A2 Biology OCR June 2015 Revision Thread

Any predictions on what questions will come up for unit 4 this year?

We learn that batch culture is used to produce secondary metabolites.

However, yeast fermentation is a batch culture process. Ethanol is a primary metabolite however. So the question is, why do we use batch culture to produce ethanol using yeast? Why not continuous culture? Ethanol would still be produced using continuous culture because ethanol is a primary metabolite. June 2014 F215 examiners report states that it is a batch culture process. WHY????

it's almost pointless trying to predict with ocr. they can literally throw anything at you. resat f211 this year and they started talking about endosymbiont theory which is in f214 so there you have it! someone even made a predicted paper for f211 and none of it came up lol, just gotta revise it all i guess. What I did for f211 was go through every past paper and write down the spec points that had come up, so I could deduce which spec points had not come up. They haven't tested slightly less than half the spec points since June 2009, so it was impossible to predict what was going to come up!

How is ethanol a primary metabolite for yeast? It's only produced when oxygen isn't available, hence anaerobic respiration, which therefore makes it a secondary metabolite. When oxygen is available, yeast undergoes normal respiration like most other organisms

Can somebody explain phylogenetic species concept please ?


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So contrasting the two, the biological species concept is the traditional concept of species - a group of similar organisms able to interbreed to produce fertile offspring. However the biological species concept fails to classify species like bacteria that reproduce asexually - as these species do not interbreed.

So this is why the phylogenetic species concept is better sometimes. This states that a species is an group of organisms similar in morphology, embryology etc, that are members of the same monophyletic group.


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Endosymbiosis? That's not in the spec for f214 nor is it in either of my books

Thank you ! Do you need to know about cladistics ?


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why waste time learning f215 chaper 4 when it almost certainly will only be 10 marks or less. Surely better to secure a higher mark in the others?

it's an application of knowledge for the mitochondria in respiration section for f214! I remember my teacher giving us a whole booklet on the theory, as extra reading around the course. didn't have the time to read over it yet, was planning to read over all the booklets she gave us extra for the f214 and f215 exam. turns out they chucked it in to the f211 exam!

Okay, thank you If i just read over it do you think that will be okay? I'm guessing its for possible suggest questions?

hi there guys, can someone explain to me why liposomes are inefficient vectors.