Edexcel Biology B3 paper 15th May 2012

nervouspupil123

Anyone have any idea of the mark scheme/answers to the questions? particularly the last one?

Reply 1

escarr15

no idea, but thank you for starting a proper thread for this :smile:

Reply 2

nervouspupil123

OP

all we need is whoever made the thread with answers (which got banned as it was too soon after the exam) to give them once again!

Reply 3

sophiekutie

11

Ermm.. What was the last question about?

Reply 4

07sid

the last Q was about the ICP gene

Reply 5

nervouspupil123

OP

There were 2 questions which i want sure about:

1.) "Why do schools of fish move to cooler areas of water?" (1 mark)

The information they gave was that mineral ions raised from the depths in these areas, the other piece of information was that these fish fed on plankton.

2.) The last question was something like:

a.) Explain how agrobacterium tumefaciens can be used to put the ICP gene into a cotton plant. ( it was 4 marks, do you think you could get 3+ if you mentioned everything, but when saying 'the plasmid is cut open' i didn't say by a restriction enzyme?

b.) "Explain how this new plant can be used to develop more ICP cotton plants?" (or something like that)

it was worth 3 marks, and i mentioned ti plasmid, the crown gall, and plant lets and the cultivation of tissue from the crown gall, would i get all 3?

Reply 6

IrfanMMS

Original post by nervouspupil123

There were 2 questions which i want sure about:

1.) "Why do schools of fish move to cooler areas of water?" (1 mark)

The information they gave was that mineral ions raised from the depths in these areas, the other piece of information was that these fish fed on plankton.

2.) The last question was something like:

a.) Explain how agrobacterium tumefaciens can be used to put the ICP gene into a cotton plant. ( it was 4 marks, do you think you could get 3+ if you mentioned everything, but when saying 'the plasmid is cut open' i didn't say by a restriction enzyme?

b.) "Explain how this new plant can be used to develop more ICP cotton plants?" (or something like that)

it was worth 3 marks, and i mentioned ti plasmid, the crown gall, and plant lets and the cultivation of tissue from the crown gall, would i get all 3?

Last question.
Mention Isolation of enzyme from Bacillus Thuringiensis using enzymes (Restriction endonuclease)
Use same enzyme to cut open the plasmid,
Complementary (Sticky ends) Attach using ligase enzyme.
Place plasmid back into backterium.
Use bacterium as a vector and infect plant.

Mention Ti plasmid,
Crown gall formation
Cut cells/tissues out and
culture them into plantlets.

Reply 7

lorobolorolo

7

For this question
1.) "Why do schools of fish move to cooler areas of water?" (1 mark)
My answer was:
The shoals of fish move to the cooler areas, because there are lots of mineral ions so more plankton and other plants are likely to grow there. Therefore there is more food for them there.
I'm not sure if this is the right answer though.

nervouspupil123 i think you would get all three marks if you have included all those things.What was the answer to the question about why humans are not hunter-gatherers anymore?

Reply 8

07sid

what did you put for the swan question?

Reply 9

Jpatch

The last question part b was actually 'how does the addition of Aspergillus and Brine in the second stage of fermentation affect the Lactobacillus?'

My answer was that 1) the aspergillus produces lactic acid from the amino acids created from broken down proteins by the enzymes secreted by Lactobacillus
2) This, along with the addition of brine, stops the lactobacillus secreting enzymes as the lactic acid lowers the pH of the solution to much for the lactobacillus to continue secreting enzymes

Reply 10

nervouspupil123

OP

ok, i think i only got 5/7 in total for the last question then!

for the swan one i think its: so that they know that the male is of the same species so they can produce fertile offspring and successfully pass on their genes, secondly, by the ritual can help a female swan to determine whether the male is suitably strong/healthy/desirable and has good genes to pass on to her offspring.
.
for the hunter gatherer one i put about the domestication of animals meaning they could settle in one place (along with the ability to build larger, more long lasting houses). i also said about farming and how this is the preferred method of getting food nowadays. Finally i said that individuals do not have to hunt/gather as their food is supplied by farms, and the mass production of food now happens due to gm crops/selective breeding etc.

