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A level Biology: Post your doubts here!

Mahnoorfatima

Mahnoorfatima

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qwertypoiu said:
At low temperature, reaction rate is low because collision between enzymes and substrate is not effective. The collision rate is low as well. When temperature increases, the bonds that maintain the three dimensional shape of the enzyme start to break and get affected, so enzyme shape changes, too high a temperature and it will be denatured permanently. The bonds that break are probably hydrogen bonds.
Click to expand...
So you mean that during cold denaturation bonds do not break?
 
Mahnoorfatima

Mahnoorfatima

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In a question asking about mutation, do we have to write about the change in tRNA due to a change in mRNA as well?
And, how there's an altered mRNA condon bring a wrong a.a attached to tRNA which has an altered anticodon complementary to the mRNA's codon? Also leading to a wrong sequence of bases on the polypeptide chain incorporating a wrong a.a on the growing polypeptide chain which alters the primary structure of the polypeptide. Is that all we write? Idk why but I find answering this question really hard. :/
 
Abdul Hanan

Abdul Hanan

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as.png
Please explain...M/J 2014 p22..^
Also please tell me one challenging P2 which i can do thanks... :)
 
princess Anu

princess Anu

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nicotine causes endothelial damage .. how? by increasing the B.P?
T.B exhibits antigenic variation & concealment or only concealment?
Can we see golgi apparatus on Light micrscope?
H+ are pumped by companion cells into their own cell walls or that of the source cell?
 
qwertypoiu

qwertypoiu

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princess Anu said:
nicotine causes endothelial damage .. how? by increasing the B.P?
T.B exhibits antigenic variation & concealment or only concealment?
Can we see golgi apparatus on Light micrscope?
H+ are pumped by companion cells into their own cell walls or that of the source cell?
Click to expand...
Both carbon monoxide and nicotine increases the chances of endothelial damage. It is not known how. High blood pressure also causes endothelial damage.
TB can conceal itself inside macrophages. It doesn't exhibit antigenic variation like Plasmodium does due to its life cycle, but it mutates and develops resistance to antibiotics. Isthis considered antigenic variation? Please tell me if you know.
Golgi apparatus may be seen under a light microscope when certain special stains are used.
I think H+ ions are pumped into the cell wall.
 
princess Anu

princess Anu

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so what can never be seen on a light micro? and no antigenic variation is when it changes its antigen! during mutation to develop resistance it doesn't change its antigen! but it actually changes the target sites for antibiotics. for example the shape of active site of an enzyme the antibiotic used to inhibit etc.
 
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Laila39

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Why do people who have a deficiency of iron in their diet are often lacking in energy and feel tired?
 
princess Anu

princess Anu

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can somebody tell me how do the staggered ends of tropocollagen molecule contribute to tensile strength of collagen??
 
nehaoscar

nehaoscar

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Albumin is the most abundant plasma protein.
Suggest why it is important that capillary walls should not be permeable to albumin?
 
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