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OCR Biology F212 Revision [3rd June 2013] (Now Closed)

Reply 1640

Minz

So basically, the paper appeared to be relatively good but ocr mark schemes are so picky :frown:

think most of my marks will be lost for incorrect wording. *sigh*

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Reply 1641

MedMed12

21

should be fine

Original post by Liamnut

I didn't out 35% glycine, I just put 35% of the molecule is made of the same amino acid.

Reply 1642

Sam_1996

If you put 5 answers for a 3 mark question.3 are right,2 are wrong and you don't contradict yourself at all,do you get all 3 marks?

Reply 1643

MedMed12

21

Original post by milworthy

What did everyone put for the question about reasons why crop yield varied? I put changing weather patterns and more/less pests

same plus availibility of water, pH of soil, climate
competition
disease

Reply 1644

username972634

Original post by Sam_1996

Q1
Polypeptide(1)
H2NCHRCOOH (3)
Collagen is flexible(1)
Collagen:
3 polypeptide chains,linked by covalent bonds to fibres,left handed helix,1 in 3 amino acids is glycine(6)
Haemoglobin combine to oxygen to transport blood(1)
Haemoglobin:
Globular,4 polypeptide chains(3)

Q2
Enzymes(1)
Similar elements,similar bonds,similar shape which is complementary to the enzyme so can for enzyme-substrate complex.(3)
It can outcompete the -thing- so it is more likely to form an enzyme substrate complex with ethanol than with -thing-.This means that more ethanol will be broken down than -thing-(3)

Q3
Cells B and C(1)
As its the bodies response to a foreign antigen(1)
As it carries of phagocytosis on all cells.Doesnt involve lymphoctes(1)
Pinches pathogen into vehicle via phagoctosis.This pathogenic vehicle fuses with lysosomes which secrete enzymes breaking down the pathogen.Then the substances can be absorbed by the phagocyte via diffusion(7)

Genus name(1)
Order(1)
Phylum(1)
Animals(1)
Eukarya(1)
Phylogeny is study of evolutionary relationships.Allows us to see how closely relate two organism are via DNA similarities etc,so can be used to group organism based on similarities therefore helpfull in classification(3)
Too small to see with the eye as its only 2-3 mm long.Only discovered when microscopes were around(2)

A very rough start to an unofficial mark scheme
If we all add to this and improve this.
Marks next to answers represent marks avaliable and not marks gained by the answer next to it.

BTW could you say that collagen has high tensile strength (instead of flexible)

Reply 1645

MarkProbio

7

Original post by MedMed12

depends if it says refer to info or not
if it ddint im sure they are acceptable as well as others

I'm just not sure why you would even begin to think of others when you're given these. As long as you don't directly quote the question you could have used two of the three points.

But I guess in an exam situation it's easy to miss the info so who knows.

Reply 1646

Sam_1996

3 reasons why lower income people are more at risk of TB?

Reply 1647

MedMed12

21

Original post by Sam_1996

If you put 5 answers for a 3 mark question.3 are right,2 are wrong and you don't contradict yourself at all,do you get all 3 marks?

even if you contradict yourself you can get some marks if you wrote both opposing statements in a seperate line hence why always do bullet points- tip from my teacher :wink:

Reply 1648

Minz

Original post by Sam_1996

If you put 5 answers for a 3 mark question.3 are right,2 are wrong and you don't contradict yourself at all,do you get all 3 marks?

Yes unless they specifically say three. :smile:

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Reply 1649

niceguy95

14

For the selective breeding question

I wrote about how it follows natural selection
Best crops with best characteristics chosen and bred together until Hugh yielding crop.
Resistance to diseases due mutation and genetic variation
Crops with the resistance can on,y survive and reproduce
Offspring are advantageous
Alleles which cause this resistance passed over many generation
Evolution occurs (long term) so crops with the resistance becomes more common I the population

Reply 1650

Sam_1996

Original post by mastermdc

BTW could you say that collagen has high tensile strength (instead of flexible)

Yes you can

Reply 1651

Dr. Django

12

Original post by Minz

So, what about the 7 marker on selective breeding to get disease resistant crops and then precautions of selective breeding.

What did people write about precautions and how to reduce implications of selective breeding?
Seed banks, botanical gardens? Or do you think they were looking for something else?

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Looking at it what you've said makes much more sense :/ but I said that they should selectively breed plants from different areas/ try and prevent inbreeding ie. the wild south american potatoes with the Irish ones to increase genetic diversity and ultimately broaden the gene pool so there was a greater chance of a genetic mutation of disease resistance occurring :/ it made sense at the time

Reply 1652

Moon1ight

15

Original post by Sam_1996

Q1
Polypeptide(1)
H2NCHRCOOH (3)
Collagen is flexible(1)
Collagen:
3 polypeptide chains,linked by covalent bonds to fibres,left handed helix,1 in 3 amino acids is glycine(6)
Haemoglobin combine to oxygen to transport blood(1)
Haemoglobin:
Globular,4 polypeptide chains(3)

Q2
Enzymes(1)
Similar elements,similar bonds,similar shape which is complementary to the enzyme so can for enzyme-substrate complex.(3)
It can outcompete the -thing- so it is more likely to form an enzyme substrate complex with ethanol than with -thing-.This means that more ethanol will be broken down than -thing-(3)

Q3
Cells B and C(1)
As its the bodies response to a foreign antigen(1)
As it carries of phagocytosis on all cells.Doesnt involve lymphoctes(1)
Pinches pathogen into vehicle via phagoctosis.This pathogenic vehicle fuses with lysosomes which secrete enzymes breaking down the pathogen.Then the substances can be absorbed by the phagocyte via diffusion(7)

Genus name(1)
Order(1)
Phylum(1)
Animals(1)
Eukarya(1)
Phylogeny is study of evolutionary relationships.Allows us to see how closely relate two organism are via DNA similarities etc,so can be used to group organism based on similarities therefore helpfull in classification(3)
Too small to see with the eye as its only 2-3 mm long.Only discovered when microscopes were around(2)

A very rough start to an unofficial mark scheme
If we all add to this and improve this.
Marks next to answers represent marks avaliable and not marks gained by the answer next to it.

Why is it cell b and c and not just cell c ?

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Reply 1653

username972634

Original post by RoseBrilliante

I don't know :/ I don't know because I'm not too sure how specific OCR are with their mark schemes. Even if you didn't, I wouldn't worry about it because it's only one mark

Marks are for Eukarote, Eukarya, or Eukaryotae

Reply 1654

sh7171

What did people put for the very first question about the sequence of amino acids?

Reply 1655

Munrot07

18

Original post by sh7171

What did people put for the very first question about the sequence of amino acids?

primary structure

Reply 1656

lauren1brown

Original post by sh7171

What did people put for the very first question about the sequence of amino acids?

Primary structure

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Reply 1657

QuantumSuicide

What was the answer for the question underneath the hydrogen bond dna structure where you had to fill in the gaps? I put ribosome and polypeptide...

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Reply 1658

Sam_1996

Original post by Munrot07

primary structure

Could you put polypeptide?

Reply 1659

Munrot07

18

Original post by Sam_1996

Could you put polypeptide?

no :/