the cytoplasm. The nuclear membrane has nuclear pores that allow the transfer of specific substances in and out of the nucleus.
2) Nucleolus: It is a small spherical body that is not bound by any membrane.
3) Chromosomes: These are thread-like structures that carry genes. Genes contain information necessary for the transfer of characteristics from the parents to the offspring. Thus, chromosomes play an important role in the inheritance of characteristics.
संबंधित प्रश्न
Who discovered cells and how?
Make a comparison and write down ways in which plant cells are different from animal cells.
What is osmosis?
State the difference between eukaryotes and prokaryotes
Name the part of the cell concerned with the following :
The entry of only certain substances into and out of the cell.
Match the name of the organelle given in Column A with its function given in Column B.
| Column A (Organelle) | Column B (Function) | ||
| 1 | leucoplast | a | help in cell division |
| 2 | nucleus | b | transport of material |
| 3 | ribosomes | c | making food |
| 4 | mitochondria | d | digesting foreign bodies |
| 5 | endoplasmic reticulum | e | storage of starch and proteins |
| 6 | golgi bodies | f | making the cell turgid |
| 7 | chloroplast | g | making proteins |
| 8 | centrosome | h | controlling all the vital activities of a cell |
| 9 | vacuole | i | releasing energy |
| 10 | lysosomes | j | synthesis of cell wall in a plant cell |
Write true or false for each statement. Rewrite the false statements correctly:
The size of a cell is usually measured in centimetres
Why was the invention of the microscope so important to the study of living beings?
Fill in the blank with a suitable word:
Cell ______ was proposed by Schleiden and Schwann.
Under the microscope, Priya observes a cell that has a cell wall and distinct nucleus. The cell that she observed is
