A level Biology: Post your doubts here!

[Idolfanatic95]

Oh my mistake, its variant 34th on 22nd of May! i have time! are you guys in lahore? if yes what's your centre for practicals?

@idol; i think the whole idea sucks the dilutions and enzyme ones bother me as well but lets hope for the best. yes plz upload them. that would be gr8! good luck to u as well!

Dilutions are easy mate! Well until now I feel they are easy unless sumthing messy comes our way xD and no I'm nt frm lhr.
Already uploaded 2 images, have a look!

 

[Mubasher96]

@"Idolfanatic95
I too have a bit of problem doing low ower plan diagrams. That first image's (a) part, cud u upload it? I did draw but im not sure if we're allowed so many wavy lines, i mean what will be considered *clear, sharp and smooth*? Like that second drawing of yours, its innermost layer is sharp n clear, but is it smooth too? Because i drew that exactly as you have drawn.

 

[confused123]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s03_qp_1.pdf
Q(1)
Q (18)
Q(19)
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s05_qp_1.pdf
Q (38)

03 ppr 1) see rough endoplasmic reticulum is concentrated with ribosomes around and r.e.r makes ribosomes which are the sites for protein sysnthesis so it will rapidly take amino acids.

18) we need to have tRNA's with the same base sequence or anticodons which will get match with the code on the mRNA. so 4 different amino acids means we need to have 4 mRNA's and then accordingly 4 tRNA's to translate it back into the original form or sequencey. correct me any1 i m wrong.

19) we stopped culturing bacteria in N15 and then cultured them in ONLY N14. so after every generation there will be a decrease in the percentage of N15 in the cells of offspring as N14 is being used now. N15 dominance will decrease gradually. B shows us no change, D shows us total clearance of the impact of N15. A shows us increasing percentage which is not possible as the bacteria previously were grown in N15 so it must have the higest percentage initially. i.e C is correct dude

q.38 : its A, see urea contains Nh4 so its out of the equation, animal's shit can act as fertilisers as well! the war is between A and B so in B you see that two entirely different kinds of crops are grown in the same field at alternate years, but in A you that same type of crop is being grown in alternate years which i guess will not allow the appropriate nutrients to be replaced or will not make the soil fertile, so this looks the least effective alternative. have fun enjoy.

 

[confused123]

Need help with few mcqs anyone?
May/june 02 paper 1. Q (30)
Oct/nov 02 p1. Q(30) how do we calculate the absorbed oxygen?

i can't find the paper dude, can you write the question or attach the link..

 

[Idolfanatic95]

@"Idolfanatic95
I too have a bit of problem doing low ower plan diagrams. That first image's (a) part, cud u upload it? I did draw but im not sure if we're allowed so many wavy lines, i mean what will be considered *clear, sharp and smooth*? Like that second drawing of yours, its innermost layer is sharp n clear, but is it smooth too? Because i drew that exactly as you have drawn.

We just have to be careful when drawing such stuff. i drew these in a hurry at skool, the thing is these were just to make the concept clearer. Im not saying these were as perfect as they cud possibly get.

 

[Idolfanatic95]

i can't find the paper dude, can you write the question or attach the link..

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w02_qp_1.pdf

 

[Idolfanatic95]

03 ppr 1) see rough endoplasmic reticulum is concentrated with ribosomes around and r.e.r makes ribosomes which are the sites for protein sysnthesis so it will rapidly take amino acids.

18) we need to have tRNA's with the same base sequence or anticodons which will get match with the code on the mRNA. so 4 different amino acids means we need to have 4 mRNA's and then accordingly 4 tRNA's to translate it back into the original form or sequencey. correct me any1 i m wrong.

19) we stopped culturing bacteria in N15 and then cultured them in ONLY N14. so after every generation there will be a decrease in the percentage of N15 in the cells of offspring as N14 is being used now. N15 dominance will decrease gradually. B shows us no change, D shows us total clearance of the impact of N15. A shows us increasing percentage which is not possible as the bacteria previously were grown in N15 so it must have the higest percentage initially. i.e C is correct dude

q.38 : its A, see urea contains Nh4 so its out of the equation, animal's shit can act as fertilisers as well! the war is between A and B so in B you see that two entirely different kinds of crops are grown in the same field at alternate years, but in A you that same type of crop is being grown in alternate years which i guess will not allow the appropriate nutrients to be replaced or will not make the soil fertile, so this looks the least effective alternative. have fun enjoy.

