AQA BIOL2 ~ 21 May 2012 ~ AS Biology

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Reply 1780

britash

Is starch unbranched or branched?
Text book says unbranched, and my other notes say branches O.o

Reply 1781

alhasan

Original post by britash

Is starch unbranched or branched?
Text book says unbranched, and my other notes say branches O.o

starch is unbranched. thats why it is compact to store. glycogen is branched so it can easily be hydrolysed into a-glucose. it is found in animal cells whereas starch is only found in plants :biggrin:

Reply 1782

AGrumpyMole

Original post by britash

Is starch unbranched or branched?
Text book says unbranched, and my other notes say branches O.o

Amylose is unbranched, and amylopectin is branched. They make up starch :}

Reply 1783

beckylewis

Original post by onelove93

what exactly do we need to know about the structure of a plant/leaf?

and what is root pressure?

root pressure is when ions and minerals in the the soil are actively transported from the endodermis into the xylem, this means that in the xylem there is a lower water potential than that of the oil which means water will move into the xylem by osmosis, this movement causes a large hydrostatic pressure

Reply 1784

onelove93

thankyou

any help on the leaf? will we ever be asked to label a diagram or anything? I am not a fan of plant science :frown:

Reply 1785

AGoodman

Hey guys, been lurking for a while reading all the posts and gotta say they've been extremely helpful for revision so thanks!
I've personally been procastinating pretty hard and I'm so nervous about tomorrow xD
Best of luck for tomorrow everyone

Reply 1786

alhasan

Original post by AGoodman

good luck to you too :smile:

Reply 1787

hazelw

Original post by onelove93

what exactly do we need to know about the structure of a plant/leaf?

and what is root pressure?

Mineral ions are actively transported into the xylem in root by endodermal cells, which reduces water potemtial so water moves in via osmosis

Reply 1788

xcristalx

i still really dont understand what to do after you have written out the equation for index diversity and added everything in, ques 7, jan 10? HELP PLEASE

Reply 1789

username890104

Original post by Mocking_bird

Reply 1790

joker11

what's the difference between an endodermal cell and endodermis? :s

Reply 1791

AGrumpyMole

Did anyone else learn most of the spec in the last 3 days like me lmao?

Reply 1792

AGrumpyMole

Original post by joker11

what's the difference between an endodermal cell and endodermis? :s

The endodermis is made of endodermal cells?

Reply 1793

goutham

doomed to fail, what does anyone think is likely to come up? i need to redeem myself by doing some extremely last minute revision

Reply 1794

3.14Pie

Original post by Mocking_bird

Do you mean higher po2 in lungs?

I think he means that due to heamoglobin having a high affinity for oxygen, even at low Po2 of oxygen it can become saturated/load oxygen more readily than if it had a lower affinity for oxygen.

Reply 1795

onelove93

Original post by goutham

doomed to fail, what does anyone think is likely to come up? i need to redeem myself by doing some extremely last minute revision

my teacher said root pressure as it was answered really badly nationally last time it came up :frown:

Reply 1796

TipTapToe

Original post by onelove93

my teacher said root pressure as it was answered really badly nationally last time it came up :frown:

Correct me if I'm wrong but aren't the papers made 4 years in advance?

Reply 1797

goutham

Original post by onelove93

my teacher said root pressure as it was answered really badly nationally last time it came up :frown:

ahhhhh do you think it'll be a 6 mark question on it? i know the basics of it but i need to get my terminology up to the excruciating aqa exam standards :frown:

Reply 1798

Erotas

Original post by Mocking_bird

OH i see where you've gone wrong.

You measure in MM and times that by 1000 :smile:

Also, if thats still wrong, are you working on an exam paper size that is identical to the size in the real thing? If not, that will give you the wrong answer too. (Ive made that mistake before :laugh:

)

Oh! So glad that's cleared up before the exam! And yeah I was measuring it from my laptop hehee :tongue:

Reply 1799

hazelw

Original post by xcristalx

i still really dont understand what to do after you have written out the equation for index diversity and added everything in, ques 7, jan 10? HELP PLEASE

You add up the column downwards so 1+1+1+5+2.... which is 29 and multiply that by 28; N=29 so N(N-1)= 812. So numertaor is 812. for the denominator you do each species so for heath rush it would be n(n-1) where n=1 so 1(1-1) which would=0 and you do this for every row which when added would give you 188 for the denomiator. Then you do 812/188 which would give 4.3.
I know its a bit messy but hope it helped :smile: