F215 - Revision thread 13th June 2011

Reply 1280

Nirgilis

14

Right guys! You've all been working hard all day, so turn to channel 4 for some laughs :smile:

Reply 1281

Rosi M

11

Original post by heartskippedabeat

I would say it's more likely to come up than the stuff that came up in june 10/jan 11, but i'm not sure. It's quite useful because it's just like another past paper :tongue:

Hello again :smile:

Can you please explain how to work out the expected numbers from a set of data for chi squared?

This is what ive got:

Grey body/normal wing: 83 (observed)
Black body/ normal wing: 85 (observed)
Grey body/ bent wing: 78 (observed)
Black body/ bent wing: 74 (observed)

Total = 320

Reply 1282

rebeccalouise_92

Original post by ekta9

What do you all know about succession? Just one example of primary succession right? If you used the Heinemann book then did you use sand dunes as that's more detailed?!

i just learn about sand dunes! embroyonic dunes or something :s-smilie:

then marram grass in yellow dunes blahblah....climax community, woodland

Reply 1283

Rosi M

11

Original post by intellectual1

Yes it is...but remember the grade boundaries are very low 45 - 65 differentiates the E from the A...ou tof 100 marks...so as long as you know 70% of the specification you should be fine :smile:

That is really really crazy.. the difference between an E and A! Not that im complaining :tongue:

Reply 1284

emma237

11

Original post by Rosi M

Hello again :smile:

Can you please explain how to work out the expected numbers from a set of data for chi squared?

This is what ive got:

Grey body/normal wing: 83 (observed)
Black body/ normal wing: 85 (observed)
Grey body/ bent wing: 78 (observed)
Black body/ bent wing: 74 (observed)

Total = 320

Isnt it just 320/4? so expected numbers would be 80 for each

Reply 1285

intellectual1

3

January 2011

F215/01 Control, Genomes and Environment (A2)
Raw 100 60 54 48 42 37 0
UMS 150 120 105 90 75 60

June 2010

F215/01 Control, Genomes and Environment (A2)
Raw 100 65 59 53 47 42 0
UMS 150 120 105 90 75 60 0

January 2011 - A was 60 out of 100...but B wwas 54 marks, and the C 48 marks...whilst the D was 42 marks and the E grade was 37 marks....seems like 5 or 6 RAW marks between each grade...

June 2010 - 65 marks for the A, but 59 marks for the B only 6 marks separated the A and the B!?! With the same 6 marks between the other grades as well...

(edited 12 years ago)

Reply 1286

R.Fanatic

You guys, i've gone over the past papers and im really confident these topics are going to come up on monday:
1. Apoptosis
2. Meiosis
3. Lac operon
4. Chi-squared x^2
5. Immobilised enzymes
6. Gene Therapy
7. Genetic engineering - Golden rice
8. Succession
9. Conservation
10. Galapagos and humans
11. The brain
12. Sliding filament model
13. Innate behaviour
14. Learned behaviour

I bet you any money they're going to come up... especially gene therapy

Reply 1287

Rosi M

11

Original post by emma237

Isnt it just 320/4? so expected numbers would be 80 for each

Ok thanks

Does this apply with all of them? Because in the book, its a 9:3:3:1 ratio thing and they have turn 9/16 x 288 (total)??

Reply 1288

rebeccalouise_92

Original post by R.Fanatic

You guys, i've gone over the past papers and im really confident these topics are going to come up on monday:
1. Apoptosis
2. Meiosis
3. Lac operon
4. Chi-squared x^2
5. Immobilised enzymes
6. Gene Therapy
7. Genetic engineering - Golden rice
8. Succession
9. Conservation
10. Galapagos and humans
11. The brain
12. Sliding filament model
13. Innate behaviour
14. Learned behaviour

I bet you any money they're going to come up... especially gene therapy

thanks, what are galapagos........\:

Reply 1289

emma237

11

Original post by Rosi M

Ok thanks

Does this apply with all of them? Because in the book, its a 9:3:3:1 ratio thing and they have turn 9/16 x 288 (total)??

