IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: kratos009 on November 16, 2009, 04:17:55 am
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Hey guys
I was wondering whether we need to know the topic concerning diets, and deficiency caused by the lack of some minerals. My teacher said that we don't need to know anything about it and i also didn't see anything on the Biology syllabus about this certain topic. But i just did the May/June 2003 paper 2 for Biology and a whole question came up concerning this topic. I know that there is a possibility that the syllabus may have changed but i want to make sure. So could someone tell me if we are required to know this chapter, and could you also state your source? Thanks a lot, i greatly appreciate it ;D.
Good luck with Biology tomorrow! ;)
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Are you from NZ? What school? What text book do you use?
Nevermind,
If you are using the same text, chapter 12 is a diet chapter. You might want to skim read that. I am pretty sure that is not in the syllabus as my teacher didn't cover it.
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Yeah i'm from NZ, i use the Advanced series Biology 1, endorsed by OCR, (a big picture of a sunflower on the front :D), i'm guessing you also use this book cause Chap 12 is Diet. Thanks yeah i'll read over it but i was wondering if we had to know these according to the syllabus. Cause usually the CIE exams only ask questions if they have listed the topis in the syllabus. Thats why i was worried when they asked the question in the past paper...
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If you read the chapter, most of it is common sense anyway so I don't think you should be too concerned.
Only the vitamin questions, which I am pretty sure is not in the syllabus. Download the syllabus and use adobe "search" and search for "Diet" or "Vitamin" and let me know! :]
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Ok i just had a check with the biology syllabus and i checked almost all the words that is linked with the diet chapter and i got no results... so i'm guessing we don't need to know it :).
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Hey
Good luck with your exams tomorrow, I have mine as well but I use a different book that is up to date as of 2009 =D And there is nothing with diets, but you need to know the uses of inorganic ions like magnesium and calcium and sodium as such.
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Yep, We definitely have to know about ions such as sodium though. Best of luck tomorrow.
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Ok thanks. Good luck guys ;).
Oh i just got one more question about the syllabus. Do we need to know anything about the production of insulin and the use of restriction enzyme in cutting DNA sequences? Its like only 2 pages in my book but my teacher never said anything about it and idon't see anything on the syllabus. Did any of your teachers go over it? thanks.
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No, that is not part of the newest syllabus nor in the book =)
And it never came up anyway, so if it did, they will provide info for us =D
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Ok that's a relief, thanks a lot.
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I have the same book. (Green OCR, sunflower blah).
Diet is not in our syllabus. Just have a look at the first table in the chapter.
Ions that are important are at the end of chapter 1 in a table. Learn those.
gl
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Good luck to you to.
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hay gd luck every1
any predictions?
I'm doing my exam in 9 and a half hours
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Hey :]
How was it guys?
[Note] :: All CIE A Level Examinations have finished globally. Thus, I believe we can discuss the paper now. (or do we have to wait 24 hours :-\ ? @admins)
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Ummm, it was not too bad, i was able to finish the exam pretty easily within the time limits unlike the physics paper 2 >:(. I made a really silly mistake on the first question, instead of putting active transport of calcium ions i put facilitated diffusion, cause i didn't see the arrows... >:(. Other than that and the very last question the rest of the paper was okay :).
Only one more exam to go ;D.
I'm hoping for an A for Biology but i doubt i'll get it...
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It was great for me! I'll stay away from discussing what did and didn't come out, but it was quite easy but quite perplexing.
I am finished with the AS! I'm celebrating today and tomorrow by not studying anything at all. :P
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I am finished with the AS!
Baby, it ain't over till it's over.
I mean the results, FYI. :>
It was good. :)
I made some silly mistakes myself. Wrote lysosome instead of vesicle, etc. Maybe because I didn't sleep so well. :-\
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Haha, were you stressed about the Biology paper? For which question did you write lysosome instead of vesicles? Cause there was a question concerning with what is the role of the lysosomes in the phagocyte, so if you used lysosome there, you should be fine...
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Haha, were you stressed about the Biology paper? For which question did you write lysosome instead of vesicles? Cause there was a question concerning with what is the role of the lysosomes in the phagocyte, so if you used lysosome there, you should be fine...
