OCR Biology F214 Communication, Homeostasis and Energy Wed 25 Jan 2012

when there is high O2 and a low CO2 concentration the heart rate is caused to decrease by nerve impulses along the vagus (parasympathetic nerve) causing it to secrete acetylcholine

This module is pretty tricky to get your head around but once you've got the hang off it it's alright I'm currently going through respiration again and chemiosmosis is so simple that its complicated haha what do you think the majority of the questions be about the f212 was based heavily on the food/diet bits

if co2 levels are low why would you lower them more.. cuz ( there toxic/ less affinity/ blah blah ...)

decrease in heart rate means that less CO2 will be exhaled, so you should get more CO2 in the body

i swer f212 as mainly based on biodiversity?!

............

in june 2010 it was only one question on biodiversity

i meant jan 2012 =\

when there is high O2 and a low CO2 concentration the heart rate is caused to decrease by nerve impulses along the vagus (parasympathetic nerve) causing it to secrete acetylcholine

oh sorry :/ I didn't re-sit in jan 2012

also remember that the chemoreceptors detection of a low PH and high concentration of CO2 leads to an increase in the heart rate which is an example of a positive feedback system and NOT homeostasis

Its okay =)



Describe the STRUCTURE/ROLE of ATP (6)

structure = adenine (nitrogenous base) + ribose (pentose sugar) + 3 phosphate groups (phosphate is a misnomer since they are actually phosphoryl )

role=univeral carrier of energy. found in all living cells. release discrete packets of energy by breaking phosphate bond via hydrolysis
Continually rehydrolysed and resynthesised

hang on though the increase in heart rate is to ensure that the more carbon dioxide is exhaled and more oxygen is inhaled.

so wouldnt that be negative a feedback- a processes that brings about a reversal to any change in condition

Correct Btw, name a process that uses ATP, like glycolysis.






Roles of synpases ( 3-4)

Allow for one way transmission (only the presynatic knob contains vesicles of ACh and only the postsynaptic has receptors for it.
Filters low level stimuli

Something about temporal and spatial summation and convergence and divergence

these words are in my notes but I dunno what they mean. can someone explain them

Allow for one way transmission (only the presynatic knob contains vesicles of ACh and only the postsynaptic has receptors for it.
Filters low level stimuli

Something about temporal and spatial summation and convergence and divergence

these words are in my notes but I dunno what they mean. can someone explain them

Summation : when low level impulses are amplified
convergence : many pre to one post
divergence : one pre to many post

( the ones below i tried to figure out from the OCR BOOK. - )

Temporal summation : many action potentials are made in pre
spatial summation : many pre to post
EDIT : the last part has been cleared earlier


How are limiting factors of photosynthesis shown on a graph? ( or how do you know when the temp/co2/light intensity has become limited on a graph ) 1 mark.