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Edexcel 6BIO2 ~ 3rd June 2013 ~ AS Biology

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Hey guys,
I found the paper decent.
Some Questions:
1-For the last question, where you had to mention 3 factors that affected genetic diversity, i said for the last one -> species distributed at different locations, forming founder effect as groups are isolated from others and form colonies and that this has the effect of reducing genetic diversity as less chance of one having allele with selective advantage
2-For the evaluation of report I mentioned nothing of peer reviewing, bias or something... I said that many scientists criticised the fact that its difficult to classify all organisms into these three domains and that the classification of the 5 Kingdoms may be a better choice. But this doesnt answer the question, right? Would I get any marks?
3- I put Interphase as there was no movement (so cant be any of 4 stages) and cell was not splitting so cant be cytokinesis.
4-I put Prophase and Anaphase...Why Metaphase? :frown:
5-For the Captive Breeding I mentioned:
-> breeding with genetically different individual
-> not allowing mating between two that have already bred
->transferring between zoos so more breeding with different individuals
->using studbooks
-> definition of genetic diversity(could this be a mark?)

6-For the reintroduction into wild, I said that risk of extinction is high when there are too few individuals as they may all be killed by predators and that genetic variety is low when population is low so there less chance of surviving as lower chance of one having selective advantage when environment changes
7-The 2 marker for the style, why the concentration thingy decreases pollen tube growth: I said no proteins were made, so less growth, also less cell specialization leading to less growth(would this be any marks?)
8-why temperature constant - said that it must be a control factor as only effect of changing concentration is investigated so must be constant for valid results(is this 2 marks?)
9- For the egg thingy worth 4 marks I had difficulties finding all marks: said that
->cortical granules are released
->that attach between zona pellucida and cell membrane
->to prevent polysperm as gap closes
-> thickens and hardens the Zona pellucida
-> also said that sperm cell fuses with cell membrane(probs not a mark)
How many marks would I get ? 3 or 4?
10-For Question 1, I can remember putting
->all three have cell membranes
->all three have ribosomes
->only animal has sER
->two of them have cell walls
->only animal has centrioles
-> only two have nucleus... CORRECT SO FAR?

11-Genetic variation introduced by crossing over(which is breaking and rejoining of chromatids) and independant assortment(which recombines alleles) - would i get the 2 marks?
12-Totipotency
->Cut explants from growing area
->Cover with cling foil to prevent microorganism from entering
->place into agar with growth hormones and nutrients
->wait till unspecialised cell differentiates into unspecialised cells
->these then differentiate into specialised cells This shows totipotency when explant develops shoots and roots
->keep temperature, humidity, light constant
->repeat experiment for more reliability
Would I get all four marks?

13-Fibre description
->measure mean masses to break fibre with adding 20g each so more valid results; the higher the masses the more tensile strength
->also measure distance as second variable and compare them
->use plant fibres of same length and age of plant the same
->temperature,humidity,light intensity constant
->repeat experiment for more reliability for each plant
->calculate mean masses and mean distances
What would I get? 4 or Full marks?

14- Was introduction to wild successful
->succefful to certain extent as number of births increased by a lot until 1999
->limited in success as in 2000 births decreased significantly almost being as low as in 1991
Is this 2 marks?

Ok everything i remember atm
(edited 10 years ago)
Original post by tsrdemi
hi guys i hope my memory of the questions can help in order to come up with an unofficial mark scheme

multiple choice questions (8 marks)

question on mRNA synthesis on pollen tube growth (3 or 4 marks)

label stage of cell cycle (2 marks)

describe how you would use the apparatus shown to experiment tensile strength of fibres (4 or 5 marks)

explain how zoos can promote genetic diversity through captive breeding programmes in black footed ferrets (5 marks?)

taxonomic groups (3 marks?)

what happens in the egg cell after the acrosome reaction (4 marks?)

cellulose and microfibrils table (4 marks)

last question on what would effect the chances of survival of the ferrets (3 marks)

what happens in PROPHASE (4 marks)

explain how meiosis brings about genetic variation (3 or 4 marks)

comment on the effectiveness of the breeding programme from 1991-2000 (3 marks?)

from the graph explain why no ferrets were released before 1991 (2 marks?)

how to make the experiment of the tensile strength more accurate and reliable (2 marks)

why was temperature kept constant in fibre strength experiment (2 marks)

william witherings experiment of digitalis soup (3 marks)

explain what is meant by the double blind trial (3 marks?)

what is the difference between totipotent and pluripotent cell (2 or 3 marks)

how would you investigate totipotency of the cotton plant (tissue culture technique) (4 or 5 marks)

what are the other two domains other than eukarya (2 marks)

Double Blind trial was 2 marks, taxonomic groups 2 marks and mrna synthesis was also only 2 marks,maybe 3 pretty sure
Cellulose molecules have no hydrogen bonding within them right? Just 1,4 bonds. It's the microfibrils that have H Bonds. Please correct me if I'm wrong
Reply 1963
Original post by Kurraiyo
Cellulose molecules have no hydrogen bonding within them right? Just 1,4 bonds. It's the microfibrils that have H Bonds. Please correct me if I'm wrong


Not 100% but thats what I thought! :P
Reply 1964
Original post by Kurraiyo
Cellulose molecules have no hydrogen bonding within them right? Just 1,4 bonds. It's the microfibrils that have H Bonds. Please correct me if I'm wrong


Cellulose molecules are chains of beta glucose bonded by 1-4 glycosidic bonds. Cellulose microfibrils are 50-80 cellulose CHAINS bonded by hydrogen bonds.
I put, Cellulose: tick only for 1-4 glycosidic bonds
Microfibril: tick for 1-4 glycosidic bonds and hydrogen bonds
Reply 1965
Original post by billyfisher100
All I can remember is peer review for Woese... :redface: I hope I didn't miss out a question or something DO you mean the one about taxonomy?


