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    Well...in a nutshell my class are constantly shouting & talking over our teacher...so she either doesn't teach anything or ignores the few who want to do well and helps the others who talk over her..

    I got a 2 & a 7 for my prelim but I really want to do well..

    I'm understanding everything apart from the inheritance unit..it talks about stuff like genotypes & phenotypes...I don't understand the questions where it asks me to predict the first generation etc :/

    Would anyone be willing to help me? I'd really appreciate it as my exam is soon "yay"

    Also I can attach a picture of the questions later thanks



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    (Original post by g3ekchick)
    Well...in a nutshell my class are constantly shouting & talking over our teacher...so she either doesn't teach anything or ignores the few who want to do well and helps the others who talk over her..

    I got a 2 & a 7 for my prelim but I really want to do well..

    I'm understanding everything apart from the inheritance unit..it talks about stuff like genotypes & phenotypes...I don't understand the questions where it asks me to predict the first generation etc :/

    Would anyone be willing to help me? I'd really appreciate it as my exam is soon "yay"

    Also I can attach a picture of the questions later thanks



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    Sure, that's what we're all here for have you read over the relevant chapter in a text book? If you don't understand a specific question, post it up here and we'll try and help you with it.
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    (Original post by Eloades11)
    Sure, that's what we're all here for have you read over the relevant chapter in a text book? If you don't understand a specific question, post it up here and we'll try and help you with it.
    It's kinda silly the way our school does it...basically we get booklets were supposed to fill out ourselves but I was at a funeral the day we done it




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    (Original post by g3ekchick)
    It's kinda silly the way our school does it...basically we get booklets were supposed to fill out ourselves but I was at a funeral the day we done it




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    i did SG biology a few years ago, attach a picture and i'll see if i can help
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    Yep, we have lots of people in Study Help who'll be willing to help. There'll be lots of people on this forum who've studied biology at school, and Eloades and I are studying biology-related degrees, so we'd be more than happy to help.

    Post up whatever you're stuck on, or if you can give us an idea of what you're supposed to learn about, we'll be happy to tell you about it and give you some relevant resources.
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    (Original post by g3ekchick)
    It's kinda silly the way our school does it...basically we get booklets were supposed to fill out ourselves but I was at a funeral the day we done it




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    I see, is there a specific part on the booklet you're stuck on? Feel free to post the question up on this thread, or if you don't want others to see feel free to pm me, but it'll be easier for you to get help if more people help and provide input
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    Ok sorry for the late reply here are the pictures
    Name:  ImageUploadedByStudent Room1366045891.663142.jpg
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Size:  80.1 KBName:  ImageUploadedByStudent Room1366046303.176672.jpg
Views: 117
Size:  78.1 KB

    Sorry I know it is a lot but the help would be appreciated

    Thanks


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    Also if some if the previous answers I have written are wrong could anyone correct this? I didnt feel too confident when I answered them haha


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    (Original post by g3ekchick)
    Ok sorry for the late reply here are the pictures
    Name:  ImageUploadedByStudent Room1366045891.663142.jpg
Views: 103
Size:  80.1 KBName:  ImageUploadedByStudent Room1366046303.176672.jpg
Views: 117
Size:  78.1 KB

    Sorry I know it is a lot but the help would be appreciated

    Thanks


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    I've answered the questions on these first two pages for you, explaining myself as I go along. I don't know what you already know and what you need to know so sorry if I've pitched it at the wrong level. Hopefully once you've worked through these answers you'll be able to answer some of the other questions yourself

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    OK, in these questions we know that there are two parent (F0) types. They are true-breeding (and therefore homozygous - their alleles always match) tall and short. We know that the F1s (the offspring of mating a tall F0 and a short F0) are all tall - this must mean that the tall allele is dominant.

    The first question asks you for the genotype of the F0s - this is the alleles they carry (TT and tt), not the physically visible trait that you've described (tall and dwarf). It then asks for the genotype of the offspring, again you've given the phenotype. Here the answer is Tt - they will always have one allele from each parent and each parent only has one allele, therefore all the offspring will have one tall (T) allele and one dwarf (t) allele.

