SAC CONFUSION

[khalil]

hello,
we just did a experiment on core of potatoes placed in solutions of different concentration of NACL.. 0.5, 1,3,5...
 
a bit of confusion i would like to clear up...

1. Does salt go through the membrane? ? or is it just water???

2. In distilled water, does the weight of the poatoe increase slightly?

3. in the concentrations of Nacl... as the concentration increase, does the weight of the mass decrease.. due to osmosis... (poatoes has high conc of water hence moves out??)

4. does isotonic occur.. when both are equal and everything stay the same?

and these questions following are likely sac questions based on the sac... says the teachers... which is hint these are the questions!

5.Purpose  of experimental control

6. Suggest a set up that could have been used as a control for this experiment and explain why this control was unesessary for this experiment

thx.. if you could help.. i realli want to do well in this subject since im doing so crap in others... and it's really annoying when no one at school can answer your questions.. espicaly teachers!!!!aRGhgggg

[jackinthepatch]

1. Mainly water. In this prac all you should talk about is the water.

2. Yes

3. Yes, the more concentrated the NaCl solution, the greater loss in mass of the potato

4. Yes there is a point, you work that out by graphing your results and looking at the point in the graph where there is no gain or loss in mass of the potato

5. The control in an experiment is basically used as a means to compare results with, to see if changing the variable had any effect on the results

6. Control would have been potato placed in a solution with the same NaCl concentration as the potato

[khalil]

but, when drawing the graph...those that have decreased we put on the - y axis,, rite//? so would x intercept be when it is isotonic.. if say for example distilled water increased by 7.2%, 0.5 concentration decreased by 22%, 1 concentration decreased by 24% (3)  25% (5) 33%... for the distilled watter, would that be the intercept of positive y axis?

i would draw the graph for you, but don't noe how to on this site!!

[hard]

go paint > draw > save > photobucket > upload > IMG code > copy here

[jackinthepatch]

I would label the y-axis as Percentage Mass Gained Or Lost, and I would have the numbers on the y-axis ranging from -33 to 7.2. Or something like that. Then on the x-axis you would put the concentration of NaCl.

Then, plot the graph, and work out the concentration of NaCl where 0% mass is gained or lost.

[khalil]

where's photo bucket??

[hard]

http://photobucket.com/ just sign up

[khalil]

okai.. i upload.. now what do i do???

[khalil]

[IMG]http://i624.photobucket

[khalil]

hmm dont seem to be seeing a graph..

[khalil]

anways.. jack.. didn't answer my question... so "imagine u plotted the grap".. from the graph.. can the isotonic solution be when the graph pass through the x intercept... as that is when the y intercept.. meaning % decrease or increase of mass is 0?

and q6 wasn't all answered..u missed the part..".explain why this control was unesessary for this experiment""... sorri if i seem fusy.. but thx.. for ur other answers realli appreciate it!


also also.. wat does treatment and control group mean?

[khalil]

oh another question!!!!!

but answer the first  one i post first.. dont' forget about them!!!!

"plants obtain inorganic nutrients from soil, however the concentration of nutrients in soil usually 100 times less than the concentration of nutrients inside the roots of a plant. Explain how plants take up the inorganic nutrients including name given to process

[TrueLight]

wild guess.... a type of active transport system is used, where energy is used!? am i right oO lol  and another wild guess is it supposed to be volume of water against concentration of NaCl and the graph is like a slope high to low....... and i didn't even read ur question properly so im probably wrong