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OCR F211/F212 AS Biology Retake 2016 Watch

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    (Original post by lucymay2)
    Water molecules form hydrogen bonds with cellulose molecules in cell walls - adhesion
    Cohesion - holds hydrogen bonds together to create surface tension on water. Since water is attracted to other molecules, adhesive forces pull the water toward other molecules.

    Water molecules cohesiveness is present without the xylem
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    (Original post by rubyisdraked)
    Yours is very good though and I forgot about that tissue question! The more the merrier I say!
    No probs man, yours is great...seems like you smashed the exam! [ I don't think I did tbh ]
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    (Original post by DeclanKeeble)
    Here it is, the unofficial mark scheme for the F211 2016 retake paper (compiled by some lovely people)....what a weird paper....some really good questions but some really bad ones too....and oh god don't get me started on the last 4 maker on the transverse section of the heart...

    *disclaimer: we are in no way; shape or form, Darwin-level experts*
    Unofficial mark scheme F211 May 2016 Resitters
    Q1(a).why don't amoeba need a specialised gaseous exchange surface(2)
    • Large Surface area to volume ratio
    • Amoeba is single-celled so diffusion distance is fast as there are no deeper cells within organisms
    • Diffusion pathway is short.
    • Idea of it being adequate/ sufficient enough to supply oxygen and prevare enting build up of toxic waste products such as CO2
    Q1(b). State a organelle in fig…that isn't present in a prokaryotic cell(1)
    • Nucleus
    • Vacuole
    Q1(c).state component of the membrane that doesn't let through mineral ions(1)
    • Phospholipid (bilayer)
    • hydrophobic fatty acid tail
    Q1(d). State two functions of cell membranes in Amoeba(2)
    • Separates organelle components from cytoplasm - the membranes divide the cell into different compartments (compartmentalisation)
    • Increases the surface area
    • Reactions within organelles are more efficient
    • Can form vesicles to transport materials between different parts of the cell
    • Hold components of metabolic pathways in place
    • Site for receptors to attach
    Q1(e). How water move through cell(1)
    • Exocytosis
    Q1(f). What happens to the cell if the vacuole thing is not present(1)
    • Cell will burst
    Q1(g). Table question water potential(2)
    • At -100kpa the water potential of the surrounding has a higher water potential than the inside of the cell
    • Water travels by osmosis into the cell down a water potential gradient
    • However at -500kpa the water potential of the surrounding has a lower water potential than the inside of the cell so water does not travel by osmosis into the cell.
    • Therefore more water is filled and expelled at -100 than at -500
    Q2(a) how is a stem cell different to specialised cell (1)
    • can divide by mitosis
    How does water move through the roots and leaves in moss (4)
    • Active transport of mineral ion into the root hair cells
    • Decreases water potential
    • Water follows by osmosis
    • Root pressure - describe
    • Capillary action - adhesion - describe
    Q - Specimens can be viewed under light microscope. What are the advantages of staining?(1)
    • A lot of biological isn’t coloured
    • Adds contrast (this would be marking point on its own i think)
    • as different chemicals take up different amounts of stain
    • Distinguish between different parts of the cell
    Q what is meant by translocation (2)
    • It is mass flow of assimilates and sucrose up and down the phloem
    • Sucrose loaded at the source and unloaded at the sink
    Q fill in the gaps (4)
    • Cell walls
    • Plasmodesmata
    • Endodermis
    • Casparian Strip
    Q calculation q (2)
    • 117 um could be a range
    Q mitosis q
    1. Anaphase (1)
    1. Justification - chromatids at the end of each side (1)
    1. Describe the events from the start of mitosis that took place to reach that stage shown in the image. (5)
    Mitosis is effectively a continuous process but consists of four stages.
    The first stage is called Prophase. In prophase the replicated chromosomes shorten and thicken (supercoil), and are now visible under a light microscope. The nuclear envelope breaks down and becomes invisible. An organelle called a centriole divides so that two daughter centrioles move to opposite ends (poles) of the cell to form the spindle (a structure made of protein threads/fibres).
    Following this, is Metaphase. In metaphase the replicated chromosomes (each with two sister chromatids) move to the centre of the spindle (the equator) and each becomes attached with their centromeres.
    The next stage is Anaphase, which is depicted in the image.
    1. Describe what happens in the rest of the cell cycle, excluding mitosis (3)
    ATP production is also increased in interphase
    Q microscopes
    1. What microscope shows the max. Magication of a TEM?(1)
    - Z
    1. ….(1)
    • Fig 3.a
    1. Why is it sem? (1)
    • 3D surface; magnification was lower
    Q what reduces water loss or something..(1) - densely packed spongy mesophyll cells and many others
    Q) how does air movement increase transpiration (2)
    • Air moves the water vapour away from the stomatal space
    • Increases the water vapour potential gradient
    • So more water evaporates from cells into stomatal space
    • More water is lost through transpiration
    Q. Define the term Tissue(2)
    • A tissue is a collection of cells that are specialised to work together to perform a common function.
    Q. Match the best statements about the ****ing heart from the other table in this table. Once has already been done for you (how sweet)....C. (4)
    • FABD??
    • FADE??
    • BADE?? Who knows
    Q. two cells present in a dicotyledonous leaf but not in the moss leaf excluding cells found in vascular tissue (2) -spongy mesophyll cells
    • Guard cells
    Q. Why can't moss leaves grow (2)
    • No xylem to transport water and minerals needed for photosynthesis
    • No phloem to transport assimilates such as sucrose
    Q the heart question (4)
    1. draw a horizontal line near the bottom of picture
    2. KLM - who knows
    1st one was the right ventricle 2nd one was septum3rd one was cardiac muscle
    Q functions of smooth muscle, cilia, goblet cells and squamous (4)
    • smooth muscle contracts to constrict the airway
    • Cilia moves in a synchronised way to waft mucus to the back of the throat
    • Goblet cells produce/secrete mucus to trap particles
    • Squamous epithelial are flattened cells which shorten the diffusion pathway for gases
    Heeey it made it online! lol the bit in bold.
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    I put exocytosis aswell because it said that water continuously moved IN to the cell (must be by osmosis) so it physically couldnt be possible for it to be osmosis on the way out again, the clue for me was it fused with the cell membrane. I also said phospholipid bilayer
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    So is everyone assuming that the Amoeba question asked for membranes within the cell due to the change of this markscheme. I put receptors for cell signalling and recognition which I dont feel is membranes within cells even though you put they can act as receptors. I have never seen it before could someone please tell me if its a thing thanks.
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    Does this make sense for the circulatory question?
    -Both atria have same thickness: both empty into ventricles
    -Thick muscle wall: arteries near heart
    -Elastic fibres: fluctuating pressure
    -Small arteries: smooth muscle maintains pressure
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    Did any one get an answer of 125 for the magnification question?
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    (Original post by President J)
    exoPINOcytosis is not a thing. pinocytosis is an example of Exocytosis
    Yes it is a real thing, pinocytosis alone doesnt not define whether or not the liquid is moving in or out. As i said read page 25. I have attached a photo
    Name:  IMG_20160526_192300.jpg
Views: 274
Size:  509.9 KB
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    (Original post by cmbell97)
    Does this make sense for the circulatory question?
    -Both atria have same thickness: both empty into ventricles
    -Thick muscle wall: arteries near heart
    -Elastic fibres: fluctuating pressure
    -Small arteries: smooth muscle maintains pressure
    Is the BADE?
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    How can water move up the moss via root hair cell method? The question states it has no roots. And there was a question already asking about apoplast pathway?! It must be cohesion theory! Else the examiner can suck my ****!
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    (Original post by Bailey2j09)
    Is the BADE?
    I don't know, I can only remember the statements not the letters
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    (Original post by Realbigboi)
    So is everyone assuming that the Amoeba question asked for membranes within the cell due to the change of this markscheme. I put receptors for cell signalling and recognition which I dont feel is membranes within cells even though you put they can act as receptors. I have never seen it before could someone please tell me if its a thing thanks.

