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Edexcel 6BIO2 ~ 3rd June 2013 ~ AS Biology

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can someone go atleast 3 control vari
Root tip squash:
MolArity of HCl
temperature heated to
Volume of hcl (careful as edexcel won't credit amount usually)

Totipotency:
concentrations of growth regulators in agar
species of plant for each replicate procedure
temperature
Light exposure

Antimicrobial properties:
temperature
species of bacterium
concentrations of each solution the paper discs are soaked in

Tensile strength:
Length of fibre
width of fibre
mass of fibre

Nitrate ion concentration
concentrations of all other mineral ions
Light exposure of plants
temperature of plants

Reply 1081

CoolRunner

Original post by The Assassin

I can see them coming up actually - I don't recall seeing regulatory authorities before so I've been making sure I know that. :tongue:

Sounds accurate overall, but the only thing I'm not certain about is cohesion-tension/pathways (because that hasn't come up before has it?)

It hasn't and I have a deep feeling its gonna come up this time round. Take my word for it. :tongue:

Reply 1082

Branny101

Original post by CoolRunner

I will be a happy man if mitosis or totipotency come up.

I'm placing my bets that plant tensile strength would come up.

The topics i'm also hedging my bets that are gonna come up are stuff about

Zoos, regulatory authorities, Ethics, Stem Cells, Plant fertilisation (if we are lucky, mammalian fertilisation), Independent assortment and chiasmata, cohesion-tension, water pathways, Definitions, Bionomial name, Linnaeus, Polygenic Punnet squares and chloroplasts.

I'm hoping my crazy predictions are correct, so grade boundaries would be lower and It be easy for all of us prepared students (in this forum) get 120ums.

Linnaeus?

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Reply 1083

CoolRunner

Original post by Randy123

could someone please explain species evenness to me

When the population numbers of each species in the habitat are similar (similar abundances).

Reply 1084

CoolRunner

Original post by Branny101

Linnaeus?

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Linnaeus = Taxonomy

Linnaeus is just the guy who come up with it.

Reply 1085

Branny101

Original post by cyberphilic_9999

hi guys i dont get why doesn't natural selection occur in humans? i saw this question believe it or not in my textbook??

thanks

We adapt for those less fortunate?

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Reply 1086

Branny101

Original post by CoolRunner

Linnaeus = Taxonomy

Linnaeus is just the guy who come up with it.

Ahhhh the Genus - Species thing?

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Reply 1087

CoolRunner

Original post by Branny101

Ahhhh the Genus - Species thing?

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Yup

Reply 1088

maryam1996

Original post by Kurraiyo

oh okay! so pits are like REDUCED cell walls whereas with plasmodesmata there are no cell walls at all? :smile:

thanks!!!

Yes you're right, i've also attached a picture of the page in the revision book which talks about it and there's a diagram, which would help make my explanation a bit more clearer. Cell wall.jpg

Reply 1089

DanielDaniels

what are the risks associated with the methods used to obtain stem cells ?

Reply 1090

jooh_23

Original post by CoolRunner

It hasn't and I have a deep feeling its gonna come up this time round. Take my word for it. :tongue:

hey

I agree this is defo coming up!

but i have no idea what to learn, do you have any answers and 'example q's they may ask

Thanks!! :biggrin:

Reply 1091

Eternity Flame

Don't know what to study in biodiversity part . It is like common sense stuff . I don't think mitosis would come because it came in 3b paper . I hope it won't be difficult , and i hope 5 marks question to write experiment procedure for nitrate would come . Chem unit 2 is more important than bio for me

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Reply 1092

Eternity Flame

I don't think there are much risks with methods to obtain stem cells but there are risks of using them like , risk of tissue rejection ( not for adult stem cells if nucleus taken from patient ) . Then risk of infection when cells received and there are ethical issues with some cells . It differs from different stem cells

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Reply 1093

Branny101

Original post by CoolRunner

Could you tell me like a bullet point answer for what happens during crossing-over at the chiasmata?

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Reply 1094

Eternity Flame

Good luck guys do study well

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Reply 1095

anonymouspie227

Lol, I accidently clicked on the AQA thread and saw magnifiication, and was like woah?!?!! :tongue:

Reply 1096

maryam1996

Can someone please explain to me what is the role of the endodermis and the Casparian strip ? Thanks :smile:

Reply 1097

Randy123

could someone explain to me what biodiversity hotspot is and how is it related to biodiversity

Reply 1098

CoolRunner

Original post by jooh_23

hey

I agree this is defo coming up!

but i have no idea what to learn, do you have any answers and 'example q's they may ask

Thanks!! :biggrin:

Probably just the usual, and remember locations of various organelles and parts of the plant (like xylem) they are bound to come up.

Original post by Branny101

Could you tell me like a bullet point answer for what happens during crossing-over at the chiasmata?

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For crossing-over.

1) Before the first meiotic division, homologous pairs of chromosomes pair up.
2) Chromatids then twist or tie around each other.
3) Bits or parts of the chromatid break off and join the other chromatid.
4) Thus a different combination of alleles in the four daughter cells.