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    I haven't seen a thread for this paper yet so let's put one together. I remember very little from the paper and my answers probably aren't great so please contribute!

    Section 1 - Multiple Choice (all one mark, 15 questions total).
    'Which is the correct change that decreases temperature in endotherms?'
    - A - Arterioles near the surface dilate Tuffyandtab

    'Photosynthesis question, diagrams'
    - C Tuffyandtab

    'Which pathway is mitosis and which one is meiosis?'
    - D

    'Stomatal density?'
    - 7.5 biologybuddy

    SA:V
    - C SatLeaguePires20

    Countercurrent (fish gills)
    - B Voltix

    hcg molecule and one property that make it detectable in urine
    Think the options were: Has a mass less than 69000 Is a polypeptide Binds with its glycoprotein receptor I can't recall the last one
    - 2 and 3 Voltix

    'Percentage change'
    - C (IIRC)

    'What explains why this hormone can act at cells near the skin? 1 - Produced and secreted by some neurone ******** 2 - It is polar and can be transported in the blood 3 - something else'
    - 2&3

    Section 2
    Endotherms & Transport Question
    'Why is the bee described as an endotherm?' [2]
    - Capable of raising body temperature using metabolism (in flight)
    - To produce an internal temperature that is independent of their external temperature.

    'Why is it easier for mammals to stay warm?' [3]
    - Mammals have a lower SA:V than the bee
    - This means that they lose heat more slowly than the bee
    - They are also more metabolically active, and produce more heat (even at rest) compared with the bee.

    'What is the name of the hole in the caterpillar abdomen?' [1]
    Spiracle

    'What is the fluid that is inside the gaseous exchange system of insects called?' [1]
    Tracheal fluid

    'Why do mammals and insects require a transport system?' [3]
    - Metabolically active, so have a demand for oxygen. Exchange surfaces such as the lungs uptake oxygen, and this needs to be transported to the tissues which need it.
    - Metabolically active, so have a need to excrete waste. For example, carbon dioxide is produced in respiration, but needs to be transported for excretion at the lungs.
    - They have a large SA:V so cannot rely on diffusion alone for these processes as it would be too slow.

    Respiration Question (sperm cell)
    Diagram shows mitochondrion wrapped around the flagellum.
    'What do the letters represent?' [3]
    A - Mitochondrial Matrix
    B - Crista
    C - Intermembranal Space

    'Explain implications of fluoride and cyanide on respiration' [1]
    - Fluoride prevents respiration completely as it inhibits phosphorylation of glucose.
    - Cyanide only allows anaerobic respiration to proceed, producing a small amount of ATP.

    Respiration Question (watering plants)
    'What conclusions can be drawn from the results?' [3]
    - The larger the volume of water added, the less the number of surviving seeds after 18 days.
    - Compare data
    - Therefore, waterlogging causes seeds to die.
    - (I assume other comparisons would be valid)

    'Water occupies air spaces in the soil and prevents oxygen from reaching the roots.
    Use your knowledge of aerobic and anaerobic respiration to discuss why waterlogging kills plants' [6]
    - Normally, oxygen will diffuse into the air spaces and then into the root, allowing aerobic respiration to proceed. If water is present, this prevents oxygen from reaching the root.
    - Therefore, there is no oxygen to act as the final electron acceptor in oxidative phosphorylation.
    - The flow of electrons along the electron transport chain stops.
    - Production of ATP by chemiosmosis stops.
    - Reduced NAD/FAD cannot be oxidised at the electron transport chain in the cristae because there is nowhere for their electrons to go.
    - This means no NAD/FAD is available for the link reaction or krebs cycle to proceed.
    - Glycolysis is allowed to proceed by aerobic respiration.
    - Pyruvate decarboxylase decarboxylates pyruvate, producing ethanal.
    - Ethanol dehydrogenase uses the hydrogen from NAD to reduce ethanal, producing ethanol, and oxidising reduced NAD to NAD.
    - NAD is free and a small amount of ATP can be produced.
    - But, ethanol is toxic and if it builds up the root cells may die (disrupting plasma/organelle membranes by dissolving them?)
    - If the root cells die, the rest of the plant cannot obtain water and mineral ions, and also dies.

