AQA AS Biology Unit 2 - 1 June 2015

Reply 780

maggie43

16

Original post by chemm

Is this likely to come up?

nahhhhh i hope not

Reply 781

skittles100

6

Original post by kpd_98

Was the answer 11?

I did 200-90= 110

110/200 x 20= 11

its 120 mins, dont know why

Reply 782

blueberry389

8

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF
can anyone explain why in q8c it's epithelium but not endothelium?

also, for meiosis and mitosis, when do you refer to chromosomes and chromatids, sooo confused :/also, what in our spec is related to inbreeding?

Reply 783

skittles100

6

Original post by kpd_98

Oh wait, doesn't matter. I just re-read the question and realised the figures in the diagram are percentages and not the number of cells in that phase!

Apologies!

could you explain please? :smile:

Reply 784

chemm

2

Original post by blueberry389

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF
can anyone explain why in q8c it's epithelium but not endothelium?

also, for meiosis and mitosis, when do you refer to chromosomes and chromatids, sooo confused :/also, what in our spec is related to inbreeding?

they will probably accept endothelium is is not incorrect its just the fact the endothemlium lining is made from epithelial cells i think, correct me if I'm wrong

Reply 785

ozzie2

12

Original post by SebastianCobain

Definitely. In my French exam they used the exact same question. This is like a major test of your revision because most people would discard learning an answer for it thinking that they wouldn't be silly enough to do it twice and then get caught in a trap haha.

I thought exam boards didn't like people learning answers and want them apply what they know to a variety of questions, this may just be due to them running out of questions to give after years of making exam papers.

Reply 786

mck9777

2

Any last minute tips for revision? So sick of looking at Unit 2

Reply 787

kpd_98

8

Original post by skittles100

its 120 mins, dont know why

Just re-read the question, it's because the numbers show the percentage of cells in that phase and not the actual number!

So;

200/100 x 90= 180 (to work out the number of cells in interphase)

180/ 200 x 20= 18 (so, interphase took 18 hours)- using the formula I gave earlier :smile:

20-18= 2 (or 120 mins)

Reply 788

kkboyk

21

Original post by blueberry389

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF
can anyone explain why in q8c it's epithelium but not endothelium?

also, for meiosis and mitosis, when do you refer to chromosomes and chromatids, sooo confused :/also, what in our spec is related to inbreeding?

Endothelium is the inner lining.

Chromosomes for both, chromatids for meiosis (second division).

Reply 789

SamuelSingleton

13

Original post by blueberry389

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF
can anyone explain why in q8c it's epithelium but not endothelium?

also, for meiosis and mitosis, when do you refer to chromosomes and chromatids, sooo confused :/also, what in our spec is related to inbreeding?

mark scheme would accept endothelium, technically speaking the lining of vessels are squamous epithelial cells - i imagine that's what the mark scheme is talking about because these cells are smooth to reduce friction
endothelium is the collective term for the specialised organ

Reply 790

Emad1993

13

Can someone plz explain question 4b 2011 may? The time required for

Reply 791

SamuelSingleton

13

Original post by Emad1993

Can someone plz explain question 4b 2011 may? The time required for

idea that damaged epithelial cells are replaced more rapidly (1 mark) if it was any more then go on to say how this maintains high surface area for absorption

Reply 792

username1533709

5

Original post by kpd_98

Just re-read the question, it's because the numbers show the percentage of cells in that phase and not the actual number!

So;

200/100 x 90= 180 (to work out the number of cells in interphase)

180/ 200 x 20= 18 (so, interphase took 18 hours)- using the formula I gave earlier :smile:

20-18= 2 (or 120 mins)

Posted from TSR Mobile

For some reason I got 186 instead of 180.

Reply 793

Emad1993

13

Original post by SamuelSingleton

idea that damaged epithelial cells are replaced more rapidly (1 mark) if it was any more then go on to say how this maintains high surface area for absorption

Thanks for that but I meant the time required to produce 8 cells, part 2 😊

Reply 794

Boundless_x

16

Do arterioles have elastic tissue? :s-smilie:

Reply 795

kkboyk

21

Original post by Tee546

Are we expected to know the evidence for why DNA is the hereditary material?

You should, but questions about it had never showed up so you dont need to learn it.

Reply 796

Emad1993

13

Original post by Boundless_x

Do arterioles have elastic tissue? :s-smilie:

They have muscles which contract

Reply 797

kkboyk

21

Original post by Boundless_x

Do arterioles have elastic tissue? :s-smilie:

Yes

Reply 798

SamuelSingleton

13

Original post by Emad1993

Thanks for that but I meant the time required to produce 8 cells, part 2 😊

ah 1 cycle is 4h 18 minutes so that's 258 minutes for 1 to divide to 2
another 258 minutes for 2 to divide into 4
and another 258 minutes for 4 to divide into 8
totaling 774 minutes

Reply 799

skittles100

6

Original post by kpd_98

Just re-read the question, it's because the numbers show the percentage of cells in that phase and not the actual number!

So;

200/100 x 90= 180 (to work out the number of cells in interphase)

180/ 200 x 20= 18 (so, interphase took 18 hours)- using the formula I gave earlier :smile:

20-18= 2 (or 120 mins)

thanks! i get the working out but why did you want to find the cells of interphase when its asking about the mean time for cells to complete mitosis?

AQA AS Biology Unit 2 - 1 June 2015

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