    Yeah...it said in the cell but wasn't bolded to trick us out. These are the generalised roles of membranes within cells, but I'm not sure about the answers to the question because of it's relation to the single-celled Amoeba and it's diagram:

    1) Separate cell components from cytoplasm - the membranes around organelles divide the cell into different compartments (compartmentalisation)

    2) Regulate the transport of materials into and out of organelles

    3) Provide surface for attachment (e.g. of enzymes and ribosomes).

    4) They can form vesicles to transport substances between different areas of the cell

    5) Hold the components of some metabolic pathways in place


    I initially answered with 1) and 5) but I quickly crossed out 5) and replaced it with 2) because the diagram showed no mitochondria...I'm not sure either way, was a weird question

    Dunno if this helped, haha
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    I wrote anaphase for the 1 mark question..
    But in the written section (5 Marks), I also spoke about telophase to be on the safe side... Will I get marked down for this?
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    (Original post by cmbell97)
    Does this make sense for the circulatory question?
    -Both atria have same thickness: both empty into ventricles
    -Thick muscle wall: arteries near heart
    -Elastic fibres: fluctuating pressure
    -Small arteries: smooth muscle maintains pressure
    I put this too apart from the second one i put something else, but i can't remember what haha
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    (Original post by Hdb;[url="tel:65214399")
    65214399[/url]]I wrote anaphase for the 1 mark question..
    But in the written section (5 Marks), I also spoke about telophase to be on the safe side... Will I get marked down for this?
    Doubt it mate. Probably just wasted your own time if anything. Don't stress about that one man!
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    (Original post by nicoleemmak)
    I put this too apart from the second one i put something else, but i can't remember what haha
    What question was this?
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    (Original post by abbieftay)
    I put exocytosis aswell because it said that water continuously moved IN to the cell (must be by osmosis) so it physically couldnt be possible for it to be osmosis on the way out again, the clue for me was it fused with the cell membrane. I also said phospholipid bilayer
    mate it was exopinocytosis
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    (Original post by GEORGEPOWELL209)
    Doubt it mate. Probably just wasted your own time if anything. Don't stress about that one man!
    Thanks bro
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    (Original post by GEORGEPOWELL209)
    What question was this?
    The circulatory one where you matched letters to numbers in a table
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    (Original post by Guls)
    mate it was exopinocytosis
    Im sure they will allow both, if a certain number of people put an answer, they add it to the 'allow' section if its correct but not what they were looking for if you get what i mean.
 
 
 
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