AQA A2 BIOL5 22nd June 2012

Does anyone know which papers from the old spec match up with the content in BIOL5??

No I mean doesn't temporal summation occurs for cones??

Isn't that Spatial summation? Temporal is repeated impulses through one neurone while Spatial is several neurones providing impulses.

Hey, are there any notes like this for unit 1? Thanks

I don't think so, otherwise we would be able to see in full colour at night

Hi, i just had a quick question. There is this essay book, not sure if you've read it, but it has about 20 essays in it. The standard they have been written to are really high i think.But my question is, sometimes the writter waffles abit in the essays, do we just write straight to the point or try to write it the way that writter has ://

There isn't much point in marking the essays you write, just make sure you can write a lot and cover a lot of different points. I wouldn't know how examiners actually mark the essays, they go to many standardisation meetings where they discuss marking. Generally, the first thing they look at is the length of the essay.

fml, haven't learnt about meiosis, mitosis, cell cycle, crossing of chromosomes.

I might have to take a strategic gamble and not learn them. Simply haven't got the time for it..

Yeah me to - i figured, since DNA and Technology came up last year, it's highly unlikely to come up again. The only thing directly related that could come up is variation / communication of information. I also find that explaining genetics requires more lines that other topics and takes more time to think about expressing yourself correctly. If I can answer the other question, I'd rather not write about it anyway...

Yep, looking back at the previous titles that came up:

The causes of disease in humans.

Carbon dioxide may affect organisms directly or indirectly. Describe and explain these effects.

Using DNA in science and technology

A cycle is a biological pathway or process in which the end product of one cycle
becomes the starting point for the next cycle. Write an essay about cycles in biology.

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So i think something related to:

inorganic ions

ATP ()

Proteins and carbohydrates.

Movement of ions/molecules via different mechanisms (active transport, osmosis etc)

I'd say those are great guesses! Although thematically, they're all biochemistry based - i'm guessing that you also study and enjoy Chemistry?
I think the second question will be more ecological/biological in nature. I'd be suprised if AQA sets two heavily based biochemistry questions together.

People!!

How do you know whether you need to use pitfall traps OR mark-release-recapture OR quadrats, to measure the population of a species?

Pitfalls are actually not specifically in the specification. They only appear if a question asks how you'd carry out mark/recapture/release as they are a method used to carry it out. Mark/recapture/release is for mobile/elusive organisms, which is pretty much any wild animal; quadrats are used for plants/stationary organisms.

The anti codons are AGC UUC. They are complementary to the mRNA sequence which would be UCG AAG right? Now mRNA sequence is complementary to the DNA sequence, except the fact that uracil is not present, instead it's thymine. So if we go complementary again you would get AGC and TTC. So in actual fact the DNA sequence and tRNA sequence are the same EXCEPT for the uracil/thymine changes. Hope that makes sense

I understand what your saying but i think the mark schem is wrong because if you think about it there are two strands of DNA one coding strand and one template strand. mRNA is synthesized from transcription of the template strand. But the question is asking for the corresponding section of bases on the DNA coding strand.

This is the theory behind my answer see below

AGC UUC - the two anticodons
UCG AAG - the mRNA codons
AGC TTC - the sequence of bases on the template strand of DNA
TCG AAG - the sequence of bases on the DNA coding strand

Now if we were to go along with the answers according to thomas reddington and work back wards we would get two different anticodons.

Do you understand what i mean.

Thanks for your help this is just so frustrating im convinced im right!!!!!

Can you type out the actual question? I see what you're doing, the only difference being you are going complementary to the DNA template strand again at the end, which is what is giving you a different answer. I've honestly never seen them want the complementary strand to the template strand. I believe you just have to assume they are asking for the one strand that the mRNA was made from and then the tRNA. So you don't do the very last step you did, again I could be wrong but I've never come across anything different, and haven't had any trouble with these questions.