A level Biology: Post your doubts here!

[hassam]

J’02

Q:3d.....its mentioned in the book....that a more intense signal greater frequency of impulses being sent...a more intense stimulus doesnt mean the the highest potential acheived ll be greater....tthat waveform remains absolutely unchanged​

 

[farhan143]

can you do it in a paper and scan it cuz i am not getting the online explanation...
if u can write it in a paper and upload it after scaning it..
then it will be better!!

 

[farhan143]

well i might not come online much bcz im preparing for my exmaz and cnt concentrate!!!!!!!!!

 

[Amy Bloom]

can you do it in a paper and scan it cuz i am not getting the online explanation...
if u can write it in a paper and upload it after scaning it..
then it will be better!!

Okay then. But you'll get it by tomorrow 'coz i'm quite busy today. Best of luck in ur revisions

 

[Noor]

Can somebody recommend me some good books for Biology?

That's not a book, but online notes, it's so good. (Y) http://en.wikibooks.org/wiki/Category:A-level_Biology

 

[farhan143]

Okay then. But you'll get it by tomorrow 'coz i'm quite busy today. Best of luck in ur revisions

ok i will be waiting
thank you!!

 

[confused123]

Does anyone have specific advice on plan diagrams or taking readings? Such as, significant figures? How much detail does drawings of [magnified] cells require? and low or high power etc... thanku

 

[hassam]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w05_qp_4.pdf
in question 4 part a markscheme says
most birds that survive drought years have larger beaks ;
because they have been able to feed on larger seeds ;
whereas the question mentions The main environmental consequences of drought is the decline in food supply, mainly
seeds.so this line does not specifies small seeds.....so this means all kind of seeds should be reduced bt why ms is assuming that large seeds are available.........is it because these large seeds were not eaten in years b4 drought?

 

[étudiante]

Does anyone have specific advice on plan diagrams or taking readings? Such as, significant figures? How much detail does drawings of [magnified] cells require? and low or high power etc... thanku

@readings... depends on da instument used..... buh usually not more dan 2 sf..... n den avg n repeat
@detail.... da main organelles need 2 b dere... nucleus, ribosomes, vacuoles, ER, chloroplasts n stuff.... just da major 1s

 

[Amy Bloom]

ok i will be waiting
thank you!!

Hello Farhan!
I've attached a file here & worked the number out, coz my scanner got some problem.
I guess that there is some misprint in your book, maybe they've put one more zero.
Test my method with another exercise and confirm if it is good if you wish. I find this one sounds more logical. What do you think?

 

[Amy Bloom]

That's not a book, but online notes, it's so good. (Y) http://en.wikibooks.org/wiki/Category:A-level_Biology

Well i guess that wikibooks are quite unreliable coz they can be edited if you are logged in. Do you have any other suggestions?
Anyways, thanks for helping me.

 

[hmlahori]

Hey fellows need some explanations of paper 1 mcqs
here are the links and questions....
Thanks......

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q29

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w02_qp_1.pdf Q32,34,35,37

 

[nerdybookworm]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w07_qp_5.pdf


q2 part (b)..please..

 

[nerdybookworm]

http://www.xtremepapers.com/communi...st-your-doubts-and-please-provide-tips.13121/


plz reply urgeeenttt

 

[Scafalon40]

A query about dilution series
It's simple: why do we do it?
I mean to get from a solution of 1 moldm^-3 to a solution of 0.0001 moldm^-3 why do we do three dilutions when we can do it with just one dilution using the formula C1V1=C2V2
I just don't get it, and in the exam we are expected to do serial dilutions instead of a single one which yields the same result!

 

[confused123]

Hey fellows need some explanations of paper 1 mcqs
here are the links and questions....
Thanks......

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf Q29

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w02_qp_1.pdf Q32,34,35,37

29 its c becuase you can see the graph is smooth for vertebrate X as both organisms r going thry bohr effect. X is releasing oxygen more easily then human. its comparatively more saturated with oxygen.

i m not sure bout any mcq no ms ) 32: A as when u r resting heart rate will be lesser, when exercise it needs to shoot up as faster supply of oxygen required plus more activity going on.

34) sickle cell anaemia caz this is highly improbable dat a wrong base may substitute and pass on to the off spring...

35) i think A as gene is a section of Dna or Rna, cell surface membrane might be present in all, protein building machine ribosomes has to be present in order to replicate and reproduce , respiration is vital for survival so A i guess.

37) B, on surface of macrophage antigen will be marked, in blood plasma dre will be numerous antibodies.

 

[hmlahori]

29 its c becuase you can see the graph is smooth for vertebrate X as both organisms r going thry bohr effect. X is releasing oxygen more easily then human. its comparatively more saturated with oxygen.

i m not sure bout any mcq no ms ) 32: A as when u r resting heart rate will be lesser, when exercise it needs to shoot up as faster supply of oxygen required plus more activity going on.

34) sickle cell anaemia caz this is highly improbable dat a wrong base may substitute and pass on to the off spring...

35) i think A as gene is a section of Dna or Rna, cell surface membrane might be present in all, protein building machine ribosomes has to be present in order to replicate and reproduce , respiration is vital for survival so A i guess.

37) B, on surface of macrophage antigen will be marked, in blood plasma dre will be numerous antibodies.

For question 34 the mark scheme answer is C malaria
but i have a rejection to that because the malarial pathogen can pass from the mother to fetus which leaves only A cholera to be correct because it is mostly water and food borne.
Your opinion............?

 

[confused123]

For question 34 the mark scheme answer is C malaria
but i have a rejection to that because the malarial pathogen can pass from the mother to fetus which leaves only A cholera to be correct because it is mostly water and food borne.
Your opinion............?

hey plz tell me the other answers from marking scheme as well!!!!!

if its malaria then i think u know dat in passing of the pathogen plasmodium, we need a vector dat is anopheles mosquito. maybe it cannot pass from mother to fetus because they both have different blood compositions. the blood doesn't mix together. oxygen, co2 and nutrients can pass but not the bloods which might have plasmodium. Certain circumstances can cause blood to mix, like miscarriage, abortion, and birth. This is when diseases can be transmitted which is less likely so malaria is the right answer but how is anaemia incorrect? :/

 

[hmlahori]

ok first the answers are 29 C 32 A 34 C 35 D 37 D

so the question said least likely to be passed directly from parent to child sickle cell anaemia is the most likely as it is genetical

 

[Scafalon40]

Another question:
Paper:http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s07_qp_31.pdf
Mark Scheme:http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s07_ms_31.pdf
Examiner Report:http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s07_er.pdf
Look at Q1 part (b)(i)
We have to prepare a space to record or results
The marking scheme says "a mean of the dilutions should be calculated"
Mean? How do we calculate the mean of a dilution?
Guys I even posted the marking scheme and examiner report, if you can't answer this then...