A level Biology: Post your doubts here!

[rz123]

time is inversely proportional to the rate of reaction. Had it been rate on the y axis, we might go for chosing B.

Hence it's A..the reaction will never go to completion when enzyme's denatured.

thanks once again.

 

[XPFMember]

thanks once again.

my pleasure

 

[rz123]

24 In a DNA molecule, the base sequence AGT codes for the amino acid serine.
What is the base sequence of the anti-codon on the tRNA to which serine becomes attached?

 

[XPFMember]

24 In a DNA molecule, the base sequence AGT codes for the amino acid serine.
What is the base sequence of the anti-codon on the tRNA to which serine becomes attached?

mRNA wud have UCA so tRNA will have AGU

 

[rz123]

shukran!

7 Some soil-borne fungi cause wilting in crop plants by growing within the xylem vessels.
Which process will be directly affected by these fungi?
A cohesion between water molecules
B development of root pressure
C mass flow during translocation
D uptake of water by root hair cells

why only A statement correct?

 

[F husna]

can some1 answer this plz..
outline the behavior of chromosomes during meiosis????

 

[shehab94]

i have a question is Classified pastpapers of Biology AS in the chapter immunity... The Question is like.. ( state the advantage of converting the number of deaths into percentage of deaths in the case of circulatory and degenerative disease ).... Need an answer Please.... THANKS!!!!

 

[majid_mohammad]

Salaam hi guys hope u all r fine, can someone plz tell me where i can find the Biology and Chemistry A Level past papers plz thnx in advance plz as soon as possible

 

[XPFMember]

Salaam hi guys hope u all r fine, can someone plz tell me where i can find the Biology and Chemistry A Level past papers plz thnx in advance plz as soon as possible

Waalaikumassalam wr wb!

Biology: http://www.xtremepapers.com/CIE/ind...al%20A%20And%20AS%20Level/9700%20-%20Biology/
Chemistry: http://www.xtremepapers.com/CIE/ind...%20A%20And%20AS%20Level/9701%20-%20Chemistry/

and
Nov 2011 papers here: http://www.mediafire.com/?dgcbc88stxh5f

 

[Amy Bloom]

I didn't understand this part !!
( the length the scale bar represents )--------------------------------------------------------> That's the actual size, that is, the real size of what's inside the microscope
so ur saying theat 1microm of the scale bar is the needed!! -------------------------------> Yep!
isn't 23000 representing the length of the scale bAR!--------------------------------------> No! That's the length of the chloroplast which u represent in micrometres (23mm -> 23000 micrometres).

so confused!!




well the book says the answer is ( 100000 times ) bt i gues its the printing fault the size of the page was either too big or too small ------> Yeah i guess so.

yes ur answer is close enough


although there is a sorrection to ur answer---------------------> huh?

23000 = 2
x = 1 -------------------------------------------------------------> if you consider x to be the length of the scalebar you measured, then x is not 1!
if 23000 micrometers represent 2 micrometer ------|
then x micrometer represents 1 micrometre---------| This is wrong
that is (23000/2) = 11500 micrometer---------------|

if ur were doing the other way around then ur right! -------------------> Have you understood the way in which i did it? Else, i'll try to explain it all over again in a better way.
Headache? not at all! Just like helping others!
sorry if i gve u a headache!!

 

[hassam]

http://www.xtremepapers.com/CIE/International A And AS Level/9700 - Biology/9700_w10_qp_43.pdf QUESTION 3......b (iii)
Suggest why growing the fused cells in a culture medium containing HAT (step 4) is an important part of the procedure shown in Fig. 3
why ms says only hybridoma cells cn be indentified since unfused b cells cn also grow in medium containing HAt

 

[saleena]

could anyone give a description of the Starlings experiment regarding the semi conservative DNA replication


thanks in advance

 

[smartangel]

guys. november 06 paper 4. Q2. PLEASE.

 

[Salaar]

Hey everybody, I need bio atp for o levels may/ june and oct/nov 2011 if anyone can tell me please, thanks!

 

[lychee26]

can somebody tell me a detailed answer of the following question?
1. describe using examples, how sensory receptors in mammals generate action potentials?

 

[DrBame]

Hey guys. . U all are awesome!
I need help on this
Pls. . Why has small pox been able to be eradicated by vaccination but not sickle-cell anaemia?.. Thanx )

 

[DrBame]

Hey guys. . U all are awesome!
I need help on this
Pls. . Why has small pox been able to be eradicated by vaccination but not sickle-cell anaemia?.. Thanx )

 

[confused123]

Hey guys. . U all are awesome!
I need help on this
Pls. . Why has small pox been able to be eradicated by vaccination but not sickle-cell anaemia?.. Thanx )

small pox is caused by bacteria hence we can create the vaccine for it, sickle cell anaemia is a genetic disease due to the wrong substitution of base. . .book

 

[XPFMember]

Assalamoalaikum wr wb!!
need help with some p4 questions

J’02

Q:3d ​

N’02

Q:1 b​

J’04

Q:1 c & d are they in the syllabus?​

Q:5c X chromosome inactivated randomly early in development :S​

Q:7b Explain the role of NADP...? :s​

N’06

Q:6 a "Large diameters and long axons/dendrons were only seen in answers from better candidates."​

This is related to the transmission of action potentials. Although I do know that large diameters , I.e. thick axons transmit action potentials faster than thin ones, but what about the length? :s​

​

 

[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​