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AS Biology P1 MCQs Preparation Thread

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View attachment 12138


Why it's 5? and not 3?

When they said air in alveolus isn't it that, to reach RBC, air from alveolus goes out of the alveolar wall, goes into endothelial wall, goes into RBC???

View attachment 12139

What does reduction division means? why can't it be T and V?

The first question is very simple. An oxygen molecule has to diffuse to 5 cell surface membranes. Let me show you how, Check the uploaded file.


Reduction division means when chromosome number is halved. In first diagram you can see at point S, from diploid number there is a change to haploid number(halved) so we got S. The second is V has again from a diploid cell, gametes are formed which are haploid(half number of chromosome)

Hope that helped! :)
 

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The first question is very simple. An oxygen molecule has to diffuse to 5 cell surface membranes. Let me show you how, Check the uploaded file.


Reduction division means when chromosome number is halved. In first diagram you can see at point S, from diploid number there is a change to haploid number(halved) so we got S. The second is V has again from a diploid cell, gametes are formed which are haploid(half number of chromosome)

Hope that helped! :)

Thanksss!!!! I've confused about the layers things for so long. THANKS!! :D
 
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yupp. i saw one of the papers it says 4 or 5..
but why 4?

It can be 4 as carbon-dioxide will be directly transported by the blood in the form of hydrogen-carbonate ions. Hence no need to diffuse out of RBC's.
 
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Screen shot 2012-06-06 at 3.10.01 PM.png
how to do this calculation?

Screen shot 2012-06-06 at 3.22.38 PM.png

why can't high temperature break ionic bond?
high temperature and pH change can break, right?
 
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View attachment 12138


Why it's 5? and not 3?

When they said air in alveolus isn't it that, to reach RBC, air from alveolus goes out of the alveolar wall, goes into endothelial wall, goes into RBC???

View attachment 12139

What does reduction division means? why can't it be T and V?

see the 5 membranes in the attachment....
2 of the alveolar wall
2 of the capillary wall
and 1 of the rbc

for the second.....reduction division is meiosis....they produce cells with half the number of chromosomes, like gametes. so where ever gametes or egg cells are produced reduction division occurs...
 

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http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_11.pdf
Q22 the answer according to the mark scheme is A....
why not D, i agree with the 1 and 2 but 3...sugar and phosphate bonds, do form...when the free mRNA nucleotides in the nucleus come and attach to the exposed template (a DNA strand) something forms the sugar phosphate backbone...so the sugar phosphate bonds are forming between the mRNA nucleotides...
4 even this seems true.....the free mRNA nuclotides in the nucleus come and pair with the exposed DNA strand according to compleentary base pairing rules....
so why A?
 

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http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_11.pdf
Q22 the answer according to the mark scheme is A....
why not D, i agree with the 1 and 2 but 3...sugar and phosphate bonds, do form...when the free RNA nucleotides in the nucleus come and attach to the exposed template (a DNA strand) something forms the sugar phosphate backbone...so the sugar phosphate bonds are forming between the RNA nucleotides...
4 even this seems true.....the free RNA nuclotides in the nucleus come and pair with the exposed DNA strand according to compleentary base pairing rules....
so why A?
Because clearly the 4th process does not occur TWICE during transcription. I'm not sure about the 3rd one.
 
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Because clearly the 4th process does not occur TWICE during transcription. I'm not sure about the 3rd one.

oh oh i ddnt even read the twice part :p now i get it....even the sugar phosphate bonds form only once, between mRNA nucleotides...thnx!
 

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View attachment 12142
how to do this calculation?

View attachment 12143

why can't high temperature break ionic bond?
high temperature and pH change can break, right?

1. The only thing that matters the most is the 'tidal volume'. A and B have the greatest, i.e 0.6.
Now B has more breaths per minute than A. So clearly B would have absorbed most oxygen during those four minutes.

2. High temperature would break the Hydrogen bonds first. pH change would exclusively affect the ionic bond.
 
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View attachment 12142
how to do this calculation?

View attachment 12143

why can't high temperature break ionic bond?
high temperature and pH change can break, right?

Okay for the first Q. multiply each breath rate by the tidal volume this should give you the total Oxygen INHALED NOT ABSORBED in 1 minuite by whoever ok, then you find the diffrence betwwen the value you obtained anf the total lung volume the person with the largest diffrence is the person who absorbed the most oxygen e.g for B 15 x 0.6 = 9 right 9 - 6 = 3, 3 was the largest diffrence when i did the question so the anwser is B.

Q2 high temperature increase's the K.E puting strain on the bonds not breaking them eventualy the bonds will only break from weakest to strongest, PH will directly effect the ionic bonding. hope that was enough :)
 
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cardiac output!!.PNG
The answer is A in the mark scheme, but why is it not C?? Heart is one of the chapters giving me a tough time. :(
 
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