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    How does the entomologist use insects to find the time of a death?can anyone explain it to me in a clear and conise way so that I NEVER forget.
    This is what I already know.
    They collect the eggs,maggots and pupa from a death body.And they find the time when it hatched on the body?
    How do they use this then to find the time of the death
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    (Original post by Maria1234)
    How does the entomologist use insects to find the time of a death?can anyone explain it to me in a clear and conise way so that I NEVER forget.
    This is what I already know.
    They collect the eggs,maggots and pupa from a death body.And they find the time when it hatched on the body?
    How do they use this then to find the time of the death
    It's not just collecting eggs, maggots, pupae and adults. Entomologists have knowledge about which species invade dead bodies and they know WHEN adults invade corpses. Some species will invade a dead body as soon as it dies and some will do so for hours after. Knowledge of how long it takes for invasion helps entomologist to determine when the eggs were laid.

    Additionally, these entomologists also have knowledge of the life cycle of these invading insects and they know how long each cycle lasts. So if they see a certain stage (egg, maggots, pupa, whatever) on a body, they can deduce how long it took to get to that stage.

    So it all just has to do with patterns of invading and lengths of life cycles.

    EDIT: Here's an example.

    Suppose Fly X invades a dead body 2 days after death and you know the following about the life cycle of Fly X

    Eggs are laid
    Larvae develop after 1 day
    Pupae develop after larvae reach a maturity of 1 day
    Pupae require 2 days to mature into adult Fly X.

    Suppose an entomologist finds pupae on a dead body, what can he conclude? Well, it would have taken 2 days for Fly X to arrive and lay eggs, 1 day for larvae to develop from eggs and another day for pupae to develop. Pupae take 2 days to mature, so the youngest pupa can be under 2 days (I guess you can assess whether the pupae are "old/young" based on appearance).

    So time of death could have been a minimum of 4 days and a maximum of 5/just under 6 days ago based just on this evidence.
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    Hey guys - when b-cells become APCs do they actually engulf the bacterium and become APCs like macrophages or is there some sort of better explanation. The orange book seems to be verry vague
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    okk thnsx
    (Original post by Iron&Wine)
    It's not just collecting eggs, maggots, pupae and adults. Entomologists have knowledge about which species invade dead bodies and they know WHEN adults invade corpses. Some species will invade a dead body as soon as it dies and some will do so for hours after. Knowledge of how long it takes for invasion helps entomologist to determine when the eggs were laid.

    Additionally, these entomologists also have knowledge of the life cycle of these invading insects and they know how long each cycle lasts. So if they see a certain stage (egg, maggots, pupa, whatever) on a body, they can deduce how long it took to get to that stage.

    So it all just has to do with patterns of invading and lengths of life cycles.

    EDIT: Here's an example.

    Suppose Fly X invades a dead body 2 days after death and you know the following about the life cycle of Fly X

    Eggs are laid
    Larvae develop after 1 day
    Pupae develop after larvae reach a maturity of 1 day
    Pupae require 2 days to mature into adult Fly X.

    Suppose an entomologist finds pupae on a dead body, what can he conclude? Well, it would have taken 2 days for Fly X to arrive and lay eggs, 1 day for larvae to develop from eggs and another day for pupae to develop. Pupae take 2 days to mature, so the youngest pupa can be under 2 days (I guess you can assess whether the pupae are "old/young" based on appearance).

    So time of death could have been a minimum of 4 days and a maximum of 5/just under 6 days ago based just on this evidence.
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    Download Edexcel Biology Revision Guide from here:

    http://www.megaupload.com/?d=L7S7O1TM
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    guys how do they use 'molecular clocks' as evidence for evolution?
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    U need to pay to download it?
    what is it?
    is it a CGP revision guide?
    (Original post by Vampire-Love4ever)
    Download Edexcel Biology Revision Guide from here:

    http://www.megaupload.com/?d=L7S7O1TM
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    (Original post by Maria1234)
    U need to pay to download it?
    what is it?
    is it a CGP revision guide?
    It's free. Edexcel revision guide.
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    (Original post by Vampire-Love4ever)
    Download Edexcel Biology Revision Guide from here:

    http://www.megaupload.com/?d=L7S7O1TM
    Thanks for the link - I already have this book as a hard copy but I have found it useful for more 'in depth' explainations so would recommend it to others
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    (Original post by Vampire-Love4ever)
    Download Edexcel Biology Revision Guide from here:

    http://www.megaupload.com/?d=L7S7O1TM
    Thanks for this
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    (Original post by JP83)
    Thanks for the link - I already have this book as a hard copy but I have found it useful for more 'in depth' explainations so would recommend it to others

