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

ibysaiyan
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#561
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(Original post by ViolinGirl)
haha. I always deny that I like physics, but somehow deep down inside I think I do like it :P

But I admit, it takes a lot of my time to go through it all

And Bio is more important to me seeing as I want to be a vet XD
LOL as i type i am doing work on faradays law + induction *yawns*.... which board you with? is it the OCR? unfortunately i am with WJEC :.( booo.Yep we have this stats table at our bio lab. where it says the most difficult of all A-levels is physics next to it comes bio.I find neither hard but chemistry :/.This is why i love physics:


=) meh anyway how is your revision going? i err don't feel in the mood to do bio. today i might spend rest of the night doing physics.

Oh also congrats on your offer. ^.^
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ViolinGirl
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(Original post by ibysaiyan)
My todays plan is to go over bio-tech stuff: such as batch culture/quorn synthesis/penicillin.. (boring i know) + a re-read of genome sequencing + err if i am able to squeeze in population stuff.
Btw feel free to question me on: Variation/meiosis/genome sequencing/evolution and on.Least this way we could clear each others doubts out.
Genome sequencing <3

Restriction enzymes...cut cut cut...yay!
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ViolinGirl
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(Original post by ibysaiyan)
LOL as i type i am doing work on faradays law + induction *yawns*.... which board you with? is it the OCR? unfortunately i am with WJEC :.( booo.Yep we have this stats table at our bio lab. where it says the most difficult of all A-levels is physics next to it comes bio.I find neither hard but chemistry :/.This is why i love physics:


=) meh anyway how is your revision going? i err don't feel in the mood to do bio. today i might spend rest of the night doing physics.

Oh also congrats on your offer. ^.^
Not on faradays law yet...well in my revision anyway. I got up to electromagnetic induction today. I do OCR. Aiming for A*

I love chemistry. I find it much easier than both bio and physics. I don't have to do much for it at all. I just seem to understand everything in an instant.

We could do bio together. Talking about topics is good.

And thanks!
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ibysaiyan
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(Original post by ViolinGirl)
I felt like talking about discontinous/continuous variation...

Discontinuous variation describes the qualitative differences between phenotypes. These are in clear distinguishable catergories, with no intermidate sub categories. Examples include:
-->Height in pea plants (either tall or dwarf)
-->Sex
-->Blood group

These tend to be controlled by one gene (monogenic), but if they are controlled by 2 or more genes then they interact in an epistatic way, so one gene will mask or influence the expression of another gene. This limit phenotypic variation.
Different gene loci have differenct effects on the phenotype
Different alleles at a single gene locus have large effects on the phenotype.

Continous variation describes the qualitative differences between phenotypes, the phenotypic differences have a large variety of variation. There are no distinct catergories.
-->height in humans
--->Mass in humans
----> Milk yeild in cattle.

These traits are controlled by more than one gene (polygenic)
Different alleles contribute additive amounts to phenotype.
Different alleles at each gene locus have small effects on the phenotype.

These characteristics are more affeted by the environment that discontinous ones.
Ah brilliant! also since we had variation in f212 it reminded me of continuous variation lying between two extremes with most of the population lying between the mean values.
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ibysaiyan
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(Original post by ViolinGirl)
Not on faradays law yet...well in my revision anyway. I got up to electromagnetic induction today. I do OCR. Aiming for A*

I love chemistry. I find it much easier than both bio and physics. I don't have to do much for it at all. I just seem to understand everything in an instant.

We could do bio together. Talking about topics is good.

And thanks!
Yea sure.
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ViolinGirl
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(Original post by ibysaiyan)
Ah brilliant! also since we had variation in f212 it reminded me of continuous variation lying between two extremes with most of the population lying between the mean values.
Yes continous variation can be represented on a normal distibution curve. But discontinuous variaton is represented by a bar chart
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student92
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Environmental factors can act as stabilising and evolutionary forces of natural selection

- Stabilising selection - maintains existing adaptations and allele frequencies.
e.g. maintaining allele frequencies of Hbs allele in malarial areas.
- Directional selection - alters allele frequencies
- Evolutionary changes:
New advantageous alleles in a population are selected.
Disadvantageous alleles are removed by stabilising selection.


