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Cell- Fundamental Unit of Life : NCERT Intext Questions

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Page 59

Q.1     Who discovered cells and how?
Sol.     It was Robert Hooke who discovered cells. He observed the cells in thin slices of cork. They appeared like small compartments when viewed through the microscope.

Q.2     Why is the cell called structural and functional unit of life?
Sol.     A cell is capable of carrying out all the life functions; such as nutrition, excretion, respiration, etc. Hence a cell is called the functional unit of life. Additionally, the cell is the smallest unit of life and all the living beings are made up of cells. Hence a cell is called the structural unit of life.

Page 61

Q.1     How do substances like CO2 and water move in and out of the cell? Discuss.
Sol.     Substances move in and out of the cell because of diffusion. Diffusion is the random movement of particles in order to attain concentration equilibrium. The movement of water through a semi-permeable membrane is called osmosis. It is important to note that plasma membrane is a semi-permeable membrane. Water always moves from high water concentration to low water concentration.

Q.2     Why is the plasma membrane called a selectively permeable membrane?
Sol.     Plasma membrane allows passage to some selected substances. Hence it is called a selectively permeable or semi-permeable membrane.

Page 65

Q.1     Can you name the two organelles we have studied that contain their own genetic material?
Sol.     Mitochondria and Chloroplast contain their own genetic material.

Q.2     If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen?
Sol.     Various parts of a cell are responsible for various functions. They work in tandem to continue life in the cell. In case, the organization of a cell is destroyed due to some physical or chemical influence, the cell will die.

Q.3     Why are lysosomes known as suicide bags?
Sol.      Lysosomes contain digestive enzymes. In case of a rupture in lysosome, the enzymes are released in the cytoplasm and end up digesting the contents of the cell. This results in cell death. Due to this, lysosome is also known as suicide bags of cells.

Q.4     Where are proteins synthesized inside the cell?
Sol.     Proteins are synthesized in ribosome.


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