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OCR F211/F212 AS Biology Retake 2016 Watch

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    What is the answer to the one about stem cells being different to specialised cells? I said that stem cells are totipotent and that specialised cells are pluripotent????
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    Was drawing a line at the bottom of the heart definitely right? Now I think about it, its a much better bid for what I've drawn, but I went for a slightly angled line going through right atrium and left ventricle.

    Looking at the unofficial march scheme, I feel pretty good about this one
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    (Original post by nicoleemmak)
    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.
    They should accept exopintocis or just exocytosis
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    (Original post by DeclanKeeble)
    Yeah...it said inthe 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
    Im guessing I lost a mark there goddammit maybe even 2 so cell recognition and cell communication wouldnt suffice?
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    (Original post by cmbell97)
    The circulatory one where you matched letters to numbers in a table
    Ok buddy cheers.
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    (Original post by robyncardy123)
    What is the answer to the one about stem cells being different to specialised cells? I said that stem cells are totipotent and that specialised cells are pluripotent????
    Same here mate. I wrote that too. Hope this boosts your morale a bit. I'm glad to see someone else wrote the same thing.
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    that was solid. I accidentally wrote what they said in the question and had to cross it out.
    (Original post by robyncardy123)
    What is the answer to the one about stem cells being different to specialised cells? I said that stem cells are totipotent and that specialised cells are pluripotent????
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    (Original post by Realbigboi)
    Im guessing I lost a mark there goddammit maybe even 2 so cell recognition and cell communication wouldnt suffice?
    Don't worry buddy! I've lost loads of marks!

    I'm not sure because I'd say that cell recognition and cell signalling would be more to do with membranes at the surface of cells, but then again...isn't that just effectively involved in "3) provide surface for attachment (e.g. of enzymes and ribosomes)"??

    I'm sure you'll be fine




    *prays for a miracle and low grade boundaries*
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    for the cell cycle question- would you get a mark for saying enzymes checking for mutations?
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    (Original post by astrostar29)
    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
    Attachment 539051
    Fair, I apologies. Thanks for the picture.
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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. 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)
    Interphase:
    - S phase: DNA (genetic material) replicates
    - Growth phase (G1 & G2): cell growth, protein synthesis, organelles replicate (thus increase in numbers)

    Also:
    - ATP production is increased in interphase
    - DNA checked for any mutations

    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


    Made some editions for: "1. Describe what happens in the rest of the cell cycle, excluding mitosis (3)"
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    Can anyone predict what the grade boundaries will be after seeing the difficulty of the exam
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    Thinking I got ~50 which i'm chuffed with seeing as I flopped last year
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    (Original post by MCmnbvgyuio)
    Was drawing a line at the bottom of the heart definitely right? Now I think about it, its a much better bid for what I've drawn, but I went for a slightly angled line going through right atrium and left ventricle.

    Looking at the unofficial march scheme, I feel pretty good about this one
    I put that aswell. Seemed like the most reasonable idea. Flat line at the bottom seems weird to have such a thin right ventricle
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    Would meristem and companion cells be right
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    Wasn't the staining question two marks? And are you sure that the answer is mitosis for the stem cell question.
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    (Original post by LB9213)
    Wasn't the staining question two marks? And are you sure that the answer is mitosis for the stem cell question.

    Yeah it was, i think you would say staining provides contrast to distinguish between cell contents eg. supercoiled chromosomes visible under light microscope.

    And the stem cell question is ''divide into different types of cells/mitosis'' I think, either may get the mark
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    I wrote about cohesion and adhesion in the moss water flow question 😭😭 do you think I'll get penalised? I also wrote about how water enters the roots due to low water potential in the roots compared to outside. But didn't mention key words such as transpiration stream though I described it 😫
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    (Original post by DeclanKeeble)
    Made some editions for: "1. Describe what happens in the rest of the cell cycle, excluding mitosis (3)"
    Hey guys, in regard to the one about water movement everyone put exocytosis but I put osmosis as it is still removal of water, so I checked about the contractile vacuole properties I came across this which states mitosis. do you think they will accept osmosis and exocytosis or be OCR picky? thanks
    Contractile Vacuole:
    "The contractile vacuole is basically a water bubble within the endoplasm of A. proteus. It’s function is to regulate the water content of the cell. It is also a means of excreeting its waste from the cell (out through the cell membrane) VIA diffusion. A. proteus regularly moves to the surface of the water, when it needs to discharge wastes and excess water. This is done via osmosis, where there is a semi permeable membrane that lets the flow of materials through the cell. Without the contractile vacuole, the amoeba may burst. Undoubtedly it is a very important organelle with an essential function to the amoeba."
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    (Original post by ToLiveInADream)
    Yeah it was, i think you would say staining provides contrast to distinguish between cell contents eg. supercoiled chromosomes visible under light microscope.

    And the stem cell question is ''divide into different types of cells/mitosis'' I think, either may get the mark
    Oh okay thank youu
 
 
 
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