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Edexcel 6BIO7/01 (International Unit 3B) ~ 7th May 2013 ~ AS Biology Watch

  • View Poll Results: Which practical do you expect? ~Biology unit 3 May 7~
    Daphnia (effect of caffeine on heart beat rate)
    13.51%
    Test for vitamin C
    16.22%
    Membrane permeability (Beetroot)
    24.32%
    Enzyme concentration
    16.22%
    Mitosis (Onion root cell)
    75.68%
    Tissue culture
    10.81%
    Tensile strength of plant fibres
    10.81%
    Mineral deficiencies
    10.81%
    Antimicrobial properties of plants
    21.62%

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    i think da answer to the last qn is fr da same reason as the first qn..

    heyyy guys.. in jan 13 i drew a smooth curve . is it ok.. .. n can ne1 give me jan13 mark scheme...
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    (Original post by Relaxedexams)
    No. They ask you to compare, so have to draw in one graph.

    Ps:- was late to post graph

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    but even if i drew 2, wont it be a comparison?
    and for the experiments, i onlt learnt the process for antibacterial and root tip ... i dun thnk they ll ask the process? did u learn the processes of all experiments?
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    for the Mitosis Experiment. Is it 12 hours or 12 Minutes. Because I got like a pile of sheets with some experiments of my teacher. The method is exactly the same as yours but it says 12 hours?!
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    Few Questions on Mitosis Experiment. Really hard imo. Can anyone answer?

    a) Use stage micrometer and eyepiece graticule make appropriate measurements to allow you to compare the size of interphase cells with those that are undergoing cytoplasmic division. Comment on your finding?
    b)Explain how you ensured, or could ensure, that the results are i) reliable ii) valid

    Explain the safety precautions during this practical?

    The cellulose walls of plant cells are held together by a cement called the middle lamella. Treatment with hydrochloric Acid breaks this down. Why is this helpful in your preparations?

    You may have found few dividing cells in your root tips. Suggest possible reasons?
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    NilFBosh do i need to learn the methods of each experiment?????? like place test tube of 2cm3 .............
    but for observing mitosis i learnt the method from my revision guide, so is it enough???
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    how will we knw what type of graph we should draw? how will we know if its a bar graph, line or curve? can we draw the lines with a scale? and if a point is out of the way, are we supposed to join it aswell?
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    (Original post by NilFBosh)
    Yes. Cause they said reference 3 is a complete and suitable bibliography. So you have to write it just like ref 3. So in ref 3 address wasn't there. So no need address of the publisher. Basically in any bibliography don't write any address.


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    So will i lose a mrk if i write the address


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    (Original post by Daniel Atieh)
    nice job! i dun hv to learn this process ryt???:eek:
    also they shud not be opened again MAYBE cauz of escape of bacteria (if present haha) i dunno rlly
    Can't say really. It's safer to have atleast a brief idea about each procedure.
    So for this experiment, a summary could be:

    Obtain seeds > germinate them > cut off tissue > place in agar gel, under lighted conditions > roots, shoots and leaves develop > totipotency of plant cells is proven.

    Yeah, that could be a reason not to open it again. Thanks
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    guys for the barchar t does the bars have to touch each other or we have to leave spaces between them ??
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    i know dt we increase reliability by repeating. so we repeat with different root tips from the same plant.

    i think we mk experiments valid by cross checking with literature survey (results on the same experiment done by well known labs or organisations). peer reviewd journals or comparing results with other students who did the the experiment with us..
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    blazingfire can i say cross checking with peer reviewed journals? and? (not the students one)
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    (Original post by bluebubbles_10)
    how will we knw what type of graph we should draw? how will we know if its a bar graph, line or curve? can we draw the lines with a scale? and if a point is out of the way, are we supposed to join it aswell?
    The type of graph can be determined from the type of data given.
    Mostly, it's either a line graph or bar graph (I've never had to draw curves in any past paper before )
    Yeah, when drawing a line graph, use a scale, and join every point.

    As for the type of data
    -line graphs are usually for trends involving continuous data, like effect of caffeine concentration on heart rate. Both concentration and heart rate are continuous, meaning they can have any value.

    -bar graphs are usually for trends involving discrete date, like diameter of inhibition zones for different plants(when investigating antimicrobial properties)
    The 'type of plant' is discrete data, it cannot take any "value";
    le.g. the plant can be either "garlic" or "onion" there is nothing in between.

    I hope I didn't confuse you
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    (Original post by elfajare)
    guys for the barchar t does the bars have to touch each other or we have to leave spaces between them ??
    You have to leave spaces between the bars.
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    thank u!
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    SKK94 can u explain to me the meaning of implications and hw to write abt it ? i cant get it rlly
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    WHAT IS THE MEANING OF FALSE POSITIVE AND FALSE NEGATIVE IN UNIT 1 ...i forgot...any one plz
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    Just wondering, chances of mineral deficiencies?

    Just need to have a good night's sleep and wake up tomorrow to try my best... as far as I'm concerned, no more revision from me tonight...
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    (Original post by Daniel Atieh)
    SKK94 can u explain to me the meaning of implications and hw to write abt it ? i cant get it rlly
    Ok, the implications we have to be able to identify are social, ethical, environmental and economical.
    An implication is an idea that is hinted at, in the article.
    social- involves the people, or society
    ethical - involves morals(whether something is right or wrong morally)
    environmental - involves the environment
    economical - involves the economy, basically cost, money, expense etc.

    so if they say, stem cell therapy reduces cost of medicines for patients, it is an economical implication, because it involves money.
    or if they say the use of fertilizers pollutes the rivers, it is an environmental implication.
    so on and so forth. Hope you get it (Y)
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    (Original post by Daniel Atieh)
    WHAT IS THE MEANING OF FALSE POSITIVE AND FALSE NEGATIVE IN UNIT 1 ...i forgot...any one plz
    Let me try explaining with an example:

    A patient undergoes a brain scan to see if he has a tumour

    If the scan shows there is a tumour, but actually, there is not, it is called a false positive result.
    the scan showed positive for presence of a tumour
    but in reality, the result is false because there is no tumour in the patient

    Now if the scan shows there is no tumour, but in reality, there is a tumour, it is called a false negative result.
    The scan showed negative for presence of a tumour
    but in reality, the result is false because the is a tumour in the patient
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    (Original post by gimme those exams)
    Few Questions on Mitosis Experiment. Really hard imo. Can anyone answer?

    a) Use stage micrometer and eyepiece graticule make appropriate measurements to allow you to compare the size of interphase cells with those that are undergoing cytoplasmic division. Comment on your finding?
    b)Explain how you ensured, or could ensure, that the results are i) reliable ii) valid

    Explain the safety precautions during this practical?

    The cellulose walls of plant cells are held together by a cement called the middle lamella. Treatment with hydrochloric Acid breaks this down. Why is this helpful in your preparations?



    You may have found few dividing cells in your root tips. Suggest possible reasons?

    a- ??
    b-i) repeat and take a mean ii)??
    Wear gloves when handling acid and cut the roots with caution keep away from fingers .
    when the middle lamella breaks down the layer of cells will only be one cell thick for easier observation through the microscope.
    Because some divide at different rates.
 
 
 
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