A2 Biology OCR June 2015 Revision Thread

The reaction goes both ways in different cycles so in the liver its lactate to pyruvate. hope that helps x

I'm pretty much doing posters for chem2 this year I got Chem 4 and 5 to start! Too! Only got two more topics for chem2 defo got the basic in my head! Been getting 50 so far hopefully that number will go up urge wish I could do that but got a synoptic paper for psychology need my B in that!!!!

Hmm might just memorise these notes i guess 2 hours every day for each unit then fingers crossed exams easy and boundaries are low 😩😩😩


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Ah thank you! Is that the same with ethanal -> ethanol ( ethanol dehydrogenase) x

Kind of, ethanal goes to ethanol to an aldehyde then a carboxylic acid which is reduction, the reverse would be oxidation, so i'm not sure if it would be a different enzyme, sorry, i can look into it further if you want?x

Guys, what's the difference between conservation and preservation?

Is the textbook right when it says ethanol dehydrogenase reduces ethanal to ethanol? Does that name make sense?

Is the textbook right when it says ethanol dehydrogenase reduces ethanal to ethanol? Does that name make sense?



Conservation involves the maintenance of biodiversity, including diversity between species, genetic diversity within species, and maintenance of varied habitats and ecosystems. Conservation is a dynamic process involving management and reclamation. By contrast, preservation simply protects species, for example by creating a nature reserve.

How much do we really need to know about the double spread on genes and body plans and the fruit fly?

For the double spreads 11 to 15 on genes, you must know:
- The different types of epistasis (learning the common ratios is not enough in my opinion)
- Be able to understand genetic diagrams and tables (you do not need to know how to construct a genetic diagram, although I find it does help to use a punnett square if you do have the time)
- Understand notations of alleles, Including those that express codominance or are sex-linked

For the fruit fly, Drosophila melanogaster (spread 6), it is a "how science works" page. Therefore, You only require a basic understanding of homeobox genes and the effect that retinoic acid can have. However, you have to be able to make comparisons of the homeobox genes of organisms like drosophila with that of humans, for example.

In terms of Transcription what is the role of RNA polymerase? My book says it unzips the DNA molecule but other books say this is the role of DNA helicase?

In terms of Transcription what is the role of RNA polymerase? My book says it unzips the DNA molecule but other books say this is the role of DNA helicase?

Oh no wait I I think DNA helicase basically just unwinds the two polynucleotide stands and then the RNA polymerase break the hydrogen bonds between the nucleotide bases


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Thank you! That makes a lot of sense