May 16th 2011 - by1 resit wjec

Original post by banana_smoothie

Oh I'm glad its not just me then! Yes, that's what I pt down - optimum temperatures and they work in different range of temperatures aswell :smile:

Yes the question was about differences between bacterial amylase and that found in humans.

I also put different optimum temperatures (didn't write about the range - didn't think more was needed as it was 1 mark).

Original post by Agolas

Wasn't too bad that osmosis question caught me off guard also everyone who I sat the exam with was confused about the Polymer of A (Amino acid) test ??

I said that a polymer of A would be a Protein which could be an enzyme so you could do a rate of reaction test...?

One of my friends put down 'carboxylic acid' test. Any ideas for that one? cheers :smile:

Polymer of A would be a protein so would give a positive Biuret's Reagent test, so the solution would turn purple.

As for the question after it with a problem with low concentrations of the polymer being in the solution, I wrote that there would not be much reaction with the reagent so a distinct purple colour would not be formed.

Original post by RATM33

Thats what I put :smile:

For the water potential one, I wrote that it was because the solute potential is equal to the water potential because it was in incipient plasmolysis (or whatever the question was showing), so the water moved into the cell through osmosis as the cell wall is fully permeable

Original post by TopWarrior

I put: the fact that the cell had a solute potential of -600 and the sucrose solution had a water potential of -600, then water would move out of the cell hence it becoming flaccid. - Osmosis.

Why were the mitochrondrion different in size? Apparently the answer was because of the photo angle? - If that is correct then WJEC are pathetic.

I also talked about incipient plasmolysis - my reasoning was that on average, the cells were in that state (remember the question said why would the student conclude blah blah blah, not why in general) so the water potential inside and outside the cell would be equal.

The one about the mitochondria was that the diagram only shows one plane, and the mitochondria are 'cut' into different planes. This has come up before apparently, although I only knew it because on the AQA syllabus you learn about microscopes and this is part of it (that microscopes only show one plane). I almost talked about microscopes before I noticed that the diagram was quite clearly just a drawing!

Original post by liverpool94

hey um when there was the cell membrane (fluid mosaic model) did you write for one of the letter phospholipid bilayer or hydrophobic tails?
i wrote phospholipid bilayer :s-smilie:

and also do you think ums will be high or low for this paper?

Original post by RATM33

I wrote phospholipid bilayer as well, but a couple of my mates said that it was pointing to the hydrophobic tails and not the phosphate head, so they wrote something like hydrophobic region or something. I didn't really see exactly where the arrow was pointing to :redface:

I wrote phospholipid bilayer too. I was annoyed because the arrows only showed the hydrophobic region, but I reasoned that if they wanted the 'tails', then they'd have only included the tails of one layer and not both. I decided against hydrophobic region just because phospholipid bilayer is a cool phrase anyway.

I didn't consider that, on the diagram, what I labelled as an extrinsic protein could have been a glycolipid. I thought glycolipids would be obvious as having a branched polysaccharide though, but in the exam I jsut immeadiately wrote extrinsic protein and thought nothing of it.

Reply 44

What about question 6/ where there was a diagram showing a few organelles (same questions as the one about mitchondrion being viewed in different planes) you had give the names of two organelles n functions,one was RER but the other one seemed like it could quite easily be interpreted as SER or gogli body, Anyone find this a problem???

Reply 45

Original post by al3xse

What about question 6/ where there was a diagram showing a few organelles (same questions as the one about mitchondrion being viewed in different planes) you had give the names of two organelles n functions,one was RER but the other one seemed like it could quite easily be interpreted as SER or gogli body, Anyone find this a problem???

I thought it was SER. I thought golgi bodies were smaller, and don't look like typical sections of endoplasmic reticulum.

What I did find a problem though was describing the functions of the labelled organelles. Why were they 2 marks each?
I named the organelles, hoping that would give the other mark. As a last resort, I gave an example of the products formed for each.

Reply 46

Hider

i put pretty much the same although for the protein test i talked about biuret A and B? not too sure, what "essay" questions did you do at the end?
i did dna structure but im not sure how i would have got 10 marks for it :s-smilie:

also for the enzyme and temperature question it was 6 marks so what did you guys put?

Reply 47

Original post by AnonyMatt

I thought it was SER. I thought golgi bodies were smaller, and don't look like typical sections of endoplasmic reticulum.

What I did find a problem though was describing the functions of the labelled organelles. Why were they 2 marks each?
I named the organelles, hoping that would give the other mark. As a last resort, I gave an example of the products formed for each.

I also went with SER as the 2nd organelle because all gogli bodies ive seen have been more like linear-ish flattened sacs with vesicles on either end! I put the name of organelle down(1 mark) and its function (2nd mark) RER- Forms an extensive transport system used to transport substances around the cell e.g proteins synthesized by the ribosomes.
SER- synthesis of lipids and transport :-)

Fingers crossed it wasnt a gogli body but even if it was then the vesicles werent very clear and the WJEC should award 1 mark for writing SER Because I said sooo :-P

Reply 48

Original post by Hider

i put pretty much the same although for the protein test i talked about biuret A and B? not too sure, what "essay" questions did you do at the end?
i did dna structure but im not sure how i would have got 10 marks for it :s-smilie:

also for the enzyme and temperature question it was 6 marks so what did you guys put?