Genetic drift

- Changes in allele frequencies that occur randomly by chance.
- Causes large changes in small populations.
- Small populations may have allele frequencies which are not representative of the main population from which they came.
- Founder effect - genetic drift in a small, isolated population which alters the allele frequencies further.


Isolating mechanisms

- geographical / ecological barriers - e.g. mountains, sea etc - prevent individuals from mating.
- seasonal (temporal) barriers - e.g. climate change throughout the year.
- reproductive mechanisms - e.g. individuals may not be able to mate due to genital problems, breeding times, courtship rituals.
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ViolinGirl
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What causes genetic drift? If anyone cares to answer...
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student92
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(Original post by ViolinGirl)
Yes continous variation can be represented on a normal distibution curve. But discontinuous variaton is represented by a bar chart
continuous can also be represented in a frequency histogram
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ViolinGirl
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*yawn* I think I will be off now...feel tired...Night guys!
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ibysaiyan
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(Original post by ViolinGirl)
Yes continous variation can be represented on a normal distibution curve. But discontinuous variaton is represented by a bar chart
Yep the way i memorize is using the words, say for example: continuous i imagine it to be a long continuous graph. LOL
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student92
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(Original post by ViolinGirl)
What causes genetic drift? If anyone cares to answer...
spontaneous mutations, separation of a smaller group from a larger population.
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ibysaiyan
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(Original post by ViolinGirl)
What causes genetic drift? If anyone cares to answer...
Genetic drift is the change in the allele frequency which occurs only within isolated,small population by chance.(Note: Its not same as natural selection since no selection pressure exists).Genetic drift could also lead into diminish of allele variety.
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smflesh
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(Original post by student92)
Environmental factors can act as stabilising and evolutionary forces of natural selection

- Stabilising selection - maintains existing adaptations and allele frequencies.
e.g. maintaining allele frequencies of Hbs allele frequencies in malarial areas.
- Directional selection - alters allele frequencies
- Evolutionary changes:
New advantageous alleles in a population are selected.
Disadvantageous allele are removed by stabilising selection.


Genetic drift

- Changes in a allele frequencies that occur randomly by chance.
- Causes large changes in small populations.
- Small populations may have allele frequencies which are not representative of the main population from which they came.
- Founder effect - genetic drift in a small, isolated population which alters the allele frequencies further.


Isolating mechanisms

- geographical / ecological barriers - e.g. mountains, sea etc - prevent individuals from mating.
- seasonal (temporal) barriers - e.g. climate change throughout the year.
- reproductive mechanisms - e.g. individuals may not be able to mate due to genital problems, breeding times, courtship rituals.
Thank you!
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student92
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(Original post by smflesh)
Thank you!
Your welcome
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student92
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Does anyone know what 'Clade' and 'Monophyletic' mean?
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v1oXx-
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Now that it is nearing the end of the school year for most of us, I'm guessing everyone has done their coursework. What did you all get /40?
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v1oXx-
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(Original post by student92)
Does anyone know what 'Clade' and 'Monophyletic' mean?
A clade is a very similar group of organism based on morphology, embryology, physiology and ecological niche. Normally used to classify bacteria which reproduce asexually.

Monophyletic is like a evolutionary tree descending from one ancestor.

That's off the top of my head though...
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xXxBaby-BooxXx
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(Original post by v1oXx-)
Now that it is nearing the end of the school year for most of us, I'm guessing everyone has done their coursework. What did you all get /40?
My teachers won't tell us our coursework score. ESPECIALLY after the huge fuss about the scoring last year. It's so we won't get "disappointed" if it changes when they're all moderated.
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v1oXx-
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(Original post by xXxBaby-BooxXx)
My teachers won't tell us our coursework score. ESPECIALLY after the huge fuss about the scoring last year. It's so we won't get "disappointed" if it changes when they're all moderated.
Argh that's a pain in the ass. This year, it was a lot harder than last year IMO. The evaluation tasks were really hard.
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