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
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
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
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
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!
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.
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!