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OCR F211/F212 AS Biology Retake 2016 Watch

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    For the vascular bundle question, I wrote that not having these bundles would mean that there would be no cambium so there isn’t as many meristematic cells that could differentiate into specialised cells which would contribute to the growth, decreasing the growth all together but I’ve realised that you’re able to find meristematic cells in the apex of the root/shoot ahhhh idkidkidk lost stupid marks everywhere
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    For the filling the gap could you put cell membrane

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    (Original post by badhand45)
    Wasn't that in question "stem cells are able to specialise into other cells"
    Isn't differentiation and specialisation the same thing?
    That's what I thought but i literally had nothing else to write..


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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
    Surely by saying cohesion isn't a factor for the water movement you can't mention root pressure or adhesion?
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    What did everyone write for the question about which leaf was most likely to live in an environment of low water availability and why, where it showed pictures of different leaves
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    (Original post by KatyRu)
    What did everyone write for the question about which leaf was most likely to live in an environment of low water availability and why, where it showed pictures of different leaves
    C due to lowest surface area meaning that the rate of diffusion was lower so less water vapour was lost.
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    (Original post by KatyRu)
    What did everyone write for the question about which leaf was most likely to live in an environment of low water availability and why, where it showed pictures of different leaves
    C due to lowest surface area meaning that the rate of diffusion was lower so less water vapour was lost.
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    Guys did anyone else get B A D E ? for that question
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    (Original post by Realbigboi)
    C due to lowest surface area meaning that the rate of diffusion was lower so less water vapour was lost.
    was C the smallest or biggest Leaf??
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    (Original post by mosahra)
    was C the smallest or biggest Leaf??
    It was the smallest leaf
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    i think ive dropped aroung 17 marks... well theres goes the A.. again
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    (Original post by Realbigboi)
    Surely by saying cohesion isn't a factor for the water movement you can't mention root pressure or adhesion?
    Nope root pressure has nothing to do with Cohesion.
    Root pressure is a pushing force on the water up the root caused by the water potential gradient across the plant.
    You do not need a xylem vessel for root pressure or Cohesion.
    Somebody will correct me if I am wrong though...
    In normal plants root pressure occurs within the xylem vessel - however it is not caused by the xylem, but osmotic pressure.
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    (Original post by Anymorefor123)
    i think ive dropped aroung 17 marks... well theres goes the A.. again
    42 was an A last year so 43 could be an A this year!!!!
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    What does everyone think grade boundaries will be??
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    (Original post by Bgxx)
    What does everyone think grade boundaries will be??
    Somewhere between 43-46 for an A
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    (Original post by student__1001)
    Somewhere between 43-46 for an A
    I really hope its not 46 . 43 for an A would be nice but i feel like it may be 45
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    I wouldn't of thought the grade would be boundary high, probably around 42. It was mainly application and not knowlegde and so even though we had longer to revise for it, you cant prepare for questions like that. I did tons of revision but found a lot of the questions difficult- especially heart one. i dont know what klm was. I though it may be the nodes/ the septum but it could of just been the walls and cardiac muscle What did other people put?
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    (Original post by Anymorefor123)
    what did everyone write for the q about how water is taken up by the mosses root cells... because it has no xylem due to no VB... so the whole transpiration thing wouldent be right surely ? im so confused.
    I was going to write about the apoplast and symplast pathways but they had already come up in one of the previous questions, so i wrote about how water can cross the plasma membrane ie through the phospholipids and via channel protiens, because the q said "mechanisms"
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    for the microscope question, was it X,Y or Z? i knw it wasnt X, i wrote down Y
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    (Original post by fizzyalfie)
    i got FADE, muscles constrict the airways, I know muscular due to high pressure makes sense but the muscles are more to do with constriction. Collagen is more for resistance to high pressure
    same
 
 
 
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