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# BIOL4 Biology Unit 4 Exam - 13th June 2011 watch

• View Poll Results: Are you resitting this unit?
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1. Oh, and also, in question 6a ii) on the same paper, one of the marks was to say that you had to measure the volume. Just to confirm, is this the volume of the tube in which the woodlouse is in? And how would this figure be used to work out the rate? (I know that isn't part of the question, but I kind of don't understand why it would be needed, because I thought you would only need to know the distance and time taken for the liquid to move ).

Could someone explain? Thank you very much.
2. (Original post by dominicdiep)
Hey guys! I was just marking the Jan 11 past paper and I was wondering whether the mark scheme did something wrong because I don't understand how it could have got this answer.

Basically on 5b) the answer says it is 2.75-2.81 for medium light intensity at 20 degrees C. But I think they got it wrong because that was for high light intensity...could someone confirm this? I got 2.4.

Thanks!
from what i remember, you use the equation : net = gross - respiratory losses

so for gross you just do net + respiratory losses. going up the line to medium light intensity, and adding the value for the line for respiratory losses it adds up to between 2.75-2.81

the first time i looked at the graph i didnt notice the line underneath the light intensity ones for respiration. make sure you use that one correctly.
3. Hi, thanks for the help and fast reply

But using your help I looked at the respiration rate at 20C and it is 0.7 mg...if you add this to 2.4 (the net rate of photosynthesis at medium light intensity) it is 3.1!!!

What am I doing wrong...
4. Oh hold on...the scale for respiration is different....

That is SNEAKY....

5. (Original post by dominicdiep)
Hi, thanks for the help and fast reply

But using your help I looked at the respiration rate at 20C and it is 0.7 mg...if you add this to 2.4 (the net rate of photosynthesis at medium light intensity) it is 3.1!!!

What am I doing wrong...
yeh i just realised what you're doing. you're reading off the left hand scale for the respiration line as well. you should read off the right hand side for that one haha, dont worry i probably did this too the first time!
6. this paper isnt synoptic like biol5 is it @[email protected]?
If it's not on the AQA website(which it isn't, I've checked) then it won't be available to anyone yet.
Shame, just thought it might have been leaked like the papers sometimes do. Would be interesting to know where the majority went wrong as it was a difficult paper.
8. (Original post by daughterofaprince)
my teacher listed on hot topics and they include everything in the book.

i think forensic science is very important.
isnt forencic science in biol5 lol
?
9. On that paper (january 2011), for the same question (5ai) on limiting factors, i can't see why it is light intensity that is limiting photosynthesis and not rate of respiration. Surely CO2 being produced there is much lower than the light intensity (when compared to the other two lines) and so it would become limiting. If you need me to take a picture of the graph and upload it ill try, but preferably can anybody who has this at hand help, thanks.
10. (Original post by ScaRR)
On that paper (january 2011), for the same question (5ai) on limiting factors, i can't see why it is light intensity that is limiting photosynthesis and not rate of respiration. Surely CO2 being produced there is much lower than the light intensity (when compared to the other two lines) and so it would become limiting. If you need me to take a picture of the graph and upload it ill try, but preferably can anybody who has this at hand help, thanks.

Well we know light intensity is definitely a limiting factor because for exact same conditions at the two higher light intensities, the net rate of photosynthesis is greater. temperature as well, because we can tell that the rate is greater for a greater temp than the temp within the two points. CO2 is not a limiting factor. we can tell this because for the lines of higher light intensity they show a greater rate of respiration (which in this case goes by HOW MUCH CO2 IS ABSORBED) - and so CO2 is in plentiful supply between the points on the line we are investigating.
11. (Original post by arvin_infinity)
Cant find any question on intensive rearing and conservation!
Would be amazing if someone tells me which paper( past paper) to look at
It's all over the June 2010 paper....God that paper sucked ass!
12. hey guys! does anybody know where i can find the jan 2011 mark scheme??? please reply as soon as you see this!!
13. (Original post by knowledgeISgood)
hey guys! does anybody know where i can find the jan 2011 mark scheme??? please reply as soon as you see this!!
look on the first page of this thread...
14. anyone else finding that they do the big 4/5/6 marker questions, even the 3 markers and you get the points in but miss that last one or last couple and then after you think ahhh why didnt i think! ... it keeps happening and its so annoying cos the markscheme is so specific with its bloomin points!
15. (Original post by SK-mar)
look on the first page of this thread...
It's AQA... im on edexcel, just wondering if any of you have the edexcel mark scheme please
16. (Original post by knowledgeISgood)
It's AQA... im on edexcel, just wondering if any of you have the edexcel mark scheme please
This is the AQA thread, so it's highly unlikely. Sorry
17. (Original post by cobra2k10)
hey, i dont have any revision notes fo this unit yet and when i get hold of some, ill upload them right away. I do have the aqa nelson thornes text book answers for this unit as they are not in the book. They may be of some help to you!
thanks! I was looking 4 ch8!!!!
18. (Original post by User12399)
I need a B atleast!! Never thought biology was going to be this hard.

What's the answer this this? Is it to do with recessive genes. The resistant gene is recessive and the two parents have the ressivw gene and the offspring are rr? (also other types would be produces). homo and hetro.
Never thought of that..true dat!

Dunno what they mean by "single gene" for ..
19. So I've always had trouble with ratios, and I'm terrfied they're going to come up, like they did in this paper:

http://store.aqa.org.uk/qual/gce/pdf...W-QP-JUN10.PDF

Question 7, fig. 3

I know the answers, but I don't understand ratios, i thought ratios were 3:1 not a decimal number.

Can someone please just talk me through what on earth they mean and how to deal with them? Not just in the context of this question, because I really don't get them at all.

+ rep and a plate of cookies for the person kind enough to help a maths phobic
20. (Original post by Tericon)
So I've always had trouble with ratios, and I'm terrfied they're going to come up, like they did in this paper:

http://store.aqa.org.uk/qual/gce/pdf...W-QP-JUN10.PDF

Question 7, fig. 3

I know the answers, but I don't understand ratios, i thought ratios were 3:1 not a decimal number.

Can someone please just talk me through what on earth they mean and how to deal with them? Not just in the context of this question, because I really don't get them at all.

+ rep and a plate of cookies for the person kind enough to help a maths phobic

the ratio has always got to be something : 1 ........ so for example in one of the past papers it said give the ratio of respiratory losses in cows to the amount of food absorbed in their gut. and these values were given in the table above. for respiratory losses the value was 12.25, and for absorption it was 12.50 ...... so the ratio of R:A (respiration : absorption) would be

12.25:12.50 ..... however to make it something:1 ... you divide the first value by the 2nd .... so 12.25/12.50 ... = 0.98:1 .....

in your case the values are ratios to 1 .... so for example if they gave a value of 1.25 ... it would mean 1.25:1 .... hope this helps...

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