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OCR Biology F211 Exam - Tues 11'th January 2011

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Original post by CullenLoverX
thanks. so if there was a 2 mark question i would just need to state
a) it gives the cell structure
b) moves organelles?


If I was answering the 2 mark question I would say that it gives structure and shape to the cell and moves organelles around inside cells, and then give the example of moving chromosomes during nuclear division.

basically what your saying :smile:
Reply 261
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Tabers
15
Just came up with a new song...I wish I was a eukaryotic cell with a nice nucleus! I was told not to do much revision tonight so therefore I class that as fun revision!
ok, i understand why fetal haemoglobin needs to have a higher affinity for oxygen, but i'm having real trouble writing it so it makes sense :s-smilie:
anyone care to write a model answer for how to answer the classic question "explain why fetal haemoglobin is different to adult haemoglobin"
do we need to understand what buffers are?
Can anyone text me? iv got a few questions but wont be online any longer. PM me.
Reply 265
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wilsea05
1
Original post by dansheriff
Wilsea, do you know the adaptations of guard cells?


gonna be honest, no i do not. I know they can open and close, that's about it.
list them?
Reply 266
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wilsea05
1
Original post by CullenLoverX
do we need to understand what buffers are?

no

Original post by CullenLoverX
ok, i understand why fetal haemoglobin needs to have a higher affinity for oxygen, but i'm having real trouble writing it so it makes sense :s-smilie:
anyone care to write a model answer for how to answer the classic question "explain why fetal haemoglobin is different to adult haemoglobin"


The foetus is not able to obtain its own O2 from its gaseous exchange system, so must obtain O2 from diffusion across the cervix(? ithink?) Foetal haemoglobin is able to pick up oxygen in areas of lower kPa of O2 than adult haemoglobin, causing O2 to dissociate from the mother's haemoglobin so the Foetus can pick it up.

something like that.
Reply 267
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Wilko94
6
Original post by dansheriff
Wilsea, do you know the adaptations of guard cells?


I believe one side of the cell wall is thicker than the other, so that when the cell becomes turgid, the thicker side bends, which is the opening of the stoma.

Gaurd cells have a large vacuole to allow a large intake of water, to become turgid.
Original post by Wilko94
I believe one side of the cell wall is thicker than the other, so that when the cell becomes turgid, the thicker side bends, which is the opening of the stoma.

Gaurd cells have a large vacuole to allow a large intake of water, to become turgid.


Thanks alot! Do you happen to know the adaptations of neutrophils and palisade cells? Its appreciated :smile:
Original post by dansheriff

Original post by dansheriff
Thanks alot! Do you happen to know the adaptations of neutrophils and palisade cells? Its appreciated :smile:


neutrophils:
-small granules of lysosomes (enzymes to help "digest" bacteria and foreign bodies
-flexible shape for endocytosis
-glycogen stores (though i'm not sure how this is of much help!)

palisade cells:
-thin walls (diffusion of gases)
-Many chloroplasts (absorb sunlight)

its a bit basic but there's not much on this in the textbook, do you think this'd do?
Reply 270
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wilsea05
1
Original post by Wilko94
I believe one side of the cell wall is thicker than the other, so that when the cell becomes turgid, the thicker side bends, which is the opening of the stoma.

Gaurd cells have a large vacuole to allow a large intake of water, to become turgid.


just remembered! they also have the extended cell wall which acts at the 'gate' for the stomata
Does anyone know any exam trends this year pleaze
Reply 272
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fahimak
can sum1 please give me an example of a source and a sink
Reply 273
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lmfw
1
Original post by fahimak
can sum1 please give me an example of a source and a sink


The leave is a source. A root can be both a source and a sink. :smile:
do we need to know how to work out oxygen uptake, breaths per minute etc from a spirometer graph?
i dont think its come up in this spec so far, so i dont think we need to know it?
Reply 275
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qasidb
20
Original post by xMaGic
Cardiac cycle;

1. Relaxation of Ventricles and atria.
2. Blood enters atria from veins returning to heart
3. Atria fill with blood
4. Atria contract (atrial systole)
5. Blood passes into ventricles
6. Through atrioventricilar valves
7. Atrioventricular valves shut to prevent backflow back into atria
8. Ventricles contract (ventricular systole)
9. Blood passes out into arteries leaving the heart through open semilunar valves
10. Semilunar valves shut to prevent backflow


Aren't 7 and 8 the wrong way round?
I thought the ventricles begin to contract pushing blood in the atrioventricular valve falps causing them to close.
Reply 276
Avatar for fahimak
fahimak
Original post by LisaWilliams
The leave is a source. A root can be both a source and a sink. :smile:


thankyou :smile:
Original post by giraffegiraffe
neutrophils:
-small granules of lysosomes (enzymes to help "digest" bacteria and foreign bodies
-flexible shape for endocytosis
-glycogen stores (though i'm not sure how this is of much help!)

palisade cells:
-thin walls (diffusion of gases)
-Many chloroplasts (absorb sunlight)

its a bit basic but there's not much on this in the textbook, do you think this'd do?


Perfect! Thanks alot!
source= leaf sink=root
Original post by CullenLoverX
do we need to know how to work out oxygen uptake, breaths per minute etc from a spirometer graph?
i dont think its come up in this spec so far, so i dont think we need to know it?


no coz u do tht in a2 i think lol

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