A2 Biology | Post your doubts here

[histephenson007]

in photosynthesis thats the calcvin cycle takes place in the stroma of chloroplast...where as
in respiration thats the krebs cycle takes place in the matrix of mitochondria...
am i right?

yeap
But I have another question,
explain why genes for antibiotic resistance are now rarely used as markers in gene technology?

 

[Mekal]

Question 4(b)

Nov 2007

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w07_qp_4.pdf

Markscheme says
http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w07_ms_4.pdf

enzyme immobilised (in biosensor) ;
H+ ions released (from gluconic acid) ;
give positive charge ;
current flows ;
size of current proportional to concentration of, H+ / glucose ;
low reading (when blood tested) indicates, hypoglycaemia / low blood glucose
concentration ;
A ora
alternative points
platinum electrodes ;
detects oxygen concentration ;


can someone please write the answer exactly that i should write ?

thank you

 

[omar hazem]

please my exam is after 2 days on 18 MAY, so please can anyone make the oogenesis process more clear to me and I need any links to revision notes before the exam if you please thanks

 

[angelgirl:)]

yeap
But I have another question,
explain why genes for antibiotic resistance are now rarely used as markers in gene technology?

here i just know that wen anibiotic resistant bacteria r used then their is risk for the other bacteria to develope resistance which makes antibiotic less effective...

 

[angelgirl:)]

Question 4(b)

Nov 2007

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_qp_4.pdf

Markscheme says
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_ms_4.pdf

enzyme immobilised (in biosensor) ;
H+ ions released (from gluconic acid) ;
give positive charge ;
current flows ;
size of current proportional to concentration of, H+ / glucose ;
low reading (when blood tested) indicates, hypoglycaemia / low blood glucose
concentration ;
A ora
alternative points
platinum electrodes ;
detects oxygen concentration ;


can someone please write the answer exactly that i should write ?

thank you

glucose oxidase enzyme is immobilised in biosensers which converts glucose to gluconic acid...H+ released from gluconic acid produces current ...therefore size of current is proportional to H+/glucose conc...low reading indecates low blood glucose concentration...

 

[girlscampisra]

Y

in photosynthesis thats the calcvin cycle takes place in the stroma of chloroplast...where as
in respiration thats the krebs cycle takes place in the matrix of mitochondria...
am i right?

yes you're right!

 

[histephenson007]

please my exam is after 2 days on 18 MAY, so please can anyone make the oogenesis process more clear to me and I need any links to revision notes before the exam if you please thanks

http://www.s-cool.co.uk/a-level/biology

 

[saeedmuqaddam]

can u tell me from where i can find biology chemguide book.

 

[angelgirl:)]

The glucose biosensor works as follows :

•
It contains a layer of immobilised glucose oxidase enzyme.
•
This enzyme binds with any glucose in the blood, which is oxidised with
dissolved oxygen from the solution to form hydrogen peroxide and gluconic
acid.
•
An electrode (usually platinum) measures the drop in oxygen concentration as
it is used to make hydrogen peroxide. The electrode generates an electrical
signal.
•
The size of the electrical signal is proportional to the concentration of glucose
in the blood.
•
A digital readout gives the user a figure for the glucose concentration

Question 4(b)



Nov 2007



http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_qp_4.pdf



Markscheme says

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_ms_4.pdf



enzyme immobilised (in biosensor) ;

H+ ions released (from gluconic acid) ;

give positive charge ;

current flows ;

size of current proportional to concentration of, H+ / glucose ;

low reading (when blood tested) indicates, hypoglycaemia / low blood glucose

concentration ;

A ora

alternative points

platinum electrodes ;

detects oxygen concentration ;





can someone please write the answer exactly that i should write ?



thank you

glucose oxidase enzyme is immobilised in biosensers which converts glucose to gluconic acid...H+ released from gluconic acid produces current ...therefore size of current is proportional to H+/glucose conc...low reading indecates low blood glucose concentration...

can any1 compile these and give the final answer?

 

[angelgirl:)]

wats use of fusogen/PEG in the production of monoclonal antibodies?

 

[user]

angelgirl:) remind me again...at the moment i have to go...have maths exam...i think i've written an answer for this...will share it.. do remind me if i dont reply

 

[angelgirl:)]

wats use of fusogen/PEG in the production of monoclonal antibodies?

its an agent, that gives rise to fusion of membranes, including cell membrane...
isnt it?

 

[angelgirl:)]

angelgirl:) remind me again...at the moment i have to go...have maths exam...i think i've written an answer for this...will share it.. do remind me if i dont reply

ok best of luck for ur exam

 

[BURHAN UL HAQ]

I am not clear with wheat polyploidy.please tell mebriefly what is it? and how hexaploid forms? the note written in book is too confusing . Moreover tell me what is non disjunction?

 

[angelgirl:)]

An organism with more than two sets of chromosomes...
means during the faulty meioses...the two sets of chromosomes stick together and move to 1 side of the cell during the cell division for gamete production...so 1 daugghter cell wont have at all the chromosome and dye but the other 1 will be having the whole set of chromosome...thats y its called polypliod cell...

 

[angelgirl:)]

An organism with more than two sets of chromosomes...
means during the faulty meioses...the two sets of chromosomes stick together and move to 1 side of the cell during the cell division for gamete production...so 1 daugghter cell wont have at all the chromosome and dye but the other 1 will be having the whole set of chromosome...thats y its called polypliod cell...

oh i have just given u the explaination of polypliod only....sorry

 

[Ghayyur.ruyyahg]

okay so i havent quite prepared for my A2 biology and the paper is on friday!
needless to say im freaking out!
so any advice on what i should study would be great!

 

[angelgirl:)]

okay so i havent quite prepared for my A2 biology and the paper is on friday!
needless to say im freaking out!
so any advice on what i should study would be great!

i guess u have to scan the whole topic...specially the topic which u r not confident at alll...
dont go in detail but have some idea about each topic...

 

[BURHAN UL HAQ]

what is non disjunction?

 

[angelgirl:)]

what is non disjunction?

The failure of paired chromosomes or sister chromatids to separate and go to different cells during meiosis.