Which question was about taxonomy :eek: I really don't remember that I get a feeling that I left this question
Reply 1966
hey guys had chemistry today so didnt post before
i found biology ok probably lost marks on the tick/ cross question and last question
damn i always seem to mess up the last question
hope eveyone did well but dont want grade boundaries too high- need my a
Original post by Meehar17
2 ticks and a cross in the box where it said he tested on healthy individuals


William withering tested on patients who had the condition, not healthy people, during that period they wouldn't see the point in testing on healthy patients.
Reply 1968
thanks to assasin for his notes they were very good used them with my own notes :bigsmile:
:hugs: also thanks to jacksgap whosaid that totipotency core practical was most likely to come up- i didnt even pay that much attention to it before that so you were literally a lifesaver
(edited 10 years ago)
Reply 1969
Withering didn't use a placebo did heee? :rolleyes:
Reply 1970
what was the experiment we had to write for that cotton one
Reply 1971
Original post by Ingamo
Withering didn't use a placebo did heee? :rolleyes:

no dont think so
Reply 1972
Original post by Ingamo
Withering didn't use a placebo did heee? :rolleyes:


Nope, only tested on patients with heart condition. Not healthy individuals either
For the last question I wrote:

- lack of prey
- loss of habitat
- Founder effect. If you looked, some of the reintroduction sites were really far from the other groups, thus they were reproductively isolated, which meant that they would inbreed and lower genetic variety, thus they are more susceptible to disease/ negative results of selective pressure.

What the hell was the microfibril question? Why couldn't they make it clear what they want us to tell them?! Also, I think I've dropped marks on the taxonomic data, critical evaluation and the microfibril question. But I bet I drop loads on the data questions. Why were there so many data questions?!?!

Do we have an unofficial mark scheme?
(edited 10 years ago)
Reply 1974
Original post by wbrian
what was the experiment we had to write for that cotton one

totipotency one
Reply 1975
Original post by StephenNaulls
For the last question I wrote:

- lack of prey
- loss of habitat
- Founder effect. If you looked, some of the reintroduction sites were really far from the other groups, thus they were reproductively isolated, which meant that they would inbreed and lower genetic variety, thus they are more susceptible to disease/ negative results of selective pressure.

What the hell was the microfibril question? Why couldn't they make it clear what they want us to tell them?! Also, I think I've dropped marks on the taxonomic data, critical evaluation and the microfibril question. But I bet I drop loads on the data questions. Why were there so many data questions?!?!

Do we have an unofficial mark scheme?


I feel ya bro, data questions seem like the ones most easiest to lose marks on because the mark schemes can be picky! That is where I lost marks in unit 1 :frown:
Original post by CoolRunner
I think i got this wrong (by the looks of everyone else)...

This is what I did:
ithinkigotitwrong.jpg

As a similar question has been asked before (i know the question we did is not about starch):

ss.jpg




Thats right lol YAAAAAAAAAAAAAAAAAAY
Reply 1977
Original post by tsrdemi
hi guys i hope my memory of the questions can help in order to come up with an unofficial mark scheme

multiple choice questions (8 marks)

question on mRNA synthesis on pollen tube growth (3 or 4 marks)

label stage of cell cycle (2 marks)

describe how you would use the apparatus shown to experiment tensile strength of fibres (4 or 5 marks)

explain how zoos can promote genetic diversity through captive breeding programmes in black footed ferrets (5 marks?)

taxonomic groups (3 marks?)

what happens in the egg cell after the acrosome reaction (4 marks?)

cellulose and microfibrils table (4 marks)

last question on what would effect the chances of survival of the ferrets (3 marks)

what happens in PROPHASE (4 marks)

explain how meiosis brings about genetic variation (3 or 4 marks)

comment on the effectiveness of the breeding programme from 1991-2000 (3 marks?)

from the graph explain why no ferrets were released before 1991 (2 marks?)

how to make the experiment of the tensile strength more accurate and reliable (2 marks)

why was temperature kept constant in fibre strength experiment (2 marks)

william witherings experiment of digitalis soup (3 marks)

explain what is meant by the double blind trial (3 marks?)

what is the difference between totipotent and pluripotent cell (2 or 3 marks)

how would you investigate totipotency of the cotton plant (tissue culture technique) (4 or 5 marks)

what are the other two domains other than eukarya (2 marks)

aceeeee thankyouuuuuuuuuu
The question on "mRNA synthesis on pollen tube growth". One of the questions was that some chemical inhibits mRNA, explain how this can effect the pollen tube length.

Is it along the lines of since mRNA is inhibits and can't transcribe and make the enzyme (which is a protein) which is necessary for the pollen tube nuclei as it releases enzymes to make the pollen tube?
Original post by kevsamuel
The question on "mRNA synthesis on pollen tube growth". One of the questions was that some chemical inhibits mRNA, explain how this can effect the pollen tube length.

Is it along the lines of since mRNA is inhibits and can't transcribe and make the enzyme (which is a protein) which is necessary for the pollen tube nuclei as it releases enzymes to make the pollen tube?


thats what i wrote :/
edit: i wroye something alond those lines this is what i wrote:
the pollen tube releases enzymes to digest and break down the style and surrounding tissues to enable the pollen tune to grow and reduces resistance, it also provides nutrients for pollen tube growth. if mrna is inhibited then the enzyme cannot be synthesised. i wrote something like that.

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(edited 10 years ago)

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