I remember in the question it already said that it was a protein, so instead of protein I put enzyme instead as it was relating to the ethanol and DEG substrate. Im about 80% sure about this. Don't worry though most questions were worded badly especially the 7 mark phagocyte question.(Original post by Tania2k9)
it think he alcohol dehydrogenase question was a little tough and some parts of others can't remember. I am in a big dilemma for this 1 mark question of 'which biological molecule does alcohol dehydrogenase belong to' i said protein am thinking this might be wrong
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The OFFICIAL OCR June 2013 AS Biology F212 Exam Thread. watch
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- 03-06-2013 17:58
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- 03-06-2013 18:33
i know, the phagocyte one is just what happens in the actual process but just continuing of from where they left us
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- 03-06-2013 18:52
(Original post by Missyeln213)
The squirrels, the alcohol dehydrogenase, the collagen, the potato effing blight, the EIA.
All the tiny gaps in my knowledge... Exposed! GAH.
So peeved off at the exam paper and myself right now. Cannot even express it into words. At all.
Actually, I think all of my exams to date this year have been a series of fails. -
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- 03-06-2013 18:53
(Original post by Dr Mick)
I remember in the question it already said that it was a protein, so instead of protein I put enzyme instead as it was relating to the ethanol and DEG substrate. Im about 80% sure about this. Don't worry though most questions were worded badly especially the 7 mark phagocyte question.
I though the questions were completely misleading -
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- 03-06-2013 18:54
(Original post by hassaniqbal99)
Guys,
What was the phagocyte in the insert, was it B or C ?
And also the question where you had to draw hydrogen bonds between the bases, instead of dotted lines i kept them solid, will it make a difference? -
LauraDaniel
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- 03-06-2013 19:10
(Original post by Jooost)
this is exactly how i feel
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- 03-06-2013 19:22
It was a decent paper overall, so I think the grade boundaries will be close to 70. I believe I've lost about 20 marks, though come August I'm almost certain I'll have done worse
.
For the infective agent of TB, would Mycobacterium bovis get the mark? For some reason I couldn't remember tuberculosis.
(Original post by Easter Bunny)
-The Lysosomes Release Hydrolitic Enzymes that '''BREAK DOWN''' Not 'Digest' the antigen (2)
(Original post by OliverG)
And for the person who said they thought it was an actual bear, one of my friends did that too (but realised!). -
Missyeln213
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- 03-06-2013 19:24
(Original post by LauraDaniel)
Same here! Everything that I didn't want to come up, came up!
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That's exactly what a friend of mine said- she then proceeded to throw her textbook against a wall.
Seriously though, I swear more than half the marks were allocated to questions on biodiversity or whatnot. And the wording of the long mark written questions were terrible- really vague! -
Missyeln213
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- 03-06-2013 19:33
(Original post by Vian)
It was a decent paper overall, so I think the grade boundaries will be close to 70. I believe I've lost about 20 marks, though come August I'm almost certain I'll have done worse.
For the infective agent of TB, would Mycobacterium bovis get the mark? For some reason I couldn't remember tuberculosis.
one mark in the bag!
I think I lost around 20 marks too. Initially it was like 6, and then the more I strolled through tsr the more marks are lost
If I get an A overall in biology, it'll be a godsent miracle. (And it's meant to be my best subject. Hahahahaha). -
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- 03-06-2013 19:38
(Original post by Missyeln213)
I think you will get the mark for saying 'Mycobacterium bovis'. In the textbook, I'm pretty sure that they say TB can be caused by either.one mark in the bag!
(Original post by Missyeln213)
I think I lost around 20 marks too. Initially it was like 6, and then the more I strolled through tsr the more marks are lost
If I get an A overall in biology, it'll be a godsent miracle. (And it's meant to be my best subject. Hahahahaha).
I love Biology, but it's my worst subject exam-wise; I just can't stand ecology, the awkward exams and the fact that I suck at memorisation! -
LauraDaniel
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- 03-06-2013 19:44
(Original post by Missyeln213)
That's exactly what a friend of mine said- she then proceeded to throw her textbook against a wall.
Seriously though, I swear more than half the marks were allocated to questions on biodiversity or whatnot. And the wording of the long mark written questions were terrible- really vague!
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- 03-06-2013 19:59
I spent a while on exam technique, and I had to come to the conclusion that at least one question almosts asks to be quoted from the textbook, but has its own special set of answers seen nowhere else on earth
I always think i've done really well in that exam when i've done a past paper, and so far i've been the better side of A, albeit borderline, which is infuriating! Watch me get a B or a C now -
_infinity_
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- 03-06-2013 20:36
the guy who said that describing the structure of collagen is saying its insoulbe is wrong thats a property not the structure you need to say primary structure 35% repeating unit glycine. Its has three polypeptide chains wound around eavh other to make a collagen fibril that has hydrogen bonds and the collagen fibrils wound round eavh other to make a collagen fibre which has covalently bonded cross-links. Probably some more stuff i forgot but even saying its a protein with amino acids gets you one mark haha
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- 03-06-2013 21:04
What I got.. I've missed a few marks out because I can't think of them
Q1
Name given to sequence of amino acids (1)
I put polypeptide
Draw the structure of an amino acid (3)
H2NCRHCOOH (drawn)
Why collagen is good for arteries (1)
I put insoluble, there were many others
Describe the structure of collagen molecule (6)
Fibrous
3 polypeptide chains twist to form triple helix
Held by hydrogen bonds
Every third is glycerine making more compact
Covalent bonds between molecules gives strength
Then I referred to primary, secondary and tertiary structure
Difference between haemoglobin and collagen
Haemoglobin has two alpha glucose and two beta glucose sub units
Has 4 polypeptide chains
Globular
Q2
Type of biological molecule (1)
Enzyme
Why can it catalyse both (3)
Both have an OH group on the end meaning they have a similar shape to one another, both substrates can bind to the complementary active site of alcohol dehydrogenase and so are able to form ESC by induced fit
Why high ethanol concentration decreases toxicity (3)
Ethanol acts as a competitive inhibitor with a similar shape. It forms enzyme inhibitor complexes to the complementary active site. Producing a non toxic product. Low amounts of Ethanol produce ESC which form a toxic product
Q3
Infective agent of TB (1)
Mycobacterium tuberculosis
How its transmitted (2)
Airborne droplet (coughing, sneezing etc), I also mentioned the fact that physical contact could spread it
Describe the data between 2000 and 2008 (3)
I can't remember which but one group remained the same one went up and one went down
(Pretty straightforward)
Why low income have greater incidence (3)
Homelessness
Poor health due to not being able to afford health care
Overcrowding
Q4.
