Chardakov method Essay examples

1382 Words Apr 22nd, 2014 6 Pages
Question: investigate the water potential of potato tissue?
Introduction
All cells require essential materials to ensure their survival. Chemical, physical, and biological processes are used to move these materials inside of cells. Similar processes move waste materials outside of cells. These processes can be passive, occurring as a result of basic physical laws and requiring no outside energy from the cell or they can be active, requiring energy expenditure. Since all molecules possess kinetic energy (energy of motion), they are constantly moving enabling the passive transfer of certain substances into and out of cells.
Diffusion is the passive movement of molecules from an area of higher concentration to areas of lower
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The diffusion of solutes (particles dissolved in water) through a semi-permeable membrane is called simple diffusion. The diffusion of water through a semi-permeable membrane is called osmosis. Both simple diffusion and osmosis involve the movement of a substance from an area of its higher concentration to one of lower concentration – down the concentration gradient. Certain molecules, for example glucose and ions move through the membrane by a passive transport process called facilitated diffusion. The transported substance either binds to protein carriers in the membrane and is ferried across or moves through water-filled protein channels. As with simple diffusion, the substance moves down the concentration gradient.
Osmosis occurs where a semi-permeable membrane (a membrane through which water can pass but some other particles cannot) separates two bodies of fluid. Plant and animal cell membranes are semi-permeable. As long as the number of particles or the concentration of ions in both of the cell compartments remains equal, osmosis helps to maintain that equalized state in each compartment. If particles are added to one compartment only, then the concentration is increased. The process of osmosis must be tightly controlled by cells, otherwise they will die. For example, if you place a red blood cell in pure (distilled) water, it will quickly take up water until it bursts. That is why plasma, the liquid portion of our blood…

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