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    (Original post by confusedgirl22)
    I was going through the January 2010 paper and i came across a question related to reverse transcriptase?
    I swear this isn't in the specification and i also checked the CGP book and it isn't there.
    I'm worried now? :/
    I think that we just need to know that it is used in the conversion of viral RNA to DNA during the infection of a cell by a virus, but not how it works.
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    (Original post by Brad0440)
    I think that we just need to know that it is used in the conversion of viral RNA to DNA during the infection of a cell by a virus, but not how it works.

    thank you! don't you think it's weird that they did that though?
    i'm worried they'll ask something else that isn't the specification now!
    and i still won't know what kind of question will need this answer :/
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    (Original post by confusedgirl22)
    I was going through the January 2010 paper and i came across a question related to reverse transcriptase?
    I swear this isn't in the specification and i also checked the CGP book and it isn't there.
    I'm worried now? :/
    Which question are you on about?
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    (Original post by confusedgirl22)
    thank you! don't you think it's weird that they did that though?
    i'm worried they'll ask something else that isn't the specification now!
    and i still won't know what kind of question will need this answer :/
    Is this for question 6C ii? If so, I think that for things like reverse transcriptase and other things that we don't need to know in detail, it is more likely that they will just be marking points as opposed to whole questions by themselves (like in 6c ii).
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    (Original post by Sravya)
    Which question are you on about?
    January 2010
    6c ii and iii
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    Wha are the argumens against global warming? In terms of why CO2 and Methane dont contribute?

    Also what is a classic answer for speciation have to include?
    I always write geographical isolation, leads to different environmental conditions thus there are increased selective pressures which leads to mutations so that you can adapt and breed therefore survive. If mutation is beneficial it is passed onto the offspring, Which leads to a change in allele frequencies in the different gene pools. This means there is reproductive isolation and a restricted gene flow therefor speciation.
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    Could someone talk me through the core practical for hatching brine shrimps? I have no recollection of doing it at college whatsoever.
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    (Original post by nukethemaly)
    Could someone talk me through the core practical for hatching brine shrimps? I have no recollection of doing it at college whatsoever.
    The actual experiment:
    you get an equal number of brine shrimp eggs and put into water baths of different temperatures. You have to keep other variables constant such as oxygen volume of water etc. Then leave for a couple of hours and then record the number of brine shrimp that have hatched. You can calculate the rate they have hatched by using the formula...number of hatched shrimp divded by the number of hours you left them.

    The reason for doing the experiment:
    This experiment shows how an increase in temperature due to global warming can effect animals such as brine shrimp.
    Bear in mind that after a certain temperature the brine shrimp will not hatch because the enzymes substrate complex will be damaged and they will denature. But in general they follow a classic enzyme graph.

    You may have done a similar experiment on seedling growth rate..this is virtually the same but you grow seeds in different temperatures and measure the change in height
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    do we need to know about the different types of reproductive barriers.. I have loads of notes on it but its no where in the syllabus that we need to know the different types
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    Could someone also go through the points of how HIV infects the human body?
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    (Original post by Sravya)
    The actual experiment:
    you get an equal number of brine shrimp eggs and put into water baths of different temperatures. You have to keep other variables constant such as oxygen volume of water etc. Then leave for a couple of hours and then record the number of brine shrimp that have hatched. You can calculate the rate they have hatched by using the formula...number of hatched shrimp divded by the number of hours you left them.

    The reason for doing the experiment:
    This experiment shows how an increase in temperature due to global warming can effect animals such as brine shrimp.
    Bear in mind that after a certain temperature the brine shrimp will not hatch because the enzymes substrate complex will be damaged and they will denature. But in general they follow a classic enzyme graph.

    You may have done a similar experiment on seedling growth rate..this is virtually the same but you grow seeds in different temperatures and measure the change in height
    Thank you! What's the optimum temperature they hatch at?
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    (Original post by Sravya)
    do we need to know about the different types of reproductive barriers.. I have loads of notes on it but its no where in the syllabus that we need to know the different types
    I think you do in the sense that they can literally give you any setting that the species are in, so you need to be able to apply it!
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    (Original post by nukethemaly)
    Thank you! What's the optimum temperature they hatch at?
    I think its 30 degrees but dont quote me..but i dont think you need to know it
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    (Original post by Sravya)
    Wha are the argumens against global warming? In terms of why CO2 and Methane dont contribute?

