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class 9 ncert
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1) Plasma membrane is called selectively permeable membrane because it allows the movement of only selected molecules inside and outside the cell .
This includes partial solvent along with some selected solute molecules .
2) A cell membrane is made up of :
•Proteins - 58 to 59 percent
•phospholipids - 40 percent
•glycolipids and glycoproteins - 1 to 2 percent
•cholesterol
3) If the plasma membrane ruptures or breaks down , then the contents of the cell will be damaged .i.e one of the functions of the plasma membrane is protection of the inner components of the cell . If the protective coat is broken then the inner components will spill out of the cell causing the cell to ultimately die .
4) Functions of the plasma membrane :
• Protection of the internal components of the cell
• providing shape to the cell
• selecting the molecules for entry and exit into the cell
• antigen - it helps in deciding the success rate of transplant
• glycolipids and glycoproteins in the cell me membrane help In cell to cell recognition and as a result the tissue formation and fusion of sperm with ovum can take place .
5) Diffusion is the movement of molecules (solids , liquids or gases) from its region of higher concentration to its regn of lower conc. without the expenditure of energy .
• the substances move towards the concentration gradient .
•diffusion is mainly for gases
ii ) osmosis is the movement of solvent (liquids) from its regn of higher conc to its region of lower conc. without the expenditure of energy .
•osmosis is mainly for solvent(liquids) .
6) diffusion is necessary in plants for photosynthesis to take place because as we know diffusion is the movement of molecules (mainly gases) from its higher conc to its lower conc . In case of photosynthesis the carbon dioxide in the atmosphere needs to diffuse from the external environment to the leaves and similarly the oxygen released after photosynthesis needs to be exchanged outside the leaves through diffusion .....
7) if we add a few drops of ink to pure water the ink will spread on its own in the water and cause the colour of the water to change .
This spontaneous intermixing of particles of two different substances is also called diffusion . In specific diffusion of liquids is called osmosis . Therefore this process can be said as osmosis .
8) endosmosis is the movement of solvent from the external environment in to the cell ; while exosmosis is the movement of solvent from the cell to the external environment .
In short ,
Entry of solvent into the cell - endosmosis
Exit of solvent from the cell - Exosmosis
Both occur with towards the concentration gradients only .
9) If a plant cell is placed in conc sugar solution then ; the cell will become plasmolysed .
A concentrated sugar solution contains more amt of solute than the cell and less amt of solvent than then cell ; therefore the mvt of solvent takes places from its higher conc I.e. the cell to its lower conc i.e the solution and as a result causes the cell to shrink..... and the shrinking of plant cell is called plasmolysis . And it can be said that the cell becomes plasmolysed .
10) raisins will swell up when placed in pure water because the water contains more solvent than the cell and as a result acts as a hypotonic solution ; and when a cell is placed in a hypotonic solution the solvent moves from its higher conc i.e. the solution to its lower conc. I.e cell which causes the cell to swell up . This process can also be said as endosmosis .
11) transportation across the cell membrane can be of two types :
1) active transport (with the expenditure of energy)
2) passive transport (without the expenditure of energy)
Active transport can be of further two types :
1) vesicular transport
2) protein pump inhibitor
Vesicular transport can be of two types :
1) endocytosis
2) exocytosis
Endocytosis is a type of vesicular transport in which the membrane forms vesicles and takes in the molecules
From the external environment into the cell .
Endocytois can further be of two types :
1) pinocytosis - cell drinking
2) phagocytosis - cell eating
Exocytosis is the transport of substances from the cell to the external environment thru the formation of vesicles . This mainly occurs for transporting the Intra cellular wastes from the cell .
12) osmosis is an important phenomenon due to which the following things happen :
1) the cells in our body are able to take in the necessary nutrients and water for their proper functioning .
2) in the reverse osmosis the water can be purified due to the phenomenon of osmosis
3) some aquatic animals can take in water and nutrients due to the difference in conc ...... through the process of osmosis .
