AQA BIOL2~3rd June 2013~AS Biology (Now Closed)

Yes even though it might be a correct statement, it has insufficient detail, therefore you wouldn't get a mark.

How on earth do we do this ?!

Any predictions on what coming up? There got to be something on haemoglobin as it wasn't on the jan 13 paper

just draw a 0.1mm by 0.1mm (using their measurements) square onto the image and count the number of stomata within the square and x10 to get it from 0.1mm^2 to 1.0mm^2. Well thats how i would do it haha

Where do we draw the square though?! I'm so confused no idea how to actually go about it

So I was disheartened after getting a C yesterday in a past paper and got 140 UMS today! So happy Not going to let it go to my head though, but needed to share my happiness haha time to watch some tv I think!

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.

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.

What stage does crossing over actually happen in meiosis

where N= total number of organisms of all species
and n= total number of organisms of each species

Do we have to know this formula or will they tell us?

where N= total number of organisms of all species
and n= total number of organisms of each species

Do we have to know this formula or will they tell us?

Late prophase or Metaphase during Meiosis I

I don't know which one, I'd like to know too

I'm having trouble understanding root pressure. The markscheme says its to do with ions moving into the xylem, lowering its water potential, causing water to enter the xylem by osmosis.

Where do the ions come from in the first place? Also, I don't see how the above has anything to do with pressure? Where does the part about water being shoved up the xylem due to pressure come in....

Thank you

Endodermal cells actively transport mineral ions into the xylem vessels, reducing water potential inside the xylem vessels, hence water can move into the xylem down a water potential gradient by osmosis. This entry of water into the xylem vessels causes root pressure which is sufficient to push water up the xylem vessels.

Root pressure is particularly important in spring, before the growing season when the leaves have not formed, therefore are not transpiring.