What is the defination of "Isotonic point"?

Question

I am looking for a defination of the "Isotonic point" of Osmosis in Potato chips.

Answer 1

Isotonic literally translates to equal solution. The term is used in several domains.

Cell biology:
An isotonic cellular environment occurs when an equal solute concentration exists inside and outside the cell. Water molecules flow in and out at an equal rate by osmosis, causing the cell size to stay the same. It will not lose or gain any solutes. Plant cells in an isotonic environment are flaccid, and they will wither. The equilibrium of water movement is unable to provide plant cells with internal pressure for structural support, and therefore plants prefer to live in a hypotonic environment. In this situation, the concentration of solutes inside plant cells is higher than outside, and the plants use active transport to transport solutes in. This also ensures the concentration of water will be higher outside plant cells than inside.


Osmosis in Plants:
Plants depend on osmosis to move water from their roots to their leaves. The further toward the edge or the top of the plant, the greater the solute concentration, which creates a difference in osmotic pressure. This is known as osmotic potential, which draws water upward. In addition, osmosis protects leaves against losing water through evaporation.

Crucial to the operation of osmosis in plants are "guard cells," specialized cells dispersed along the surface of the leaves. Each pair of guard cells surrounds a stoma, or pore, controlling its ability to open and thus release moisture.

In some situations, external stimuli such as sunlight may cause the guard cells to draw in potassium from other cells. This leads to an increase in osmotic potential: the guard cell becomes like a person who has eaten a dry biscuit, and is now desperate for a drink of water to wash it down. As a result of its increased osmotic potential, the guard cell eventually takes on water through osmosis. The guard cells then swell with water, opening the stomata and increasing the rate of gas exchange through them. The outcome of this action is an increase in the rate of photosynthesis and plant growth.

When there is a water shortage, however, other cells transmit signals to the guard cells that cause them to release their potassium. This decreases their osmotic potential, and water passes out of the guard cells to the thirsty cells around them. At the same time, the resultant shrinkage in the guard cells closes the stomata, decreasing the rate at which water transpires through them and preventing the plant from wilting.

http://www.answers.com/isotonic&r=67

Answer 2

The isotonic point is the point where the concentration of the solution is the same as the concentration of the cell. It means that there is equal amounts of 'free' water (not bound to solutes) in the solution and the potato.
If you weighed a potato chip before placing it in this solution, then reweighed it after leaving it for say 20 minutes, the potato chip will not have changed in mass.

If you need to find it from an osmosis experiment, you would probably put potatoes chips in a range of different solutions e.g 0-2M sucrose. If you weigh each potato before then after and work out the change in mass, then plot the concentration against the mass, you will find that as conc of sucrose increases the mass decreases. The graph will have some chips that have gained mass in low concs and some chips that have lost mass in higher concs. If you place a line of best fit through the plots in the graph. The isotonic point is the point where the trend line hits 0 on the mass change. You can work out the conc which is the isotonic point.

Answer 3

Isotonic Point

Answer 4

"Tonicity is the effective osmolality and is equal to the sum of the concentrations of the solutes which have the capacity to exert an osmotic force across the membrane."
BE CAREFUL: solutes which can diffuse FREELY through the membrane DO NOT exert an osmotic force and thus do not contribute in tonicity.

According to
http://www.anaesthesiamcq.com/FluidBook/fl2_3.php

So the isotonic point is the concentration of solutes or osmotic pressure for which the effective osmolality of the cell is equal to that of its environment.
You can read more details in the above link , especially in order to differentiate between effective osmolality and osmolality in general.

Answer 5

1

Answer 6

isotonic point is when the concentraion outside the cell is equivalent to the concentration inside the cell.

Answer 7

well i am not sure what you mean but isotonic is when something is at equilibrium.

Answer 8

it is the point where you have similar concentration of salts in certain solution relative to a comparator solution.

like 0.9 for normal saline relative to blood in humans.