Edexcel 6BIO2 ~ 3rd June 2013 ~ AS Biology

For the cellulose question I think it was:
Alpha glucose
1,4 bonds
1,6 bonds
Hydrogen bonds

For 1,4 I ticked both, but for hydrogen bonds I only ticked microfibrils. Do you think thats right? :rolleyes:

Reply 1902

jcao03

7

Original post by billyfisher100

I'm pretty sure two crosses for 1,6 and two ticks for 1,4 as a microfibril is still made of cellulose, so it will have 1,4 bonds. None of them have 1,6 bonds. What were the other boxes?

The other box was something like 'does it have hydrogen bonds'

Reply 1903

jcao03

7

Original post by Ingamo

For the cellulose question I think it was:
Alpha glucose
1,4 bonds
1,6 bonds
Hydrogen bonds

For 1,4 I ticked both, but for hydrogen bonds I only ticked microfibrils. Do you think thats right? :rolleyes:

I think cellulose is made out of B glucose as starch is made out of A glucose! But you did get the 1,4 right I think and I also ticked hydrogen bonds for microfibrils!!

Reply 1904

Original post by jcao03

I think cellulose is made out of B glucose as starch is made out of A glucose! But you did get the 1,4 right I think and I also ticked hydrogen bonds for microfibrils!!

Oh yeah I put crosses in the 1,6 and alpha glucose sections I forgot to say! They were the only ones I was sure about haha! Yaay!

Reply 1905

Marshymallow

5

Original post by Ingamo

For the cellulose question I think it was:
Alpha glucose
1,4 bonds
1,6 bonds
Hydrogen bonds

For 1,4 I ticked both, but for hydrogen bonds I only ticked microfibrils. Do you think thats right? :rolleyes:

I only ticked 1,4 for the cellulose molecule, because there aren't any 1,4 bonds holding any of the molecules together in the microfibril

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Reply 1906

diggy

19

that paper had so many graphs, however i think that makes it easier because with graphs you state whats going on and then you manipulate the data which isnt particularly hard

When it asked what meosis does i wrote something like

It creates genetic variation through crossing over and independant assortment

Reply 1907

Original post by Marshymallow

I only ticked 1,4 for the cellulose molecule, because there aren't any 1,4 bonds holding any of the molecules together in the microfibril

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Ohh, I suppose but you could argue that they are still within the microfibril holding it together? :confused:

Reply 1908

ALevel96

10

For the factors I put the following:

only 1% of their natural habitat is undisturbed; damage to niche/ecosystem

prairie dogs are usually poisoned if ferrets eat them they too will become poisoned

ferrets were reintroduced at similar positions; competition for food

Reply 1909

jcao03

7

Original post by Meehar17

What do you guys think the grade boundaries will be for an A guys? Tbh it wasn't too difficult but some question were a little weird though

Edexcel can be so annoying in the way their grade boundaries fluctuate! I know that many found it an alright paper so I reckon it's gonna be high. I think I've seen it 64 marks high for an A in previous past papers. That's really high but they can't go any higher than that! Well they can but I don't think they're that horrible. I'm hoping a 60 but there's a chance that 64 is what they'll do. I remember in Jan when everyone found the paper alright and I thought I got sufficient marks to get me an A which was 54+ but I got a 57 and it was a C and A was 63 :frown:

Reply 1910

Marshymallow

5

Original post by Ingamo

Ohh, I suppose but you could argue that they are still within the microfibril holding it together? :confused:

Yeh it was a weirdly worded question :/ but i think whenever they talk about bonding they mean the type of bonding holding that structure together not just within the structure generally...oh well it's only 1 mark :smile:

Reply 1911

Original post by jcao03

Edexcel can be so annoying in the way their grade boundaries fluctuate! I know that many found it an alright paper so I reckon it's gonna be high. I think I've seen it 64 marks high for an A in previous past papers. That's really high but they can't go any higher than that! Well they can but I don't think they're that horrible. I'm hoping a 60 but there's a chance that 64 is what they'll do. I remember in Jan when everyone found the paper alright and I thought I got sufficient marks to get me an A which was 54+ but I got a 57 and it was a C and A was 63 :frown:

Same happened to me! :P

Reply 1912

Simone739

Original post by MissGeek

Heu guys, I'm going to try get started on an unofficial mark scheme, I think I remember quite a few of the questions. My answers may be wrong. I have a Chemistry exam in a few hours, so I'll start of with a few of the questions first, then after my exam, I'll try and update the mark scheme. Personally, I found the paper okay, it wasn't too hard, but there were a few odd questions here and there. The multiple choice at the beginning was confusing. Apologies in advance if my mark scheme confuses anyone or if it's wrong.

Ferrets question

Explain how zoos have the captive breeding programme (5 marks)
Allow ferrets to mate with individiuals different to previous mating
Allow only those with different genes to mate
Keep a record book of which ferret has mated with which
Afterwards, reintroduce them back into the wild

From the graph, explain why no ferrets were released before 1991 (I think it was 2 marks)
The number of births was quite low before 1991, therefore if they were released back into the wild they would be endangered and threatened and at risk of extinction

Comment on the effectiveness of the breeding programme from 1991-2000
Overall increase, so must have been effective, even though there were a few years where the births were decreasing. In 1997 (i think it was), highest number of ferrets born.

Explain factors on survival (can't remember exactly how it was worded)
If the dogs are killed by poison, easier for ferrets to catch them, but population may reduce because more ferrets will die, because they will be poisoned (probably wrong answer)
Competition with other species within the area will affect its chances of survival (competing for food and territory)
Most of area disturbed by human activity, therefore, loss of natural habitat (e.g. roads being built), and hunting, so more difficult to adapt.

Meiosis

Explain after acrosome reaction what egg cell does (Can't exactly remember how it was worded)
Acrosome ruptures and digestive enzymes are released which break down zona pellucida layer. This allows sperm to get through to egg. Sperm head fuses with cell membrane. Egg cell releases cortical granules into space between zona pellucida and cell membrane. Zona pellucida thickens, so that only 1 sperm reaches fertilised egg.

Explain how meiosis brings about genetic variation.
Crossing over occurs. The 2 chromatids are wrapped/twisted around each other. Bits of 1 chromatid break and join bits of the other chromatid (on chiasmata).This leads to a combination of different alles in the 4 daughter haploid cells produced. Independent/random assortment also occurs. This is when any number from 0 to all 23 from the maternal or paternal chromatids are distributed into the gametes (hence offspring) completely at random.

I'll be able to add to the mark scheme when after my exam today. If anybody else wants to add to it, or correct anything which is wrong, please feel free to.

What do people reckon the grade boundaries on this paper are going to be?

it was actually in 1999 was the highest rate of birth

Reply 1913

Original post by Marshymallow

Yeh it was a weirdly worded question :/ but i think whenever they talk about bonding they mean the type of bonding holding that structure together not just within the structure generally...oh well it's only 1 mark :smile: