OCR Biology F211 Exam - Tues 11&#x27;th January 2011

Original post by shooby_doo

On the gap filling question
Did heamogoblin have an "attraction" for oxygen, or an "affinity" ?

Affinity I think.

Reply 461

shooby_doo

4

Original post by Ambrosse

Affinity I think.

yea thats what i put, but thinking about it now, doesnt affinity in itself mean attraction to oxygen?
So an affinity for oxygen, would mean an attraction for oxygen, for oxygen lol if you know what i mean

Reply 462

No affinity just means that it has an attraction I believe, you would only use the word in a certain conext though but it doesnt just apply to oxygen.

Reply 463

adilh301

Original post by Nima11

About the pathways the water takes throug the cell membrane - 2mark question .

I thought that was symplast and apoplast pathway?

Yeah symplast and vacuolar pathway across the membrane, going through channel proteins would be wrong even if the question asked how water moved through the phospholipid bilayer i think bc water molecules are an exception to that rule as theyre small enough to travel through the hydrophobic tails. but yeah symplast and vacuolar pathway :smile:

Reply 464

Nima11

Original post by adilh301

Yeah symplast and vacuolar pathway across the membrane, going through channel proteins would be wrong even if the question asked how water moved through the phospholipid bilayer i think bc water molecules are an exception to that rule as theyre small enough to travel through the hydrophobic tails. but yeah symplast and vacuolar pathway :smile:

Would apoplast count? P:

Reply 465

what about the histamine causing more permeability question? i put more substances that would not usually pass out of the capillary would do so and that the scells in the tissues would become plasmolysed because the water potential of the tissue fluid would decrease and water would leave the cells in the tissue :smile:

Reply 466

wilsea05

1

Original post by Nima11

Would apoplast count? P:

it said in the question something about water not having to go through the membrane and taking the apoplast pathway, so i'm guessing no

Reply 467

Original post by adilh301

Yeah symplast and vacuolar pathway across the membrane, going through channel proteins would be wrong even if the question asked how water moved through the phospholipid bilayer i think bc water molecules are an exception to that rule as theyre small enough to travel through the hydrophobic tails. but yeah symplast and vacuolar pathway :smile:

No, water travels across the cell membrane by diffusion as molecules small enough to pass right through charged area and also channel proteins and aquaporines to allow bulk movement of water, pinocytosis.

Apoplast and symplast just refers to water travelling through the root doesnt it.

Reply 468

Anyone already thinking about a resit?

Reply 469

surely, the movement of water molecule across a membrane is by osmosis? The net movement of water molecules from an area of high water potential to an area of low water potential across a selectively permeable membrane

Reply 470

I just guessed the cambium part of the stem cross-section, just checked on my revision book and I it was right!

Reply 471

Original post by blahblah772

surely, the movement of water molecule across a membrane is by osmosis? The net movement of water molecules from an area of high water potential to an area of low water potential across a selectively permeable membrane

In the text book it uses osmosis and diffusion interchangably, but I put diffusion across membrane, now im thinking the OCR markscheme may only allo osmosis because the like to suck like that. But it doesnt just pass through the membrane by osmosis.

Reply 472

Original post by alz-93

i just guessed the cambium part of the stem cross-section, just checked on my revision book and i it was right!

u
r
v

?

was u the middle?

Original post by ALZ-93

I just guessed the cambium part of the stem cross-section, just checked on my revision book and I it was right!

Dam I got that wrong, feel so annoyed, the question tried to trick you by pointing toward centre and I was rushing. Feel so foolish about that question

Reply 475

Original post by Ambrosse

In the text book it uses osmosis and diffusion interchangably, but I put diffusion across membrane, now im thinking the OCR markscheme may only allo osmosis because the like to suck like that. But it doesnt just pass through the membrane by osmosis.

I know what you mean man the ocr textbooks are truly awful... i only said osmosis but i described it in enough detail passive, high to low etc. hopefully get the marks :smile:

Reply 476

Original post by thinkofaname

and also what did u write down for the sturcutre of the lung part A was it Bronchi / Bronchus /bronchiole ?

I put bronchiole :confused:

Reply 477

Original post by blahblah772

I know what you mean man the ocr textbooks are truly awful... i only said osmosis but i described it in enough detail passive, high to low etc. hopefully get the marks :smile:

Yes if I get that marked wrong then im going to post text book back to author and tell them to give me my money back because them and their text book is a disgrace. :smile:

Reply 478