F215 - Revision thread 13th June 2011

anyone have any practise questions for working out growth in producers or net productivity because im kind of stuck :/ (maybe make some up on the spot :P)

Don't have any questions.. but as far as I know we just need to remember that net primary priductivity is gross primary productivity- respiratory heat loss.

Net primary productivity is the rate at which carbohydrates accumulate in the tissue of plants of plants of an ecosystem.

Whereas, gross primary productivity is teh rate at which plants convert light energy to chemical energy. :smile:

Reply 1141

Waqar Y

11

Original post by science rules! :)

Rhizobium bacteria convert nitrogen in the atmosphere to nitrates (and also ammonium ions) in the soil. Yes, rhizobium bacteria have a mutualistic relationship with the plant. Theyprovide the plant with fixed nitrogen and gain carbon compounds such as glucose in return. :smile:

Rhizobium only coverts nitrogen to ammonium ions. In return the plant provides carbohydrates, and oxygen for respiration BUT the reaction is anaerobic, because of the enzyme nitrogenase.
Oxygen is absorbed by leghaemaglobin :P

Reply 1142

heartskippedabeat

10

Original post by DontPropositionMe

Does anyone use the CGP OCR A2 guide here? How have you found it? x

Yeah, I think it's really good but I wouldn't rely on it solely because the OCR textbook has a lot more information in and they could technically ask you anything from that. But the OCR textbooks huge and there's no way I could learn it all off by heart so I tend to use CGP for memorising the main topics and then keep reading over the OCR book for more information :smile:

Reply 1143

There will be Particles

1

Original post by heartskippedabeat

Yeah, I think it's really good but I wouldn't rely on it solely because the OCR textbook has a lot more information in and they could technically ask you anything from that. But the OCR textbooks huge and there's no way I could learn it all off by heart so I tend to use CGP for memorising the main topics and then keep reading over the OCR book for more information :smile:

I used to think that but tbh I haven't really found anything in the official textbook of importance that isn't contained in the CGP book - I've used both and have covered the majority of both when making notes. I think it's best to read the official book fully and then make notes according to the CGP (also note any key things from the official textbook too) since it's very concise.

Reply 1144

Kaph

Original post by ManPowa

Can anyone distinguish between reliability and accuracy?
Also, Can they ask about validity?

Basically, all the OCR exams so far ive sat for biology this jan/june have a lot of reliability/accuracy questions and i always get them confused and thus wrong. They carry between 2-4 marks and its also 'How science works', so I have a bad feeling they're going to come up on Mondays exam.

Can anyone simple distinguish between them and keep it simple? thanks :biggrin:

Reliability: Getting the same answer over and over/consistent answers
Accuracy: How close the answer is to the actual answer.

eg. High reliability low accuracy is getting the same answer over and over, but it's not very close to the actual answer.

Low reliability high accuracy would be getting very close to the actual answer once or twice out of say 5-6repeats.

Another way of explaining it is firing arrows at a target. Getting the arrows consistently in the same spot, but not hitting the target, is high reliability and low accuracy. Getting them all over the place, but hitting the centre of the target once is accuracy and low reliability.

Reply 1145

heartskippedabeat

10

Original post by There will be Particles

I used to think that but tbh I haven't really found anything in the official textbook of importance that isn't contained in the CGP book - I've used both and have covered the majority of both when making notes. I think it's best to read the official book fully and then make notes according to the CGP (also note any key things from the official textbook too) since it's very concise.

Yeah, good point. I mostly use the CGP book, it's easier to understand and the textbook can be a bit confusing, especially the biotechnology section which they've put in a bit of a weird order I think.

P.S. Who needs UCL, come to Queen Mary! :tongue:

Reply 1146

Mcfilly

Ok so i have done all of the questions possible, I've gone through the specification loads and loads of times and with just three days left I seriously don't know what else I can do!

Anyone got any suggestions? I don't just wanna waste the last three days wondering how else I can revise.. kind of wish the exam was today haha!

Reply 1147

Waqar Y

11

Original post by Mcfilly

Ok so i have done all of the questions possible, I've gone through the specification loads and loads of times and with just three days left I seriously don't know what else I can do!

Anyone got any suggestions? I don't just wanna waste the last three days wondering how else I can revise.. kind of wish the exam was today haha!

Read your notes, highlight then read again.

