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    hey im struggling with succession!! can someone please help me out?
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    (Original post by SKK94)
    What is clonal selection??
    I'm finding it hard to put in words

    Is it in the specification?? i dont think so. why dont u use the specification to revise now? i mean as we dont hve much time
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    (Original post by raves)
    hey im struggling with succession!! can someone please help me out?
    Succession occurs when pioneer species arrive and grow in environments where there isn't any life. They break up the rocks and add organic matter into the little/ no soil that is present. This changes the soil structure and allows it to retain water.Due to this more species of plant arrive begin to grow in the newly made soil. They change the soil structure/environment and attract other species. As new species arrive the older species tend to get out competed, this carries on until a stable climax community is achieved. A dominant species (usually the most abdundant/ largest) also establish. Correct me if wrong guys.
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    thank you! i understand it now
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    (Original post by raves)
    hey im struggling with succession!! can someone please help me out?
    It is the gradual change in structure and species composition in a community.
    There are two types:
    - Primary
    - Secondary

    Primary succession:
    - starts with bare rock
    - pioneer species like lichen/moss appear
    - they grow, with time filling up small cracks/holes in the rock
    - the rocks start breaking down ( sometimes with the help of erosion as well) - organic matter starts to collect
    - eventually forming humus (organic matter that cannot be broken down further)
    - humus soon becomes soil
    - this allows for more species, like grass to grow and develop roots
    - as more water and nutrients collect in the soil, bigger plants can grow, like trees etc.
    - finally a climax community is formed.

    Features of a climax community:
    - made up of species of animals and plants
    - maximum biodiversity is reached
    - biodiversity remains constants until an interruption (e.g natural disaster, human activity)

    Secondary succession:
    - similar to primary succession
    - but starts off with soil, instead of rock
    - occurs after major damage to the habitat (fire, natural disaster etc)

    Note:
    *a climax community formed due human intervention is known as a plagioclimax
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    (Original post by tsr1)
    could some explain the correlation value and the critical values... it was asked in jan 2013 paper? question 6cii?
    have u done unit 6B ?

    critical value is the value beyond which we reject the null hypthesis.
    correlation value or calculated value is what we get from the experimet we do by T test or U test. (if u havent done unit 6b already, i dont think u will understand anything im saying) for example, the critical value given is 1, and if the calculated value we get is more than 1, then we reject the null hypothesis, meaning the is no significant correlation between the 2 variables we are measuring.
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    (Original post by SKK94)
    No, they can be involved in phagocytosis as well. Labelling done by antibodies help phagocytes detect and engulf pathogens faster.
    Lysosomes are organelles that contain hydrolytic enzymes (like lysozymes)
    These lysosomes fuse with vacuoles carrying the bacteria and release the lysozymes, which then digest the bacteria.
    Thanks a lot but shouldn't lysosome also get the mark since the text book does mention that it is the lysosome that fuses with vacuoles?
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    (Original post by iwantopas19)
    have u done unit 6B ?

    critical value is the value beyond which we reject the null hypthesis.
    correlation value or calculated value is what we get from the experimet we do by T test or U test. (if u havent done unit 6b already, i dont think u will understand anything im saying) for example, the critical value given is 1, and if the calculated value we get is more than 1, then we reject the null hypothesis, meaning the is no significant correlation between the 2 variables we are measuring.
    yep, just remembered it... had forgotten it. thanks
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    Can someone give me the sequence of the specific immune response please listed in bullet points from the mark scheme as i dont want to understand what goes on i just want to memorise
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    whats the difference between photophosphorylation and chemiosmosis? the chemiosmosis is when the H+ ions move back to the stroma and convert the ADP to ATP but isn't the photophosphorylation the same thing?
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    (Original post by Huntx)
    ****ing hell I have a clash between bio 4 and Eco 4. Mother****
    Me too. I don't understand why exams on the same exam board clash! :mad:
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    (Original post by tsr1)
    whats the difference between photophosphorylation and chemiosmosis? the chemiosmosis is when the H+ ions move back to the stroma and convert the ADP to ATP but isn't the photophosphorylation the same thing?
    Photophosphorylation: When light is used to add a phosphate to a molecule.

    Chemiosmosis: When H ions released from Reduced NAD and FAD are pumped out of mitochondria into the stroma using the enzyme ATP Synthase, thus synthesising ADP + Pi to ATP (ATP synthesis)
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    (Original post by [email protected])
    Thanks a lot but shouldn't lysosome also get the mark since the text book does mention that it is the lysosome that fuses with vacuoles?
    Yeah it does, but the statement in the question is that "H is released into the vacuole..." right?
    Lysozymes are released into the vacuole when the lysosomes fuse with them(the vacuole). So H = Lysozymes
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    (Original post by Selym95)
    Chemiosmosis: When H ions released from Reduced NAD and FAD are pumped out of mitochondria into the stroma using the enzyme ATP Synthase, thus synthesising ADP + Pi to ATP (ATP synthesis)
    Isn't this chemiosmosis during cellular respiration?
    I thought in photosynthesis, the H ions from reduced NADP are pumped out of the thylakoids into the stroma?
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    What the difference between lysosome and lysozyme?


    Posted from TSR Mobile
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    (Original post by AHarris)
    What the difference between lysosome and lysozyme?


    Posted from TSR Mobile
    Lysosome is the vacuole that the digestive enzyme lysozyme is inside. LysoZYME is an enZYME. LysosOME is their hOME.
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    (Original post by AHarris)
    What the difference between lysosome and lysozyme?


    Posted from TSR Mobile
    Lysosomes are organelles that contain powerful enzymes to assist in destroying cellular debris and the breakdown of proteins. Lysozymes are one of the proteolytic enzymes found in lysosomes that catalyze (breakdown) the protein wall of bacteria, especially gram positive bacteria, making lysozymes a vital part of our first-line defense against bacterial infection.
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    (Original post by Lgambo)
    Lysosome is the vacuole that the digestive enzyme lysozyme is inside. LysoZYME is an enZYME. LysosOME is their hOME.
    (Original post by EstebanK0)
    Lysosomes are organelles that contain powerful enzymes to assist in destroying cellular debris and the breakdown of proteins. Lysozymes are one of the proteolytic enzymes found in lysosomes that catalyze (breakdown) the protein wall of bacteria, especially gram positive bacteria, making lysozymes a vital part of our first-line defense against bacterial infection.
    thank you!
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    (Original post by Selym95)
    Photophosphorylation: When light is used to add a phosphate to a molecule.

    Chemiosmosis: When H ions released from Reduced NAD and FAD are pumped out of mitochondria into the stroma using the enzyme ATP Synthase, thus synthesising ADP + Pi to ATP (ATP synthesis)
    that's unit 5 stuff.. but I have understood it now... thanks
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    (Original post by SKK94)
    Isn't this chemiosmosis during cellular respiration?
    I thought in photosynthesis, the H ions from reduced NADP are pumped out of the thylakoids into the stroma?
    the chemiosmosis occurring here is just the H+ moving back to stroma.. but the photophosphorylation is involves the whole process of electrons getting excited using photons from light and falling to lower energy levels... leading to production of NADPH and ATP
 
 
 
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