A level Biology: Post your doubts here!

[mrpaudel]

if they pity us providing easy questions, they will make the threshold higher....so...its the same..they dont want students to get grades easily..!!

 

[AAestar]

i m freaking out about the exam tomorrow i just feel that i m going to mess things up
gud luck to u all :good:

Thank you! Goodluck to you too!! Sleep early so you have adequate energy and sleep early can also reduce your anxiety...in a way.

 

[AAestar]

Somebody plz make the question clear to me...and then answer plz...!!

Well, if cells are to divide whenever they want, they would grow into an irregular mass of cell, meaning a tumour would be formed. So elaborate that a lil. ^^

 

[princesszahra]

Somebody plz make the question clear to me...and then answer plz...!!

Well, if cells are to divide whenever they want, they would grow into an irregular mass of cell, meaning a tumour would be formed. So elaborate that a lil. ^^

There are certain growth factors and regulators so cells cant divide whenever they want!

 

[hassam]

agreee reading CIE markschemes of biology is hell of a job.......

 

[princesszahra]

agreee reading CIE markschemes of biology is hell of a job.......

atleast u have mark schemes!!!
when u come to uni, u'll cry cuz don;t get to see them!

 

[hassam]

EXPLAIN how natural selection may bring about evolution? need an anser for this one in continuous prose......just a sample to see.....how we have to explain ms points and link them wid examples

 

[pennies]

why is the answer A not B??

 

[mrpaudel]

For dotted line in option B, the rate has stopped...!! and..if inhibitors were present, does the reaction rate doesnot stop for the same substrate...like...i mean.in opt B for the straight line..not the dotted one, it shows the reaction is still happening when the same amount of substrate when reacted without adding any inhibitors stop at the pt..!!

 

[byhn222]

hey guys, i had a question, in an exam is it okay to go underneath the lines given to answer a question, if let's say you cross something out in your answer and change it so you need more space? and another question, in an exam i had to draw a table, and i drew it in pencil, which i know is okay, but i filled in the headings with a pencil too. would i lose the marks?

 

[AAestar]

hey guys, i had a question, in an exam is it okay to go underneath the lines given to answer a question, if let's say you cross something out in your answer and change it so you need more space? and another question, in an exam i had to draw a table, and i drew it in pencil, which i know is okay, but i filled in the headings with a pencil too. would i lose the marks?

click here

 

[mrpaudel]

goin underneath the lines wont reduce ur marks.. and as far as filling headings thing...i dont think u will lose marks..!!

 

[M95Caire]

why is the answer A not B??

A non-competetive inhibitor doesnt compete with the substrate for the active site of the enzyme, it bind to the allosteric site of the enzyme instead, alters the shape of the enzyme so it can no longer bind to its substrate. Therefore, incresing the substrate concentration won't increase the rate of the reaction.

 

[nano9595]

pls help my exam s tomorrow
could anyone pls explain to me the following questions: :unknown:

http://www.xtremepapers.com/CIE/International A And AS Level/9700 - Biology/9700_s11_qp_11.pdf

1)question 13 the answer is A why couldnt it be B
2)question 14 the answer is C why couldnt be A , isnt the active site changed during non competitive inhibition
3)question 16 the answer is B why couldnt it be D

thnx in advance

 

[yuliana95]

pls help my exam s tomorrow
could anyone pls explain to me the following questions: :unknown:

http://www.xtremepapers.com/CIE/International A And AS Level/9700 - Biology/9700_s11_qp_11.pdf

1)question 13 the answer is A why couldnt it be B
2)question 14 the answer is C why couldnt be A , isnt the active site changed during non competitive inhibition
3)question 16 the answer is B why couldnt it be D

thnx in advance

1) The answer is A because haemoglobin is a complex protein and therefore it makes up the quartenary structure..
2) The active site does not change during non competitive inhibition, its just that the shape of enzyme changed...
3) The function of chloroplast is a site of photosynthesis and not to capture carbon dioxide..

I hope this is quite clear, I'm trying my best..

 

[rz123]

1) as all these structure's gives the enzyme its characteristic 3 d globular shape used to bind with the substrate so all of them are important in determining its specificity. quaternary structure gives the enzyme its globular coiled shape. hydrogen, ionic, di sulphide and hydrophobic interactions all important in attaching with the substrate

2)yes non competitive inhibitor alters the active site. but in this case the active site is already occupied by the substrate molecule :/

3) the membrane protein uses energy from ATP in mitochondria for the exchange of substances against the gradient and the membrane protein to my knowledge is not found in the mitochondrial membranes but i m not sure!

 

[princesszahra]

1) as all these structure's gives the enzyme its characteristic 3 d globular shape used to bind with the substrate so all of them are important in determining its specificity. quaternary structure gives the enzyme its globular coiled shape. hydrogen, ionic, di sulphide and hydrophobic interactions all important in attaching with the substrate

2)yes non competitive inhibitor alters the active site. but in this case the active site is already occupied by the substrate molecule :/

3) the membrane protein uses energy from ATP in mitochondria for the exchange of substances against the gradient and the membrane protein to my knowledge is not found in the mitochondrial membranes but i m not sure!

the membrane protein uses energy from ATP in mitochondria for the exchange of substances against the gradient and the membrane protein to my knowledge is not found in the mitochondrial membranes but i m not sure---IT IS PRESENT

 

[rz123]

OKAY :shock:

 

[Mia4005]

http://www.xtremepapers.com/CIE/Interna ... 8_ms_1.pdf

is this MS correct :S

 

[rz123]

u want any1 to check all the MCQ's and match the answers? :| or is dre any particular mcq in which u have doubt !