A level Biology: Post your doubts here!

[♣♠ Magnanimous ♣♠]

I hate CIE

well i dont hate CIE

 

[-rimsa]

I am too confused in that question.

Its C coz mean is taken as mean number of bubbles per minute. Number of bubbles will always be a whole number, never a decimal. You cant have a 0.2 bubble like in A.

 

[♣♠ Magnanimous ♣♠]

Its C coz mean is taken as mean number of bubbles per minute. Number of bubbles will always be a whole number, never a decimal. You cant have a 0.2 bubble like in A.

are you 110% sure?

 

[ZaqZainab]

Its C coz mean is taken as mean number of bubbles per minute. Number of bubbles will always be a whole number, never a decimal. You cant have a 0.2 bubble like in A.

Thanks

 

[-rimsa]

are you 110% sure?

200%. I attempted that paper.
It makes sense anyway. Half bubbles are not possible. And the unit is bubbles per minute.

 

[♣♠ Magnanimous ♣♠]

200%. I attempted that paper.
It makes sense anyway. Half bubbles are not possible. And the unit is bubbles per minute.

thanks.

 

[Exo_luhan]

"The light microscope used a x10 eyepiece lens and a x1000 objective lens"
What's the magnification then?

 

[Exo_luhan]

1. disulfide
2.hydrogen
3.hydrophobic
4.ionic
5.hydrophillic
Can ne1 plz gimme sequence "bonds break first.....bonds break last" when an enzyme is heated & when there's a change in pH

 

[Karim Nabil]

"The light microscope used a x10 eyepiece lens and a x1000 objective lens"
What's the magnification then?

if no actual length given then; 10*1000=x10000 is the magification.

 

[Snowysangel]

1. disulfide
2.hydrogen
3.hydrophobic
4.ionic
5.hydrophillic
Can ne1 plz gimme sequence "bonds break first.....bonds break last" when an enzyme is heated & when there's a change in pH

I'm guessing its 5,3,4,2,1

 

[Snowysangel]

..

 

[Karim Nabil]

1. disulfide
2.hydrogen
3.hydrophobic
4.ionic
5.hydrophillic
Can ne1 plz gimme sequence "bonds break first.....bonds break last" when an enzyme is heated & when there's a change in pH

disulphide bonds are the most strongest covalent bond, then comes ionic then hydrogen then hydrophobic interaction

1. disulphide bonds broken by reducing agents
2. hydrogen bonds broken by high temperatures or ph change
3. ionic bonds broken by ph change

 

[Snowysangel]

disulphide bonds are the most strongest covalent bond, then comes ionic then hydrogen then hydrophobic interaction

1. disulphide bonds broken by reducing agents
2. hydrogen bonds broken by high temperatures or ph change
3. ionic bonds broken by ph change

Are ionic bonds stronger than hydrogen? Are you sure about that?

 

[Karim Nabil]

Are ionic bonds stronger than hydrogen? Are you sure about that?

yes 200%

 

[Snowysangel]

yes 200%

Also could you answer the mcq questions I just posted? Thanks in advance

 

[Karim Nabil]

Also could you answer the mcq questions I just posted? Thanks in advance

sure..
so first question is D as after antigen binding to antibody no histamine should be released
2nd, inner membrane folded to expand as it could easily stretch and recoil, answer is A
3rd, glucose and fatty acids contains c=o, but glycerol doesn't, answer is A
4th, -reduction division is only important to prevent doubling of chromosomes no.,-at metaphase chromosomes are arranged at equator, and -when cell just before prophase , dna number is 4n(92) and 1 chromatid equals 1 dna molecule so answer is D,q23> 1 amino acid=3 nucleotides, so 120/3=40,answer is B
5th, sucrose is actively moved to seive tube elements which decrease water potential, hence more water enter increasing hydrostatic pressure

 

[zain ul abidin]

what numericals we should know?

 

[Snowysangel]

sure..
so first question is D as after antigen binding to antibody no histamine should be released
2nd, inner membrane folded to expand as it could easily stretch and recoil, answer is A
3rd, glucose and fatty acids contains c=o, but glycerol doesn't, answer is A
4th, -reduction division is only important to prevent doubling of chromosomes no.,-at metaphase chromosomes are arranged at equator, and -when cell just before prophase , dna number is 4n(92) and 1 chromatid equals 1 dna molecule so answer is D,q23> 1 amino acid=3 nucleotides, so 120/3=40,answer is B
5th, sucrose is actively moved to seive tube elements which decrease water potential, hence more water enter increasing hydrostatic pressure

Isn't histamr released when an antigen binds to an antibody on the mast cell?! Don't the elastic tissues perform the function of recoiling and stretching and bronchi have them...why isn't the trachea folded then? Where is the c=o in glucose? Isn't sucrose diffused I to the drive tube through a cotransport protein??

 

[DeViL gURl B)]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

Please explain question no.1 ... The answer is B
Thank you

 

[Snowysangel]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

Please explain question no.1 ... The answer is B
Thank you

3H is an isotope of hydrogen which has 2 neutrons...the same no as 4He