No, not that.
I am talking about the one after the labeling.
I also did a silly mistake on the calculation of biomass or whatever.
Furthermore, many other silly mistakes in the xylem question. >:|
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The labeling part.. Wasn't it the Vacuole or tonoplast?
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The labeling part.. Wasn't it the Vacuole or tonoplast?
It was Vacuole for that.
The part b one. Where the cell components help its function.
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Good. What about the very last question abt the Nitrogen thingyy??? :)
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Good. What about the very last question abt the Nitrogen thingyy??? :)
I wrote a huge random answer.
I just remember I wrote "After breaking down the organic compounds and forming raw materials like N2, their cells absorb the N2. This gives them energy".
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gaaaah did fool flaw at the enzyme question....somehow plotted linear graph instead of "increase-then-constant" curve....and I EXPLAINED THE QUESTION BY QUOTING LE CHATELIER'S PRINCIPLE!!! AAAAAHHH LOSE 7 MARKS!
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gaaaah did fool flaw at the enzyme question....somehow plotted linear graph instead of "increase-then-constant" curve....and I EXPLAINED THE QUESTION BY QUOTING LE CHATELIER'S PRINCIPLE!!! AAAAAHHH LOSE 7 MARKS!
omg same here!!! i don't know what's up with me while doing the paper.. i plot a curve without the constant line.. :'(
so i obviously dont get marks for explaination of the constant line too.
what really scares me about this paper is that each question has like 3-5 marks..
and for some questions i'm not sure what do they actually want us to write :(
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and for some questions i'm not sure what do they actually want us to write Sad
for example?
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plz discuss after 24hours..
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plz discuss after 24hours..
Paper's finished globally.
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Paper's finished globally.
yea sure it must have been buh advisable to wait for 24hrs.
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what the...
It isn't facilitated diffusion...? O.M.G FAIL >_>
I am pretty sure the question said "It is 1000x LESS concentrated inside..." so is it really active transport?
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Yeah cause apparently when i came out of the exam room there were arrows indicating the direction of movement of calcium ions... >:(. It was moving against the concentration gradient out of the cell...apparently...
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Yeah its 100% active transport. Since the arrows indicate which way the ion was moving. I screwed up the last question and I think I lost a mark where "why does the daughter cells have to be genetically identical". I said it prevents mutations but what else?
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what the...
It isn't facilitated diffusion...? O.M.G FAIL >_>
I am pretty sure the question said "It is 1000x LESS concentrated inside..." so is it really active transport?
I thought all ions move via active transport and glucose moves via facilitated diffusion..
@Doorven - for growth and repair of tissues?
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Yeah its 100% active transport. Since the arrows indicate which way the ion was moving. I screwed up the last question and I think I lost a mark where "why does the daughter cells have to be genetically identical". I said it prevents mutations but what else?
If you have the same organism, and your daughter cells are different. Your characteristics would change, right..?
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I think for that genetically identical cells you just have to say that if genetically identical cells are not produced this would lead to mutation of the DNA, which may result in the formation of cancerous cells due to the mutated DNA. Thats what i put.. ;).
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hope i can get A in all four subject lol....
i need 4 A's for my medicine ::)
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Ok good luck ;). Its still a long time away from getting our results, a long wait... :D.
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yay! i put active transport :D
i got so freaked...the lysosome thing was 4 marks!
what did u guys put for why they raised the temp to 85 degrees??
and what did u write about the cell surface membrane's role?! it was 3 marks!
i just said it folds inwards to engulf materials outside of cell into a vesicle.
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For the 85 degrees Celsius one they did it to denature the enzyme because the whole point of the experiment was to see when it reached the green colour first. So they needed to kill the enzyme so that it does not keep producing more reducing sugars which would change the colour of the solution of Benedict ;). And for the cell membrane one you just had to say it consists of receptors, which seek the bacteria via anitgen on bacteria's membrane, and then the bacteria binds to the phagocyte. then the cell membrane engulfs the bacteria via endocytosis.
