Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    1
    ReputationRep:
    Hello.

    I've got my Biology unit 2 exam coming up on Monday,I think i'm okay with it all apart from Active Transport. I was wandering if you could help me a little bit by telling me what exactly it is please? In my book it says it's the process where a cell takes in molecules that have a higher concentration inside the cell than outside of it. So does this mean that inside the cell there is a high concentration and it gains more cells from active transport from outside the cell with a lower concentration?

    Or is it that there is a high concentration outside the cell and is moving into a cell with a lower concentration?

    Thanks in advanced, i'm really struggling with this!
    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    "Active transport is the mediated process of moving particles across a biological membrane against a concentration gradient. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient. Active transport uses energy, unlike passive transport, which does not use any energy."

    Basically there is a higher concentration of the substance inside of the cell, and a lower concentration outside. Therefore, the substance cannot diffuse down the concentration gradient, so the cell must actively uptake the substance outside of the cell via spending energy - such as a pump, which pumps certain substances in the cell, but uses energy to do so.
    Offline

    14
    ReputationRep:
    active transport at GCSE now? :s


    wow
    Offline

    0
    ReputationRep:
    The substance moves up its concentration gradient, i.e. there is a higher concentration of it inside the cell than outside.
    The particles hit the cell membrane by random movement, and using energy released by respiration, transport proteins in the cell membrane move the molecules across it.
    Hope that helps.
    Offline

    3
    ReputationRep:
    From what I remember, you don't have to know a lot about it. Or I certainly didn't

    It's likely a question will ask you to explain what is happened in a picture etc.

    When explaining just remember the points:
    active movement or requiring ATP energy
    against the concentration gradient
    across partially permeable membrane (maybe semi-permeable membrane, not sure on that, it was fine for me at GCSE but the A-level specification requires partially so maybe check with your teacher on this, depending on exam board etc.)

    Occasionally, I think they've asked for an example etc. - used to absorb glucose for example, in the small intestine.

    There will be a high concentration inside the cell, and it should also show molecules moving into the cell. If you have your head around diffusion, it's fairly similar.
    Offline

    0
    ReputationRep:
    At GCSE you only have to state what it means simply...when substances are absorbed against a concentration gradient ie...from low to high. The key is 'against a concentration gradient'
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by hannahradford)
    "Active transport is the mediated process of moving particles across a biological membrane against a concentration gradient. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient. Active transport uses energy, unlike passive transport, which does not use any energy."

    Basically there is a higher concentration of the substance inside of the cell, and a lower concentration outside. Therefore, the substance cannot diffuse down the concentration gradient, so the cell must actively uptake the substance outside of the cell via spending energy - such as a pump, which pumps certain substances in the cell, but uses energy to do so.
    (Original post by Justbuildingmydam)
    The substance moves up its concentration gradient, i.e. there is a higher concentration of it inside the cell than outside.
    The particles hit the cell membrane by random movement, and using energy released by respiration, transport proteins in the cell membrane move the molecules across it.
    Hope that helps.

    (Original post by Nymthae)
    From what I remember, you don't have to know a lot about it. Or I certainly didn't

    It's likely a question will ask you to explain what is happened in a picture etc.

    When explaining just remember the points:
    active movement or requiring ATP energy
    against the concentration gradient
    across partially permeable membrane (maybe semi-permeable membrane, not sure on that, it was fine for me at GCSE but the A-level specification requires partially so maybe check with your teacher on this, depending on exam board etc.)

    Occasionally, I think they've asked for an example etc. - used to absorb glucose for example, in the small intestine.

    There will be a high concentration inside the cell, and it should also show molecules moving into the cell. If you have your head around diffusion, it's fairly similar.



    Thank you for the help everybody, you've really cleared this up for me, +rep for your time, I can only rep once a day so I'll go in order of posting. Also this is a bit cheeky of me but I was wandering if you could also tell me if this is right?

    In Mitosis when it splits from a parent cell(23pairs) to make two daughter cells both have 23 pairs as well?
    Meiosis has 23 pairs but makes 4 non identical cells with only 23 single chromosomes?

    Again, Thank you:P

    Thanks for cl
    Offline

    0
    ReputationRep:
    (Original post by d_aan)
    Thank you for the help everybody, you've really cleared this up for me, +rep for your time, I can only rep once a day so I'll go in order of posting. Also this is a bit cheeky of me but I was wandering if you could also tell me if this is right?

    In Mitosis when it splits from a parent cell(23pairs) to make two daughter cells both have 23 pairs as well?
    Meiosis has 23 pairs but makes 4 non identical cells with only 23 single chromosomes?

    Again, Thank you:P

    Thanks for cl

    well in mitosis, it results in 2 identical cells being produced from the daughter cell- ie yes as they are identical, they both have 23 pairs
    with meiosis, before the cell divides, it makes a copy of all the chromosomes (ie a cell with 93 chromosomes) this cell then divides twice to form 4 sex cells each with inly 23 chromosomes (not pairs just single)
    had to dig out my old gcse book for this so i hope its right and ive not got it wrong :P but hope this helps
    Offline

    3
    ReputationRep:
    Mitosis - The cell has DNA number "n". The DNA is replicated so there are 2n chromosomes, then when the cell divides each daughter cell has n chromosomes (the same as originally started with) - genetically identical is your key point.

    Meiosis - Cell starts with "n" chromosomes, the result is 4 daughter cells with 1/2n chromosomes - not genetically identical.

    It's probable they won't ask you about human cell division - so read the question because humans are the only ones with 46 single chromosomes.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by _anum)
    well in mitosis, it results in 2 identical cells being produced from the daughter cell- ie yes as they are identical, they both have 23 pairs
    with meiosis, before the cell divides, it makes a copy of all the chromosomes (ie a cell with 93 chromosomes) this cell then divides twice to form 4 sex cells each with inly 23 chromosomes (not pairs just single)
    had to dig out my old gcse book for this so i hope its right and ive not got it wrong :P but hope this helps
    (Original post by Nymthae)
    Mitosis - The cell has DNA number "n". The DNA is replicated so there are 2n chromosomes, then when the cell divides each daughter cell has n chromosomes (the same as originally started with) - genetically identical is your key point.

    Meiosis - Cell starts with "n" chromosomes, the result is 4 daughter cells with 1/2n chromosomes - not genetically identical.

    It's probable they won't ask you about human cell division - so read the question because humans are the only ones with 46 single chromosomes.

    Ohh thank you both. Cheers for clearing this up as well for me.

    Okay I'll make a list who i need to rep because you all helped me out.



    hannahradford
    Justbuildingmydam
    Nymthae ( Thanks for helping me out both times, really appreciate this)
    _anum
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 23, 2010
Poll
Do I go to The Streets tomorrow night?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.