    Also what is a classic answer for speciation have to include?
    I always write geographical isolation, leads to different environmental conditions thus there are increased selective pressures which leads to mutations so that you can adapt and breed therefore survive. If mutation is beneficial it is passed onto the offspring, Which leads to a change in allele frequencies in the different gene pools. This means there is reproductive isolation and a restricted gene flow therefor speciation.
    Yep, yours is correct, I write this:
    Speciation:
    · Geographical isolation happens when a physical barrier divides a population of a species – floods, volcanic eruptions, and earthquakes can all cause barriers that isolate some individuals from the main population
    · Conditions on either side of the barrier will be slightly different. For example, there may be different climate on each side. This will lead to selection pressures.
    · Since the environment is different on each side, different characteristics (phenotypes) will become more common due to natural selection:
    Ø Because different characteristics will be advantageous on each side, the allele frequencies will each change in each population, eg: if one allele is more advantageous on one side of the barrier, the frequency of that allele on that side will increase
    Ø Mutations will take place independently in each population, also changing the allele frequencies
    Ø The change in allele frequencies will lead to changes in phenotype frequencies, eg – the advantageous characteristics (phenotypes) will become more common on that side
    · Eventually individuals from different populations will have changed so much that they won’t be able to breed with one another to produce fertile offspring (definition of species) – they’ll have become reproductively isolated
    · The two groups will have become separate species
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    (Original post by Sravya)
    I think its 30 degrees but dont quote me..but i dont think you need to know it
    Ah okay, thank you!
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    (Original post by nukethemaly)
    Yep, yours is correct, I write this:
    Speciation:
    · Geographical isolation happens when a physical barrier divides a population of a species – floods, volcanic eruptions, and earthquakes can all cause barriers that isolate some individuals from the main population
    · Conditions on either side of the barrier will be slightly different. For example, there may be different climate on each side. This will lead to selection pressures.
    · Since the environment is different on each side, different characteristics (phenotypes) will become more common due to natural selection:
    Ø Because different characteristics will be advantageous on each side, the allele frequencies will each change in each population, eg: if one allele is more advantageous on one side of the barrier, the frequency of that allele on that side will increase
    Ø Mutations will take place independently in each population, also changing the allele frequencies
    Ø The change in allele frequencies will lead to changes in phenotype frequencies, eg – the advantageous characteristics (phenotypes) will become more common on that side
    · Eventually individuals from different populations will have changed so much that they won’t be able to breed with one another to produce fertile offspring (definition of species) – they’ll have become reproductively isolated
    · The two groups will have become separate species
    Wow thats amazing...THANKYOU!
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    (Original post by nukethemaly)
    Could someone talk me through the core practical for hatching brine shrimps? I have no recollection of doing it at college whatsoever.
    Basically, it is about finding the effect of temperature on the hatch rate of brine shrimp eggs.
    Independent variable: Temperature
    Dependent variable: Hatch rate

    Procedure:
    1. Take 5 beakers and fill them with equal volumes of salt solution. Label each beaker with temperature ( 5oC, 20oC, 30oC, 35oC, 40oC)
    2. Place a pinch of brine shrimp eggs on a white card
    3. Wet some graph paper and place it over the eggs. Use a magnifying glass to count 40 eggs (cut off some of it so that 40 eggs are present)
    4. Place the graph paper on the solution for 5oC (egg-side facing into the solution) Leave for 3 mins. and remove the paper.
    5. Place the beaker in a thermostatically controlled water bath (set at 5oC) for 24 hrs.
    6. After 24 hrs, place a lamp near the beaker and count the number of eggs hatched.
    7. Calculate hatch rate (no. of eggs hatched/no. of hours)
    8. Carry out experiment for all temperatures. Repeat twice for each temperature and calculate average hatch rate.

    Controlled variables:
    - Concentration of salt solution
    - No. of eggs used
    - same batch of brine shrimp eggs
    - time kept in water bath

    Hope this helped
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    (Original post by SKK94)
    Basically, it is about finding the effect of temperature on the hatch rate of brine shrimp eggs.
    Independent variable: Temperature
    Dependent variable: Hatch rate

    Procedure:
    1. Take 5 beakers and fill them with equal volumes of salt solution. Label each beaker with temperature ( 5oC, 20oC, 30oC, 35oC, 40oC)
    2. Place a pinch of brine shrimp eggs on a white card
    3. Wet some graph paper and place it over the eggs. Use a magnifying glass to count 40 eggs (cut off some of it so that 40 eggs are present)
    4. Place the graph paper on the solution for 5oC (egg-side facing into the solution) Leave for 3 mins. and remove the paper.
    5. Place the beaker in a thermostatically controlled water bath (set at 5oC) for 24 hrs.
    6. After 24 hrs, place a lamp near the beaker and count the number of eggs hatched.
    7. Calculate hatch rate (no. of eggs hatched/no. of hours)
    8. Carry out experiment for all temperatures. Repeat twice for each temperature and calculate average hatch rate.

    Controlled variables:
    - Concentration of salt solution
    - No. of eggs used
    - same batch of brine shrimp eggs
    - time kept in water bath

    Hope this helped
    I think you've successfully been everyone's savior today!

    Would you please be able to talk me through how the HIV virus infects the body?
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    (Original post by SKK94)
    Basically, it is about finding the effect of temperature on the hatch rate of brine shrimp eggs.
    Independent variable: Temperature
    Dependent variable: Hatch rate

    Procedure:
    1. Take 5 beakers and fill them with equal volumes of salt solution. Label each beaker with temperature ( 5oC, 20oC, 30oC, 35oC, 40oC)
    2. Place a pinch of brine shrimp eggs on a white card
    3. Wet some graph paper and place it over the eggs. Use a magnifying glass to count 40 eggs (cut off some of it so that 40 eggs are present)
    4. Place the graph paper on the solution for 5oC (egg-side facing into the solution) Leave for 3 mins. and remove the paper.
    5. Place the beaker in a thermostatically controlled water bath (set at 5oC) for 24 hrs.
    6. After 24 hrs, place a lamp near the beaker and count the number of eggs hatched.
    7. Calculate hatch rate (no. of eggs hatched/no. of hours)
    8. Carry out experiment for all temperatures. Repeat twice for each temperature and calculate average hatch rate.

    Controlled variables:
    - Concentration of salt solution
    - No. of eggs used
    - same batch of brine shrimp eggs
    - time kept in water bath

    Hope this helped
    Also if its not too much to ask would you mind making something similar for the antibiotics effectiveness experiment?
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    Could someone explain DNA transcription/ translation..including what happens with the exons and the introns..and what is post transcriptional change?
 
 
 
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