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I almost gave a "facilitated diffusion" answer and a friend of mine actually answered "facilitated diffusion". :D
What are the vacuoles/lysosomes?? ??? I can't remember anything about that.
And about the Nitrogen, I thought that the nitrogen will be used by the plant to make protein and proteins have energy values. LOL (Are the leaves even able to?)
I had no idea so I just made a wild guess.
Anyone got confused for the TMP-1 Protein question? I had no idea what I need to mention in that one.
By the way, will the examiners deduct some points if the answers contain bad grammar? I think my brain wasn't working right during the exam and some of the sentences I wrote sounded awfully strange in my head.
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For the TMP 1 .. you only need to trace it out.. Starting from the nucleus blah blah.. replication... transcription... bla blaa.. and sososoosososoo until it reaches the cell membrane.. I am quite positive thats the one they want..
No.. As long as it is still understandable and don't change the meaning, the examiners wont care for your English..
Anybody did Chem P2?? I cant find a post in the forum abt that..
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Stangely I do not remember any arrows seen. Maybe there was a difference in the variants of the paper done right? One of them had active transport, other had facilitated diffusion because the question specifically said 'the concentration of the calcium ions inside the cell is thousand times less than the concentration outside.' How do these ions move into the cells?
The ions can only move into the cells by facilitated diffusion in that case.
I think there was a variation in the question in both the variants.
That energy level had to do with denitrifying bacteria and decomposing bacteria present in the soil which would increase the energy flow by decomposing amino acids found in tissues (decomposing) and by decomposing the nitrogen compounds to nitrogen (denitrifying bacteria). Mostly denitrifying bacteria as they obtain energy directly by breaking down nitrogen compounds while decomposing bacteria obtain energy by feeding on dead tissue.
For that TMP-1 structure, it had to do with DNA unwinds, mRNA replication, moves out, ribosome, translation, amino acid coded and finally packaged by the Golgi body and leaves via the cell membrane. A number of organelles could be involved from nucleolus to nucleus to ribosomes to Golgi body to cell membrane.
Hopefully the paper was not that bad.
A change in genetical code would result in mutation and would result in different cells hence repair, growth would not be able to take place. In other words, yes characteristics would be changed of the cell.
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For the 85 degrees Celsius one they did it to denature the enzyme because the whole point of the experiment was to see when it reached the green colour first. So they needed to kill the enzyme so that it does not keep producing more reducing sugars which would change the colour of the solution of Benedict ;). And for the cell membrane one you just had to say it consists of receptors, which seek the bacteria via anitgen on bacteria's membrane, and then the bacteria binds to the phagocyte. then the cell membrane engulfs the bacteria via endocytosis.
The question was not suggest, it was 'explain.' Suggest would be an assumption as made by you, explanation has a fairly proven reason behind it I assume. Heat was needed to speed up the reaction by providing extra activation energy to the molecules so that colour changes could be observed faster. Without heating, Benedict's solution does not produce results, as we've done in the laboratory. So it was just to speed up the reaction, by providing them with activation energy and increasing kinetic energy of the molecules hence.
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Umm, i think in the question they had already stated that the reaction was taking place at temperature around 30 degrees Celsius. That temperature alone would be sufficient to carry out the reaction between the enzyme and the substrate. And anyway the temperature is meant to be kept constant until the point of increase at 85 degrees Celsius. this suggests that they want to find out the rate of reaction using the concentration of the substrate as the variable, which they did. The temperature must be kept constant to obtain a fair result for each of the concentrations of substrate they used. Therefore the only reason in which why they had increased the temperature was to stop the activity of the enzyme in order to have a definite end point to the reaction as it stated in the passage that the end point in which they were observing was the expected green colour, which is fairly early on and would be obtained with the presence of the smallest amount of reducing sugars.
I agree that you had to heat the Benedict at school but most of the time we were just testing the solution itself for the presence of Reducing sugars. In this circumstance there is an enzyme within the solution as well, which is catalysing the breakdown of the sucrose. therefore if you heat the solution too early then the enzyme would be denatured before the reaction has proceeded and no results would be obtained as there would be no reducing sugars present.
This is just my opinion, don't know if its right or wrong....
