HSA-2011-maria-12

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1st Annual School-wide VIRTUAL SCIENCE FAIR

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10. Background Research Paper

For most updated instructions and requirements of this assignment, please click here.

Once you are ready to work on your assignment, click Edit (or the pen icon) located at top right corner, then start to type below.
For step number 6 i created some question that can be tested.

1-For each of the bags, indentify whether the solution inside was hypertonic , hypotonic or isotonic in comparison to the beaker solution it was placed in.
2-Which bag increased the most in volume?Why?
3-What does this tell you about the relative tonicity between the contents of the bag solution in  the beaker?
4-What would happen if the bag 1 is placed in a beaker of distilled water?

On step 7 I found information in websites.


On step 8 I researched information of osmosis. 

A major determinant of diffusion in a biological system is membrane permeobility. Small, uncharged
molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass
through the membrane.
 
Osmosis occurs when a membrane separates solutions of different concentrations.
The membrane allows the solvent to pass through, but not the solutes. Ultimately, membrane
selectivity and the movement of water in and out of the cell regulates the concentration of intracellular
material.
 ln the context of a cell, the intracellular and extracellular fluids are the solvents which
contain dissolved material (solutes).

Tonicity is a relative term used to describe osmotic pressure of two solutions separated by a semipermeable
membrane.

- A hypertonic solution contains a greater concentration of solutes unable to cross the membrane
compared to the solution on the other side of the membrane.

- A hypotonic solution contains a lower concentration of solutes unable to cross the membrane
compared to the solution on the other side of the membrane.

- An isotonic solution has an equal concentration of impermeable solutes on both sides of the
semi-permeable membrane.

When osmosis takes place, water flows from hypotonic solutions to hypertonic solutions, until the solutions
become isotonic.
 lf placed in pure water, they will burst (lyse) as a result of the increased pressure on the
membrane from the additional water that diffused into the cell.
Osmotic pressure (the force required to prevent osmosis) is directly correlated with tonicity (higher
tonicity causes an increase in osmotic pressure).
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