AQA A2 Biol4 January 2012 pre- exam discussion

I predict:

How is glucose turned into pyruvate? (5)
Co2/methane greenhouse gas issue and the effects of it (6)
The advantages and disadvantages of either inorganic or organic fertilisers (4)

Would somebody help me with what you would write for the first question?

Reply 1181

Chuck1993

1

Original post by EffKayy

I predict:

How is glucose turned into pyruvate? (5)
Co2/methane greenhouse gas issue and the effects of it (6)
The advantages and disadvantages of either inorganic or organic fertilisers (4)

Nice predictions :biggrin:

How would you answer the second one? I never understood the whole distribution of insects/crop yield thing it talks about in the specification.

Reply 1182

Cryptorchid306

Original post by EffKayy

I predict:

How is glucose turned into pyruvate? (5)
Co2/methane greenhouse gas issue and the effects of it (6)
The advantages and disadvantages of either inorganic or organic fertilisers (4)

First and bottom questions sound easy. What sort of things could you right about the 6 marker? :s-smilie:

I can only think of the fact it stays in the atmosphere for longer and causes temperatures to rise...melting ice caps etc :L

Reply 1183

EffKayy

16

Original post by Shopaholic94

Would somebody help me with what you would write for the first question?

Basically I think the marking points would be:

Glycolysis takes place in the cytoplasm (1)
Glucose is made reactive and is activated by phosphorylation (1)
Two Phosphate groups from 2ATP being hydrolysed phosphorylate it (1)
Split into two molecules of TP (1)
TP is oxidised so hydrogen is removed, reducing NAD(1)
Split into two molecules of pyruvate (1)
Two ATP molecules are generated in the process (1)

7 marking points, but max 5.

Reply 1184

EffKayy

16

Original post by Accalia

Advantages of biological:

•

Specific to the pest organism, so won't affect the wider food chain/web

•

Is self-perpetuating, so only needs one application (in theory, anyway)

•

Genetic resistance cannot be built up by the pest organism

•

You can sell your food as organic, so charge more - I'd avoid this advantage though, sometimes they allow it but most of the time it's ignored.

Disadvantages of biological:

•

May become a pest itself

•

Will not fully eradicate the pest population (predator-prey relationships, one never totally disappears)

•

There is a time-lag as the control population needs to become established, so no immediate impact on pest population

Advantages of chemical:

•

Could fully eliminate the pest population

•

No time delay between application and effect (for the most part, it depends on what chemical you're using)

Disadvantages of chemical:

•

Could leave a chemical residue, so may lead to bioaccumulation of the chemical within local food chains

•

Not specific to the pest organism (bioaccumulation again, if the chemical accumulates in the tissues of the pest and this dead pest is eaten by a non-pest species)

•

It's possible the pest could develop genetic resistance to this chemical

This isn't a definitive list, and obviously if the question has a 'stem' you should apply the relevant points only.

EDIT: And if it's only a six marker you'll only need to provide six points, from the sound of that question, all of them should be focused around the top two lists.

Why the hell is this getting negged?! CRAZY PEOPLE

Reply 1185

Besakt

3

Original post by Shopaholic94

Would somebody help me with what you would write for the first question?

Glucose is phosphorylated to 2 molecules of triose phosphate this is done by using 4 molecules of ATP (so 2xATP turns into 2xADP)
2 molecules of triose phosphate is turned into 2 molecules of pyruvate this oxidation as 2 molecules of hydrogen is given to 2 molecules of NAD to form NADH (or reduced NAD). And 4 molecules of ATP produced.
This all happens in the cytoplasm of the cell.
triose phosphate and pyruvate are both 3 carbon molecules so for each glucose 2 molecules of TP and pyruvate are formed.
There is a net production of 2 ATP because 2 molecules of ATP were used to get from glucose to TP and 4 molecules were produced when TP is oxidised to pyruvate (4-2 = 2ATP).

(edited 12 years ago)

Reply 1186

nimo09

Original post by Rahmeh.

43, 54

Should we count these as A* grades?

Reply 1187

nimo09

Original post by Erotas

50 - June
56 - Jan

Should we count these as A*'s ?

Reply 1188

Besakt

3

Original post by Cryptorchid306

First and bottom questions sound easy. What sort of things could you right about the 6 marker? :s-smilie:

I can only think of the fact it stays in the atmosphere for longer and causes temperatures to rise...melting ice caps etc :L

CO2 increases growth of plants.
CO2 might affect abundance and distribution of plants and animals.
CO2 leads to increase temp, which affect life cycle of some insects and also distribution and abundance of insects across the world.
Methane linked to global warming and were it comes from (Cattle farting).

Reply 1189

EffKayy

16

Original post by Besakt

CO2 increases growth of plants.
CO2 might affect abundance and distribution of plants and animals.
CO2 leads to increase temp, which affect life cycle of some insects and also distribution and abundance of insects across the world.
Methane linked to global warming and were it comes from (Cattle farting).

Sounds like a CGP regurgitation ..
Not enough detail I don't think

Reply 1190

Shopaholic94

Original post by EffKayy

Basically I think the marking points would be:

Glycolysis takes place in the cytoplasm (1)
Glucose is made reactive and is activated by phosphorylation (1)
Two Phosphate groups from 2ATP being hydrolysed phosphorylate it (1)
Split into two molecules of TP (1)
TP is oxidised so hydrogen is removed, reducing NAD(1)
Split into two molecules of pyruvate (1)
Two ATP molecules are generated in the process (1)

7 marking points, but max 5.

Thank you!

Reply 1191

Besakt

3

Original post by EffKayy

Sounds like a CGP regurgitation ..
Not enough detail I don't think

CGP is the bible of academic studies. How dare you insult CGP.
At GCSE all the subjects I used CGP to me help me revise I got A/A*s in.
At AS Level all the modules I used CGP to revised from I got A grades in.

Reply 1192

Rahmeh.

Original post by EffKayy

I predict:

How is glucose turned into pyruvate? (5)
Co2/methane greenhouse gas issue and the effects of it (6)
The advantages and disadvantages of either inorganic or organic fertilisers (4)

Right i don't like that second question at all

what the hell would you say for 6 marks?

Reply 1193

Cryptorchid306

Very VERY much doubt global warming would be a 6 marker, CO2 and deforestation came up at 4 marks one year, 5 at a push. Definitely not 6 - there isnt enough detail in the book is there? :L

Reply 1194

EffKayy

16

Original post by Besakt

CGP is the bible of academic studies. How dare you insult CGP.
At GCSE all the subjects I used CGP to me help me revise I got A/A*s in.
At AS Level all the modules I used CGP to revised from I got A grades in.

For one of the 5markers in the January 2011 paper (biological control), the CGP guide covers around maybe 2-3points MAX.

I agree that the CGP guide is amazing - for chemistry A2 (edexcel) its good, but not as good for biology a2 ..............

Reply 1195

Kandy_Kain_94

16

Original post by Rahmeh.

Right i don't like that second question at all

what the hell would you say for 6 marks?

Same, I hope that doesn't come up at all. I don't know what you could say for 6 marks :s-smilie:

Reply 1196

Rahmeh.

Original post by EffKayy

I predict:

How is glucose turned into pyruvate? (5)
Co2/methane greenhouse gas issue and the effects of it (6)
The advantages and disadvantages of either inorganic or organic fertilisers (4)

Tell me the answers before i start crying :L

Reply 1197

EffKayy

16

Original post by Cryptorchid306

Very VERY much doubt global warming would be a 6 marker, CO2 and deforestation came up at 4 marks one year, 5 at a push. Definitely not 6 - there isnt enough detail in the book is there? :L