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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011

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Reply 1140
Avatar for Mina!SS
Mina!SS
Thank you.
if we get a 6mark Q on Tissue fluid and how it returns back to the capillary, is mentioning presence of large proteins a mark? how pressure has overcome friction? and lymph vessels?

Im really feeling the pressure now :/
Reply 1141
Avatar for iguess
iguess
Original post by Mina!SS

Original post by Mina!SS
What on earth is plant classification?
What ways are used to determine evolutionary history between 2 organisms?
what are the features of cellulose, starch and glycogen? I know cellulose is made of beta-glucose, present in plant cell walls, provides turgidity and strength. But whats the role of hydrogen bonds and microfibrills?


I need to know myself, is it even in our syllabus!
DNA hybridisation - DNA is obtained from both species, one is radioactively/fluorescent marked, then heated to seperate the DNA strands. As it cools the complementary bases from each strand combine to form hydrogen bonds. More complementary bases in DNA are identified by more hydrogen bonds, so upon heating higher temperature will be needed for two species which are more closely related - hence have a recent ancestor.

Evolutionary comparisons of proteins - Serum extracted from Species A inject >>> species B. Species B produces antibodies complementary to the antigens of Species A. So these antibodies extracted from Species B and serum extracted from Species which need to be compared (eg. C,D, E...) are mixed. The antibodies will make an antibody-antigen complex with corresponding antigens. These complexes are the precipitate, so more precipitate = more closely related because they contain the same proteins, which are coded by similar amino acids, which are coded by similar nucleotide bases.

Hydrogen bonds only exist in cellulose because of long unbranched chain and rotation of b-glucose. The cellulose is a polymer of the b-glucose monomers joined by condensation reactions, forming glycosidic bonds. These only exist as layers because of no branching. So.. to connect these layers (cross linkages) together hydrogen bonds form. Microfibrils are basically lots of these b-glucose molecules bonded together to make thin fibrils (hence the name).
Hope that helped.
Original post by EffKayy
GOOD LUCKKKKKKKKK AAH I'm nervous as hell


Thanks. My dad was trying to get me psyched up. Lol.
Good luck to you too.
Original post by Mina!SS
Thank you.
if we get a 6mark Q on Tissue fluid and how it returns back to the capillary, is mentioning presence of large proteins a mark? how pressure has overcome friction? and lymph vessels?

Im really feeling the pressure now :/


Yeah all those things will get you a mark. I hope a question on this does not come back it is the only thing I am weak at.
Stuck on 5dii on June 2010. Why is the answer 8?
Original post by Some random guy
Stuck on 5dii on June 2010. Why is the answer 8?


MAXIMUM PAIRS = 2^pairs of chromosomes
e.g.
2^3 = 8
Original post by EffKayy
MAXIMUM PAIRS = 2^pairs of chromosomes
e.g.
2^3 = 8


I still don't get it :frown:
I really hope there aren't many questions about the movement of water through plants!
Original post by heavencanwait_
What plant classification bit...? :s-smilie:


The bit where they got 565 plant species and mapped 3 genes in order for a more accurate comparisons and a phylogenitic tree can could be constructed.
Original post by SmithytheDrummer
The bit where they got 565 plant species and mapped 3 genes in order for a more accurate comparisons and a phylogenitic tree can could be constructed.


That's easy :smile: I would love if that came up. LOL
Original post by Limitless
Thanks. My dad was trying to get me psyched up. Lol.
Good luck to you too.


Yeah all those things will get you a mark. I hope a question on this does not come back it is the only thing I am weak at.


It will definitely come, I've researched the past papers and concluded that they all contain tissue fluid in some form.

I'm guessing the six marker will be about haemoglobin and the bohr effect.
Probably also a question about transpiration in plants.

And as usual the kpcofgs table with questions about comparing amino acids, dna hybridisation and perhaps the rare precipitate questions(which I'm currently reading on).
Reply 1150
Avatar for ryan02
ryan02
10
can anyone explain the: mass of DNA, and mass of cell during the cell cycle graph??
Original post by mclovin123
no its not. Basicly. Oxygen inters the insect through the spiricles. It then goes through the thecheae, these tracheae run off into smaller pipes called trachioles. These thrachioles literraly just run straght onto cells. They are thin and so oxy then diffuses from them into the cells. If you think about it in a simple way it will make sense. Their is more oxygen outside then in the insect so the H2 will move through these pipes down the concentration gradient, and c02 goes down its concetration gradient from the cells up these pipes and out of the spiricles.


I know this is unrelated but worms don't have spiracles instead they have a different form of haemoglobin which I found interesting since I assumed them to be of the insect ancestry. So we're related closer to worms than to insects.
Oh god, i forgot about the spiracles in insects! :O Woulda forgot to write it in the exam tbh
Original post by ryan02
can anyone explain the: mass of DNA, and mass of cell during the cell cycle graph??


The mass of a cell steadily rises until it is twice what it was at the start. Then it drops back to the original value because the cell replicated. DNA mass stays the same during first growth but doubles during synthesis phase when DNA is replicated. It then remains at that value until the whole cell divides after which it drops back to the initial value.
(edited 12 years ago)
-.- it is raining, i have to walk to school in the pouring rain to sit my biology exam for 1hour 45 mins. I will be wet. I am not happy with this. At all. Damn you British weather !!!
Original post by Wonderwoman93
-.- it is raining, i have to walk to school in the pouring rain to sit my biology exam for 1hour 45 mins. I will be wet. I am not happy with this. At all. Damn you British weather !!!


I am in exactly the same position, not happy :/
Original post by Wonderwoman93
-.- it is raining, i have to walk to school in the pouring rain to sit my biology exam for 1hour 45 mins. I will be wet. I am not happy with this. At all. Damn you British weather !!!


Better to be cool headed than to be hot headed.
Off to school to kinda ish revise. Laters :P
Good luck everyone!
how can the index of diversity be used to conserve biodiversity?

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