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Help Please With Some Questions

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Help Please With Some Questions

Postby matt100 » Wed May 09, 2007 12:35 pm

i know this is my first post but im having trouble finding good, quality answers on the internet, so can someone help me out with these questions?


1. Which organelle would be involved in active transport.
2. advantages and disadvantages of electron microscope over light microscope
3. Why does active transport require energy
4. Why is the cell theory important
5. Does difffusion not occur across a semi permeable membrane, and can i say thats one way in that its different from osmosis
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Postby Geordie Boy » Wed May 09, 2007 2:47 pm

What the hell is the cell theory?
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Postby canalon » Thu May 10, 2007 2:10 am

2-wave lengths and their link to separating power and colors.
3-Isn't that the definition of active transport? But if you think how passive transport works, that will tell you why you nee energy when it cannot work...
5-There is some diffusion across a semi-permeable membrane, but it is lmited, and it creates osmotic pressure. So you would have to be more precise
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Postby Dustfinger » Thu May 10, 2007 8:07 am

Cell theory by Schleiden and Schwann:
All living organisms consist of cells.
All cells are built out of cells. (Omnis cellula e cellula).
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Postby matt100 » Thu May 10, 2007 12:25 pm

thanks.

can you also help me with these.

if a freshwater protozoan was put in saltwater wat would happen?? would it expand or shrink

and if a RBC was taken out of its saline matrix and put into a medium freshawater wat would happen??
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Postby Dustfinger » Thu May 10, 2007 7:35 pm

The freshwater protozoan would shrink because the saltwater surroundings contain more ions than inside and water would move out.
With your RBC it's the other way round.
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Re: Help Please With Some Questions

Postby satrohraj » Sat May 12, 2007 2:24 pm

matt100 wrote:Why is the cell theory important


Cell theory is important because, its the base of all the biology we are having now.

Cell Theory

* The cell is the fundamental unit of structure and function in living things.
* All organisms are made up of one or more cells.
* All cells come from cells during cellular division.
* All cells are essentially the same in chemical composition.
* Energy flow (metabolism and biochemistry) occurs within cells.

This theory also contains two exceptions:

1. Viruses are considered by some to be alive, yet they are not made up of cells.
2. The first cell did not originate from a preexisting cell.



from Wikipedia
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Postby Geordie Boy » Thu May 17, 2007 7:50 pm

I have never heard of it described as a "theory" i don't really see anything theoretical about it.
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Postby Darby » Fri May 18, 2007 3:33 pm

It's biology - the rules that govern naming often aren't applied. Once something gets a label - hypothesis, theory, law - it often will hold that forever, even if the "rules" say it shouldn't.

Cell Theory is the closest to a classic law that biology has.

On the other question, I don't believe that most freshwater amebas are more dilute than marine environments (I know that vertebrates are, but I don't believe that protozoans followed that evolutionary path - could be wrong on this). There would be trouble with ion movement, but until that flux started up, probably no ionic issues
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Postby Funny_chap » Thu May 24, 2007 6:10 pm

Geordie Boy wrote:What the hell is the cell theory?


Cell Theory is something that needs to be learnt at AS Level Biology
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Postby Yazeed » Sun Jun 03, 2007 5:37 pm

3. Why does active transport require energy?

because it moves against the concentration gradient
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