Hope this answer is satisfactory
This includes partial solvent along with some selected solute molecules .
2) A cell membrane is made up of :
•Proteins - 58 to 59 percent
•phospholipids - 40 percent
•glycolipids and glycoproteins - 1 to 2 percent
•cholesterol
3) If the plasma membrane ruptures or breaks down , then the contents of the cell will be damaged .i.e one of the functions of the plasma membrane is protection of the inner components of the cell . If the protective coat is broken then the inner components will spill out of the cell causing the cell to ultimately die .
4) Functions of the plasma membrane :
• Protection of the internal components of the cell
• providing shape to the cell
• selecting the molecules for entry and exit into the cell
• antigen - it helps in deciding the success rate of transplant
• glycolipids and glycoproteins in the cell me membrane help In cell to cell recognition and as a result the tissue formation and fusion of sperm with ovum can take place .
5) Diffusion is the movement of molecules (solids , liquids or gases) from its region of higher concentration to its regn of lower conc. without the expenditure of energy .
• the substances move towards the concentration gradient .
•diffusion is mainly for gases
ii ) osmosis is the movement of solvent (liquids) from its regn of higher conc to its region of lower conc. without the expenditure of energy .
•osmosis is mainly for solvent(liquids) .
6) diffusion is necessary in plants for photosynthesis to take place because as we know diffusion is the movement of molecules (mainly gases) from its higher conc to its lower conc . In case of photosynthesis the carbon dioxide in the atmosphere needs to diffuse from the external environment to the leaves and similarly the oxygen released after photosynthesis needs to be exchanged outside the leaves through diffusion .....
7) if we add a few drops of ink to pure water the ink will spread on its own in the water and cause the colour of the water to change .
This spontaneous intermixing of particles of two different substances is also called diffusion . In specific diffusion of liquids is called osmosis . Therefore this process can be said as osmosis .
8) endosmosis is the movement of solvent from the external environment in to the cell ; while exosmosis is the movement of solvent from the cell to the external environment .
In short ,
Entry of solvent into the cell - endosmosis
Exit of solvent from the cell - Exosmosis
Both occur with towards the concentration gradients only .
9) If a plant cell is placed in conc sugar solution then ; the cell will become plasmolysed .
A concentrated sugar solution contains more amt of solute than the cell and less amt of solvent than then cell ; therefore the mvt of solvent takes places from its higher conc I.e. the cell to its lower conc i.e the solution and as a result causes the cell to shrink..... and the shrinking of plant cell is called plasmolysis . And it can be said that the cell becomes plasmolysed .
10) raisins will swell up when placed in pure water because the water contains more solvent than the cell and as a result acts as a hypotonic solution ; and when a cell is placed in a hypotonic solution the solvent moves from its higher conc i.e. the solution to its lower conc. I.e cell which causes the cell to swell up . This process can also be said as endosmosis .
11) transportation across the cell membrane can be of two types :
1) active transport (with the expenditure of energy)
2) passive transport (without the expenditure of energy)
Active transport can be of further two types :
1) vesicular transport
2) protein pump inhibitor
Vesicular transport can be of two types :
1) endocytosis
2) exocytosis
Endocytosis is a type of vesicular transport in which the membrane forms vesicles and takes in the molecules
From the external environment into the cell .
Endocytois can further be of two types :
1) pinocytosis - cell drinking
2) phagocytosis - cell eating
Exocytosis is the transport of substances from the cell to the external environment thru the formation of vesicles . This mainly occurs for transporting the Intra cellular wastes from the cell .
12) osmosis is an important phenomenon due to which the following things happen :
1) the cells in our body are able to take in the necessary nutrients and water for their proper functioning .
2) in the reverse osmosis the water can be purified due to the phenomenon of osmosis
3) some aquatic animals can take in water and nutrients due to the difference in conc ...... through the process of osmosis .
Hope this answer is satisfactory
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