    (Original post by InItToWinItGetIt?)
    Thanks for this
    Welcome!
    It'd be nice if you all could send the link to others who might be in need of this.
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    (Original post by angel1992)
    basically am stuck on genetics part. If a gene codes for a specific polypeptide chain how can you have different alleles which are the same gene because different alelles have different polypeptide chains( they usually have one amino acid thats different) and that would therefore make them different genes

    Is it that the differences are so small, i.e. one amino acid difference still makes it the same polypeptide chain?

    very confused
    any ideas or explanation would be helpful?basically am stuck on genetics part. If a gene codes for a specific polypeptide chain how can you have different alleles which are the same gene because different alelles have different polypeptide chains( they usually have one amino acid thats different) and that would therefore make them different genes

    Is it that the differences are so small, i.e. one amino acid difference still makes it the same polypeptide chain?

    very confused
    any ideas or explanation would be helpful?
    A gene will code for a specific polypeptide chain which may contribute towards a characteristic. An allele is an alternate version of the gene. A gene that contributes towards hair colour for example may have alleles that would lead to either light or dark hair. The cystic fibrosis allele codes for a defective transmembrane protein as opposed to a working protein. It is my understanding that the change in the polypeptide chain may be very small but it may provide variation such as alleles that help determine height, eye colour, hair colour etc, or the variation may make a functioning protein dysfunctional as in the case of CF.

    This is just my understanding, I'm happy to be corrected if someone else has a deeper understanding of this topic.
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    does anybody here have the pastpaper from Januray 2011 for unit 4?? pls send it to me if you do have it! thank you!!
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    it's allright peeps, i found it here, just missed the somebodys post! thanks!
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    (Original post by Vampire-Love4ever)
    Welcome!
    It'd be nice if you all could send the link to others who might be in need of this.
    Yeah will post it on the unit 5 thread. Thanks again, the book looks really good.
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    (Original post by Vampire-Love4ever)
    Download Edexcel Biology Revision Guide from here:

    http://www.megaupload.com/?d=L7S7O1TM
    Thanks!
    hey umm have yu got a link for fyzx?
    Lol i noe this is not a fyzx thread, but if yu have plz post!
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    (Original post by Samia99)
    Thanks!
    hey umm have yu got a link for fyzx?
    Lol i noe this is not a fyzx thread, but if yu have plz post!
    I have posted the link on the physics thread, please check it.
    (Original post by InItToWinItGetIt?)
    Yeah will post it on the unit 5 thread. Thanks again, the book looks really good.
    Welcome! Good luck!
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    hellow poeple does anyone no where i can get handouts/questions based on 6bio5??oh please poeple if you knoew let me no cuz i im sick from pastpapers they are not helpfull,most of them contain questions that is not in the sylabus at al.
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    (Original post by hassib)
    hellow poeple does anyone no where i can get handouts/questions based on 6bio5??oh please poeple if you knoew let me no cuz i im sick from pastpapers they are not helpfull,most of them contain questions that is not in the sylabus at al.
    this is very true!
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    (Original post by hassib)
    hellow poeple does anyone no where i can get handouts/questions based on 6bio5??oh please poeple if you knoew let me no cuz i im sick from pastpapers they are not helpfull,most of them contain questions that is not in the sylabus at al.
    dude do you mean 6bio4? because 6bio5 is not this thread. And yes you are absoloutely correct. Old spec Past papers are not useful for biology because the specification has completely changed!! I got an A for Unit 5 but never got an A in any of the old spec mocks I done prior to the actual exam.
 
 
 
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