Biologists! How was it?

[Essein]

Chemical composition for a polypeptide could have being C O H N some Sulfur, cause polypeptides are short proteins and proteins are made of amino acids, and all those chemicals are in an amino acid.

[Saraime2003]

I wrote the number '11' on my hand so i would remmeber to come back to the fibrous protein question, cos i couldn't think of one, i thought collagen was a structural protein so i didn't write that... i got to my next exam n looked at my hand wondering why i had 11 on my hand, then i remembered and i was like OMG IDIOT!!! lol.... it was only 1 mark though. for the antigen one i wrote Th cells too n i said because Th cell recognise the antigens which are presented on the surface of the macrophages or phagocytes or whatever, then the Th cells stimulate the B cells to produces antibodies to fight the antigens. or something like that.

I wrote amino acids for the polypeptide subunits... For the tasmanian tiger thing about why the tumour cells were recognised as self cells i worte because the MHC markers on the tumour cells surface probabaly had species MHC markers so the tiger without the tumour recognised the tumour as self. lol i probably got that wrong but it was the best i could think of. lol

Aimee

Edit:

Just thought i'd let you all know about my stupid mistakes i made...
on the question where you had to give 2 reasons for each why DNA and RNA are different i wrote the most obvious one first:
DNA has 4 nitrogen bases: adenine, guanine, cytosine and thymine. then i wrote RNA has 4 nitrogen bases too, but they are: Adenine, Uracil, Guanine and Cytosine.

Then i had a mental blank and wasn't sure if adenine was adenine or adenisine, so i crossed it out and wrote adenisine, then crossed it out n wrote adenine then decided later it was adenisine. i meant to go back n change it to adenine again before i left, but i forgot

Then for the next part of the question i wrote DNA has a linear sequence and  then i think i wrote RNA has a circular DNA sequence XD lol...

i was worried it would be really hard n i'd make mistakes it ended up being reeally easy but i made many stupid mistakes. lol

[lacoste]

1). the first question was ridiculous,
chemical composition?? elements or actual molcule eg. phospholipid molecule?

2). last qst. was too general, something about the stimulus, i mean the ansnwer was in the paragraph above;
change in amount of copper? is that what everyone got? but i also mentioned about the enzyme jst in case

3). experiment,,, 5marks? what the?
1 mark for hypo, 1 mrk for results, 1 mrk for steps involving?? what else??

[nancy]

has any1 in this biology forum been to the tsfx intensive program in semester 1? im wonderin if its worth doin for UNIT 4?

[hoopa]

i had a massive mental blank on the fibrous protein example and the electron transport chain!?! anybody else have trouble with that?

[ahmed]

Oh god..I stuffed up that antigen question, I had to guess it. I think I wrote Th cells lol. And I left the final part of the 1st short answer (something about a feature of a fibrous protein and how the arrangement of chains gives that feature) blank because I forgot absolutely everything I learned about that! It was only 1 mark so I suppose it's not the end of the world for me lol :S ...I put collagen for a fibrous protein, and said that its key function is that it gives strength and elasticity to skin. My friend and I came out freaking about our hormone definitions...ours were basically identical to the one they gave on the paper! My biology teacher said the paper was very easy, so they're going to mark it hard. I was actually expecting a hard paper, but even last year's was marginally harder than this one.  

The correct answer is Th cells. The elasticity is due to the beta-plated sheets in the secondary structure of the protein. I think i will probably get an A.

[JL_91]

Yes, that's correct about the beta sheets, but I was referring to the second-last part of that first short answer question, where they asked us to name a fibrous protein and state its function (not what feature gives it a certain property) The one I blanked on was the last part of that question..which annoys me immensely, because I knew the answer..I just wasn't able to pull it out under exam conditions But I'm so glad so many people are saying that Th cells is right lol! I think the most I can hope for is a high A-low A+..

[username]

For the antigen question, do you think they would have accepted my answer if I specified that the MHC markers on the surface of T cells and B cells were involved in the recognition of self and non self?

[JL_91]

For the antigen question, do you think they would have accepted my answer if I specified that the MHC markers on the surface of T cells and B cells were involved in the recognition of self and non self?

Hmm..but MHC markers are present on the surface of the body's 'self' cells (e.g. cells in your organs), and recognised BY the T and B cells...so I'm not sure if they would or wouldn't!

I'm feeling so paranoid now. I know I've made a few dumb mistakes, but I don't know how costly it will be I'm just hoping I haven't made any more silly mistakes! I guess all we can do is sit back and wait until August 4th to find out. Does anyone think that getting a low A+ on this exam would completely remove the possibility of a mid-high 40s score in Bio?

[jajab]

what about a high A?

[username]

There was a question, kinda like "Students wanted to test the effect of the <b> lack of sunlight </b> in a sample of seeds of the same plant.

Name one variable that you'd keep constant.

Name one that you'd change."

What did everyone get?

[annie]

The correct answer is Th cells.

Well today my teacher told the class that was the wrong answer, he's an ex VCAA assessor for Biology, he told us it was meant to be an easy one but that quite a few people got it wrong: the question was "What cells are responsible for the Initial recognition of foreign antigens", the answer is not Th cells, but rather antigen presenting cells (Dendritic cells and macrophages etc..)

Th cells do not recognise foreign antigens , they require the antigens to be presented to them on a Class II MHC marker of an anti-gen presenting cells..

See:
http://en.wikipedia.org/wiki/T_helper_cell

"unprocessed antigens do not interact with T cells and are not involved in their activation"
"antigen presenting cells are primarily dendritic cells, macrophages and B cells"


There goes another mark...... At this rate im not sure if ill make an A+

[yonis_d]

There was a question, kinda like "Students wanted to test the effect of the <b> lack of sunlight </b> in a sample of seeds of the same plant.

Name one variable that you'd keep constant.

Name one that you'd change."

What did everyone get?

One variable you would keep constant would be the water given to the plants
Whilst, the variable that you'd change could be the amount of sunlight given to the plant

[username]

I dont get it though, if its testing the lack of sunlight, wouldn't the variable kept constant be the lack of sunlight?

[jajab]

no - because you need to be able to see what effect the lack of sunlight actually has on plants which are otherwise in an environment with the same conditions (i.e. water and temperature)