    Next you are asked for the ratio of phenotypes of the next generation (F2). We know that all the F1s are genotype Tt and they are going to be crossed with themselves. We can therefore draw a punnett square

    T t
    T TT Tt
    t Tt tt

    Here we have crossed two sets of Tt mice together to show the relative probabilities of the offspring having each genotype - 1/4 will be TT, 1/2 will be Tt and 1/4 will be tt. However the question asks for the phenotype! We know that all the F1s were tall and all had the Tt genotype - this must mean that the tall (T) allele is dominant and therefore as long as T is present they will be tall. The 1/4 that are TT will be tall, the 1/2 that are Tt will be tall and the 1/4 that are tt will be small. This gives us an expected ratio of 3 tall to 1 dwarf.

    The answer to the next question is that the 3:1 ratio is only a probability -there will be variation. Just like if you toss a coin - you'd expect a ratio of 1:1 heads:tails but if you tossed it 100 times and got 60 heads the probability wasn't wrong.

    On the next page - the first answer's correct, well done.

    The information that tells you the left-on-top gene is dominant is that the B is heterozygous - they have one allele of left and one allele of right. They have the left-on-top phenotype and therefore the left-on-top gene must be dominant to cancel out the right-on-top gene.
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    What we're not going to do is do your homework for you, or just tell you the answers, but hopefully - as Rob has done above - we can explain the concepts behind the questions, and then with that knowledge, you should be able to go on and answer the questions yourself. Rob has given a really good explanation for those two pages above, but I'll define some of his vocabulary for you:

    You know how you have two copies (alleles) of a gene? One from your mum, one from your dad?

    If the two alleles are the same (i.e. they both code for tall plants), then the genotype is homozygous (homo means the same).
    If the two alleles are different (i.e. one codes for tall, the other codes for dwarf), then the genotype is heterozygous (hetero means different).

    Genotype refers to the "genetic set" of a cell, and is usually used to refer to a specific characteristic. For example, if we have a T allele that codes for tall plants, and then we have t that codes for dwarf plants, then a dwarf plant has the genotype "tt". A heterozygous genotype would be "Tt", and a homozygous genotype would be "TT" or "tt".

    "Phenotype" refers to the physical characteristics that the genotype manifests itself as - it refers to the appearance of an organism. So "tall plant" is the phenotype of a plant with genotype TT or Tt, whereas "dwarf plant" is the phenotype of "tt".

    BBC bitesize has lots of good information on this stuff. I think you'll especially find the information on the monohybrid cross useful!

    Also here has a good slideshow on inheritance!
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    (Original post by Hype en Ecosse)
    What we're not going to do is do your homework for you, or just tell you the answers, but hopefully - as Rob has done above - we can explain the concepts behind the questions, and then with that knowledge, you should be able to go on and answer the questions yourself. Rob has given a really good explanation for those two pages above, but I'll define some of his vocabulary for you:

    You know how you have two copies (alleles) of a gene? One from your mum, one from your dad?

    If the two alleles are the same (i.e. they both code for tall plants), then the genotype is homozygous (homo means the same).
    If the two alleles are different (i.e. one codes for tall, the other codes for dwarf), then the genotype is heterozygous (hetero means different).

    Genotype refers to the "genetic set" of a cell, and is usually used to refer to a specific characteristic. For example, if we have a T allele that codes for tall plants, and then we have t that codes for dwarf plants, then a dwarf plant has the genotype "tt". A heterozygous genotype would be "Tt", and a homozygous genotype would be "TT" or "tt".

    "Phenotype" refers to the physical characteristics that the genotype manifests itself as - it refers to the appearance of an organism. So "tall plant" is the phenotype of a plant with genotype TT or Tt, whereas "dwarf plant" is the phenotype of "tt".

    BBC bitesize has lots of good information on this stuff. I think you'll especially find the information on the monohybrid cross useful!

    Also here has a good slideshow on inheritance!
    Thank you so much I understand it a lot better now


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