I'm going to be doing this tommorow :P

Reply 1148

Mcfilly

Original post by Waqar Y

Read your notes, highlight then read again.

I'm going to be doing this tommorow :P

Haha, are you also running out of things to do? This exam is going to be the end of me!!

Reply 1149

aquarius00

can someone please explain the process of replica plating? i dont understand it......im properrrr stressing

Reply 1150

sportycricketer

Original post by aquarius00

can someone please explain the process of replica plating? i dont understand it......im properrrr stressing

Basically the plasmid for Insulin used has antibiotic resistance for two antibiotics: ampicilin and tetracycline. When the Recombinant Plasmid is formed, the restriction site for the Insulin gene is between tetracycline.
So you place the various colonies you have from the Insulin GE in different agar plates with different antibiotics to see which Plasmid has the Insulin gene.
First you place them in the ampicilin agar plate. This allows all the colonies to grow into the ampicilin. Then using a smooth nylon sheet you press against the ampicilin agar. This picks up any colonies which grew there.
Keeping the nylon in the same orientation you place those colonies onto the tetracycline agar. On this agar only certain colonies which have the tetracycline resistance.
These two agars can then be compared with each other and the colonies which are not present on the tetracycline agar but were on the ampicilin agar, you know have the insulin gene.
Finally these bacteria can be cloned and therefore be used

Hope this helps :smile:

Reply 1151

katie93

if anyones struggling with plant hormones, and their uses, watch this
http://www.youtube.com/watch?v=ZbRiKlIYa-k

i recommend youtube for looking up any topics your struggling with, loads of useful videos

Reply 1152

NWA

13

I understand replica plating, but do you think we will have to remember the names of the two antibiotics ?

Reply 1153

sillysal

9

deflected succession anyone? :s-smilie:

Reply 1154

Strythall

i hate the lac operon :frown:

Reply 1155

heartskippedabeat

10

Original post by sillysal

deflected succession anyone? :s-smilie:

Deflected succession is when the plagioclimax (an artificially stopped climax community - human activities have prevented succession) that develops is one that's different to any of the natural seral stages of the ecosystem.

For example, continuously mowing a field will stop woody plants from developing and only the grasses will survive. This means the climax community (which is also a plagioclimax as humans are mowing the field) will be a grassy field, which isn't a normal seral stage that would occur in the ecosystems succession.

Hope that makes sense :smile:

Reply 1156

katie93

Original post by Strythall

i hate the lac operon :frown:

http://www.youtube.com/watch?v=ea35iuUT5C8&feature=fvwrel
have a watch of that

Reply 1157

aquarius00

Original post by sportycricketer

Basically the plasmid for Insulin used has antibiotic resistance for two antibiotics: ampicilin and tetracycline. When the Recombinant Plasmid is formed, the restriction site for the Insulin gene is between tetracycline.
So you place the various colonies you have from the Insulin GE in different agar plates with different antibiotics to see which Plasmid has the Insulin gene.
First you place them in the ampicilin agar plate. This allows all the colonies to grow into the ampicilin. Then using a smooth nylon sheet you press against the ampicilin agar. This picks up any colonies which grew there.
Keeping the nylon in the same orientation you place those colonies onto the tetracycline agar. On this agar only certain colonies which have the tetracycline resistance.
These two agars can then be compared with each other and the colonies which are not present on the tetracycline agar but were on the ampicilin agar, you know have the insulin gene.
Finally these bacteria can be cloned and therefore be used

Hope this helps :smile:

Thankyouuuu sooo much!! thats great help

Reply 1158

SharkTooth194

oh, i'm really worried about this exam >.< but I'm thinking it might be a nice-ish paper, which is good. I did the january exam (my college do F215 before F214 for some reason) and only just scraped a B :frown:

damn needing an A :'( been revising and doing all past paper questions under the sun, but some bits of it just don't make sense to me :'(

Reply 1159

katie93

Original post by SharkTooth194

oh, i'm really worried about this exam >.< but I'm thinking it might be a nice-ish paper, which is good. I did the january exam (my college do F215 before F214 for some reason) and only just scraped a B :frown:

damn needing an A :'( been revising and doing all past paper questions under the sun, but some bits of it just don't make sense to me :'(

for bits that don't make sense, look them up on youtube. theres videos about pretty much everything, really does help!

F215 - Revision thread 13th June 2011

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