AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

How does an action potential travel along an axon? The explanation in the book is vague

I saw somewhere that the recently influxed sodium ions diffuse along the axon, causing the voltage gated sodium channels further long to open, but why does this cause them to open? Do they open in responce to a big change in voltage?

IAA - auxin (plant hormone) produced at the tips of shoots and roots

(looking at a shoot/root tip horizontally)

At the tips of shoots, it stimulates growth of cells by elongation. IAA at the tips of the shoots diffuse to the bottom half of the shoot , increasing growth of cells on the bottom half so that the bottom half of the shoot is longer than the top half and hence, curves upwards towards the light.

At the root tips, IAA inhibitis growth. IAA diffuses downwards to the bottom half of the root tip and inhibits growth of the bottom half of the root tip. Hence, the upper half of the root tip has grown more and so the whole root tip bends downwards towards gravity.

Can someone tell me everything I need to know on the DNA side of the course, we've been taught very fragmented. Also what do I need to know about the eye? Thanks in advance!

Its not too late at all, panicking isn't going to help.

At my college we have been practicing for the essay by doing essay plans for some of the old essay titles. Hopefully one of the old essay titles will come up again (they have done for the past two years), but if it doesn't then we're supposed to know enough to create an essay from the things we do know.

Learn certain topics that relate to lots of possible essay titles i.e.
- CHOLERA - could be used on essays about importance of water, bacteria affect human lives, disease, osmosis, plasma membranes
- NITROGEN CYCLE - could be used on essay about inorganic ions, importance of nitrogen, cycles essay, the environment
- POLYSACCHARIDES - relates to carbohydrates and polymers essay

- If you read the specification AQA note certain topics that are assessed as part of "synoptic skills". They are found at the end of the details of each module under "biological principles" and are quite vague but you could think about how different topics relate to each other and could be used in an essay.

- Think back to any topics you "enjoyed" and learn the basics (you don't need that many details really, only 5 relevant points). You don't need to relearn all the content of units 1,2 and 4, and its probably going to waste precious revision time anyway.

- At this point there isn't that much point spending too much time on the essay, its probably better to focus on the unit 5 content (which is worth at least 75% of the UMS marks, possibly more if you write about it in an essay). But if you remember its there it could be worth up to 25 easy(ish) marks (it is just recall).

GOOD LUCK

Its not too late at all, panicking isn't going to help.

At my college we have been practicing for the essay by doing essay plans for some of the old essay titles. Hopefully one of the old essay titles will come up again (they have done for the past two years), but if it doesn't then we're supposed to know enough to create an essay from the things we do know.

Learn certain topics that relate to lots of possible essay titles i.e.
- CHOLERA - could be used on essays about importance of water, bacteria affect human lives, disease, osmosis, plasma membranes
- NITROGEN CYCLE - could be used on essay about inorganic ions, importance of nitrogen, cycles essay, the environment
- POLYSACCHARIDES - relates to carbohydrates and polymers essay

- If you read the specification AQA note certain topics that are assessed as part of "synoptic skills". They are found at the end of the details of each module under "biological principles" and are quite vague but you could think about how different topics relate to each other and could be used in an essay.

- Think back to any topics you "enjoyed" and learn the basics (you don't need that many details really, only 5 relevant points). You don't need to relearn all the content of units 1,2 and 4, and its probably going to waste precious revision time anyway.

- At this point there isn't that much point spending too much time on the essay, its probably better to focus on the unit 5 content (which is worth at least 75% of the UMS marks, possibly more if you write about it in an essay). But if you remember its there it could be worth up to 25 easy(ish) marks (it is just recall).

GOOD LUCK

Hey do you happen to have a list of the old spec essay titles?

Hi , just wondering what you lot would give me out of 25 for this essay?

It would probably be worth at least 20, 22-23 (not that I really know)
- I wouldn't bother much with an introduction, your not going to get any marks for it
- the stuff about DNA and proteins at the start of the 2nd paragraph isn't really relevant - this is mentioned on the June 10 exam report
- the cancer and emphysema sections seem a bit short, could probably be beefed up abit
- the paragraph on lifestyle factors is a bit flaky, you've just listed lots of factors and the problems they can cause without going into detail. Maybe it would be better to chose a couple of lifestyle factors and write about them in detail rather than list everything you can think of. Similarly you didn't really go into enough details about STDs.

Thanks for your feedback. I sent this to my teacher, and i was given 13/25 for this... just wanted someone else's opinion on my essay.

Did your teacher give you any other feedback?

but doesnt IAA causes elongation if cells therefore more growth on the side withh IAA on? if IAA diffuses to the bottom half why would it inhibit growth on thr bottom half of the root tip?

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IAA inhibits cell growth in root tips (when IAA conc. is high) and IAA increases cell growth in the tips of shoots.

yeah she said the last few paragraphs need to be more specific...eg which lifestyle choice links to what risk etc. fair point. For scientific knowledge i got 8/16... do you think this is fair? Anyone? Feeling a bit depressed about it now..

is IAA a hormone or a growth factor thingy?

Ok so , I need 25/25 in the essay

does anyone have useful tips for the essay bar include stuff out of the spec?