Great help. thanks

 

[Mubasher96]

We just have to be careful when drawing such stuff. i drew these in a hurry at skool, the thing is these were just to make the concept clearer. Im not saying these were as perfect as they cud possibly get.

No i didn't mean it that way, what i meant was, we cud draw it the way u did, right? If the specimen has foldings or curves we will make them as such even if its a low power plan diagram?

 

[Idolfanatic95]

No i didn't mean it that way, what i meant was, we cud draw it the way u did, right? If the specimen has foldings or curves we will make them as such even if its a low power plan diagram?

Yes i think we can, since that's all we get to see, right? if a specimen has curves or foldings, we cud draw 'em BUT never go sketchy, just neat and clear foldings.
not 100% sure though :s

 

[Idolfanatic95]

@"Idolfanatic95
I too have a bit of problem doing low ower plan diagrams. That first image's (a) part, cud u upload it? I did draw but im not sure if we're allowed so many wavy lines, i mean what will be considered *clear, sharp and smooth*? Like that second drawing of yours, its innermost layer is sharp n clear, but is it smooth too? Because i drew that exactly as you have drawn.

Just an idea of how plan diagrams are supposed to be drawn.
Ignore the minor mistakes

 

[Mubasher96]

Yes i think we can, since that's all we get to see, right? if a specimen has curves or foldings, we cud draw 'em BUT never go sketchy, just neat and clear foldings.
not 100% sure though :s

Right, k thanks.

 

[Idolfanatic95]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w08_qp_1.pdf
Q (4) How do we calculate it? :s
Q (12)
Q (13) Can't it be option A?

 

[confused123]

Need help with few mcqs anyone?
May/june 02 paper 1. Q (30)
Oct/nov 02 p1. Q(30) how do we calculate the absorbed oxygen?

is it A? ms answer?

 

[Idolfanatic95]

is it A? ms answer?

Nov 02 Q (30): The answer to it is B.

 

[Idolfanatic95]

Right, k thanks.

Yeh. No deal.

 

[confused123]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w08_qp_1.pdf
Q (4) How do we calculate it? :s
Q (12)
Q (13) Can't it be option A?

4) the wall of the alveoli is about 1 cm distance with the blood capillary around in the image. so 10,000 / 2500 = 4 closer to B

12)D , because enzyme is usually inactive at low temperatures. the rate of reaction doubles after every 10 degree rise in temperature. A is very steep, B shows no activity until 30 degree, C is impossible, enzyme denatures after optimum temperature, graph has to go less steep.

13)X has the highest water potential. much higher then the other two. as the cells adjacent towards each-other. so water will start moving simultaneously to the other 2 solutions from X...

 

[Idolfanatic95]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_s08_qp_1.pdf
Q 16?

 

[Idolfanatic95]

4) the wall of the alveoli is about 1 cm distance with the blood capillary around in the image. so 10,000 / 2500 = 4 closer to B

12)D , because enzyme is usually inactive at low temperatures. the rate of reaction doubles after every 10 degree rise in temperature. A is very steep, B shows no activity until 30 degree, C is impossible, enzyme denatures after optimum temperature, graph has to go less steep.

13)X has the highest water potential. much higher then the other two. as the cells adjacent towards each-other. so water will start moving simultaneously to the other 2 solutions from X...

Thanks

 

[Idolfanatic95]

For 4th, measure the length between the alveolar airspace n either of the two capillaries' lymen cuz that is where the rbc wud be. I get that 7 mm the least. Thw magnification is given 2500 so divide the length measured by it. In my case its 0.0028 mm. Converting it into micrometer, i got 2.8, approx. = 3 microm.

Thnx mate

 

[confused123]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w02_qp_1.pdf

the only confusing thing is that the lung volume has to do something with todal capacity or breathing rate???
i think no. :/
in A : if we multiply number of breaths per minutes with tidal volume we get 8.4.( this is the amount of oxygen absorbed in one minute. )
in B : 9
in C: 8
in D : 6.8

B absorbs the max if ignoring lung volume