AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

how come adrenaline forms a substrate receptor complex with the receptor on the CSM then? i thought that only applied to enzymes when their active site binds to a substrate

are you serious?!

summation means the body can respond to smaller stimuluses, because the threashold level for neurotransmitter/ action potential can be exceeded more easily, so it's more finely tuned so to speak

Do we have to know photosynthesis and respiration in as much detail as we did for the january unit for synoptic essays? Because I can only remember the basic equations

I got 65 without really revising (I was expecting an epic fail) when I did it as a mock under exam conditions so it can easily be done

Totipotent cells are undifferentiated, meaning they can develop into ANY cell. Stem cells are totipotent and they are found in the lining of the small intestine, skin, and bone marrow. Also, fertilised eggs are totipotent, technically known as 'embryonic stem cells'. In plants, however, loads of their cells are totipotent, and this is why you can grow a plant from a cutting, but you can't grow a body from a leg!!

Basically, because every cell in your body contains the same DNA, every cell has the potential to code for ANY protein. However, we don't want that, as for example, we don't need insulin to be coded for and made anywhere else other than beta cells. So...different genes in different cells are turned on or off (expressed/not expressed), depending on the cell function/requirements. This is called gene expression, and is controlled by preventing transcription or breaking down mRNA before it's translated.

Hope this helps

Does anyone have a past papers link? I can only find June 2010, already done that one three times...

There's a specimen paper on the AQA website but that's it. They don't run Unit 5 in January.

your describing pluripotent stem cells. you don't use totipotent cells in research



Pluripotent cells cannot turn into the blastocyst - but they can turn into everything else.

Is this in the spec? In the book, all it says is "stem cells also occur at the earliest stage of development of an embryo, these are embryonic cells."

Haven't seen anything about the error being an issue. If it was then surely in DNA replication , where a full strand is copied, the chance would be highest and yet that is still valid?

In Kinesis , more turns means organism moves away from unfavourable to favourable env. right? And turns less while they're in the favourable env.?

Orthokinesis: in which the speed of movement of the individual is dependent upon the intensity of the stimulus. Take, for example, the locomotion of a woodlouse in relation to temperature. With increased humidity there is an increase in the percentage time that the woodlouse will remain stationary.

PCR is used before the restriction endonucleases, so PCR amplifies the entirety of the sample. This will probably be fairly small regardless in genetic fingerprinting. When using genetic fingerprinting in paternity tests, you're working on the basis that half the bands will match with the offspring - you're not specifically picking the paternal DNA in the first place.



As long as you remember the key features (e.g. replica plating if the antibiotic is going to kill the bacteria that have incorporated the plasmid), you should be fine. Can't help you with the number of marks per question thing though; we don't really have enough to go on yet.

Well Kinesis is just a non-directional response that changes the rate of turning and speed. It doesn't have to work like that...

for example

But in the NT book questions, it says more turns= stays in favourable conditions longer

I don't know. Totipotent stem cells are not embryonic stem cells...

Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of the blastocyst