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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011 watch

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    (Original post by clairen886)

    How can a mutation cause cancer to develop?
    I actually don't know the answer to this.
    Care to share?
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    (Original post by Circadian_Rhythm)
    I was waiting for this thread

    Have some note babes:

    http://www.mediafire.com/?sunk9g8vdowk5ds

    Mitosis - phases
    Genetic Comparisons: DNA and proteins
    Biodiversity
    Antibiotics: mechanism +resistance
    Starch, Glycogen, Cellulose
    Haemoglobin (basic)
    Courtship behaviour - why is it necessary?


    Directly from NT aqa textbook, everything we need to know for those topics
    So vertical gene transmission does not involve conjugation? Makes sense, the textbook doesn't really specify though.
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    (Original post by SteveCrain)
    So vertical gene transmission does not involve conjugation? Makes sense, the textbook doesn't really specify though.
    Hmm
    Do you use the NT book?
    If so, it doesn't specify in that either!

    And for the Cancer, i think it's about the mutation as in the development of abnormal cells, effecting the cell cycle, making it an 'uncontrollable growth' or something.
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    (Original post by SteveCrain)
    I actually don't know the answer to this.
    Care to share?
    A mutation in the nucleotide base sequence of a protein could cause a frame shift. This will change the sequence of amino acids therefore the primary structure of the protein will change. This changes the tertiary structure. If the tertiary structure is changed it can create a non functional protein, if it happens in a tumour suppressor gene then cells will keep dividing uncontrollably forming a tumour.
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    Explain step of Mitosis in very specific detail (8 Marks) Ill answer this later

    Try and answer these questions as if in an exam, some of the previous answers look as though they are directly copied from the textbook :cool:

    Cheers and please quote any answers
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    (Original post by EffKayy)
    Hmm
    Do you use the NT book?
    If so, it doesn't specify in that either!

    And for the Cancer, i think it's about the mutation as in the development of abnormal cells, effecting the cell cycle, making it an 'uncontrollable growth' or something.
    Yeh I do; I think he's right in that vertical gene transmission doesn't involved conjugation because a) other generations of the same bacteria would have the same genes anyway b) I've been doing some revision on TB, and it has in brackets only "(horizontal gene transmission)" next to conjugation
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    (Original post by NinjaRikki)
    Explain step of Mitosis in very specific detail (8 Marks) Ill answer this later

    Try and answer these questions as if in an exam, some of the previous answers look as though they are directly copied from the textbook :cool:

    Cheers and please quote any answers
    Chromatids are replicated to form two identical sister chromatids joined at one centromere.

    These Chromosomes condense during Prophase, and the nuclear envelope disintegrates.

    During Metaphase, these chromosomes line up on the equator of the cell, and spindle fibres attach to their centromeres.

    During Anaphase, these spindle fibres shorten, pulling sister chromatids to the opposite poles of the cell.

    During Telophase, the spindle fibres disintegrate, nuclear envelope reforms and the chromatids become indistinct.

    Cytokenesis ensures.



    "Explain why the increased use of antibiotics leads to strains of bacteria resistant to multiple antibiotics."

    answer in the spoiler

    Spoiler:
    Show


    Increased use of antibiotics kills the least resistant strains of bacteria.
    Those with genes for resistance survive, and multiply due to the reduced competition- they have been selected.
    The alleles for antibiotic resistance increase in frequency in the population, as the genes are passed down to generations by vertical gene transmission.
    One strain can pass genes for antibiotic resistance to another strain by horizontal gene transmission.
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    (Original post by SteveCrain)
    So vertical gene transmission does not involve conjugation? Makes sense, the textbook doesn't really specify though.
    Sorry for the late response, no it doesn't it is normal reproduction for bacteria.
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    "Explain why the increased use of antibiotics leads to strains of bacteria resistant to multiple antibiotics."

    Antibiotic kill the bacteria which doesnt have the resistance gene
    bacteria which survive has resistance gene these survive and replicate passing on their R plasmid (vertical gene transmission)
    R plasmid can be passed on by horizontal gene transmission to bacteria which doesnt have the R plasmid by conjugation.

    Explain "the formation of tissue fluid and its return to the circulatory system" ( much detail as possible)
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    anyone got the AQA AS Biology Unit 2 18th January 2011 markscheme?
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    (Original post by Master S P)
    anyone got the AQA AS Biology Unit 2 18th January 2011 markscheme?
    http://www.sendspace.com/file/kl6h84
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    (Original post by leesh18)
    "Explain why the increased use of antibiotics leads to strains of bacteria resistant to multiple antibiotics."

    Antibiotic kill the bacteria which doesnt have the resistance gene
    bacteria which survive has resistance gene these survive and replicate passing on their R plasmid (vertical gene transmission)
    R plasmid can be passed on by horizontal gene transmission to bacteria which doesnt have the R plasmid by conjugation.

