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A level Biology: Post your doubts here!

daredevil

daredevil

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2 From which cell organelle are nucleic acids absent?
A chloroplast
B Golgi apparatus
C mitochondrion
D ribosome
 
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hela

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strangerss

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When they say the distance between each division on a stage micrometer is for example 0.1mm , do they mean the small divisions or the big divisions?
 
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strangerss

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HEY alsalum allaykum , can some one please help me put in question 2 Oct/Nov 2008 32 , how they said to draw five cells and their drawing showing more than that :S I don't understand can some please explain? and what about those dots on the right of the drawing , aren't they chloroplasts??
 
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Irfan1995

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hela said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_12.pdf Q13 Q15

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_13.pdf Q39 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q9 D Q26 D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf Q24 B Q31 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_12.pdf Q40 D Q1 A
Click to expand...

1) Every single protein is held together by peptide bonds. It's not something unique found in collagen only. Plus, some proteins have a very low tensile strength, so they're not even used as structural proteins.
2) Lets say you have one of those inflatable beach boards and it's curled up. When you pump it with air, it becomes less curled and more 'straight'.
Taking this analogy to the real question, the tissue in X is deflated while it is 'inflated' (with water) in Y.
This means that water has entered the cells in Y. So the water potential in Y is less negative than that of X, and the cells in Y have a lower potential than in X (because water entered them).
3) The energy used for photosynthesis is the total energy taken in by the plant. That includes the energy used for respiration. (27,000 + 3,000 = 30,000)
30,000/1,000,000 x 100% = 3.00%
4) Triglycerides have fatty acids which are made up of pure carbon-hydrogen chains. The only portion containing oxygen are the 6 atoms (out of over 150) in glycerol. So less than 4% of the atoms are oxygen.
Glucose (an example of a carbohydrate) has the formula C6H12O6. It has 6 oxygen atoms out of 24. So 25% of the atoms are oxygen.
5) In xylem vessels, water only moves from the roots to the top of the shoot (stem). In phloem vessels, mass flow is from source (site of production) to sink (site of consumption) in which either could be leaves or roots.
6) I already answered this!
Water uptake is a passive process (by osmosis). It doesn't require any energy. So mitochondria isn't going to help at all.
7) I'm pretty sure I answered this too.
The tidal volume is the volume of air exchanged while at rest. This is the distance between the maximum and minimum (of the small peaks). The distance is two vertical squares, which is equivalent to 500 ml.
The vital capacity is the maximum volume than can be taken in by the lungs. This is the distance between the maximum and minimum (of the big peak). The distance is 15 vertical squres, which is 3,750 ml.
8) They tell you that the total energy synthesized is the GPP.
Some of the energy is respired, and some is used to store organic nutrients (NPP).
The sum will give you the total: NPP + respiration = GPP. So NPP = GPP - respiration
9) Take it this way. Lets say you're up in the sky, and you want to keep the maximum amount of trees in your vision. The higher you go, the smaller the trees seem to be, and the more trees you can see. As you go closer, the trees look bigger, but you can see a smaller number of trees.
With a small magnification, you can see many tiny cells. With a large magnification, you can see very few cells, but they seem large and detailed.
 
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hela

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hela said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_12.pdf Q13 Q15

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_13.pdf Q39 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q9 D Q26 D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf Q24 B Q31 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_12.pdf Q40 D Q1 A
Click to expand...
CAN ANYONE EXPLAIN

]http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_12.pdf Q13 Q15

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_13.pdf Q39 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q9 D Q26 D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf Q24 B Q31 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_12.pdf Q40 D Q1 A
 
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Irfan1995

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hela said:
CAN ANYONE EXPLAIN

]http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_12.pdf Q13 Q15

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_13.pdf Q39 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q9 D Q26 D
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf Q24 B Q31 D

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_12.pdf Q40 D Q1 A
Click to expand...

I just explained this in the post above!
If anything needs further clarification, just say so!
 
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Nader Ihab

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confirmed and 90% sure for paper 32 that the experiment of the effect of surface area to volume ratio of potato discs on rate of osmosis
the slide will be somehow weird and will be a section in the liver but don't worry only plan diagram needed
 
falcon678

falcon678

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can anybody please explain me the diff b/t plasma cells n memory cells? or are they the same thing?
o_O
 
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