1) Describe the structure and function of plasma membrane. 2) What do you mean by passive and active transport? Write a short note on diffusion? 3) Describe the mechanism of osmosis. Give its importance. (Answer these questions between 30-40 words.)
Answers
"1) Plasma Membrane""
""Plasma membrane"" is the ""outermost layer"" which provides structure and fluidity to a cell. It is a semipermeable membrane made up of a ""phospholipid bilayer"" in which proteins and cholesterol molecules are embedded.
It is responsible for ""selective transport"" of ""molecules"" into or outside the cell and also to provide protection from the surroundings.
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2) Passive and Active Transport; Diffusion
Passive transport refers to those cellular processes by which molecules can cross the plasma membrane without using cellular energy. Example: ""Diffusion of lipids"", ""Osmosis of oxygen"", and ""Glucose transporters"".
Active transport refers to those cellular processes by which molecules can ""cross the plasma membrane"" by consuming cellular energy. Example: Sodium potassium pump.
""Diffusion"" is the ""process of movement"" of ""molecules"" from a ""region of higher concentration"" to that of lower concentration.
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3) Mechanism of Osmosis
""Osmosis"" is the process of movement of solvent from a region of lower solute concentration to that of higher concentration through a ""semi-permeable membrane"". The semi-permeable membrane prevents the movement of solutes and so the solvent molecules diffuse through the membrane until ""equilibrium is reached"".
It is essential to maintain homeostasis in cells. It aids in ""uptake of nutrients"" and ""removal of wastes"".
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