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AQA BIOL2~3rd June 2013~AS Biology (Now Closed)

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Hi does anyone have the January 2013 paper they could e-mail me? my e-mail is [email protected] - would really appreciate it!!

Reply 1001

homefind

Original post by Jimmy20002012

Why does a large surface area:volume ratio reduce water loss?

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sorry ignore that, SA:Vol ratio effects heat loss.

Reply 1002

Suzanna5678

Dunno if anyone can help but just reading my notes and it's like 'haemoglobin picks up oxygen more readily in the lungs as there is a high partial pressure' I thought haemoglobin picks up oxygen more readily when it's on the left of the curve, surely that's a low partial pressure?! So confused !

(edited 10 years ago)

Reply 1003

kashagupta

Could anyone please give me a quick summary of all the polysaccharides?

(edited 10 years ago)

Reply 1004

Sumi Prakash

Could someone please explain to me why the hydrostatic pressure forces tissue fluid out of the blood plasma? :confused:

Reply 1005

homefind

Original post by Suzanna5678

haemoglobin has a higher affinity for oxygen at higher partial pressures of O2, which is at the lungs, so at the lungs oxygen readily associates with haemoglobin.

Reply 1006

SophieL1996

Original post by homefind

1c) measure the length of the chloroplast then times that by 1000 to get it into um, then divide that by the magnification.

3b) 5, count how many different genus there are (which is the generic name i.e the genus for Synodontis batensoda is Synodontis

wait sorry I get it thanks! :smile:

(edited 10 years ago)

Reply 1007

Suzanna5678

Original post by homefind

haemoglobin has a higher affinity for oxygen at higher partial pressures of O2, which is at the lungs, so at the lungs oxygen readily associates with haemoglobin.

Isn't higher partial pressure to the right though? I thought the more to the right the curve moves the lower the affinity and the more readily haemoglobin gives up oxygen??

Reply 1008

SophieL1996

Original post by PeaceLovePink

you measure the chloroplast from one end to the other (the long way) in mm, which should give you 76mm. times that by 1000 to get it into um. and then divide 76000 by the magnification which is 30000 to get your answer which should be 2.53.

The equation for this is Image length= magnification x original/actual length or you can use a triangle with I (image length) on the top and M (magnification) and O (original/actual length) at the bottom

thanks you :smile:

do you know how to do 10b? thanks

Reply 1009

Jimmy20002012

Original post by Suzanna5678

I think your notes may be a bit wrong. From what I know when you have a low partial pressure you have a a higher affinity of oxygen which means you load oxygen more readily in the lungs which moves the curve to the left (I think), for example llamas live in high altitude and therefore have a lack of oxygen, so needs a higher affinity for oxygen. Another example would be an elephant which as a small surface area:volume ratio so diffusion doesn't happen as rapidly, so needs to load oxygen more readily in order to compensate for this.

On the other hand if you have a high partial pressure you have a lower affinity of oxygen which mean you unload oxygen from the heamoglobin molecule more easily to respiring tissues, so you can have more cellular respiration and produce more ATP for rigorous activities needed for muscles.

Hope this helped :biggrin:

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Reply 1010

Hayley-27

do we need to know the process of ventilation in fish? or just gas exchange in fish?

(edited 10 years ago)

Reply 1011

Suzanna5678

Original post by Jimmy20002012

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maybe my notes are wrong, thank you! Would you be able to answer this for me then, think its 6 marks.. 'How haemoglobin loads oxygen in the lungs and unloads it in a tissue cell?'

Reply 1012

bad8oy

Original post by Suzanna5678

maybe my notes are wrong, thank you! Would you be able to answer this for me then, think its 6 marks.. 'How haemoglobin loads oxygen in the lungs and unloads it in a tissue cell?'

Talk about pH changes...shape changes of haemoglobin at different pHs and whether the shape change means oxygen binds loosely or more readily or released ect.

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Reply 1013

Jimmy20002012

Original post by Suzanna5678

maybe my notes are wrong, thank you! Would you be able to answer this for me then, think its 6 marks.. 'How haemoglobin loads oxygen in the lungs and unloads it in a tissue cell?'

How haemoglobin loads oxygen in the lungs and unloads in a tissue cell?:

Firstly you a low partial pressure in the lungs, so haemoglobin will have a high affinity for oxygen, so oxygen therefore binds to the haemoglobin molecule by alosteric inhibition. Oxyhemoglobin is now formed, when it reaches the reaches the respiring tissues, you have a high partial pressure, therefore you have a low affinity of oxygen. Consequently, oxyhemoglobin unload the oxygen to the respiring tissues which means cellular respiration occurs. This means that carbon dioxide is produced, which happens to lower the ph of the blood, causing a higher partial pressure, so the cells would rapidly need oxygen to be unloaded from haemoglobin, in order to compensate for this production of carbon dioxide.

This should get you 6 marks, probably need to put half of what I put :smile:

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Reply 1014

kingster123

hi ,everyone i have an question regarding the jAN 2013 paper the magnification question 1d i measured the lenght of the arrow and i got 11 mm which is wrong ? can anyone help me do it thanks

Reply 1015

Hayley-27

Original post by kingster123

hi ,everyone i have an question regarding the jAN 2013 paper the magnification question 1d i measured the lenght of the arrow and i got 11 mm which is wrong ? can anyone help me do it thanks

11mm isn't the correct length, it should be in the region of 23mm, which you then multiple by 1000 to convert it to micrometres, then you divide your length by the actual length of 48um. And i got an answer of 479.2 times (using 23000)

Reply 1016

chelley2

Original post by hannah2101

Hi does anyone have the January 2013 paper they could e-mail me? my e-mail is [email protected] - would really appreciate it!!

I'll email you .I've got it on my USB :smile:

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Reply 1017

chelley2

If anyone wants the Jan 13 biol2 paper and the mark scheme tell me.i've got it saved on my USB but I don't know how to link it on here -.-

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Reply 1018

Linked

Does anyone want the link for the January 2013 past papers?

Reply 1019

homefind

hold on, hold on!

HAEMOGLOBIN

Where the partial pressure of oxygen is high (i.e in the lungs) haemoglobin has a higher affinity for oxygen and therefore readily associates with it. THAT'S WHY ON THE GRAPH IT HAS A HIGH SATURATION OF OXYGEN

Where partial pressure of oxygen is low (i.e respiratory tissues) haemoglobin has a lower affinity for oxygen and therefore readily dissociates with it to supply respiratory tissues with oxygen to carry out respiration. THAT'S WHY ON THE GRAPH IT HAS A LOW SATURATION OF OXYGEN.