OCR Biology F211 Exam - Tues 11'th January 2011

Yes! Like you, I also put simple diffusion/osmosis because although they are polar, water molecules are small. Also like you I didn't get the second mark (I was never even taught that there was a chance water molecules could hit the hydrophilic -you said hydrophobic but I assume you mean hydrophillic, phosphate group heads).

Some of my friends came out of the exam having put the symplast/apoplast pathways but it deliberately said cell surface membrane. Cell surface membranes can be both in animal or plant cells, so for one reason why would the answer be the pathways that are only present in plant cells?

can you also put flexible shape (for phagocytosis engulfment) for the neutrophil one?

also, what was the answer to the stem one? I put some thing like the distance for the water to travel to the cells which need it for photosynthesis is now shorter, so it is more likely to have the required energy to survive longer; does this make sense? was kinda guessing lol

I wasn't talking about the onion epidermis cell question. I was talking about the question "how does water move through the cell surface membrane", nothing was mentioned about cell types here.

the question: what routes do water molecules take across the cell surface membrane
which was within a question about onion epidermis cells.

the question you had to answer was in the specification you just had to use your knowledge to apply it.
-Cell signalling for the first one
- something related to tissue fluid/water potential for the second one.
a really easy paper just really varied answers across the paper.

hmm k leave it at that and i let the fact that u called the heads hydrophobic because i assumed it was a typo on your part im sure everyone knows that the heads are water loving.

It wasn't, was it? Even if it was, it didn't directly mention what rout does water take accross onion epidermis cell membranes. Therefore I assume that it can be any cell membrane.

It wasn't, was it? Even if it was, it didn't directly mention what rout does water take accross onion epidermis cell membranes. Therefore I assume that it can be any cell membrane.

For the question about "What ultrastructure of the Neutrophils enables it to carry out their function" I was reluctant to put lobed nucleus although I knew it was right, because I'm sure a nucleus doesn't count as "ultrastructure" because it can be seen in a light microscope as well as an electron microscope. I wrote instead about lysosomes, many vesicles and complex cytoskeleton (actin filaments to move the vesicles containing foreign material to lysosomes to be digested by hydrolitic enzymes). Is it right to say a nucleus isn't ultrastructure?

the bronchioles are much narrower than the bronchioles. the larger bronchioles may have some cartillage

yes,yes it was that my friend isn't a grey area. The question was a subquestion in the question about onion epidermis cells. it didnt directly ask whate route it took across onion epidermis membranes but it did ask for routeS implying you need to mention one pathway nyway no need to get all stressed out over 2 marks one will be wrong one will be correct it will never be down to both being correct it will always say R: one of them.
none of us are examiners so none of us can say any of the possibilities in such a grey area are wrong.

Yep, you're right, it said 'cell surface membranes'.

The wording of these questions is also a pain in the ****ing arse, its really annoying (as pains in your arse tend to be...)

I've revised wrongly then. Don't try and patronise me 'everyone knows that'.

wasnt patronising you you just made a typo.
Hydrophobic tail is water hating
Hydrophillic head is water loving
you said hydrophobic head, so either you made a typo or yeah youve been revising wrong.

Its not in the spec or the book, but bear in mind, that they ask you to apply your knowledge to situations you haven't been in before, and with the knowledge that water molecules are very small and slightly polar, you could have applied that to the 'cell surface membrane', as worded in the question, which has hydrophobic phosphate ends. Im sure I didnt mishear her, she, in fact, said that the apoplast/symplast route was wrong, and irrelevant, although as you said, there is a small chance she herself could be wrong (I really doubt it, I've told you her credentials. She got one of our students to 3rd in the Biology Olympiad last year). Hydrophobic is repelling water, I'm sure? phobia = fear, phyllic = phallus = love?

Again, its a grey area. What I can say is, we can have a bet, in the form that, when the markscheme comes out, and I am right, you can rep me, and if you are right, I'll rep you

hahahahahaah pain in the arse

the lipid tails are hydrophobic the phosphate heads are hydrophillic.

yes thank you for pointing that out again, very nice of you. You're only the 4th person to tell me. tyvm.