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I agree.
Umm, i think in the question they had already stated that the reaction was taking place at temperature around 30 degrees Celsius. That temperature alone would be sufficient to carry out the reaction between the enzyme and the substrate. And anyway the temperature is meant to be kept constant until the point of increase at 85 degrees Celsius. this suggests that they want to find out the rate of reaction using the concentration of the substrate as the variable, which they did. The temperature must be kept constant to obtain a fair result for each of the concentrations of substrate they used. Therefore the only reason in which why they had increased the temperature was to stop the activity of the enzyme in order to have a definite end point to the reaction as it stated in the passage that the end point in which they were observing was the expected green colour, which is fairly early on and would be obtained with the presence of the smallest amount of reducing sugars.
This is just my opinion, don't know if its right or wrong....
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Umm, i think in the question they had already stated that the reaction was taking place at temperature around 30 degrees Celsius. That temperature alone would be sufficient to carry out the reaction between the enzyme and the substrate. And anyway the temperature is meant to be kept constant until the point of increase at 85 degrees Celsius. this suggests that they want to find out the rate of reaction using the concentration of the substrate as the variable, which they did. The temperature must be kept constant to obtain a fair result for each of the concentrations of substrate they used. Therefore the only reason in which why they had increased the temperature was to stop the activity of the enzyme in order to have a definite end point to the reaction as it stated in the passage that the end point in which they were observing was the expected green colour, which is fairly early on and would be obtained with the presence of the smallest amount of reducing sugars.
I agree that you had to heat the Benedict at school but most of the time we were just testing the solution itself for the presence of Reducing sugars. In this circumstance there is an enzyme within the solution as well, which is catalysing the breakdown of the sucrose. therefore if you heat the solution too early then the enzyme would be denatured before the reaction has proceeded and no results would be obtained as there would be no reducing sugars present.
This is just my opinion, don't know if its right or wrong....
Hi, well we won't know the final answer till the MS comes out but a clearer idea can be given only if the chemistry of glucose is understood.
The Benedict's tests positive with glucose only by the reaction of Copper 2+ ions to Copper 1+ ions. What heat does is it isomerizes glucose into an aldehyde, which otherwise is in a ketone form. Ketone is not a good reducing agent, unlike aldehyde which has that C-H bond, if you have done chemistry you would understand that is why aldehyde tests positive with Fehling's, Tollen's as well. Obviously, this chemistry of glucose is really not required at AS-level but the basic idea that a high temperature of 85 degrees would faciliate the precipitation of Copper (II) oxide (responsible for colour change) would be the key to the answer. However as I said, we will not know the final till MS comes out.
Cheers :)
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Also, if you do want to read up on this,
http://en.wikipedia.org/wiki/Benedict's_solution
:)
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Ok, i think we both seem to have different interpretation of the question. I understand what your saying, i do AS Chemistry, but i thought that it would be irrelevant in this particular Biology question because the whole question is about enzymes and concentration of the substrates. That is why i put an answer concerning enzymes and relating it to the enzymes topic. Well no one knows what the correct answer is going to be....(other than the Cambridge markers :D).
All we can do is hope for the best ;). No use thinking about it now. I got to concentrate on my Chemistry multi-choice >:(.
And to all those who are doing the Chemistry multi-choice tomorrow GOOD LUCK.
Ace it and then you can enjoy your holidays after ;).
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Ok, i think we both seem to have different interpretation of the question. I understand what your saying, i do AS Chemistry, but i thought that it would be irrelevant in this particular Biology question because the whole question is about enzymes and concentration of the substrates. That is why i put an answer concerning enzymes and relating it to the enzymes topic. Well no one knows what the correct answer is going to be....(other than the Cambridge markers :D).
All we can do is hope for the best ;). No use thinking about it now. I got to concentrate on my Chemistry multi-choice >:(.
And to all those who are doing the Chemistry multi-choice tomorrow GOOD LUCK.
Ace it and then you can enjoy your holidays after ;).
Haha you're right mate.
For all we know either of us are out of line on this one OR the MS is flexible enough to accomodate both the answers :P
Take care, cheers mate. :D