A2 Biology OCR June 2015 Revision Thread

Does anyone have the mark scheme for the June 2014 f215?

I know the paper is up on the bio tutor but can't find the MS anywhere!

Reply 3161

TeeLisa55

6

Read the specification for what needs to be known for homeobox genes, but I'm still not sure of what sort of questions, apart from the definition which could be asked.

Could they ask a question about outlining homeobox sequences as a 4/5 marker?

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Reply 3162

mic_3_3

1

Has anyone got any predictions for f215, I don't know what topics to prioritise :frown:

can someone help me out

Reply 3163

Beni24

2

Can someone outline the whole genome sequencing please? :smile:

Reply 3164

jessicadanby1996

5

I think cellular control will have a big question this year but of course that is just a guess

Reply 3165

alexthehuman

2

The specification just says to be able to explain the term crossing over but the text book has a big section explaining how it happens? Do i need to learn that part or just be able to define it?
Sometimes i think they dont even know what they want us to learn -_-

Reply 3166

jessicadanby1996

5

Original post by alexthehuman

The specification just says to be able to explain the term crossing over but the text book has a big section explaining how it happens? Do i need to learn that part or just be able to define it?
Sometimes i think they dont even know what they want us to learn -_-

I think the book is terrible for the section of genetic crosses,epistasis etc. Try to find some other resources for a good understanding, like the notes on biotutor

Reply 3167

jesss7

1

I've got 47 out of 50 in my isa, what grades would I need for a B?

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Reply 3168

zXx AJL xXz

2

Anyone have the unit 1 f214 june 2015 paper? or unofficially mark scheme? could you send the link if you do thanks

(edited 8 years ago)

Reply 3169

alexthehuman

2

Original post by jessicadanby1996

I think the book is terrible for the section of genetic crosses,epistasis etc. Try to find some other resources for a good understanding, like the notes on biotutor

It seems to have so much irrelevant information thats not on the spec? Most of the past paper questions ive seen are pretty straightforward but the book is so much more complicated.
Like for epistasis the spec doesnt say anything about recessive and dominant epistasis but theres a whole section on the book explaining it. Maybe they just want us to have a better understanding but when you only have a week to revise you really need to prioritize 😂😂
Ill check out biotutor and see if its any help

Reply 3170

loperdoper

15

Original post by TeeLisa55

Read the specification for what needs to be known for homeobox genes, but I'm still not sure of what sort of questions, apart from the definition which could be asked.

Could they ask a question about outlining homeobox sequences as a 4/5 marker?

Posted from TSR Mobile

I've only done about four past papers so far, but I've only ever seen homeobox sequences be a two mark question about why they're similar across species, and then a short question about what they are. There aren't all that many things they could ask you about it, there's not much to compare/contrast it with, it's got no synoptic opportunity, and it's pretty hard to twist into an application question, so I doubt they'd spend focus too many marks on it.

Reply 3171

GH1996

2

Original post by Alanine

Does anyone have the mark scheme for the June 2014 f215?

I know the paper is up on the bio tutor but can't find the MS anywhere!

I have it, I'll try and find a way to post it on here tomorrow

Reply 3172

loperdoper

15

Original post by Alanine

Does anyone have the mark scheme for the June 2014 f215?

I know the paper is up on the bio tutor but can't find the MS anywhere!

Here!

f215_june_2014_ms.pdf424.0KB

Reply 3173

Wateriscool1

1

Original post by Beni24

Can someone outline the whole genome sequencing please? :smile:

Shear the genome into fragments using restriction enzymes
Insert each fragment into Bacterial Artifical Chromosomes
Insert the BACs into E.coli bacteria
Culture the bacteria. Each colony will have a different fragment to make a clonal library
Take a colony and use restriction enzymes to cut the DNA into even smaller fragments of different sizes using different enzymes
Use electrophoresis to order by size
Use an automated method to sequence each fragment as follows:
Mix the DNA fragment with primers, free DNA nucleotides (some modified with fluorescent marker) and DNA polymerase
95 degrees - break hydrogen bonds so single stranded
55 degrees add primers so annealed at template strand
72 degrees - Optimum temp forDNA polymerase which will add nucleotides
the enzyme will be thrown off if modified nucleotide added
Modified nucleotide added at different points to get different chain lengths
Run through laser to read colours
Use computer to compare overlapping fragments to sequence the whole BAC
VOILA

(edited 8 years ago)

Reply 3174

brooklyniona

can someone explain succession to me please? like as if it was a 6 mark question??

Reply 3175

loperdoper

15

Original post by brooklyniona

can someone explain succession to me please? like as if it was a 6 mark question??

The book uses a sand dune example, although I prefer the Surtsey Island/bare rock example. You need to know an example for the exam, although the spec doesn't specify which one.

Okay, so the enviroment is bare rock. Lichen begin to grow on the rock, as they can survive the salt spray from the ocean. This is the pioneer species, the first to grow.
Lichen begin to die and a thin soil forms, allowing for small ferns to grow in the soil.
The soil deepens, allowing small plants that have roots and require more water to take hold.
The soil further deepens, until shrubs start to grow. These outcompete the smaller plants and initially become the dominant species.
Finally, the soil thickens until large plants and trees are able to root and grow. These are the dominant species, and the community is unlikely to change much from this state. Therefore, it is known as the climax community.

Reply 3176

Missy1x

2

Original post by Luciellaa

Really odd question- hopefully someone can help me out and put my mind at rest tho. In the question about grana i spelt photosystem as photostem instead. I have no clue why i did this but will they give me benefit of the doubt and give me the mark? I used it in the correct context.

But did you describe what the photo system consists of like what it is then yeah you would

Reply 3177

araura

Is there an unofficial mark scheme for biology f214 OCR june 2015?

Reply 3178

Student23478

2

Original post by loperdoper

I've only done about four past papers so far, but I've only ever seen homeobox sequences be a two mark question about why they're similar across species, and then a short question about what they are. There aren't all that many things they could ask you about it, there's not much to compare/contrast it with, it's got no synoptic opportunity, and it's pretty hard to twist into an application question, so I doubt they'd spend focus too many marks on it.