The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

A2 Biology OCR June 2015 Revision Thread

Scroll to see replies

I really hope there isn't much on genetics (epistasis etc),
Reply 3341
Avatar for Cdp3
Cdp3
2
Original post by zahra -year 10
thanks so much,and do you know the cerebral cortex one?


Nope, sorry! Had a look in my textbox and it didn't say anything about the cerebral cortex!
What even is it?
Reply 3342
Avatar for Cdp3
Cdp3
2
Original post by Student23478
"Can someone look at the markscheme for 1bii on jan 2013 is it me or are the f1 genotype supposed to be the other way around???" Could you explain this please im sure it's the other way round ?


I thought the same when I did the paper, by teacher said it's just an error in the mark scheme
Reply 3343
Avatar for Cdp3
Cdp3
2
Original post by Amelia_21
Can someone tell me what exact stuff we need to know for the green species page (p.142) and for the DRD4 gene page.


Dopamine is just a neurotransmitter which affects certain behaviours, e.g. mood.
There are 5 different receptors for dopamine, the effects of dopamine vary depending on which receptor is binds to and each receptor is coded for by a different gene, so for D4 receptor, DRD4 codes for it.

Having many D4 receptors has a negative effect, it links to abnormal behaviour, in for example, Schizophrenia (a disorder impacting thinking, perception, memory and emotion), and there is certain pieces of evidence to prove this.
Original post by alexthehuman
Can anyone help me out with genetic engineering of insulin? The 2 ocr books and biotutor all have different methods I dunno which one I'm supposed to learn :frown:


High concentrations of mRNA in the pancreas of animals which can be translated to produce polypeptides (insulin). This mRNA can be extracted using centrifusion techniques.

The mRNA can then be treated with 'reverse transcriptase' (an enzyme) to produce cDNA. This can be cut with restriction enzymes. A plasmid can be cut using the same restriction enzymes, and can be mixed with the cDNA and DNA ligase to form a plasmid containing recombinant DNA.

The plasmid vector can be inserted in bacterial cells. Replica plating can be used to determine which bacterial colonies have taken up the recombinant plasmid. These bacteria can be extracted and placed into a fermenter to produce large quantities of human insulin :smile:
(edited 8 years ago)
is anyone else annoyed by how the papers are set, like they are all basically, whats the impact of this or whats the reason for that and then 3 sub questions. i feel like it goes into to much detail for one question and then doesnt even cover most of the topics :/ its really off putting.

also anyone found any chunky sustainable management questions from past papers?? cus i cant find much and its one of the bits im iffy about.
Can anyone explain southern blotting ?
Reply 3347
Avatar for Cdp3
Cdp3
2
Original post by Beni24
Can someone outline the sliding filament model please? :smile:


The sliding filament model is basically used to show the contraction of muscles.

Myosin and actin slide over one another, making the sarcomere contract (the myofilaments do not contract at all).

REMEMBER:
A bands are the only bands that stay the same length, whereas the I band and the H zones get shorted
Swear down you dont even have to learn in so much detail

Some of the past papers have so much ticking boxes and filling in gaps in sentences, along with basic definitions and descriptions of graphs lol

And advantages/disadvantages and shiz
Posted from TSR Mobile
(edited 8 years ago)
Original post by TheLegalDealer
Can anyone explain southern blotting ?


I've not heard of that, what's the context?
Reply 3350
Avatar for LA_95
LA_95
1
Guyssss what are the predictions?? :smile:

Posted from TSR Mobile
Reply 3351
Avatar for Cdp3
Cdp3
2
Original post by maisie__x
How are gibberelins involved with elongation?


Gibberellins stimulate seed germination, stem elongation, side shoot formation and flowering. They help plants grow tall.
Reply 3352
Avatar for Cdp3
Cdp3
2
Original post by LA_95
Guyssss what are the predictions?? :smile:

Posted from TSR Mobile


Lac Operon
Original post by loperdoper
I've not heard of that, what's the context?


A way of identifying DNA fragments from electrophoresis
Original post by TheLegalDealer
A way of identifying DNA fragments from electrophoresis


pretty sure thats not on the syllabus
Original post by LMottram
Hi!
Could someone help me with this please?
Is the polymerase chain reaction basically the same process at the Chain termination method? Except the CT method uses modified terminator nucleotides to create strands of different lengths?
Thanks! :smile:

PCR and electrophoresis are used in the Chain termination method. But yeah, it's just that terminator free nucleotides are used instead of the normal free nucleotides for the PCR part.
Original post by TheLegalDealer
A way of identifying DNA fragments from electrophoresis


Oh, yeah. It's essentially when the DNA fragments (which are flourescent), are blotted onto a sheet and put under UV light. I've just never heard it be called southern blotting.
There's two methods for human genome sequencing in the textbook, anyone know which one I should learn for the exam?
Original post by LA_95
Guyssss what are the predictions?? :smile:

Posted from TSR Mobile


I bet my textbook there's going to be a genetics question in there.. A nasty one..

Recently there are so many MORE "suggest" type questions that it's almost not testing knowledge but more common sense (something I lack!) :rolleyes:
Reply 3359
Avatar for Klesia
Klesia
HOW ARE WE MEANT TO GET THE WHOLE OF F215 IN OUR HEADS?

feel like my brain is going to explode!

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you