Quiz 3 Biol-102 Fall17 1. Describe fluid mosaic model of cell membrane. 2. Defin
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Quiz 3 Biol-102 Fall17 1. Describe fluid mosaic model of cell membrane. 2. Define terms turgid, flaccid and plasmolyzed. 3. Describe the role of cholesterol in maintaining cell membrane functional. Why inside the dialysis bag become blue? 5. 4. 6. 7, 8. Betacyanin pigment is in beet root is stored in Maximum leaching of betacyanin takes place at AOC B) 5- C) 40 s D) so-c Draw red blood cells placed in water, 0.5% salt solution and 1.9% salt solution. Absorption of water by plants is A) Diffusion B) active transport C) osmosis D) facilitated diffusion 9. How do cells recognize one another? 10. Define facilitated diffusion. 11. Describe sodium potassium pump 0Explanation / Answer
Fluid Mosaic Model:-
the cell membrane is made up of a bunch of different molecules that are distributed across the membrane. If you we observe cell membrane using a microscope, we see a pattern of different types of molecules put together, also known as a mosaic. These molecules are constantly moving in two dimensions, in a fluid fashion, similar to icebergs floating in the ocean. The movement of the mosaic of molecules makes it impossible to form a completely impenetrable barrier.
The phospholipids acts as a layer of ocean, in which peripheral protein are seen as icebergs.
2.
Turgid cell are those cells when placed in a hypotonic solution, water diffuses into the cell causing the cell to swell. The pressure developed on the cell wall is called turgor pressure.
Flaccid cell are those cells when placed in a hypertonic solution, water diffuses out of the cell causing the cell to shrink.
Plasmolysis is the process in plant cells where the plasma membrane pulls away from the cell wall due to the loss of water through osmosis.
3.
Cholesterol adds firmness and integrity to the plasma membrane and prevents it from becoming overly fluid, it also helps maintain its fluidity.
It prevents crystallization at high concentrations, cholesterol helps separate the phospholipids so that the fatty acid chains can't come together and cyrstallize.
Hence, cholesterol helps in preventing extremes conditions I.e too fluid, or too firm, in the consistency of the cell membrane.
4.
The iodine molecules come in to contact with the starch, turning them blue.
5.
It is found in the large central vacuole of the beetroot cells. The vacuole is enclosed by a single membrane called the tonoplast and the whole cell is enclosed by the cell membrane made up of phospholipids and proteins.
9.
Every cell in our body has a set of 'identity tags' on its surface. It is unique to every human being. Some are only found on cells from the same tissue or organ. The tag’s on these molecules are called antigens. The antigens are unique, unless you have an identical twin. Our immune system recognises invading infection because they have unmatched antigens on their surfaces.
10.
Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a biological membrane. It does not require chemical energy from ATP hydrolysis. The molecules and ions move down due to concentration gradient reflecting its diffusive nature.
11.
The process of moving sodium and potassium ions across the cell membrane is an active transport process. The energy needs obtained from hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase. This process is responsible for maintaining the large excessof Na+ outside the cell and the large excess of K+ ions on the inside the cell.
The sodium-potassium pump plays a key role in action potential produced by nerve cells.
8.
Plants absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis.
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