The essay questions werent the most kindest ive seen, I mean a question about the sequence of mitosis would hav been smashing :-) or even a nice compare structures of DNA and RNA at least then theres a lot more scope to get marks than just describe the structure of dna. I picked DNA essay question btw and I two found it a challenge to put down suffish points to gain the marks, I talked about every thing possible, judging by that DNA essay question mark scheme posted here I should do rather well.

Reply 49

Original post by al3xse

I also went with SER as the 2nd organelle because all gogli bodies ive seen have been more like linear-ish flattened sacs with vesicles on either end! I put the name of organelle down(1 mark) and its function (2nd mark) RER- Forms an extensive transport system used to transport substances around the cell e.g proteins synthesized by the ribosomes.
SER- synthesis of lipids and transport :-)

Fingers crossed it wasnt a gogli body but even if it was then the vesicles werent very clear and the WJEC should award 1 mark for writing SER Because I said sooo :-P

I just wrote "site of protein synthesis, such a hormones" and "site of lipid synthesis, such as triglycerides". Come to think of it, I don't think I went back and wrote my example of a lipid. :frown:

And I just realised that the 2 marks probably come from writing "site of..." and TRANSPORT! :frown:

Either way, you definitely got your 2 marks there! :smile:

Reply 50

Original post by Hider

i put pretty much the same although for the protein test i talked about biuret A and B? not too sure, what "essay" questions did you do at the end?
i did dna structure but im not sure how i would have got 10 marks for it :s-smilie:

also for the enzyme and temperature question it was 6 marks so what did you guys put?

I don't even know what you mean by Biuret A and B tbh.

I did DNA structure too. Mentioned most of the points posted earlier. Didn't use the word nucleotide once though, fml. Used nucleic acid extensively.

What question do you mean? Refresh my memory. :smile:

Reply 51

RATM33

Original post by al3xse

What about question 6/ where there was a diagram showing a few organelles (same questions as the one about mitchondrion being viewed in different planes) you had give the names of two organelles n functions,one was RER but the other one seemed like it could quite easily be interpreted as SER or gogli body, Anyone find this a problem???

I wrote SER at first, but I read the question again and it said something about the cell being involved in enzyme secretion or something, so I went back and changed it to golgi body. I really don't know now :redface:

Reply 52

Groberts00

Original post by banana_smoothie

umm im not sure how i did my calculations but i had 11.6 cm / mn! anyone got htat aswell?

yeah I got 11.6 as well. I had 5.8/.5 since the time taken was in seconds when the units was supposed to be in minutes. I hope we're right.

Reply 53

mj_smith

Did anyone do the Mitosis/Meiosis essay? I haven't come across one person who has yet! I was quite happy with my answer for it, but seeing as no-one else seems to have chosen it I'm beginning to wonder if it was harder than I thought! Oh well, not much I can do about it now haha...

Reply 54

Original post by Groberts00

yeah I got 11.6 as well. I had 5.8/.5 since the time taken was in seconds when the units was supposed to be in minutes. I hope we're right.

We are.

Tbh I was shocked at seeing hands fly up asking for calculators. I wish WJEC included more calculations - easy marks!

Original post by mj_smith

Did anyone do the Mitosis/Meiosis essay? I haven't come across one person who has yet! I was quite happy with my answer for it, but seeing as no-one else seems to have chosen it I'm beginning to wonder if it was harder than I thought! Oh well, not much I can do about it now haha...

I avoided that question because it talked about advantages or uses or something. If it was just explain the stages of cell division, and then describe the differences between mitosis and meiosis I probably would have chosen it instead of the DNA one!

Reply 55

pink_floyd

8

For the protein sticking out of the cell membrane i put peripheral protein, its what we were taught but who knows if it is what WJEC was after!

Original post by RATM33

I wrote SER at first, but I read the question again and it said something about the cell being involved in enzyme secretion or something, so I went back and changed it to golgi body. I really don't know now :redface:

I also put Golgi Body instead of SER arghhh questioning that now :s-smilie:

Reply 56

mj_smith

Original post by AnonyMatt

I avoided that question because it talked about advantages or uses or something. If it was just explain the stages of cell division, and then describe the differences between mitosis and meiosis I probably would have chosen it instead of the DNA one!

Hmm, uh-oh! I described the stages of Mitosis, but also said how it was of use (wound repair etc) and how it is different to Meiosis - or something like that! Fingers crossed I will get some marks for explaining the stages of mitosis, at least. I couldn't think of 10 marks worth of answer for the DNA question, although I am now hoping I interpreted the mitosis question correctly!!

Reply 57