A level Biology: Post your doubts here!

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Irfan1995

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hela said:
can u solve please
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_11.pdf Q 6
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s12_qp_13.pdf Q2 Q3
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1) Didn't I already answer this question before?
Anyways, the first column shows how much reducing sugar is present.
After hydrolysis, all the non-reducing sugar is broken down to reducing sugar. So the second column represents reducing sugar + non-reducing sugar
So if you want the amount of non-reducing sugar, all you have to do is find the difference between the two columns:
A: 55 - 30 = 25
B: 55 - 55 = 0
C: 85 - 65 = 20
D: 80 - 70 = 10

2) You need to find the total biomass of a population. This is the number of individuals x biomass of one individual. Then arrange them in descending order (since energy is generally lost along a food chain).
R: 10,000 x 0.1 = 1,000
S: 5 x 10 = 50
T: 500 x 0.002 = 1
U: 3 x 300,000 = 900,000
Arranging them gives U --> R --> S --> T

3) Primary consumers = herbivores
The net productivity that's passing to herbivores is literally how much of the net productivity (from the previous trophic level) was successfully integrated in the herbivore's body. So that's 0.75/1.8
0.75 is the energy integrated into the herbivore's system from the 1.8 net productivity available.
I'm not really sure if that makes much sense to you :(
 
LMGD33

LMGD33

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Hey guys! How are you going to prepare for paper 5 A2? I'm a private candidate, and all throughout the year, I wasn't able to analyze any labs found in the syllabus. I joined the ib class for some dissection and reflex labs, even some chromatography, and I have all my knowledge from the previous year with my lab teacher. The past papers seem pretty straight forward, I'm going to tackle youtube, but any advice you could give me?

Much appreciated!
 
Wanderer

Wanderer

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LMGD33 said:
Hey guys! How are you going to prepare for paper 5 A2? I'm a private candidate, and all throughout the year, I wasn't able to analyze any labs found in the syllabus. I joined the ib class for some dissection and reflex labs, even some chromatography, and I have all my knowledge from the previous year with my lab teacher. The past papers seem pretty straight forward, I'm going to tackle youtube, but any advice you could give me?

Much appreciated!
Click to expand...

I guess go through all the pastpapers thoroughly and revise your Olevel and Alevel books for the designing part.......that's all you could do about it :)
 
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hela

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I

Irfan1995

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hela said:
can u solve thanks
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf Q24 Q31

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_12.pdf Q13 Q15

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_12.pdf Q1

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_13.pdf Q39

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf Q9 Q26
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1) Water enters by osmosis, a passive process. There is no need for mitochondria to uptake water.
2) The tidal volume (distance between a maximum and minimum) is 500 ml (equivalent to two vertical squares). The vital capacity (distance between the maximum and minimun in the large peak) is 3.75 dm^3 (equivalent to 15 squares)
3) I don't take CIE Chemistry, but I'll do my best. The first three chlorides are neutral (no effect on litmus). The oxide of phosphorous is acidic (non-metal oxide) and the chloride of phosphorous is PCl5, which reacts with hydroxyl group (like in carboxylic acids, alcohols, and water) producing HCl which is acidic.
4) Electrolysis of brine (salty water):
Anode: 2Cl- --> Cl2 + 2e-
Cathode: 2H2O + 2e- --> H2 + 2OH-
5) In equation B, chlorine is oxidized from 0 to +5
6) Ethanoic acid only has two carbon atoms. There is no way it could react with calcium to produce a compound with 4 carbon atoms. Eliminate option 1 and you will only have C
7) When the voltage is set to match that of copper, all elements that are more electropositive than copper will form a sludge underneath the anode.
8) Option A is a dialdehyde which does not react with sodium.
 
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hela

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h4rriet

h4rriet

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hela said:
can u solve thanks​
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24. B, because water enters by osmosis. Osmosis is a passive process, requiring no energy.
31. All you have to do is read the graph.

13. Phosphorous chloride and oxide are both acidic.
15. The electrolyte contains Na+ Cl- H+ & OH-. H2 is given off; for that, two molecule of H2O are need. Cl2 is given off; 2 molecules of NaCl are needed for that. Therefore, what's left is 2 Na+ and 2 OH-.

1. The smallest magnification will enable you to see the most number of cells.

39. There is no habitat described. The niche of an organism requires us to know everything that the organism eats and all the organisms that eat it, including how these two vary according the seasons of the year.

9. Ag+ is positive, so it should go to the cathode; it doesn't because it's lower in the reactivity series.
26. Alcohols and carboxylic acids react with Na. A is the only compound that doesn't have an alcohol or caboxylic acid group; all the other have either or both. You have the draw the compounds to know.
 
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