A level Biology: Post your doubts here!

[thats_me]

q3 (a)(iv)...http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s07_qp_2.pdf
Is my diagram ok?..check the M.S ...i dont understand what they've drawn to be honest

Centromeres should be shown

 

[princeali97]

View attachment 41164
Centromeres should be shown

Hmm..ok..Thanks

 

[JutniP]

does anyobdy have a guess paper for this years biology exam?

 

[joanna omar]

Erm which question again? There's no iii part

sorry Q3 c(ii)

 

[Exo_luhan]

Hey can anyone please check this answer?? Lemme knw if i need to add more and if you have a better answer plz gimme

 

[BeBeskii108]

Hey can anyone please check this answer?? Lemme knw if i need to add more and if you have a better answer plz gimme View attachment 41185View attachment 41185

I wish I could rotate it 90*

 

[kitkat <3 :P]

What is TB's mode of transmission?

 

[kitkat <3 :P]

What's the function of casparian strip in plants and the hydrophillic part of the phospholipid in membrane??

 

[VelaneDeBeaute]

What is TB's mode of transmission?

The bacterium spreads when a healthy person inhales air that contains the bacterium (usually when around a TB-infected person).

 

[kitkat <3 :P]

The bacterium spreads when a healthy person inhales air that contains the bacterium (usually when around a TB-infected person).

Thanks alot can u tell me why is it difficult to develop an effective vaccine for malaria

 

[VelaneDeBeaute]

What's the function of casparian strip in plants and the hydrophillic part of the phospholipid in membrane??

The Casparian Strip regulates water and mineral salts uptake by the plant and also prevents water from being 'sucked' up into the xylem.

 

[joanna omar]

Thanks alot can u tell me why is it difficult to develop an effective vaccine for malaria

1.they have many antigens
2.eukarayote have many different satges of life cylce
3.mutation changes antgens
4.Parasite only vulurnable at certain stage of life cycle

 

[Wolfgangs]

Can someone please tell me the importance of proteins in mitosis?

 

[goodluckayesha]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_42.pdf can anyone plz tell the labelling in Q4b im a little confused
http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w13_qp_42.pdf also explain how 8a is done im not able to get the answer

 

[Mohammed salik]

sorry Q3 c(ii)

There could me more than one code for Amino acid. Because There are 4 bases ( A-T-C-G) on DNA and 3 bases are required to form an aminoacid (triplet)
so 4^3=64 possible combination for 20 essential amino acids in Human Body !

 

[Mohammed salik]

http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w08_qp_2.pdf
Q4 )a) Its easy But i need a Model ans!

 

[Mohammed salik]

Can someone please tell me the importance of proteins in mitosis?

Which Proteins? Histones? if yes :
Histones Basically help in Packaging of DNA!
These are proteins that DNA wraps around so the DNA can be more condensed. During mitosis, the DNA has to be very tightly compacted into mitotic chromosomes so at the end of mitosis, the sister chromatids can be separated properly into the two daughter cells. Without histones, the DNA wouldn't be able to be packed into chromosomes.

 

[joanna omar]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s11_qp_23.pdf

I don't understand Q 4 b (ii)

 

[Mohammed salik]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_23.pdf

I don't understand Q 4 b (ii)

It asks Why we dont see any symptoms..
It is because when Haemoglobin has Higher affinity for Oxygen.. Oxygen transport is reduced causing Body to produce more Haemoglobin.. so we cant see any symptops.. because body compensates

 

[princeali97]

Hey can anyone please check this answer?? Lemme knw if i need to add more and if you have a better answer plz gimme View attachment 41185View attachment 41185

There is a major mistake in your answer which i must clarify.U have mentioned "plasma cells produces memory cells and antibodies" which is completely a false statement and will be penalized.After clonal selection,specific B-lymphocytes are stimulated which divide by mitosis into memory cells and plasma cells.Plasma cells produce antibodies against the parasite and memory cells remain in blood and divide into plasma cells and more memory cells if the same antigen is reintroduced in the body.