AQA BIOL2 Biology Unit 2 Exam - 26th May 2011

Here is a question with answer, add if I miss anything out please

List the differences between eukaryotic and prokaryotic DNA.

1) Eukaryotic is associated with proteins called histones, prokaryotic DNA is not
2) Eukaryotic DNA is linear whereas in prokaryotic, the ends join together to form a loop
3) Eukaryotic contains non coding DNA in the form of introns and multiple repeats. Prokaryotic does

Also, can anyone answer my 2 questions please

1) When in meiosis does independant segregation take place
2) when in meiosis does crossing over take place

Thanks

(edited 12 years ago)

Reply 201

ChessMister

12

Original post by Insanity514

What actually is root pressure? It just salts being actively transported into the xylem and so water moves in by osmosis?????????

The volume of water in the root xylem increases, so pressure increases

Reply 202

CityTrader

12

Does a lower partial pressure i.e the Bohr curve shifts left, mean that the person has a higher affinity of oxygen?

Reply 203

AspiringGenius

15

I did this exam yesterday?...

Reply 204

nasira372

1

Original post by AspiringGenius

I did this exam yesterday?...

Really...how?

EDIT: This is for AS Level mate, not GCSE

(edited 12 years ago)

Reply 205

AspiringGenius

15

Original post by nasira372

Really...how?

EDIT: This is for AS Level mate, not GCSE

Oh... Awkward turtle... I feel retarded now :smile:

I'll go back to pyramids of biomass and mitosis shall I? ^_^

Reply 206

Respected_Member

Original post by insanity514

what actually is root pressure? It just salts being actively transported into the xylem and so water moves in by osmosis?????????

insanity i have found you :redface:

Reply 207

aleema1992

Original post by xkate1019x

Can somebody please go over haemoglobiin? i get really confused with 'high affinity for oxygen' and 'high partial pressure' :/
Really worried about this exam as it's worth 47%, hoping i manged at least a C on unit 1, and a B on my isa!

Remembree it like this,
when there is high oxygen that means always co2 is the opposite so lower co2
so:
High O2
Low Co2]

and the affinity for oxygen is always the same to how much oxygen is present
so High affinity

affinity is the attraction of hameoglobin for oxygen
so just think of it like this if ur attracted to and guy/ u are more likly to go towrds this individual
same with oxygen
if hameoglobin has high affinity more likely they will bind and oxygen will load onto haemoglobin

Ok
so inr espiring tissues
where Carbon dioxide is bing produces
Co2 levels are high so
Co2 high
O2 levels low( O2 levels are alwais the opposite to CO2 so if co2 high then o2 low or if co2 is low then o2 high)
So as the affinity is alasys the same as concentration of oxygen present
as oxygen is low so hameoglobin has a low affinity for oxygen
so it wont attach or load oxygen
it wil release it
and it makes sene kuzin repiring tissues
they need O2

let me know if u dont get it still

Reply 208

aleema1992

Original post by nasira372

Here is a question with answer, add if I miss anything out please

List the differences between eukaryotic and prokaryotic DNA.

1) Eukaryotic is associated with proteins called histones, prokaryotic DNA is not
2) Eukaryotic DNA is linear whereas in prokaryotic, the ends join together to form a loop
3) Eukaryotic contains non coding DNA in the form of introns and multiple repeats. Prokaryotic does

Also, can anyone answer my 2 questions please

1) When in meiosis does independant segregation take place
2) when in meiosis does crossing over take place

Thanks

crossing over takes place in meisosis 1
in meiosis the chroatids wrap around each other in equivalent prortion
the chromatids break of kuz of the tentions and bind with homoglous partner
this is known as crossing over and this takes place in meiosis 1

what is independant segregation/

Reply 209

aleema1992

Original post by Respected_Member

insanity i have found you :redface:

root pressure is basicalcly the reuslt of the water moleules being draged up by the adhesion beetween molecules
so more water evaporates from the top of leaves throigh thee stomata
and then more water is pulled up kuz of adhesion
this is root pressure when molecules replace water moelcules
just think of it as magnets
there is a long chain of magnets
2 or 3 removed from the top ones at the bottem move up

Reply 210

aleema1992

Original post by CityTrader

Does a lower partial pressure i.e the Bohr curve shifts left, mean that the person has a higher affinity of oxygen?

yes it meanas higher affinity for oxygen
just think of it like this
to the left of the curve partial rpessur eof oxygen is lower so therefore haemoglobin must be releasing it less
so therfore it must have a high affinity for it thats hwy it not releasing it

hows revision,,

hey any ideas of what should/could come up in the bio 2 paper?

Reply 213

Master S P

Question 6(b)i in June 2009 paper, the number of different genera is 6 according to the markscheme. Can somebody explain?

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL2-W-QP-JUN09.PDF

Plz Quote me, Thanks

Reply 214

ChessMister

12

Original post by Master S P

Question 6(b)i in June 2009 paper, the number of different genera is 6 according to the markscheme. Can somebody explain?

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL2-W-QP-JUN09.PDF

Plz Quote me, Thanks

The genera is the first name. So if you look at the first names, there are only six different types.

Reply 215

liviaaa

How much does everyone know about cell differentiation? I seem to have hardly any notes on it / in my text book?

Reply 216

heavencanwait_

Original post by CityTrader

Does a lower partial pressure i.e the Bohr curve shifts left, mean that the person has a higher affinity of oxygen?

The Bohr shift is just when the dissociation curve moves to the right, due to an increased partial pressure of CO2.
Higher affinity is where there's a larger saturation of haemoglobin with O2 loaded onto it, i.e. in the lungs.
On the far left of the scale is where the Haemoglobin unloads it's O2 in the tissues due to a lower affinity (i.e. less attraction to the O2, as it's needed in respiring tissues for respiration)
If there's a curve to the right of a human one, this means that the other animal's haemoglobin has a higher affinity for O2 because they need to load the O2 onto their haemoglobin more readily, for example a llama up a mountain like in Jan '11.
If it's an active animal the curve shifts to the right as it releases more CO2 and hence it's haemoglobin needs a lower affinity for O2 as it is respiring more and so needs more O2 in order to respire and remain active, such as a hawk.

Hope this helps anyway lol