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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 353764 times)

Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1560 on: May 23, 2010, 01:27:07 pm »
Quote from: guMnam on May 23, 2010, 01:26:12 pm
okay is this organ transplant thingy in our syllabus

yup very much .. u wanna know abt it ??
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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1561 on: May 23, 2010, 01:30:15 pm »
Quote from: ~VIN1094~ on May 23, 2010, 01:27:07 pm
yup very much .. u wanna know abt it ??
not really...my doubt is tht y do the antibiotics only efect bacteria nad not viruses ///???
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Offline ambitious94

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1562 on: May 23, 2010, 01:32:58 pm »
Quote from: guMnam on May 23, 2010, 01:30:15 pm
not really...my doubt is tht y do the antibiotics only efect bacteria nad not viruses ///???

Antibiotics prevent the bacterial cell wall from developing hence preventing bacterial growth. however, viruses do not have cell walls, so the antibiotics do not attack them.
This came in Paper 6...It ain't coming tom, for sure!

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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1563 on: May 23, 2010, 01:34:20 pm »
Quote from: ambitious94 on May 23, 2010, 01:32:58 pm
Antibiotics prevent the bacterial cell wall from developing hence preventing bacterial growth. however, viruses do not have cell walls, so the antibiotics do not attack them.
This came in Paper 6...It ain't coming tom, for sure!


haha i noe it wont come again just had a doubt...Thanks aneways
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Offline ambitious94

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1564 on: May 23, 2010, 01:35:10 pm »
Explain why food chains have fewer than 5 trophic levels.

The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1565 on: May 23, 2010, 01:41:58 pm »
 chem doubt
sumtyms for mcqs dey ask which 1 is a reversible reaction <n the forwd n bckwrd rctn arrows are not dere  >
hw do we noe which 1 is a revesible rctn???????
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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1566 on: May 23, 2010, 01:42:35 pm »
Quote from: ambitious94 on May 23, 2010, 01:35:10 pm
Explain why food chains have fewer than 5 trophic levels.

The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(
for a 2 mark q...this should work...this is becaz the energy in the chain produced by the producers is lost at each trophic level and by the tyme it reaches the 5th it is all used up..so there wont be enough energy left for an other level :)
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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1567 on: May 23, 2010, 01:43:12 pm »
Quote from: 6394 on May 23, 2010, 01:41:58 pm
chem doubt
sumtyms for mcqs dey ask which 1 is a reversible reaction <n the forwd n bckwrd rctn arrows are not dere  >
hw do we noe which 1 is a revesible rctn???????
can u give example plz..
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1568 on: May 23, 2010, 01:43:46 pm »
Quote from: ambitious94 on May 23, 2010, 01:35:10 pm
Explain why food chains have fewer than 5 trophic levels.

The answer's pretty obvious, but can anyone explain this in a manner fit for an IG paper. XD
Man I hate ecology :(

lol its is the 'stupid' answer .. because energy is lost in huge amounts as you go up the trophic levels, due to metabolism, heat loss n stuff .. further down the chain suppose 6 level .. u hav to eat LOTS of food !!!  ;)
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Offline Raywin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1569 on: May 23, 2010, 01:45:49 pm »
Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1570 on: May 23, 2010, 01:47:49 pm »
Quote from: guMnam on May 23, 2010, 01:43:12 pm
can u give example plz..

reaction of nitrogen and hydrogen
usually all decomposition carbonate reactions are reversible
sulfur dioxide and oxygen reaction to form SO3
oxygen to ozone .. many ..
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1571 on: May 23, 2010, 01:51:21 pm »
Quote from: Raywin on May 23, 2010, 01:45:49 pm
Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D

You should be able to learn this.
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1572 on: May 23, 2010, 01:52:43 pm »
Quote from: Raywin on May 23, 2010, 01:45:49 pm
Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D

YES !!


http://www.bbc.co.uk/schools/gcsebitesize/geography/population/
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1573 on: May 23, 2010, 01:56:43 pm »
Quote from: Raywin on May 23, 2010, 01:45:49 pm
Hey guys, do v need to learn a sigmoid curve or something? Like its phases and everything? If yes can someone explain it? Thanks a lot! :D

I'll give you an example of phases in bacterial growth.

Lag phase:  When doubling of the numbers has little effect as the numbers are so small.  Bacteria take up water and nutrients, make new cytoplasm, DNA and enzymes.

Log phase:  When the population is increasing rapidly.  The populatoin increases by doubling and there are no limiting factors, such as food or water.

Stationary phase:  When bacterial cells are dying at the same rate at which they are being produced.  This may be because of shortage of food or because waste products are building up.

Death phase:  When more cells are dying than are being produced, so the population declines.  Causes of death may be lack of food, shortage of oxygen or a build-up of toxic waster products.

Hope that helps!
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Always willing to help!  8)
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Offline ambitious94

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1574 on: May 23, 2010, 01:58:45 pm »
Quote from: guMnam on May 23, 2010, 01:42:35 pm
for a 2 mark q...this should work...this is becaz the energy in the chain produced by the producers is lost at each trophic level and by the tyme it reaches the 5th it is all used up..so there wont be enough energy left for an other level :)
thanks :)
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