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Hiya about the magnification questions if you print the paper out it's not to scale with the actual exam paper so your measurement won't be the same as the original :smile:
Original post by Suzanna5678
Do hepatic veins take blood from the liver and hepatic arterys take blood to the liver or the other way round?!


Yep, you're good :-)
Original post by Aidn
Ok, and what does 'negative pressure mean' the mark scheme in june 2012 said something about the pressure in the xylem being lower than in the atmosphere but that doesn't make sense to me :frown:

Thanks for answering btw! Especially tonight of all nights haha ^_^


As long as you put tension you don't need to put negative pressure. They mean the same.

I don't know how to explain it scientifically but 'sucking' creates negative pressure (as in the water is being sucked up the plant by cohesion tension) . Sorry the explanation sucks. Say you have a straw, if you pinch the straw, the sides will cave in due to positive pressure. If you suck really hard, the sides will cave in again, but this is negative pressure. Does that make any sense? You don't really need to know the definition anyway :smile:
Reply 2763
Original post by Suzanna5678
Do hepatic veins take blood from the liver and hepatic arterys take blood to the liver or the other way round?!


Other way around i think
can someone give a definition for hierarchical system????
Original post by Zebrajess
For the magnification question, the image length is 50mm.
convert this to micrometres = 50x1000 = 50000
magnification = image/actual = 50000/20 = 2500
Just make sure you convert everything to micrometres.


but the question said the magnification was 30000X
Reply 2766
Original post by PrimusInterPares
can someone give a definition for hierarchical system????


Groups within larger groups
Original post by Suzanna5678
Do hepatic veins take blood from the liver and hepatic arterys take blood to the liver or the other way round?!


Hepatic artery - blood to the liver
Hepatic vein - blood away from the liver.
Original post by PrimusInterPares
can someone give a definition for hierarchical system????


Groups within larger groups

With no overlap




2 mark question, 2 mark answer!
Original post by ajv1000


Groups within larger groups


With no overlap

Posted from TSR Mobile
Original post by PrimusInterPares
can someone give a definition for hierarchical system????


A system of groups within groups. No overlap between the different levels.
Original post by ajv1000


Groups within larger groups


And there is no overlap. :smile:
Original post by FatHeadedKing
Okay, bacteria stops penicillin from working by producing enzymes which break down the penicillin.

A different penicillin will have a different Group X which isn't complementary to that bacteria's enzyme's active site so that enzyme can't break it down. So the penicillin can do it's job.

:-)

Thank you!
Its so confusing because when you talk about enzymes and anitbiotics, you dont expect it to be about bacteria producing enzymes to break the antibiotic down!
Original post by iLoveMyCatsx
Can someone summarize gas exchange in insects?

Oxygen diffuse via spiricals on body surface down a diffusion gradient into trachea which are associated with all cells oxygen diffuse into cells, abdominal movements maintain ventilation.
Original post by Manni
Ooo feisty one :tongue:


:redface:

Are you sitting Chem2 on Tuesday? :smile:
Original post by FatHeadedKing
Ewwww...


We got taught
Keep
Penis'
Clean
Or
Forget
Good
Sex
!!
Reply 2776
What is blood plasma?
Original post by anonymousecheese
but the question said the magnification was 30000X


The question didn't say what the magnification was. The question asked you to find the magnification.
The answer was anything between 2350 - 2500.
Reply 2778
Please how would you answer 6 mark question how does meiosis lead to genetic diversity?


Posted from TSR Mobilehh
Original post by 2013leaver
Thank you!
Its so confusing because when you talk about enzymes and anitbiotics, you dont expect it to be about bacteria producing enzymes to break the antibiotic down!


Hey...a bacteria's gotta make a livin' too.