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A2 Biology OCR June 2015 Revision Thread

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Reply 4020

Wing:)

Original post by doctor_2_be

Yep, the sad thing is ill have to do the same thing tommorow night fory physics exam on thursday

Same for me. I have one day to learn 50% of the whole A2 :frown:

Reply 4021

Cdp3

Original post by WishIHadRevised

What's the difference between preservation and conservation?

Conservation involves protections, management and sometimes reclamation of an ecosystem, preservation is just protecting the environment by leaving it basically untouched, not removing anything from the area and not adding to it

Reply 4022

samboosa0

For 2b iii) how do you find the expected value in the chi-squared table?

http://www.ocr.org.uk/Images/61493-question-paper-unit-f215-control-genomes-and-environment.pdf

Reply 4023

Ahem-

Original post by samboosa0

For 2b iii) how do you find the expected value in the chi-squared table?

http://www.ocr.org.uk/Images/61493-question-paper-unit-f215-control-genomes-and-environment.pdf

Expected would be 25 each as a 1;1 ratio and 50 of them

Reply 4024

Benhughes97

So I'm glad I'm not the only one in the same boat that doesn't have a clue. Nothing seems to be in this mush of a brain anymore. Hopefully tomorrow it will all just flood back into it!

Reply 4025

amorrison

Original post by doctor_2_be

Yep, the sad thing is ill have to do the same thing tommorow night fory physics exam on thursday

That 's peak, especially it being physics *barfs* . But I had to do the same last night for my psychology exam today. Luckily tomorrow's my last exam :biggrin:

, so what's one more sleepless night for an exam which even if you prepare and prepare may still end up flopping it. Is physics your last one?

Reply 4026

h4mz4

Yo, I need some help with the following

Can someone please explain to me the Power Stroke and The Sliding Filament Model?

Thanks

#LastMinute.com

Reply 4027

Ahem-

Is it just me or is there a ridiculous amount of content thats absolutely boring, reckon i'll get 4 hours of sleep tonight.

Reply 4028

samboosa0

Original post by Ahem-

Expected would be 25 each as a 1;1 ratio and 50 of them

thanks!

Reply 4029

amorrison

Original post by THEMathlete

:'( yes fcking bricking it

Posted from TSR Mobile

How UNprepared are you for it? Or is it just nerves?

Reply 4030

hukdealz

Original post by ahem-

is it just me or is there a ridiculous amount of content thats absolutely boring, reckon i'll get 4 hours of sleep tonight.

get off tsr and start working!!!!!!!!!!!!!!!!!!

Reply 4031

Ahem-

Original post by samboosa0

thanks!

Sorry, the end part of my answer didnt make much sense lol meant to say as theres 50 all together,

Reply 4032

Ahem-

Original post by hukdealz

get off tsr and start working!!!!!!!!!!!!!!!!!!

Good idea

Reply 4033

amorrison

Original post by domcandrews

LMFAO,,,cheer you all up a bit aha https://www.youtube.com/embed/ID6KY1QBR5s

Dude that was hilarious, certainly did cheer me up. Everyone needs to watch this to lighten their mood over this dick of an exam.

Reply 4034

samboosa0

Original post by Ahem-

Sorry, the end part of my answer didnt make much sense lol meant to say as theres 50 all together,

np i got it :smile:

how do you calculate df (degrees of freedom) in that question? :confused:

Reply 4035

ChoccyPhilly

Original post by amorrison

How UNprepared are you for it? Or is it just nerves?

Her sympathetic nervous system is playing up. If she wants to calm down, her parasympathetic nervous system will need to be more dominant

Reply 4036

hibaj

Original post by mushyD

Feel free to ask

idk what to ask cos idk what i need to know :P

Reply 4037

Saltedcaramel1

Original post by h4mz4

Yo, I need some help with the following

Can someone please explain to me the Power Stroke and The Sliding Filament Model?

Thanks

#LastMinute.com

Muscle Contraction:

Action potential arrives at the neuromuscular junction which trigger vesicles containing neurotransmitter substance to fuse with pre synpatic membrane and diffuse across the synaptic space. the neurotransmitter substance then binds to receptors on the sacrolemma. This triggers opening of sodium ion channels which intiate action potential in the the muscle. the action potential travels down t-tubules which cause sarcoplamsic reticulum to release their store of calcium ions. the calcium ions then bind to troponine to expose the binding site on actin. myosin can now bind to actin and form a crosslink and ATP molecule is hydrolysed and powerstroke occurs. another ATP is hydrolysed and the myosin head is rest. this process repeats until it stop receiving stimulation.