    Explain "the formation of tissue fluid and its return to the circulatory system" ( much detail as possible)
    Tissue fluid bathes the tissue cells outside the capillaries. Tissue fluid is forced out of capillaries due to high hydrostatic pressure at the arteriole end of the capillaries. Plasma proteins are too large to pass through the capillary wall, thus their concentration increases in the capillaries. Tissue fluid moves back into the capillary due to osmosis, as the WP gradient in the capillaries is lower than that outside. The hydrostatic pressure at the venule end of capillaries also forces tissue fluid back in. The tissue fluid that cannot be returned directly is returned to a vein via the lymph vessels, which carry the fluid when muscles contract and squeeze them.


    What are the three components of biodiversity and what do they each mean?
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    (Original post by SteveCrain)
    Tissue fluid bathes the tissue cells outside the capillaries. Tissue fluid is forced out of capillaries due to high hydrostatic pressure at the arteriole end of the capillaries. Plasma proteins are too large to pass through the capillary wall, thus their concentration increases in the capillaries. Tissue fluid moves back into the capillary due to osmosis, as the WP gradient in the capillaries is lower than that outside. The hydrostatic pressure at the venule end of capillaries also forces tissue fluid back in. The tissue fluid that cannot be returned directly is returned to a vein via the lymph vessels, which carry the fluid when muscles contract and squeeze them.


    What are the three components of biodiversity and what do they each mean?
    Ecosystem diverity - range of different habitats
    genetic diversity - variety of different genes possessed by individuals that make up any species
    Species diversity - number of different species and the number of individuals of each species within a community


    Explain the gas exchange system in fish and how maximum exchange is possible (6)
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    (Original post by EffKayy)
    Ecosystem diverity - range of different habitats
    genetic diversity - variety of different genes possessed by individuals that make up any species
    Species diversity - number of different species and the number of individuals of each species within a community


    Explain the gas exchange system in fish and how maximum exchange is possible (6)
    Water enters through the mouth and is forced over the gills. The rate of diffusion of O2 from the water into the blood is increased due to numerous gill filaments and numerous gill lamellae. The gill lamellae have a single thin epithelium cell, so diffusion pathway is short. Conc gradient is maintained by the constant introduction of water with a high O2 concentration, and the constant removal of blood with a high O2 conc. Countercurrent flow, in which the conc of O2 is always higher in the water than in the waters equivalent section of blood, allows diffusion gradient to be maintained over the entire length of the gill.

    Describe the structure of haemoglobin
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    (Original post by SteveCrain)
    Water enters through the mouth and is forced over the gills. The rate of diffusion of O2 from the water into the blood is increased due to numerous gill filaments and numerous gill lamellae. The gill lamellae have a single thin epithelium cell, so diffusion pathway is short. Conc gradient is maintained by the constant introduction of water with a high O2 concentration, and the constant removal of blood with a high O2 conc. Countercurrent flow, in which the conc of O2 is always higher in the water than in the waters equivalent section of blood, allows diffusion gradient to be maintained over the entire length of the gill.

    Describe the structure of haemoglobin
    It has a quaternary structure of 4 polypeptide chains, linked to form a spherical molecule. Each chain associated with a haem group (containing a ferrous Fe2+ ion) each of which can combine with 1 oxygen molecule.

    Write the formula to work out magnification ?

    (I know this isn't in this section of the course but it's been in a couple of unit 2 past papers).
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    Magnification=Image/Object

    How is the structure of cellulose related to its function in cell walls?
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    (Original post by SteveCrain)
    Tissue fluid bathes the tissue cells outside the capillaries. Tissue fluid is forced out of capillaries due to high hydrostatic pressure at the arteriole end of the capillaries. Plasma proteins are too large to pass through the capillary wall, thus their concentration increases in the capillaries. Tissue fluid moves back into the capillary due to osmosis, as the WP gradient in the capillaries is lower than that outside. The hydrostatic pressure at the venule end of capillaries also forces tissue fluid back in. The tissue fluid that cannot be returned directly is returned to a vein via the lymph vessels, which carry the fluid when muscles contract and squeeze them.


    What are the three components of biodiversity and what do they each mean?
    Are you guys sitting unit 1 aswell?
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    (Original post by clairen886)
    Magnification=Image/Object

    How is the structure of cellulose related to its function in cell walls?
    Cellulose is a polysaccharide formed of long linear, unbranched chains of B-glucose, which is the same as alpha glucose except the hydrogen and hydroxyl groups on the 6th carbon are the opposite way round. It also forms hydrogen bonds between adjacent chains of B-glucose, these bonds having an accumulative effect which makes cellulose very strong and resistant to large amounts of material stress and give it rigidity which allows a cell to remain rigid and strong in places where such properties are required, such as in prokaryotic cells and in plants.
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    (Original post by Master S P)
    Are you guys sitting unit 1 aswell?
    Nope not me
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    (Original post by Circadian_Rhythm)
    I was waiting for this thread

    Have some note babes:

    http://www.mediafire.com/?sunk9g8vdowk5ds

    Mitosis - phases
    Genetic Comparisons: DNA and proteins
    Biodiversity
    Antibiotics: mechanism +resistance
    Starch, Glycogen, Cellulose
    Haemoglobin (basic)
    Courtship behaviour - why is it necessary?


    Directly from NT aqa textbook, everything we need to know for those topics
    you are amazing!!!! thank you !!!! btw any chance you might have biol1 notes?? thanks again!
 
 
 
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