IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: 247sports on May 22, 2010, 10:44:03 am

Title: BIOLOGY AS LEVEL---doubts
Post by: 247sports on May 22, 2010, 10:44:03 am
wt the organells which we can view from an electron microscope n the organells that we cant ???

this is imp thnk you to any one who replies n answers my question
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 10:53:29 am
You Can View Anything With An Electron Microscope. You Mean What Can't Be Viewed Except With An Electron Microscope Right?
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: abuyusef on May 22, 2010, 11:30:49 am
everything can be seen using an electron microscope ... while light microscope can view nucleus +cytoplasm +cell wall+cell membrane+chloroplast +starch
Plant cell under light microscope  (http://www.saburchill.com/IBbiology/ICT/images/031007001.jpg)
Animal cell (http://upload.wikimedia.org/wikibooks/en/thumb/d/d5/Anatomy_and_physiology_of_animals_an_animal_cell.jpg/400px-Anatomy_and_physiology_of_animals_an_animal_cell.jpg)
while under electron microscope
Animal cell (http://upload.wikimedia.org/wikibooks/en/e/e6/Anatomy_and_physiology_of_animals_animal_cell_electron_microscope.jpg)
Plant cell (http://www.google.co.il/imgres?imgurl=http://2.bp.blogspot.com/_9ydCglR0YGc/SaurnenXtcI/AAAAAAAAAx0/1efshG-Fbsw/s400/Animal-Cell.jpg&imgrefurl=http://firebrands-irri.blogspot.com/2009/03/upacara-perasmian-pembukaan-kumpulan.html&usg=__3DI38l8aJ2IawZ89np9dhekFKk4=&h=397&w=400&sz=45&hl=en&start=18&sig2=KOnYW7sPYHmsGtSkTtG90Q&itbs=1&tbnid=dr5dmuHimClT7M:&tbnh=123&tbnw=124&prev=/images%3Fq%3Dplant%2Bcell%2Bunder%2Belectron%2Bmicroscope%26hl%3Den%26sa%3DG%26tbs%3Disch:1&ei=S7P3S46pJcKe_AaBtbzECg)

Remember my friend .... Google is your friend!
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 11:35:56 am
im sorry but this is wrong, You cant view a cell membrane by electron microscope
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: abuyusef on May 22, 2010, 11:38:22 am
IT can't be seen it's electron microscope!!!!!!!!  ??? ... it's plasma membrane right
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: abuyusef on May 22, 2010, 11:39:32 am
http://upload.wikimedia.org/wikipedia/commons/a/ae/Plant_cell_structure_svg.svg
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: AS-Girl on May 22, 2010, 12:05:07 pm
im sorry but this is wrong, You cant view a cell membrane by electron microscope

yes u can!! cell membrane is 7nm and the electron microscope can view anything which is 0.5nm and above!!
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 12:42:54 pm
im sorry i meant you cant see it with a light microscope because he said you can view cell membranes with light microscope, false:)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 01:01:21 pm
im sorry i meant you cant see it with a light microscope because he said you can view cell membranes with light microscope, false:)

you can, but only the outlines, but u cant see what its made off with a light microscope!
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 01:06:03 pm
exactly, alah 3alek ya nash ;)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 01:08:55 pm
exactly, alah 3alek ya nash ;)

hahaha ;)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: abuyusef on May 22, 2010, 01:41:38 pm
wein wallah spy! .... keef 7alak ... hada inta 3arbi!
 
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 02:17:12 pm
ah*
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 03:03:53 pm
since nobody is answering it on student doubts::

Q 21, jun 07

why is it 20 ??? ??? ???   
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 04:44:03 pm
Nashhhh
it told you its double strand with 120 nucleotides ya3ni 60 in each. and mRNA is copied of one only. which means itself kaman its 60.

and when tRNA comes, its uses each three for one amino acid ya3ni total 60/3=20 amino acids in one polypeptide

;)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 05:16:11 pm
Nashhhh
it told you its double strand with 120 nucleotides ya3ni 60 in each. and mRNA is copied of one only. which means itself kaman its 60.

and when tRNA comes, its uses each three for one amino acid ya3ni total 60/3=20 amino acids in one polypeptide

;)

now i get it, bas when did u ever tell me that?? :P
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 05:17:25 pm
:) hahaha i didnt say i told you that, i said IT told you that. a7wal :P
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 05:24:46 pm
:) hahaha i didnt say i told you that, i said IT told you that. a7wal :P

hahaha, i need to start sleepin more!!
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 05:29:31 pm
exactly :P

wala nov 09 variant 2, question 15 its supposed to be B why is it A -.-
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 05:41:59 pm
exactly :P

wala nov 09 variant 2, question 15 its supposed to be B why is it A -.-

for the fist part its talkin about difference in cells at X in solution Y compared to the same cells in
solution W
cell  which is in Y is not coiled so that means that its less negative ( 3ashan there are not alot of solutes dissolved in Cell X, we kaman 3ashan if it was more negative in Y, cell X would coil up like in solution W)
second part: solution Y is less negative 3ashan it does not have alot of solutes dissolved in it unlike solution W ( which caused cell X to coil)

if u didnt understand tell me and i will give u a different example, ok ? ;)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 05:51:09 pm
ana fahem 2awal part. bas eno if water has been diffused into the leaf, then the water potential has to drop in the solution which means now it should have less water ya3ni more negative?
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 06:04:19 pm
ana fahem 2awal part. bas eno if water has been diffused into the leaf, then the water potential has to drop in the solution which means now it should have less water ya3ni more negative?

ok look if u read the question carefully it tells u that u put cell X in solution W FIRST then moved the cell after it coiled into solution Y so difference in cells at X in solution Y compared to the same cells insolution W is less negative ( u know this part), the second part asks u the difference in solution Y
compared to solution W ( y3ni wat caused the cell to coil in solution W and uncoil in solution Y )
so that means that the water potential in W is more negative causing water to diffuse out the cell, while in solution Y water potential was LESS NEGATIVE as compared to the inside of the cell so water moved in!!

do u get it now?? ;)
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: [Spy] on May 22, 2010, 06:23:41 pm
ohhhhhhhhhhh
so its asking the potential of the solutions BEFORE the actual diffusion occurs hahaha i thought eno what is the potential after water diffuses into the cells :P

bas thanks bro <3
Title: Re: BIOLOGY AS LEVEL---doubts
Post by: unknown 101 on May 22, 2010, 06:24:59 pm
ohhhhhhhhhhh
so its asking the potential of the solutions BEFORE the actual diffusion occurs hahaha i thought eno what is the potential after water diffuses into the cells :P

bas thanks bro <3

hahaha when i fist read it i also could confused by that part, but then i got it

anytime 7bb <3