Author Topic: ALL CIE BIOLOGY DOUBTS HERE !!!  (Read 74556 times)

Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #255 on: May 29, 2011, 10:53:13 am »
"An eye for an eye, only makes the whole world go blind."

-Gandhi

Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #256 on: May 30, 2011, 12:18:49 pm »
How to show synaptic knob in a myelinated sensory neurone? !
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Offline Master_Key

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #257 on: May 30, 2011, 02:09:15 pm »
How to show synaptic knob in a myelinated sensory neurone? !
You can show the synapse at the transmitting end to intermediate neuron. Use a cleft in diagram to show it.

Offline Sue T

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #258 on: May 31, 2011, 07:45:42 am »
Specimen Paper 4, Q8 part (a) and (ci). For part a, I attached the MS answer but it makes no sense and part ci how do we do the calculation?
my dear you are looking at the wrong marking scheme hehehehehe - here ive attached th right one - hope it clears things up ;)
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Offline Sue T

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #259 on: May 31, 2011, 07:55:04 am »
Knowledge is knowing a tomato is a fruit; Wisdom is not putting it in fruit salad.

Offline Sue T

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #260 on: May 31, 2011, 08:05:31 am »
From Oct/Nov '05
*Q1b
look at the cycle in your text book, how after citrate, you go directly to a 6C intermediate - now after this, th 6C intermediate changes into a 5C sugar after being decarboxylated and dehydrogenated by NAD - the next step also there is decarboxyyy and dehydrogennaa. also, they have included not only th krebs cycle but the link reaction as well - remeber there is decarboxylation and dehydrogenation in th link reaction so, you'll put in th labels at three sites (attached). dehydrogenation is the removal of the hydrogen which here is done by NAD or FAD - so there are two more sites for dehydrogenation also... hope im clear...
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Offline Sue T

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #261 on: May 31, 2011, 08:22:12 am »
From Oct/Nov '05
*Q1b
*Q2a- don't know how to do (getting stuck in between) & we get the chi square value as 1.8 and so answers to part d & e doesn't make much sense! :S

so they've described the offsprings and from the appearance of the numbers you should no this 9:3:3:1 ratio is typical of two heterozygous-for-both-alleles type of parent - ive attached th working.. incomplete though
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Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #262 on: May 31, 2011, 09:39:07 am »
Thank youuuuuuuuu, Sue T!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! <3
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Offline Sue T

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #263 on: May 31, 2011, 12:03:56 pm »
From Oct/Nov '05
*Q2a- don't know how to do (getting stuck in between) & we get the chi square value as 1.8 and so answers to part d & e doesn't make much sense! :S


you got a value of 1.8 and in the chi table the values increase as the probability decreases - so - 1.8 lies at a probabilty greater than 0.05 ryt? then once u've established that you say tht the fact that th probability is grater than .05 then, the diffferences between the observed and expected values are insig and only due 2 chance - so the expected ratio of offspring 9:3:3:1 is observed and the assumptions u made (as in th parents being heterozygous) are correct ;)
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Offline da_rockstar

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #264 on: May 31, 2011, 12:14:07 pm »
is there any need to go through t test, standard error and standard deviation for paper 4? cuz i haven't seen any questions from there in paper 4's yet. just thought i'd ask and double check.... :D

Offline poisonedrose

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #265 on: May 31, 2011, 08:43:19 pm »
OctNov06- number 2.. How is it done? ._. It seems to be so confusing!

Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #266 on: May 31, 2011, 09:20:30 pm »
OctNov06- number 2.. How is it done? ._. It seems to be so confusing!

Which paper?
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Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #267 on: May 31, 2011, 09:48:04 pm »
IF YOU ARE DOING PAPER 4 (which I'll assume you are :p)

Anyways, I hope you see this- poisonedrose!

See the attachments! (I hope it's clear enough)

Explanation: As the question mentions, a cross between two dogs with copper hair tips always produces copper hair tips- meaning it must be homozygous recessive. As only one allele is being expressed.
A cross with two black dogs will produce off springs SOME with red hair tip & copper hair tip (some black off springs too). Meaning both the parents must be heterozygous.


I am sorry if my explanation isn't clear enough! :$

Re-read the question and I am sure you'll get it!
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Offline poisonedrose

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #268 on: May 31, 2011, 10:37:04 pm »
:) you're amazing. Thank you so much.
After reading the question.. 6?7? times, with your explanation, I finally got it.
Time to hit the hay however.
Good luck all of you guys here :)

Offline Vampire-Love4ever

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Re: ALL CIE BIOLOGY DOUBTS HERE !!!
« Reply #269 on: June 01, 2011, 12:59:21 am »
Welcome! ;) Good luck!
"An eye for an eye, only makes the whole world go blind."

-Gandhi