OCR Biology F211 Exam - Tues 11'th January 2011

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Reply 20

xMaGic

Original post by KDudley

can anyone teach me about xylem and phloem? and transpiration etc. :biggrin:

Transport through xylem/phloem or adaptations/features

Reply 21

emmaD96

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

Makes more sense now, thanks

Reply 22

xMaGic

Original post by emmaD96

Makes more sense now, thanks

No problem :smile:

Reply 23

KDudley

Original post by xMaGic

Transport through xylem/phloem or adaptations/features

Transport through xylem/phloem pleasee :smile:

Reply 24

xMaGic

Translocation is the movement of assimilates from one part of a plant to another via the phloem;

1. Hydrogen ions are pumped out of the companion cell (requires energy - ATP)

2. Hydrogen ions diffuse back into companion cell through a cotransporter protein.

3. At the same time as the cotransportr transports H+ it
also transports sucrose.

4. Sucrose diffuses into seive tube elements through plasmodesmata

5. Diffusion of sucrose into seive tube elements reduces water potential

6. Water moves in by Osmosis from surrounding tissue

7. This increases the pressure (hydrostatic)

8. In the cells surrounding the phloem, sucrose is used up which decreases the sucrose concentration

9. Sucrose from phloem diffuses in to surrounding tissue

10. Water potential gradient is now higher sieve tube element than surroundng tissue so water moves by osmosis out of the sieve tube element

12. This decreases the pressure

13. Water in phloem moves down PRESSURE gradient and carries with it the sucrose.

Reply 25

Charm&Witt_93

Oh gosh..why do i feel the need to pull out a tex t book now! :L

Reply 26

xMaGic

Original post by KDudley

Transport through xylem/phloem pleasee :smile:

Water transport from root to leaves;

Water enters the roots by osmosis. At the same time, minerals are actively pumped from the root cortex into the xylem. This causes the water to move from the root hair cells along the symplast pathway to follow the xylem. Thw symplast pathway is where water enters the cytoplasm from cell to cell. Water can also travel through the apoplast pathway, where water travels between the cell walls without passing through the plasma membranes. The Casparian strip blocks the apoplast pathway between the cortex and the xylem meaning that, to reach the xylem the water MUST join the symplast pathway.
When thw water reaches the top of the xylem, it enters the leaves and leaves through the stomata.

Reply 27

KDudley

thankyouu

thats just what i needed, written in a simple way for me to understand!

Reply 28

xMaGic

Original post by KDudley

thankyouu

thats just what i needed, written in a simple way for me to understand!

Np.
Let me know if anything else ur stuck on

Reply 29

beanstalkgirl_24

Biology!

Although I love it to bits, it is rather stressful. There are too many words to learn :frown:

Reply 30

xMaGic

Original post by beanstalkgirl_24

Biology!

Although I love it to bits, it is rather stressful. There are too many words to learn :frown:

Yep, too much content.
Keep copying notes and stuff until you get it in your head :biggrin:

Reply 31

beanstalkgirl_24

Original post by xMaGic

Yep, too much content.
Keep copying notes and stuff until you get it in your head :biggrin:

Thanks thats good advice.

Also have any of you used Quizlet the online flashcards website before??? Its rather splendid (I do love that word!!) and in my revision last week I managed to find loads of flashcards by someone called '03harmal' who obviously did the exam last January. They are for all of the topics in the January exam and worth a look as a different style of revision....(you can play games with them :biggrin:

)

Link: http://quizlet.com/user/03harmal/

PS If this has been helpful can you rep me...I'm determined to get to level 2!!!

TY

(edited 13 years ago)

Reply 32

daniellestaunton

Original post by VetApplicant

I have a 50 slide revision powerpoint for OCR AS Biology last year
If anyone wants it, just tell me how to send it and I will :biggrin:

Hiya could you possibly send it to me......It would be great. Thanks Danielle

Reply 33

xMaGic

How much are you guys revising daily?

Reply 34

Mally-xo

Original post by daniellestaunton

Hi would it be possibly if you could send them to me as well. Thanks

sure, just private message me your email thingy :smile:

Reply 35

shamzika

Original post by beanstalkgirl_24

)

Link: http://quizlet.com/user/03harmal/

PS If this has been helpful can you rep me...I'm determined to get to level 2!!!

TY

Thank you so much for this!!!

Its a really helpful website and its the thing that got me revising!

Thanks again for the link :biggrin:

(edited 13 years ago)

Reply 36

Dave23

So, based on what's come up on the last few papers of this spec, what topics do you reckon will come up on the January 2011 paper!? :confused:

Reply 37

VetApplicant

sorry, just looked through the powerpoint I sent people and it looks a bit rubbish!
I remember it being better than that!
Sorrryy!

Reply 38

Tabers

Does anyone have an easy way of remembering things about cells e.g. the organelles as I just can't remember them at all? It does not go into my head. Actually to be honest none of this stuff is going in my head, I sit there, basically write it all out and it still doesn't go in.