    Standard Deviation Question
    'Calculate SD of bottom right data' [3]
    sd = 5

    'Plot the SD on this bar chart of means' [2]
    One SD up, one SD down (from the mean)

    'Calculate % diff between anaerobic and aerobic for this species'
    61.54%

    'Evaluate statements 1 and 2:
    1 - All yeasts tested produced more CO2 aerobically
    2 - Significant difference between aerobic/anaerobic in (species)'

    1 - Reject, (rightmost) species had a higher mean CO2 production when respiring anaerobically.

    2 - Reject, the SD bars overlap significantly.

    Orders of Magnitude
    ???

    Plant Hormone
    'Evaluate statement' [6]
    - Yes, statement is accurate because before hormone was applied there was no yield of seedless fruit.
    - However the statement is limited because it does not discuss whether non-seedless fruit is also yielded.
    - The statement does not discuss how much is yielded, and the data shows that this depends on the volume applied.
    - Other cytokinin hormones have a similar effect (as shown by data), it is not just this one.

    Stages of Meiosis
    'Which letter shows the stage in which each phase occurs?' [2 or 3??]
    B Tuffyandtab
    C Tuffyandtab
    B Tuffyandtab

    Nucleic acid gap fill
    'Fill in the gaps with these words' [4]
    Nucleotide
    Phosphate
    Pentose
    Strands

    Phototropism Practical
    <method>

    'Identify, explain, correct' [6]

    Weaknesses:
    1 - Sample not taken at random
    2 - Small sample taken
    3 - Light intensity not controlled

    Explanation:
    1 - Sample may therefore be biased
    2 - Sample may not be representative, larger samples are better
    3 - Light intensity affects phototropism

    Correction:
    1 - Number the seeds and use a random number generator to select the sample.
    2 - Use a larger sample.
    3 - Use the same type of lamp/bulb at the same distance from the seeds for each trial

    Endodermal Cells
    'Explain what causes water to move into the endodermal cells' [2]
    - Active transport of mineral ions into the endodermal cells, across the plasma membrane from low to high concentration.
    - Low water potential in the endodermal cell.
    - Water moves in by osmosis down a water potential gradient.

    Nephron
    'Identify on the insert the region with high hydrostatic pressure' [1]
    - Label pointing to glomerulus, top left.

    'Identify the regions which will not contain large proteins' [1]
    - Central label pointing to tubule lumen and Bowman's Capsule lumen.

    'Compare (given processes) at DCT and PCT' [3]
    - PCT reabsorption is an active process, requires ATP.
    - PCT reabsorption occurs to the same degree at all times (i.e. same amount of sodium ion uptake)
    - The DCT process depends on whether a concentration gradient is present as it is passive.
    - DCT process involves Calcium ions, PCT process does not.

    'Why is a leaf classed as an organ?' [4]
    - Tissues are collections of specialised tissues
    - That work together to carry out a specific function
    - Leaves are made up of various tissues (e.g. mesophyll, vascular (xylem/phloem vessels))
    - And provide the function of photosynthesis

    'Why do podocytes not undergo mitosis (lmao)' [3]
    - They are differentiated.
    - Differentiated cells do not undergo mitosis.
    - ...because they are too specialised, e.g. foot processes/pedicels in podocytes.
    - cells go into a permanent G0 phase leading to senescence OR they leave the cell cycle HeadHoncho

