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solutions A and B are separated by a semipermeable membrane, solution A contains 1 mM sucrose and 1 mM urea. solution B contains 1 mM sucrose. the reflection coefficient for sucrose is one and the reflection coefficient for urea is zero. which of the following statements is correct?
a- solution A has higher effective osmotic pressure than sol B
b-sol A has lower effective osmotic pressure than sol B
c-sol a and B are isoosmotic
d-sol A is hyperosmotic with respect to sol B ;and the solutions are isotonic
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cuz the urea penetrates the membrane slowly so the amount of urea becomes equal in both A and B......hence the answer is CCCCC
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bump, for more ppl to contribute..
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effective osmolarity depends on non-penetrating substance. Sucrose, manitol, inulin are non-penetrating substances. Urea is rapidly penetrating substance. Glycerol is slowly penetrating substance. Both A and B are hypo-osmotic because their osmolarity
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effective osmolarity depends on non-penetrating substance. Sucrose, manitol, inulin are non-penetrating substances. Urea is rapidly penetrating substance. Glycerol is slowly penetrating substance. Both A and B are hypo-osmotic because their osmolarity less than 300 mOsml, however, they have the same effective osmolarity. I choose C with caution.
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guys can you explain wat reflection coefficient is??
otherwise its CCC
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"Effective Osmotic Pressure" depends on
1-Concentration of solute particles
2-The EXTENT to which a solute crosses the membrane represented as R.Coefficient(RC).
RC ranges from 0 to 1
*o = membrane is freely permeable to solute
*1 = membrane is complete Impermeable to solute
*b/w 0 and 1 = somewhat permeable to solute
In the stem it says RC for urea is "0" , which means it is freely permeable----so it will diffuse thru the membrane and will equalize on both sides hence not participating in Effective Osmotic pressure.
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sorry for posting the answer late folks:
the correct answer is DDDD..
relfection coefficient is a number between 0 and 1, that describes the ease with which a solute permeates a membrane. so if the reflection coefficient is one, the solute is impermeable, if its 0, the solute is completely permeable..
getting back to the answer:
solution A contains both sucrose and urea at concentrations of 1mM, whereas solution B contains only sucrose at a concentration of 1mM.. the calculates osmolarity for solution A is : osm=g*c (g: number of particles in solution, c: is the concentration) so, osm = 2*1 = 2, however the calculated osm for solution B is only 1.
therefore, solution A is hyperosmolar with respect to solution B.
now: BOTH solutions A and B have the same effective osmotic pressure, so they are isotonic, because the only effective solute is sucrose which has the same concentrations in both A and B, however, urea is not an effective osmole, because its highly permeable..
in summary, two terms that we have to know here: isoosmotic means equal osmolarity, and isotonic, means equal effective osmotic pressures...
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this is crazy...got the concept now . thanks er12 
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