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AQA Biology B2 - Unofficial Mark Scheme Watch

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    What did you guys put for the stem research questions?
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    (Original post by afghan-superman)
    The genotypes was the parents genotypes which were Bb and Bb. You were meant to put the offsprings genotypes in separately. And yes sorry, the gametes were XX and XY
    The gametes were as follows: B and b, and B and b. 'Gamete' does not refere to the genetics that determine gender. It refers to the cells (sperm/egg) that are haploid and carry a variated set of 23 single chromosomes, with genes from the mother and the father. In each one, only a single 'B' or 'b' could exist to influence the hair colour - the other would come from the other gamete from the sexual partner.

    So yea, gametes are: B / b on both (written separately).
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    (Original post by JakeHorsey)
    The gametes were as follows: B and b, and B and b. 'Gamete' does not refere to the genetics that determine gender. It refers to the cells (sperm/egg) that are haploid and carry a variated set of 23 single chromosomes, with genes from the mother and the father. In each one, only a single 'B' or 'b' could exist to influence the hair colour - the other would come from the other gamete from the sexual partner.

    So yea, gametes are: B / b on both (written separately).
    Yep, and 'bb' alleles for the offspring basically meant having red hair instead of brown. Making it a 25% chance of having red hair
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    (Original post by 11masanda002)
    how many marks were these questions worth?
    One mark each
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    For The mitosis It didnt double to 13.2. It said that they duplicated so it was stilll 6.6 so they then halved to 3.3 and then to 1.65.
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    (Original post by mmgnaahk123)
    I have completed the whole mark scheme except for 1 question worth 1 mark. I have also put all the mark allocations on. https://docs.google.com/document/d/1...p=docslist_api
    Hey there, have you made the b3 mark scheme?
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    (Original post by ajs12)
    0.25m^2 = 0.0625
    0.0625 * 10 = 0.625 <<<< 0.065 (what you have said as the area of one quadrat) is only 6.25cm squared??? Thats smaller than the sides of the quadrant???
    20/0.625 = 32

    There are 32 plantains in 10m^2, NOT 1 m^2

    5000/10=500
    500 * 32 = 16000
    Surely the plantain question is this:

    Total number of plantain in 10 quadrats: (add them together) = 20 plantains in 10 quadrats

    Area of 10 quadrats in metres squared: 1quadrat= 25x25 = 625cm squared
    Divide 625 by 100 to get it in metres = 6.25, then times by 10 for ten quadrats= area of ten quadrats is 62.5 metres squared.

    Average number of plantains per quadrat = 20 plantains in 10 quadrats so its 20/10 = 2 plantains per quadrat

    Area of field = 100 x 50 = 5000 metres squared

    Estimated number of plantains in field = the number of metres squared times by the average number of plantains per quadrat = 5000 x 2 = 10 000 plantains

    Even if you got a different value for the total number of plantains in 10 quadrats you could still do the mean number of plantains per quadrat x area of field...

    Is this right? It's so confusing...
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    (Original post by asox)
    Surely the plantain question is this:

    Total number of plantain in 10 quadrats: (add them together) = 20 plantains in 10 quadrats

    Area of 10 quadrats in metres squared: 1quadrat= 25x25 = 625cm squared
    Divide 625 by 100 to get it in metres = 6.25, then times by 10 for ten quadrats= area of ten quadrats is 62.5 metres squared.

    Average number of plantains per quadrat = 20 plantains in 10 quadrats so its 20/10 = 2 plantains per quadrat

    Area of field = 100 x 50 = 5000 metres squared

    Estimated number of plantains in field = the number of metres squared times by the average number of plantains per quadrat = 5000 x 2 = 10 000 plantains

    Even if you got a different value for the total number of plantains in 10 quadrats you could still do the mean number of plantains per quadrat x area of field...

    Is this right? It's so confusing...
    In the great scheme of things this all now seems somewhat insignificant, I think I also made a few more corrections later on, but 625 cm^2 is not 6.25m^2, its 0.0625m^2... according to Google, because you're working with areas not lengths you don't divide by 100 but instead 100^2, which is 10000
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    (Original post by Reykaif)
    For The mitosis It didnt double to 13.2. It said that they duplicated so it was stilll 6.6 so they then halved to 3.3 and then to 1.65.
    thats what i got too
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    (Original post by ajs12)
    In the great scheme of things this all now seems somewhat insignificant, I think I also made a few more corrections later on, but 625 cm^2 is not 6.25m^2, its 0.0625m^2... according to Google, because you're working with areas not lengths you don't divide by 100 but instead 100^2, which is 10000
    http://prntscr.com/bffiyk
    ???^

    edit// ohhh i get you
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    (Original post by Dauntless27)
    So you didn't mention anything about fatigue or lactic acid either? Do you think we will get the marks?
    noo not at all - i thought we'd get points for:
    -(smaller surface area so) less oxygen diffuses from air to alveoli
    -less oxygen delivered to cells so
    -less respiration happens, so less energy is released and they find it difficult to exercise

    reading all the other comments ha made me think this is wrong thoughh
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    For Question 7, didn't they say Cell A has 6.6? So Cell B must have 13.2 after DNA replication, Cell C should be 6.6 and the gametes at the bottom with 3.3 each. A normal cell has 6.6. Correct me if I'm wrong.
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    (Original post by Reykaif)
    For The mitosis It didnt double to 13.2. It said that they duplicated so it was stilll 6.6 so they then halved to 3.3 and then to 1.65.
    Duplication still means making a copy of all of its DNA, so 6.6 becomes 13.2 after the first stage (DNA replication). The gametes' DNA would combine to become 6.6, like a normal cell (same as Cell A). This means each gamete has DNA of 3.3 pictograms.
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    if u get a u in one paper and a c in the other 2 what grade do you get overall?
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    do you think any marks will be awarded for the mass of cells question. I basically lost 5 marks in that question ffs. I forgot that the cell dna duplicates and thus mass would be 13.2. Because i got that wrong I also got the others wrong. But will they allow error carried forward???

    also for the hair gametes question it wasn't asking about gender gametes so I didn't put XX and XY. However, lots of people on tsr are saying it was XX and XY
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    Does anyone know where you can get an unofficial mark scheme where it's complete ?
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    (Original post by asox)
    Surely the plantain question is this:

    Total number of plantain in 10 quadrats: (add them together) = 20 plantains in 10 quadrats

    Area of 10 quadrats in metres squared: 1quadrat= 25x25 = 625cm squared
    Divide 625 by 100 to get it in metres = 6.25, then times by 10 for ten quadrats= area of ten quadrats is 62.5 metres squared.

    Average number of plantains per quadrat = 20 plantains in 10 quadrats so its 20/10 = 2 plantains per quadrat

    Area of field = 100 x 50 = 5000 metres squared

    Estimated number of plantains in field = the number of metres squared times by the average number of plantains per quadrat = 5000 x 2 = 10 000 plantains

    Even if you got a different value for the total number of plantains in 10 quadrats you could still do the mean number of plantains per quadrat x area of field...

    Is this right? It's so confusing...
    I got all of them except from the area of 10 quadrats. I just put 625 times by 10 which is 6250
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    did any one had the full mark scheme for B2
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    (Original post by nisha.sri)
    I got all of them except from the area of 10 quadrats. I just put 625 times by 10 which is 6250
    When you convert 625cm squared to metres squared, you divide by 100*2 (hundred squared) because it is a compound unit.
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    (Original post by rihana.c)
    I did , I put it would still contain the diseased allele but I'm not sure if its right


    I put testicles instead of testes, same thing right???
    Yeah thats right
 
 
 
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