Which cells are phagocytes? (1)
B&C
Why "secondary"? (1)
Because primary defence occurs first (I.e skin). If the pathogen is able to get past this then phagocytes are initiated
Why is it non-specific? (1)
Does not involve B&T lymphocytes to have receptors complementary to certain antigens
What happens after pathogen attaches to phagocyte? (7)
Pathogen attaches to receptors on phagocyte (already stated)
Pathogen engulfs bacteria by phagocytosis
Becomes a phagosome and moves to the lysosomes by the cytoskeleton
Lysosomes engulf the phagosome making it into a phagolysosome
Release lysins which hydrolyse polymers into monomers
Antigens move to the surface of the membrane, cytoplasm absorbs all other products
Q5.
Calculate SI of Diversity (3)
I got 0.633 something like that
Species richness (1)
Number of species present in a habitat (I also put measured using line transect, qualitative and visual observations)
Species evenness (1)
Measures the abundance of individuals in a species (quantitative using quadrants)
Low SI Index (2)
Certain species is dominant, unstable habitat, low frequency of useful alleles
Improve accuracy of sampling (2)
Use a key to identify species
Sample more than one area
Q6.
Question but I'm unsure what is was
Why crop yield varies (2)
Use of fertilisers, different selection pressures, different alleles
How genetic variation arises (1)
Random gene mutation
Selective breeding
I mentioned that the American plants with the resistant allele need to breed
Offspring with desired characteristic are the ones that will breed over generation to pass on their gene
Inbreeding to keep the desired gene in the population
After many generation frequency of alleles resistant will have increased
Long term - I think I mentioned use of fertilisers or pesticides, and also isolating some of the species with different selection pressures so if a new disease was to break out then the whole population would not be affected
Q7.
define biodiversity (2)
Number and variety of species in the world, the genes they carry and the habitats in which they live
Why conservation methods needed for the specific area (2)
Ecotourism
Gene pool/genetic diversity (there were many more)
Suggest why people against culling (1)
Ethically wrong, we have a moral responsibility to conserve biodiversity
Why red squirrel population may be higher than counted (2)
People might not be able to identify red and grey squirrels properly
Not representative as some areas may have more grey squirrels which were counted
EIA criteria (3)
Effects biodiversity
Harm habitats or endangered species
Affect and ecosystem or food chain
Q8.
Draw dotted lines (3 between C&G), (2 between A&T) (2)
Components of DNA (2)
Cytosine
Nucleotide
Complete gaps (2)
Protein? (Might be polypeptide)
Ribosome
How RNA would be different to DNA (2)
RNA is not double stranded
RNA would have uracil
Why it is "semi-conservative" (2)
Old stand and new strand form, template is old strand
Why complementary base-pairing is important (2)
Determines primary structure of protein
Would not form double helix
Draw in the R1 and R2 (2)
I did one intermediate DNA then on the next. Intermediate and light DNA
3 precaution in centrifugation (3)
Same speed of centrifugation
Same volume of sugar solution
Same time for centrifugation
Q9
(5)
genus? (Can't remember)
Can't remember it was class or order
phylum
Kingdom = Animalia
Domain = Eukaroyta
Phylogeny (3)
Study of evolutionary relationships between species, looks at how closely related they are are whether they have common ancestors. Helps taxonomists classify (anatomy, morphology, cytochrome c), also compares there characteristics
Why water bear was undiscovered (2)
Too small to be seen
Technologies were not up to date
(I got this wrong not really sure about it)
This is what I put and by no means am I correct but you can compare. Also see what I would roughly get maybe? As I said it would be a guess because I've missed some marks out -
NataliaWojcicka
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- 03-06-2013 21:08
i thought the paper wasn't extremely hard but it wasn't great either :P
the first question on collagen threw me, i kinda blanked out and didn't remember much......... :/ but the rest wasn't too bad i answered everything...
You know the causative agent of TB, did you have to underline it? i didn't but some of my friends did.... -
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- 03-06-2013 21:08
did the hydrogen bonds have to be drawn as dotted lines?
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_inthewoodshed
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- 03-06-2013 21:10
Realised when the invigilator told us to stop writing that I'd made an awful pun in the selective breeding question - I said something about a new disease cropping up
I thought on the whole it was an alright paper - hoping I've only lost 20 or so marks.
x -
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- 03-06-2013 21:11
(Original post by kited4)
did the hydrogen bonds have to be drawn as dotted lines? -
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- 03-06-2013 21:12
(Original post by ClarkyC...)
I think it would be fine to draw straight lines as long as they were correct -
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- 03-06-2013 21:15
(Original post by kited4)
ahh that's okay - i did 3 lines between the G&Cs and 2 lines between the A&Ts
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