Ocr f215: 27/1/11

Scroll to see replies

Nope been living here for almost 3 years now.On second thoughts I will just try to make max. out of this paper.

cool ok, well ye thats the only attitude to go in with

sorry just noticed earlier edit, im doing OCR MEI for maths, ive got c3, s1 and c1 inshallah
and 5am! no idea how you can manage that ona regular basis

(edited 13 years ago)

Reply 21

ibysaiyan

Original post by clad in armour

lol :s not daily but as exams are getting closer :redface:

Reply 22

duibb

Original post by ibysaiyan

Nope been living here for almost 3 years now.On second thoughts I will just try to make max. out of this paper.

Are you an arab, I have links to arab ancestors about 1400 years ago but am Somali.
I have went to many arab countries such as Saudi,Egypt and Syria and spoke to many arabs in my travels. I would like to ask why you chose to come to the U.K and not to the U.S as It seems to have better links with the Saudi government e.g. King Fahd medical centre.

Reply 23

ibysaiyan

WTH is no body doing it this WINTER!?

Reply 24

aimz08

(e)use genetic diagrams to solve problems involving sex linkage and codominance;
(f)describe the interactions between loci (epistasis). (Production of genetic diagrams is not required);
(g)predict phenotypic ratios in problems involving epistasis;

Any help on the above would be greatly appreciated. I am so not gonna do well again :s-smilie:

Reply 25

ibysaiyan

Original post by aimz08

For bit E: All you need to know is how to cross either homozygotic or heterzygotic geneotypes.A punnet square or any other variation could be used.I prefer punnet square.Also make sure you assort "alleles" randomly.make sure you are aware of sex linkage,autosomal linkage,and codominance in detail.That should suffice for the points noted in the spec.

F and G:

Epistasis is a type of gene interaction.In this interaction quite often more than one gene happens to share same metabolic pathway.In other words: A gene interaction in which a characteristic's expression is controlled by two or more genes.
We end up with Hypostatic and epistatic genes:
Epistatic gene is the one which suppresses other gene's phenotype while hypostatic is a gene which has it's phenotype suppressed by an epistatic gene.
Epistatic reduces the no. of phenotype unlike your classic 9 : 3: 3 : 1 ratio.
A dominant epistasis gives a ratio of: 12 : 3: 1 while a recessive epistasis 9 : 4: 3

Take mice coat colour as an example:
Gene A basically codes for the distribution of melanin while gene C codes for the making of melanin.We know that black coat is recessive "aa" while agouti color is AA or Aa.A genotype CC or CC codes for the melanin while a recessice homozygote would result in no melanin being produced at all (albino) hence Gene A doesn't make any cameo appearance.So we get epistatic gene being:C and hypostatic:A
It has been five days since I did f215 :/
Grr

Reply 26

aimz08

Original post by ibysaiyan

Thank you for your help :smile:

What do you mean when you say assort alleles randomly?

Epistasis makes a lot more sense now. I understand epistatic and hypostatic but not sure I fully understand the example.

Could you just explain a little what you meant by this part?

A genotype CC or CC codes for the melanin while a recessice homozygote would result in no melanin being produced at all (albino) hence Gene A doesn't make any cameo appearance.So we get epistatic gene being:C and hypostatic:A.

Reply 27

ibysaiyan

Original post by aimz08

Thank you for your help :smile:

Oh a typo there.The two genetopyes are: CC or Cc .What I mean by cameo appearance is that Gene A can't express itself "(both)it's dominant or recessive versions) because to vary melanin concentration you need melanin to begin with.
=] Any clear? oh as for "assort alleles randomly" bit all that means is: say for example a male dragonfly has genotype: X^AX^a
then his gametes are:
(X^A ) (X^a)

Reply 28

aimz08

Original post by ibysaiyan

Yup get it now :smile:

I'll have to try the exam questions to see if I actually get it though :P

I have a question bank for module 1,2 and 3 if anyone wants them. I think I got them from someone on TSR anyway :P so credit to them

Reply 29

ibysaiyan

Original post by aimz08

Yup get it now :smile:

I finished all exam questions on genetics.Not sure about the other modules.Can I have it please. :tongue:

Reply 30

aimz08

Original post by ibysaiyan

I finished all exam questions on genetics.Not sure about the other modules.Can I have it please. :tongue:

Can you pm me your email add?
Can't attach the docs they are too large

Reply 31

ibysaiyan

Just finished variation and stuff....

