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Original post by Potential Medic
This was also the ISA experiment and we had to calculate the standard deviation afterwards and plot it on a bar chart. But I'm pretty sure we don't have to calculate the standard deviation for this exam?!


Nope you won't need to calc SD.

Does anyone know how to calculate biodiversity index? We need to know that but i forget how to.
Reply 1581
Original post by LiamDaly
I am confused.

If a daughter cell contains 23 chromatids when this fuses with another gamete surely you end up with 23 chromosomes.

23 chromosomes is not diploid.

What? Please





Posted from TSR Mobilehh


2b. There are 12 base pairs, and 3 base pairs = 1 amino acid so 12/3 = 4

4a. 26 and 30 due to the division in telophase so each cell halves the mass
13 and 15 since it is a haploid cell

:smile:
Original post by Simran Mars Foster
Nope you won't need to calc SD.

Does anyone know how to calculate biodiversity index? We need to know that but i forget how to.


They give you the formula in the paper.
Reply 1585
Original post by zbert
So I think I get meiosis now.
It is Mitosis except:
in Prophase you get crossing over
in Anaphase the centromeres don't separate so the whole chromosome is pulled to the poles of the cell
then telophase as in mitosis except you have chromosomes instead of chromatids
then cytokinesis, and mitosis as normal on the 2 cells.

Is this correct?


No surely in metaphase you'd get crossing over? When they line up


Posted from TSR Mobilehh
Reply 1586
Original post by zbert
So I think I get meiosis now.
It is Mitosis except:
in Prophase you get crossing over
in Anaphase the centromeres don't separate so the whole chromosome is pulled to the poles of the cell
then telophase as in mitosis except you have chromosomes instead of chromatids
then cytokinesis, and mitosis as normal on the 2 cells.

Is this correct?


I wouldn't really think of it in that way....

Homologues chromosomes line up at the equator maternal and paternal at either side of the equator

Crossing over occurs this crosses over alleles and increases diversity.

Stage one division via spindle fibres 2 cells 1 set of genetically diverse chromosomes

Stage two division spindle fibres and centromeres break. Creating 4 haploid cells (gametes)


I think....
Posted from TSR Mobile
What stage does crossing over actually happen in meiosis :s-smilie:
Reply 1588
Original post by WheezyT
I wouldn't really think of it in that way....

Homologues chromosomes line up at the equator maternal and paternal at either side of the equator

Crossing over occurs this crosses over alleles and increases diversity.

Stage one division via spindle fibres 2 cells 1 set of genetically diverse chromosomes

Stage two division spindle fibres and centromeres break. Creating 4 haploid cells (gametes)


I think....
Posted from TSR Mobile



the stage 2 division is the same process as mitosis though isn't it? :s-smilie:
Reply 1589
Original post by Sum786
how many marks would you need to get in the paper to get 120 UMS


around 67/68 depends on boundries though
Original post by elliewoodheadx
2b. There are 12 base pairs, and 3 base pairs = 1 amino acid so 12/3 = 4

4a. 26 and 30 due to the division in telophase so each cell halves the mass
13 and 15 since it is a haploid cell

:smile:


I am confused as there are 24 bases so wouldn't it be 24/3 = 8

Thanks I actually get q4 now because of you :smile:
Reply 1591
Original post by Simran Mars Foster
Nope you won't need to calc SD.

Does anyone know how to calculate biodiversity index? We need to know that but i forget how to.


d = N(N-1)/Sum of n(n-1)

You are given the formula.

N = Total number of organisms of all species
n = Total number of one species
Reply 1592
Original post by Suzanna5678
That's horrid ! What have you got?


i know right :'( so much pressure from everyone aswell :angry:.. ive got Information technology exam on the same day 2 hours long :O (IT) and business unit 2 the next morning :L x
Original post by Simran Mars Foster
Nope you won't need to calc SD.

Does anyone know how to calculate biodiversity index? We need to know that but i forget how to.


If you have a table for example

n n(n-1)
Lions 10 90
Tigers 5 20
Bears 2 2
Total 17 112
Index of diversity= N(N-1) over the sum of n(n-1)

In this case: N(N-1) is the total of the species x the total of the species-1 divided by the sum of the total species

17x16 over 112 = 2.43
Reply 1594
i just want to ask any year 13's... has anyone flopped meaning failed there AS biology exams and had to re-do all so all together 4 units at the end of june? anyone? and is it possible to actually do well and get an A...anyone want to share their experience? I feel like I will need to well i kinda know from gut instinct that i will have to do all four units next June im in year 12 currently and need an A :L


thank you.. whoops its not as relevant buts it still biology :biggrin:
Original post by SchoolKid.
I am confused as there are 24 bases so wouldn't it be 24/3 = 8

Thanks I actually get q4 now because of you :smile:


It's ok glad to help :smile:
Nah you just the complementary base pair no. not the actual amount of bases
Reply 1596
Original post by bookworm1
June 2010, 5dii, how do you get 8? :confused:


2^3 = 8.

If there's A1, A2, B1, B2, C1, C2:
A1 B1 C1
A1 B1 C2
A1 B2 C1
A1 B2 C2
A2 B1 C1
A2 B1 C2
A2 B2 C1
A2 B2 C2

For n pairs of chromosomes, number of possible arrangements is 2^n

If there are 2 pairs, 2x2 = 2^2=4. Adding one more pair doubles the possible no. of arrangements as for each of the current arrangements you can add either N1 or N2.
Reply 1597
Original post by Nima123
I don't understand question 5dii from the june 2010 paper can someone explain it to me image.jpg


I as well have no idea about this?


Posted from TSR Mobilehh
image.jpgHow on earth do we do this ?!
Original post by MehvishM
i just want to ask any year 13's... has anyone flopped meaning failed there AS biology exams and had to re-do all so all together 4 units at the end of june? anyone? and is it possible to actually do well and get an A...anyone want to share their experience? I feel like I will need to well i kinda know from gut instinct that i will have to do all four units next June im in year 12 currently and need an A :L


thank you.. whoops its not as relevant buts it still biology :biggrin:



I'm in year 13 and i'm not re-sitting all units but just unit 2 on monday then my unit 5 exam on the 17th! I wouldn't worry, even if it does come to that and you have to do re-sits next June it would actually be really helpful for the unit 5 exam as there is a 25 mark essay at the end which could be on anything from AS and A2! so re-sitting may actually be not that bad since you will have to revise it all any ways, maybe even quite motivating to do more bio work!

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