    'Potential for stem cell therapy, why can adult stem cells regenerate nephron tissue?' [2]
    - Adult stem cells are multipotent.
    - They can divide by mitosis and differentiate into the different tissues in the nephron (e.g. endothelium, podocytes (lmao))
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    they have a small SA:V that is y they need an exchange system. they are also active and have a high metabolic rate. simple diffusion is too slow to meet their metabolic needs
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    Multichoice:
    Q1 - Decrease temp. in endotherms - A: Arterioles dilate
    Q2 - Photosynthesis - C (the one with NADP)
    Q3 - Stomata - B: 0.13
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    DNA Questions
    B, C, B
    Nucleotide, phosphate, pentose, strands
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    (Original post by 11...)
    they have a small SA:V that is y they need an exchange system. they are also active and have a high metabolic rate. simple diffusion is too slow to meet their metabolic needs
    Question was about -transport- systems namely IIRC
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    (Original post by Tuffyandtab)
    Multichoice:
    Q1 - Decrease temp. in endotherms - A: Arterioles dilate
    Q2 - Photosynthesis - C (the one with NADP)
    Q3 - Stomata - B: 0.13
    Thank you, will add.
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    Ive lost so many marks looking at this :cry: thoughts on grade boundaries??
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    (Original post by ForestShadow)
    Ive lost so many marks looking at this :cry: thoughts on grade boundaries??
    This MS is mainly made up of my own attempts! You may have the right ideas, I might be wrong. Grade boundaries on last years AS exams for the new spec were 67% A, 60% B for the total raw mark.
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    (Original post by DoubleDoors)
    This MS is mainly made up of my own attempts! You may have the right ideas, I might be wrong. Grade boundaries on last years AS exams for the new spec were 67% A, 60% B for the total raw mark.
    Hope the AS ones are near A2 ones then, I need a B at least for bio :rofl:

    nah some of my stuff was clearly wrong I know lol, there was so little actual biology in this one and so much calculations and practical stuff

    I didnt get the n-1 in SD for starters

    this guy even made a petition with 2.5k signatures for it :lol:

    https://www.thestudentroom.co.uk/sho...8#post72098098
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    For the podocytes q might want to add that some cells go into a permanent G0 phase leading to senescence
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    I think the stomata one was 7.50 mm^-2 (A)
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    http://www.bbc.co.uk/news/education-40059967
    (Original post by ForestShadow)
    this guy even made a petition with 2.5k signatures for it :lol:

    https://www.thestudentroom.co.uk/sho...8#post72098098

    Lmao, in the past the standard response to these kind of petitions has just been 'hello this is how we make grade boundaries, they reflect if it was a hard paper anyway, thanks bye', and I don't understand how they'd cancel the paper (although - they better have the decency to admit their mistake in not providing the formula and also anaerobic respiration in plants!)

    OCR have made 2 other serious errors this series:
    http://www.bbc.co.uk/news/uk-england-40204259
    http://www.bbc.co.uk/news/education-40059967

    I suppose looking at that second one we could have been much worse off
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    brilliant looking at this makes me more confident that i got 80 ish marks
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    (Original post by DoubleDoors)
    http://www.bbc.co.uk/news/education-40059967


    Lmao, in the past the standard response to these kind of petitions has just been 'hello this is how we make grade boundaries, they reflect if it was a hard paper anyway, thanks bye', and I don't understand how they'd cancel the paper (although - they better have the decency to admit their mistake in not providing the formula and also anaerobic respiration in plants!)

    OCR have made 2 other serious errors this series:
    http://www.bbc.co.uk/news/uk-england-40204259
    http://www.bbc.co.uk/news/education-40059967

    I suppose looking at that second one we could have been much worse off
    Id take any error lol, didnt realise podocytes were already specialised and messed up half of the other things

    will have to nail the other papers then :moon:
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    (Original post by h3rmit)
    I think the stomata one was 7.50 mm^-2 (A)
    definitely not, i spent 5 mins on that question and im 100 percent sure its 0.13
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    (Original post by eryk_laroche)
    definitely not, i spent 5 mins on that question and im 100 percent sure its 0.13
    yeah I agree. I did (no of stomata x mag)/(width x height) = (17 x 60)/(74 x 106) = 0.13
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    (Original post by Tuffyandtab;[url="tel:72099816")
    72099816[/url]]yeah I agree. I did (no of stomata x mag)/(width x height) = (17 x 60)/(74 x 106) = 0.13
    It was 7.5. Your method is incorrect as you have to divide each of the width and height by 60. Or divide the area by 60^2.
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    Hardest paper i have ever done ngl
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    I think the order of magnitude was 10^8 (10^9-10^1)
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    And for the phototropism I think you could have the gravity should be controlled due to the stem a negative response to it
 
 
 

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