OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

right guys just need ur opinion on a few of my answers and how many marks you think i would lose, if its not too much trouble ofcourse:

For the why is the milk pasturied i said to remove harmful bacteria and to break the bonds between the milk?

The 8 marker on the genetic engineering I didnt mention reverse transcriptase instead said gene is located using a gene probe and then cut out using restriction enzymes and a small amount of the gene can be amplified into many copys using PCR and then mentioned the bacteria taking it up and replica plating. How many would I lose?

The question on why cant it be heterozygote or w.e I just put that two X chromosomes arent present due to it being a male or something?

Then the next question on the interaction i specified dominant epistasis (wrong isnt it?) and said that A was epistatic to the other alleles which were hypostatic and needed A to be expressed.

The question on the squirrel i totally didnt realise it was carrying capacity and stuff i just mentioned that food,water,space are all factors taht can affect it and over time the resources were used up so the amount would decrease and not stay large indefinitely. Any idea of how many marks?

The question on the way polypeptides are synthesised and coded for the 8 marker, i mentoned transcription and translation in alot of detail then said the sequence of amino acids determined the primary structure which leads to the tertiary structue which allows specifc functioning and they are the starter molecules for many structures such as proteins and muscles.

Then the question on how is the DRD4 thing passed on, i just said genetic drift and then defined it then i said these indiviuals would be more keen to explore allowing them to surivve finding food and suitable habitat reproducing and pasing on their alleles creating the current population.

I really appreciate you guys taking ur time i know it seems extremely obsessive and stupid but im just so nervous that i wont meet my offer for medicine and its stopping me revising chemistry. Thanks alot anyways you guys! <3

responses seem pretty good!

even if ur just trying to make me feel better, thanks means alot

when examiners set boundaries, how do they do them.

like how do they know if it is a tough paper or not, as they made the paper themselves

I feel pathetic putting on "e" on the end but otherwise it would be "low" which wouldn't make sense

But that IS correct!!!! lol

FOCUS on chemistry. what did you get in you're other modules for AS and ISAs. they will help you with UMS points

right guys just need ur opinion on a few of my answers and how many marks you think i would lose, if its not too much trouble ofcourse:

For the why is the milk pasturied i said to remove harmful bacteria and to break the bonds between the milk?

The 8 marker on the genetic engineering I didnt mention reverse transcriptase instead said gene is located using a gene probe and then cut out using restriction enzymes and a small amount of the gene can be amplified into many copys using PCR and then mentioned the bacteria taking it up and replica plating. How many would I lose?

The question on why cant it be heterozygote or w.e I just put that two X chromosomes arent present due to it being a male or something?

Then the next question on the interaction i specified dominant epistasis (wrong isnt it?) and said that A was epistatic to the other alleles which were hypostatic and needed A to be expressed.

The question on the squirrel i totally didnt realise it was carrying capacity and stuff i just mentioned that food,water,space are all factors taht can affect it and over time the resources were used up so the amount would decrease and not stay large indefinitely. Any idea of how many marks?

The question on the way polypeptides are synthesised and coded for the 8 marker, i mentoned transcription and translation in alot of detail then said the sequence of amino acids determined the primary structure which leads to the tertiary structue which allows specifc functioning and they are the starter molecules for many structures such as proteins and muscles.

Then the question on how is the DRD4 thing passed on, i just said genetic drift and then defined it then i said these indiviuals would be more keen to explore allowing them to surivve finding food and suitable habitat reproducing and pasing on their alleles creating the current population.

I really appreciate you guys taking ur time i know it seems extremely obsessive and stupid but im just so nervous that i wont meet my offer for medicine and its stopping me revising chemistry. Thanks alot anyways you guys! <3

Can I just clarify something?-

On that silly mutation question where it asked which type of mutation would cause the biggest effect or whatever

When it referred to 13 and 21 base pairs. Did it mean 13 and 21 PAIRS were deleted, or did it mean that the 13th and 21st pair was deleted? Because I dont think it was very clear? I think it said '13 base pair deletion'

Also check this out:

"A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms....... This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution."

"Often, model organisms are chosen on the basis that they are amenable to experimental manipulation. This usually will include characteristics such as short life-cycle, techniques for genetic manipulation (inbred strains, stem cell lines, and methods of transformation) and non-specialist living requirements. Sometimes, the genome arrangement facilitates the sequencing of the model organism's genome, for example, by being very compact or having a low proportion of junk DNA (e.g. yeast, Arabidopsis, or pufferfish). When researchers look for an organism to use in their studies, they look for several traits. Among these are size, generation time, accessibility, manipulation, genetics, conservation of mechanisms, and potential economic benefit."

Guess those are the "correct" answers to those 2 suggest questions - I doubt those will be exhaustive of the mark scheme because anything that is reasonable / logical will probably gain credit since it is a suggest question...

No problem bud a long post to decode,re-interpret and come up with a reasonable answer/s.

Yes.I said exact the same and as for the second mark I mentioned heating provides optimum condition for the enzymes to work.

Hmm.... I would give it 4? maybe five. Did you mention about what is being probed here : DNA OR RNA ? going by your post it doesn't mention it clearly though PCR is DNA exclusive (according to the book I read) also did you mention sticky ends?They alone should score you a mark.


It carried two marks so I mentioned that as we know that each human typically (not always) has two sets of chromosome hence each chromosome has "one" allele and during fertilization when the zygote is formed by fusing of sperm with the ovary.Edit: Oh I misread your question here is what I wrote:I think it was to do with alleles? where I said it shares antagonist relationship and all...


Yes its epistasis.

I think it carried 3 marks where we had to look at the figures and speak of prey + predator relationship. The question asked for Suggest so.. I spoke about no. of predator increases , Limiting factors such as food and their own reproductive capacity and above all destruction of their habitat.
Not too sure but thats close enough to what I wrote.