OCR Biology F211 Exam - Tues 11'th January 2011

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Reply 40

Tabers

Original post by Ishman2k10

Which book do you revise from people?. I have the fear that the thin revision book doesn't go into enough detail.

I'm using the questions in the thin book and then the textbook as well.

Reply 41

786girl

http://www.ocr.org.uk/download/sm/ocr_13129_sm_gce_unit_f211_csa_h.pdf

i was going through this and found it pretty useful! :smile:

Reply 42

xMaGic

Original post by Ishman2k10

Which book do you revise from people?. I have the fear that the thin revision book doesn't go into enough detail.

You should have the thin and thicker one.
The thin one covers the specification but is brief!
If you are stuck on anything just post it here.

Reply 43

xMaGic

Original post by 786girl

http://www.ocr.org.uk/download/sm/ocr_13129_sm_gce_unit_f211_csa_h.pdf

i was going through this and found it pretty useful! :smile:

Thanks!

Reply 44

stressedoutbadly247

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:

Hey, any chance i could have this 50m slide powerpoint?
:smile:

would be much appreciated

Reply 45

dansheriff

Hi people, I've decided to type up some notes on Translocation in hopes of cementing this topic in my head.

What is translocation?

Translocation is the transport of assimilates throughout the plant, in the phloem tissue.

What is a source?

A source releases sucrose into the phloem.

What is a sink?

A sink removes sucrose from the phloem.

Describe how the phloem is actively loaded at the source...

ATP is used by companion cells to actively transport hydrogen ions out of their cytoplasm and into surrounding tissue. This sets up a diffusion gradient and hydrogen ions diffuse back into the companion cells. Diffusion occurs across cotransporter proteins allows hydrogen ions to bring sucrose molecules into the companion cells. As the sucrose concentration builds up inside the companion cells, the sucrose molecules diffuse into the sieve tube elements through plasmodesmata.

Describe the movement of sucrose along the phloem...

Sucrose entering the sieve tube elements reduces the water potential inside the sieve tube. Water molecules enter by osmosis, increasing hydrostatic pressure in the sieve tube at the source. Sucrose is used in cells surrounding the phloem. Sucrose may be converted to starch or used in respiration. This reduced the sucrose concentration in these cells. sucrose molecules move by diffusion/active transport from sieve tube elements and into surrounding cells.

How do we know the phloem is used?

- If a plant is supplied with radioactively labelled carbon dioxide then the labelled carbon appears in the phloem

- Ringing a tree to remove the phloem results in sugars collecting above the ring

- An aphid feeding on a plant stem leaves mouth parts showing that it is taking food from the phloem.

How do we know Translocation requires ATP?

- The companion cell has many mitochondria

- Translocation can be stopped using a metabolic poison that inhibits the formation of ATP

- The flow of sugars in the phloem is so great that energy must be needed to drive the flow

__________________________________________
If you have any questions don't hesitate to ask!

Reply 46

Ishtiaq

heyy... i kinda understand pretty much everything, its just the following thats really annoying me atm!
How is tissue fluid formed?

what is the lymphatic system, what does it do?

what are plasma proteins?

lymph formation?

cheers :smile:

Reply 47

emma363

Original post by Ishtiaq

hey. tissue fluid is formed when the blood passes through the capilliary, so basically it's the substances left after blood has diffused through the capillary wall to go to the tissue cells. it has the same contents as blood plasma apart from most blood cells and large plasma proteins as these are too big to fit through the capiliary walls.

Plasma proteins are just the proteins carried in blood plasma, so albumin, fibrinogen, haemoglobin etc

After tissue fluid has bathed the tissues, most of it goes back to the venious end of the capilliary and returns to the heart. If not it can drain into the lymphatic system where it is called lymph, this drains into larger vessels and the fluid is moved along by contractions of muscle (it also has valves to prevent backflow) and eventually this is returned back into a vein at the neck. Generally the lymphatic system plays a role in the immune system, formation of fatty acids and helping the digestive tract digest food for efficently. + as lymph passes through the lymph nodes it's filtered of potentially hazardous material.

^.^

(edited 13 years ago)

Reply 48

Ishtiaq

thankyouuuuu :smile:

How about......
Describe the functions of Glycolipids in the plasma membrane? (5 marks)
i think its the same as the Glyco protein however it is different in structure, are there any other ways it is different?

Reply 49

emma363

Original post by Ishtiaq

thankyouuuuu :smile:

(as far as i'm aware) it's the same apart from the structure as you said
functions: antigens which allow cell signalling so it can be recognised by the immune system/ go to the right place in the digestive system , carbohydrate chains can attach to eachother so they're a site for binding (cell adhension) + carbyhydrate chains can also break off if they're needed elsewear. i've got "forms bonds with water molecules to stabilise the membrane" written down but i can't really expand on that lol

Reply 50

Ishtiaq

yeahh i know what you mean :smile:

just confuses me a little! lol. thankyou for your help

erm final thing... hehe :wink:

What do we need to know about the ECG?

Reply 51

Rosi M

Original post by Ishtiaq

yeahh i know what you mean :smile:

just confuses me a little! lol. thankyou for your help

erm final thing... hehe :wink:

What do we need to know about the ECG?

Hey its not directed at me but thought i'll tell you.. just the Myocardial Infarction ECG pattern so its elevated ST peak (i think!) Then ventricular hypertrophy which is a deep 's' peak. Irregular 'p' peak is atrial fibrillation. I think thats about it really

Re-sitting this exam..

Reply 52

emma363

Original post by Ishtiaq

yeahh i know what you mean :smile:

just confuses me a little! lol. thankyou for your help

erm final thing... hehe :wink:

What do we need to know about the ECG?

haha

I can't guarantee this is right 'cause i'm doing f221 human biology which is about 75% the same (but that doesn't have a thread :frown:

) but we need to know the PQRST wave and which part is what and I don't think we HAVE to know it but it'd help to know what ventricular fibrillation/tachycardia/heart block etc are

Reply 53

Ishtiaq

ohh right thankyouu both of you...
iv got some pastpaper questions on the ECG so just going to work through them :smile:

cheers for all your help! :biggrin:

Reply 54

xMaGic

Original post by Ishtiaq

ohh right thankyouu both of you...
iv got some pastpaper questions on the ECG so just going to work through them :smile:

cheers for all your help! :biggrin:

We dont really need to know much about ECGs
Do you have the ocr bio revision guide?
Learn what happens at the different points

Reply 55

levantine

what about cell cycle. what happens at different stages of interphase?? all the g1. g0 g2 stuff?

Reply 56

xMaGic

Original post by levantine

what about cell cycle. what happens at different stages of interphase?? all the g1. g0 g2 stuff?

Just remember g1 is for growth - all the g' stuff is pre-mitosis
Dont need to know it much

Reply 57

abu125

what is the role of cholesterol molecules in a plasma memembrane?

Reply 58

levantine

Original post by abu125

what is the role of cholesterol molecules in a plasma memembrane?

mechanical stability. it is found in the between the lipids and helps the membrane fluidity.

that'll normally get you the marks

Reply 59

kimmey

cell signaling is when a receptor on a extrinsic protein binds to a trigger that has a complementery shape, to trigger a respose in the target cell

but wats cell recognition ??