Reply 11

nervouspupil123

OP

and just to confirm i got at least 5/7, this is what i think i put (but shortened)"

a.) .the gene for ICP is isolated and cut out/ a ti plasmid from an agrobacterium cell is also cut out/ the gene is put in the ti plasmid which is then inserted into the cell of a plant without the ice gene/ the agrobacteriums tumour inducing plasmid means that its genes infect the new plant and spread its genes (including the ICP one) throughout the dan of the cell, creating a plant with the ICP gene. (what would i get out of 4 ?)

b.) the ti plasmid in the agrobacterium will form a cancerous tumour (a crown gall) in the plant, and this tumour contains the ICP gene/ the grown gall forms plant lets/ tissue can be cut off of the crown gall and grown/cultivated to produce other plants with the ICP gene. (out of 3)

i know i missed out a lot of key words, but as you only need 4 and 3 correct points, out of a few more, surely at least 5 of my points are valid?

Reply 12

nervouspupil123

OP

Original post by Jpatch

The last question part b was actually 'how does the addition of Aspergillus and Brine in the second stage of fermentation affect the Lactobacillus?'

My answer was that 1) the aspergillus produces lactic acid from the amino acids created from broken down proteins by the enzymes secreted by Lactobacillus
2) This, along with the addition of brine, stops the lactobacillus secreting enzymes as the lactic acid lowers the pH of the solution to much for the lactobacillus to continue secreting enzymes

that wasn't the final question, as the final question was definitely about agrobacterium and the ICP gene. This question was earlier on in the paper, but what you have said sounds similar to what i put

Reply 13

nervouspupil123

OP

Original post by Jpatch

The last question part b was actually 'how does the addition of Aspergillus and Brine in the second stage of fermentation affect the Lactobacillus?'

My answer was that 1) the aspergillus produces lactic acid from the amino acids created from broken down proteins by the enzymes secreted by Lactobacillus
2) This, along with the addition of brine, stops the lactobacillus secreting enzymes as the lactic acid lowers the pH of the solution to much for the lactobacillus to continue secreting enzymes

on second thoughts, I'm not sure this is right, i thought the lactobacillus was added after the aspergillus, i think its the other way round mate

Reply 14

Jpatch

Original post by nervouspupil123

on second thoughts, I'm not sure this is right, i thought the lactobacillus was added after the aspergillus, i think its the other way round mate

soz, yeah your right, my bad; it's the aspergillus that secrets enzymes

Reply 15

Frontierlandwdw

oh no I've messed up the last question completely...

what did you guys put for the question on soy sauce?
it was like what does the Lactobacillus do...

I put that it's converted to lactic acid which clots the milk and it ferments the milk after aspergillus fungus and yeasts... not sure if i'm on the right lines here. my CGP revision guide only really described the steps.... and not why its used.

I would not recommend the CGP books for B3... but to be fair the other units were perfectly fine (well they got me on an A so far in bio and A*s in chem and phys).

Reply 16

Chloee123

Original post by Jpatch

The last question part b was actually 'how does the addition of Aspergillus and Brine in the second stage of fermentation affect the Lactobacillus?'

My answer was that 1) the aspergillus produces lactic acid from the amino acids created from broken down proteins by the enzymes secreted by Lactobacillus
2) This, along with the addition of brine, stops the lactobacillus secreting enzymes as the lactic acid lowers the pH of the solution to much for the lactobacillus to continue secreting enzymes

I don't think that was even the question, I thought it was the addition of lactobacillus and brine?

Reply 17

nervouspupil123

OP

um...there is no milk involved in soy sauce production, you accidentally have quoted the process on yoghurt production :/ the lactobacillus stops the activity of the agrobacterium (stops its secreting enzymes) and brine gives it its salty taste, and then there was something else i said about proteins and carbs being stopped or something but i can't remember.

Reply 18

Chloee123

Original post by Frontierlandwdw

oh no I've messed up the last question completely...

what did you guys put for the question on soy sauce?
it was like what does the Lactobacillus do...

I put that it's converted to lactic acid which clots the milk and it ferments the milk after aspergillus fungus and yeasts... not sure if i'm on the right lines here. my CGP revision guide only really described the steps.... and not why its used.

I would not recommend the CGP books for B3... but to be fair the other units were perfectly fine (well they got me on an A so far in bio and A*s in chem and phys).

It think that's about the yoghurt production (your answer)

Reply 19

Chloee123

Original post by Frontierlandwdw

oh no I've messed up the last question completely...

what did you guys put for the question on soy sauce?
it was like what does the Lactobacillus do...

I put that it's converted to lactic acid which clots the milk and it ferments the milk after aspergillus fungus and yeasts... not sure if i'm on the right lines here. my CGP revision guide only really described the steps.... and not why its used.

I would not recommend the CGP books for B3... but to be fair the other units were perfectly fine (well they got me on an A so far in bio and A*s in chem and phys).

It think that's about the yoghurt production (your answer)

Edexcel Biology B3 paper 15th May 2012

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