It depends on the expected ratio, if they expected 2:1:1 the expected numbers would be 160 80 80

Reply 1290

Rosi M

11

Original post by R.Fanatic

You guys, i've gone over the past papers and im really confident these topics are going to come up on monday:
1. Apoptosis
2. Meiosis
3. Lac operon
4. Chi-squared x^2
5. Immobilised enzymes
6. Gene Therapy
7. Genetic engineering - Golden rice
8. Succession
9. Conservation
10. Galapagos and humans
11. The brain
12. Sliding filament model
13. Innate behaviour
14. Learned behaviour

I bet you any money they're going to come up... especially gene therapy

Wouldn't mind them topics but im worried about how tight mark schemes are and for stuff like gene therapy which hasnt come up, dont know how to word answers!

Reply 1291

R.Fanatic

Original post by rebeccalouise_92

thanks, what are galapagos........\:

stuff about how humans have affected species on the Galapagos islands and all that..

Reply 1292

heartskippedabeat

10

Original post by Rosi M

Hello again :smile:

Can you please explain how to work out the expected numbers from a set of data for chi squared?

This is what ive got:

Grey body/normal wing: 83 (observed)
Black body/ normal wing: 85 (observed)
Grey body/ bent wing: 78 (observed)
Black body/ bent wing: 74 (observed)

Total = 320

Hello

I'm not too good on chi squared but I think you do you it like this :redface:

Because it's a dihybrid cross (I think :tongue:

) you'd expect the ratio to be 9:3:3:1 like this- 9 both dominant genes : 3 dominant first gene recessive second gene : 3 recessive first dominant second : 1 both recessive

I don't know which out of grey/black is dominant but if we say grey is, and normal wings are:
So to work out the expected value of having both grey and normal wings you take 320 (total) divided by 16 (ratio total - 9+3+3+1) times by 9 (predicted ratio for grey and normal - both dominant)
This gives 180

Black/normal: 320/16 x 3 = 60
Grey/bent: 320/16 x 3 = 60
Black/bent: 320/16 x 1 = 20

To check, 180 + 60 + 60 + 20 = 320 (total)

Is that all you needed help with?
Someone else may be able to explain better, especially as i'm confused that the expected results are that different from the observed :s-smilie:

Reply 1293

emma237

11

Original post by R.Fanatic

You guys, i've gone over the past papers and im really confident these topics are going to come up on monday:
1. Apoptosis
2. Meiosis
3. Lac operon
4. Chi-squared x^2
5. Immobilised enzymes
6. Gene Therapy
7. Genetic engineering - Golden rice
8. Succession
9. Conservation
10. Galapagos and humans
11. The brain
12. Sliding filament model
13. Innate behaviour
14. Learned behaviour

I bet you any money they're going to come up... especially gene therapy

I would add cloning to that list, absolutely nothing from module 2 5.2.1 has come up whereas bits have come up from all of the other modules

Reply 1294

R.Fanatic

Original post by emma237

I would add cloning to that list, absolutely nothing from module 2 5.2.1 has come up whereas bits have come up from all of the other modules

yeah, you're right. Cloning too.

Reply 1295

mazam

1

Original post by jak67m

COmplementary epistasis?? someone please explain this tooo meee ... kinda confused PLEASEPLASE PLEASEAPLEAPLSEPLAPSELELE :smile:

thanks

ANYONEEEEEEEEEEEEEEE!!!!!!!!!!!??????

You have to remember the ratio is 9:7 i think
Thats all i can remember off the top of my head lol

Reply 1296

rebeccalouise_92

Original post by R.Fanatic

stuff about how humans have affected species on the Galapagos islands and all that..

thanks hunni xoxo

Reply 1297

ekta9

Original post by rebeccalouise_92

i just learn about sand dunes! embroyonic dunes or something :s-smilie:

then marram grass in yellow dunes blahblah....climax community, woodland

ahh okay thanks! I've sort of memorised how succession occurs at sand dunes :smile:

Reply 1298

sportycricketer

Original post by R.Fanatic

You guys, i've gone over the past papers and im really confident these topics are going to come up on monday:
1. Apoptosis
2. Meiosis
3. Lac operon
4. Chi-squared x^2
5. Immobilised enzymes
6. Gene Therapy
7. Genetic engineering - Golden rice
8. Succession
9. Conservation
10. Galapagos and humans
11. The brain
12. Sliding filament model
13. Innate behaviour
14. Learned behaviour
15. Cloning

I bet you any money they're going to come up... especially gene therapy