POST-MORTEM: AQA Additional Science Biology B2 (May 2013)

No, mesophyl is where photosynthesis takes place. Xylem transports water around the plant and phloem transports sugars.
i got 8 for the squares
and 8d is 12 because gametes have half the number of chromosomes to normal cells

That should be fine you could have had oxygen, carbon dioxide or water vapour

Its not carbon dioxide, its either Water vapor or Oxygen as it said from B to A (which means what diffused out of the plant cell not into the plant cell, which carbon dioxide does)
and Water vapor diffuses out the plant cell through transpiration and Oxygen through photosynthesis..

...It could have been carbon dioxide, in Respiration, the opposite happens and although it insinuated that it wanted you to write with regard to photosynthesis many will have written carbon dioxide and thus they will not be able to deny that on a hot day..or even on any day, respiration also occurs and thus carbon dioxide is given off as a waste product. - CO2 will diffuse out of the plant.

8.
a) The chromosomes duplicate the genetic material to create two identical sister chromatids. (1 mark)
b) Gametes have half the number of chromosomes as a normal body cell. As meiosis consists of two divisions, this means that they need to duplicate the DNA so that the gametes formed will have half the number of chromosomes. (2 marks)
c) Four chromosomes in species A, eight chromosomes in species B (1 mark)
d) The offspring will have 12 chromosomes. (1 mark)

For b) would it be okay to talk about mitosis? Because the question simply says about cell division and doesn't specify which one.
and
for c) I know I'm wrong but don't know why. I got 2, 4 because I thought the chromosomes in the diagram had been replicated so there would be a double division for meiosis so I halved the numbers twice.

For the quadrants question i did 50x50=2500(for the area of the feils) then did 7x2500=17500. Will i get any marks for this or was i just plain stupid?

The chromosomes in the diagram had doubled, however each X represented four different chromosomes, each little arm being one chromosome, if you look on google images you can see that chromosomes in the process of 'doubling' look like a cross before they split.


Posted from TSR Mobile

The chromosomes in the diagram had doubled, however each X represented four different chromosomes, each little arm being one chromosome, if you look on google images you can see that chromosomes in the process of 'doubling' look like a cross before they split.


Posted from TSR Mobile

Ohh I get it now, thanks I think I got confused because in the diagram it pointed to one cross like shape and said that was one chromosome. At least it was only 2 marks. Do you think I'll get a mark for the offspring one due to error carried forward? I added the gametes of species A and B but since my answer was wrong I got 6, which is also wrong.

That's right. Each chromosome in the picture had a duplicated sister chromatid (but it's still stuck on to the original), so on the first divison, the number of chromosomes stay the same. It's the second division that really divides the chromosomes.

Yeah it was very ambiguous! however i think that it was simply referring to the bottom left section of the cross, rather than the whole left hand side. Yeah you almost certainly will, so only one marked lost