Reply 32

clad in armour

Original post by ibysaiyan

Just finished variation and stuff....

well done

Ive still got the whole of biotech, all that plant hormones stuff

Reply 33

ibysaiyan

Original post by clad in armour

well done

Ive still got the whole of biotech, all that plant hormones stuff

Cool.Yea been about a week since I last did any bio. revision So I am going through variation stuff again =]
I find bio,other stuff easy but animal psychology :s
I think in about a weeks time I should be done with the whole module,you ?

Reply 34

ibysaiyan

Come on people.Only 20 days left...

Reply 35

aimz08

Original post by ibysaiyan

Come on people.Only 20 days left...

Eek. 16 days :O

How much detail have you learnt for these two points from variation?

explain the significance of the various concepts of the species, with reference to the biological species concept and the phylogenetic (cladistic/evolutionary) species concept (HSW1);

describe how artificial selection has been used to produce the modern dairy cow and to produce bread wheat (Triticum aestivum) (HSW6a, 6b).

Reply 36

ibysaiyan

Original post by aimz08

Ouch not much time left damn.So far I have just completed variation/and stuff related to genetics. Gr...

Alrighty lemme recall... hmm
Biological def. of species: A group of individual organisms that share same morphology,physiology,anatomy and are able to breed with each other to produce fertile offspring.

In biological species concept two criteria are needed:
1) It applies to sexually produced organisms.
2)Species extinct,produced asexually/fossils don't get categorized.
Hence the disadvantage over this concept is that it limits the no. of species(less diversity)/ignores organisms produced asexually.

Evolutionary (phylogenetic) concept deals with how close do two organisms are to each other i.e how back do they share common ancestry.If there are signs of having common linkage then these are classified as other species without even knowing whether there is a reproductive isolation btw. the two species or not.

for example: A duck living in region X and other one living in region Y,have different colour ,nothing is known about their isolation = classified separately.

The advantage of this method is that it widens the no. of species and includes what the above concept excluded.The only dis-advantage is that it's not reliable since any person/organisation could come up wit their own no. of species based on their said assumptions.

The book which I have by Mary jones includes only A.I of cow :frown:

(

Artificial Insemination:
A.I is done to increase the rate of offspring's compared to the wild population.
A chosen bull's semen is collected.In the wild this would only impregnate a cow but in A.I a large no. of cows are impregnated with the semen.

The bull goes through progeny testing.To check whether it has the suitable traits or not.If it's female offspring's show the desired traits,farmers use it's sample for the breeding programme.All this takes time hence why semen is stored/frozen for a longer period (2 years approx).In during which the calf matures and so forth.

Embryo transplantation:
A chosen cow with the desired trait is a. inseminated with semen.She's fed with different hormones for her to super ovulate.At the oviducts embryo (fertilizes).In the uterus it's washed out of the cow/ Now it could either be further divided into two embryo + or transfered into surrogate mother/s.
The surrogate mother needs to be fed with same hormones for her uterus to carry.
Surrogate mother is of low value compared to the parent cow.

Reply 37

ibysaiyan

I am really starting to get worried. I suppose not many people are sitting this paper now. :/

Reply 38

mathsclown

Original post by ibysaiyan

I am really starting to get worried. I suppose not many people are sitting this paper now. :/

Hi there! I'm retaking it, got a D in the June paper, my own fault I guess the only revision I did was, memorise the OCR revision guide but that doesn't really help in a paper that requires extra knowledge around each topic area! :frown:

This time I say i'm more prepared for it as in for each topic I've done some research on the web for it but not sure if it'll go, as far as biology papers go they are always unpredictable.

Reply 39

ibysaiyan

Original post by mathsclown

This time I say i'm more prepared for it as in for each topic I've done some research on the web for it but not sure if it'll go, as far as biology papers go they are always unpredictable.

Yea same boat.I got a D too but anyways this time My plan is to ace it.Last time I completely skimmed through genetics and left awful lot on animal behavior LOL.
Not happening now.So when are you planning to revise? I have 3 more exams before this one.I have completely finished variation/genetics.I am good with biotech,that shouldn't be a worry.