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OCR F211/F212 AS Biology Retake 2016

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Original post by RescueToast
For Q4b) i said he should do a curve instead of doing dot-to-dot, and then find the enzyme concentration.


I dont think it would have made a difference? Surely dot to dot more accurate right ?
Original post by Redman789
I dont think it would have made a difference? Surely dot to dot more accurate right ?


A curve is a better way to represent that data, but you'd have still gotten the same answer. I put measuring 1.5 mg cm-3, using smaller intervals (e.g. 0.25mgcm-3) and I'm sure I put something else too but I can remember.


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The question asked specifically how the method could be improved, not the data presentation. Oh yeah I remember, I said to do repeats haha.


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Repeats ? I think wrote that .... hopefully i did ! Maybe a larger range perhaps i dunno
Original post by Rajan_S97
Q3
a) Active Artificial
b) .....don't remember
c) Viral RNA code changes, amino acid sequence changes, different tertiary structure

Not sure what other questions

Q4

a) Biuret test, Blue -> Lilac
b) 1.4
c) 0.35g
d) Use a better colorimeter, less gaps between enzyme concentrations
e) Use no enzyme, just water and biuret

Not sure on last two


Q5 - explain the effects of tar on the lungs

Tar settles on lining of airways and alveoli increasing diffusion distance for oxygen entering blood and CO2 leaving blood
Chemicals in tar can cause allergic reaction causing airways to contract - reduced lumen so restricts airflow
Tar damages cilia therefore they are unable to move mucus
Tar stimulates goblet cells and mucus secreting glands to secrete more mucus
Bacteria collect in mucus - smoker is more susceptible to infection
Smokers cough damages lining of airways replacing it with scar tissue - this is less flexible and thicker
Presence of bacteria in mucus causes inflammation - chronic bronchitis
Phagocytes attempt to fight pathogenic material - they release an enzyme elastase which reduces the elasticity of airways - emphysema
Reduction of elasticity can cause alveoli to burst as pressure increases due to alveoli walls not recoiling and expelling all air out
Chronic pulmonary obstructive disease is a combination of chronic bronchitis, emphysema and asthma
Tar contains carcinogens such as benzopyrene - can cause mutations in the DNA and cells divide uncontrollably causing lung cancer


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Original post by Redman789
Repeats ? I think wrote that .... hopefully i did ! Maybe a larger range perhaps i dunno


Yeah, you could test it a few times and then calculate the mean absorbance to reduce random error and eliminate anomalous results. To be honest I don't think a larger range would help, seeing as the absorbance measurement was only 1.4 whilst the absorbance at 2.00mgcm-3 was higher than that I think. It's like if you're measuring an insect, you don't need a meter stick because the insect is so small anyway.


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Original post by Anymorefor123
I doubt you'd have to state the number hence it was only 1 mark and the q just asked for the bond


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yeah pretty sure it was between alpha glucose sub units which could have either 1-4 or 1-6 so i think just glycosidic would be fine. If not, then i doubt most people got it anyway.
Reply 667
Avatar for LB9213
LB9213
What did you guys write for the question about how the students got the (0.0, 0.0) point in the graph on the enzyme experiment?
I was so confused. I wrote about how they'd have to calibrate the colorimeter using pure water/ white paper, or the students could form a solution containing 0% enzyme conc
If you get like an A at AS overall and get A*s in A2 exams would you end up with an A* overall?
I put subunits in the fill in the blank space first then crossed it out and put chains:ashamed2::ashamed2::ashamed2: Would that not be right too, alpha and beta chains?
Original post by mosahra
I put subunits in the fill in the blank space first then crossed it out and put chains:ashamed2::ashamed2::ashamed2: Would that not be right too, alpha and beta chains?


I put chains too, it should be fine. I googled '2 alpha and 2 beta' and the word chains was used. I think subunits would refer to the amino acids, so maybe the person who wrote subunits may not be correct.


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Reply 671
Avatar for emsyp6
emsyp6
6
In the grid about primary & secondly response asking for speed and quantity of antibodies produced, what kind of this were we meant to put in the boxes?! Seemed a bit vague! I just put low & high kind of thing... 😖
Original post by GetOverHere
I put chains too, it should be fine. I googled '2 alpha and 2 beta' and the word chains was used. I think subunits would refer to the amino acids, so maybe the person who wrote subunits may not be correct.


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It specifically referred to the Quaternary Structure though? If so then it is sub-units
Reply 673
Avatar for hilam1
hilam1
Original post by Rajan_S97
Q1
a) C, O, OH
b) OH and H inverted around the Carbon
c) 1,4 Gylcosidic Bond, Maltose
d) Compact, Branched so glucose easily broken off, Animals require lots of glucose due to high levels of activity

Q2
a) beta pleated sheet
b) Hydrogen bonds
c) tertiary structure
d) subunits
e) quaternary

Anyone else fancy continuing? Cheers


What were the questions for Q2 c,d and e again?
Original post by Rajan_S97
Q1
a) C, O, OH
b) OH and H inverted around the Carbon
c) 1,4 Gylcosidic Bond, Maltose
d) Compact, Branched so glucose easily broken off, Animals require lots of glucose due to high levels of activity

Q2
a) beta pleated sheet
b) Hydrogen bonds
c) tertiary structure
d) subunits
e) quaternary

Anyone else fancy continuing? Cheers


Q2C) Is the secondary structure I'm pretty sure
Reply 675
Avatar for DiegoC
DiegoC
5
The question about protein structure, I) c) Secondary structure, hydrogen bonds stabilize it.
Tertiary structure would be disulfide bridges, ionic bonds, polar interactions and hydrophobic/philic interactions.

The question on classification of the lily plant, what did you guys write?
Original post by GetOverHere
I put chains too, it should be fine. I googled '2 alpha and 2 beta' and the word chains was used. I think subunits would refer to the amino acids, so maybe the person who wrote subunits may not be correct.


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YAY! thank god I was literally kicking myself for it!! :tongue:
Reply 677
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hilam1
Original post by Lion2121
Q2C) Is the secondary structure I'm pretty sure


Thats what I thought, I put tertiary for e as well because it was referring to a single polypeptide
Reply 678
Avatar for emsyp6
emsyp6
6
Original post by Lion2121
Q2C) Is the secondary structure I'm pretty sure


I put tertiary as well... It was the left handed helix right? Because it's the way it's folded & all that: so its the 3D structure


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Reply 679
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school2
anyone got the unofficial mark scheme

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