A2 Biology OCR June 2015 Revision Thread

Hey, does anyone have a link to the 2014 paper? Want to do a bit of question spotting but only June 2013 comes up on the OCR past paper thing!! Thanks )

Sorry to wander off topic a little, but are there any predicted grade boundaries for the F214 exam? Would like a rough idea of what marks/UMS I need in F215 to get an A*. Cheers and good luck!

BAC is literally just recombinant DNA in a plasmid.

BAC is bacterial artificial chromosome, essentially a plasmid with your desired DNA inserted into it. Nothing big

I think we just need to know the basic idea of the homeobox sequences and how they control the development of the body plan. I don't think we need to know the drosophila example, but it will probably help to have a rough idea of it.

Is that the question about the triplet codons?

Just to check - you mean "Using the information in Fig. 5.1, list the three triplet codons that would cause termination of a polypeptide chain (stop codons) and explain why these codons have this effect."

The three triplet codons are just the ones that code for "stop" - so following the diagram, this is UAA, UAG, and UGA (read from the diagram).

They code for a "stop" because, whilst there is a tRNA with the complementary anticodon, there is no associated amino acid on the tRNA. This means the amino acid on the previous tRNA has nothing to create a peptide bond with, and the whole chain breaks away from the tRNA and therefore forms the primary structure.

Thanks! I'll have a look tomorrow and see if I get it also could you list me the adv of each innate and learning behaviour so habituation classical c operant C and innate:reflexes taxes and kinnesis?

Adv
Innate: Learnt from birth, stereotyped, does the right thing first time, less complex organisms can have it

Learning: Can adapt to enviroment, can be more complex.
The main specific advantages I can name for this is
habituation: learns to filter out unimportant stimuli in order to concentrate on any unfamiliar stimuli that can crop up
operant: learns to get reward which can be a benefit
imprinting: learns to follow parents so they don't get separated as anatomy doesn't allow for same kind of "clinging on" as other species.
insight: can be faster than trial-and-error, more complex

classic and latent learning don't really have any specific advantages outside of the general learning advantages to be honest, the same with specific types of innate behaviour.

You could say an advantage for classic is that you can train an animal to prepare to respond to a certain stimulus.
Latent could be useful in escaping predators. A rabbit can explore burrows and retain the information so it could quickly escape if a predator comes.

You could say an advantage for classic is that you can train an animal to prepare to respond to a certain stimulus.
Latent could be useful in escaping predators. A rabbit can explore burrows and retain the information so it could quickly escape if a predator comes.

How about innate advantages eg kinesis and taxes as it's come up in exams before

my least revised for exam and I know I'm gonna regret it :'(

Why is sterile air entered into fermentation vessels rather than normal air?

I'd assume its done to prevent contamination (whilst still supplying oxygen necessary for the microorganism to carry out aerobic respiration)