OCR Biology F211 resit - 16th May

Do you think i'll get the marks for what i wrote on the last question about translocation?

I wrote something along the lines of: Assimilates like sucrose are actively loaded into the sieve tube via active transport. This decreaes water potential so water moves into the sieve tubes via osmosis. Increases hydrostatic pressure. Meanwhile at the sink sucrose is used by the phloem. this increases water potential so water leaves the sink end creating low hydrostatic pressure. This creates a pressure gradient in which assimilates move from source to sink end.

Ya' think i'll pick up a few for that? :/

Reply 262

Straight up G

Original post by Groat

Most likely, yes.

Disagree, I think they like the word 'particular ' or 'specialised'.

Reply 263

Original post by Shabba101

Do you think i'll get the marks for what i wrote on the last question about translocation?

I wrote something along the lines of: Assimilates like sucrose are actively loaded into the sieve tube via active transport. This decreaes water potential so water moves into the sieve tubes via osmosis. Increases hydrostatic pressure. Meanwhile at the sink sucrose is used by the phloem. this increases water potential so water leaves the sink end creating low hydrostatic pressure. This creates a pressure gradient in which assimilates move from source to sink end.

Ya' think i'll pick up a few for that? :/

I would say 2 maybe more. The qu. did say how substances load into phloem, not the whole process.

Reply 264

Straight up G

Original post by Shabba101

Do you think i'll get the marks for what i wrote on the last question about translocation?

I wrote something along the lines of: Assimilates like sucrose are actively loaded into the sieve tube via active transport. This decreaes water potential so water moves into the sieve tubes via osmosis. Increases hydrostatic pressure. Meanwhile at the sink sucrose is used by the phloem. this increases water potential so water leaves the sink end creating low hydrostatic pressure. This creates a pressure gradient in which assimilates move from source to sink end.

Ya' think i'll pick up a few for that? :/

Doubt it unfortunately. The question was about assimilates being loaded into the phloem not translocation. One mark for the first sentence, maybe.

Reply 265

Groat

13

Original post by Ivo

Ah sweet, thanks. I was kinda worried as they said liver is an eg of an organ, so I thought that to get 2nd mark you had to put this in context.

I remember there being a question about why the lungs were considered an organ. However it simply said define an organ!

Original post by Straight up G

Disagree, I think they like the word 'particular ' or 'specialised'.

He had the word specialised in his answer? I put a group of tissues working together towards a common function.

Reply 266

Original post by Straight up G

Doubt it unfortunately. The question was about assimilates being loaded into the phloem not translocation. One mark for the first sentence, maybe.

i thought translocation was the movement of sugars e.g sucrose in a plant?

Reply 267

Original post by Shabba101

i thought translocation was the movement of sugars e.g sucrose in a plant?

It is, but the qu. wanted you to explain how sucrose is loaded at sink. So process of H+ ions being pumped out of companion cells by active transport etc.

Reply 268

Original post by Ivo

It is, but the qu. wanted you to explain how sucrose is loaded at sink. So process of H+ ions being pumped out of companion cells by active transport etc.

surely if you get chemistry related the H+ ions would come from the water moving out due to the increase in water potential?

:P

Reply 269

arcticwombats

Can someone please check my answers and give an estimate how many marks i got on the questions that i'm not sure about?

- the active transport question: i said it's a non passive process used to bring large substances, or polar substances in to the cell that are too big too diffuse through the phospholipid bi layer (forgot about ATP and against conc gradient... feel like an idiot)

- the one where you had to say what transports etc - i said - blood transports, exchange surface is the lungs, and valves control pressure ( i think all of these are wrong, fml )

- and for how seive elements are adapted - i just wrote they have no organelles, allowing transport of assimilates, do you think i'll get any marks for that

- also the calculation question, if you just put 18% and not18.00 % do you think you'll lose a mark????

cheers whoever answers this!

EDIT: oh, and for the where are meristems located, is root tips and stem tips enough for the 2 marks!??

Reply 270

Straight up G

Original post by arcticwombats

Can someone please check my answers and give an estimate how many marks i got on the questions that i'm not sure about?

- the active transport question: i said it's a non passive process used to bring large substances, or polar substances in to the cell that are too big too diffuse through the phospholipid bi layer (forgot about ATP and against conc gradient... feel like an idiot)

- the one where you had to say what transports etc - i said - blood transports, exchange surface is the lungs, and valves control pressure ( i think all of these are wrong, fml )

- and for how seive elements are adapted - i just wrote they have no organelles, allowing transport of assimilates, do you think i'll get any marks for that

- also the calculation question, if you just put 18% and not18.00 % do you think you'll lose a mark????

cheers whoever answers this!

1,1,1 and unsure really. Probably get the two marks. I looked through the past papers for similar questions, both times where they insist on sig figs or d.ps it says in the question explicitly in bold. though obviously in this question it says it implicitly, I think both of us will be okay with 18%.

Reply 271

Oh oh and for the mitosis question instead of writing 18% i put 82%!!
But i wrote a note on the side stating that i was aware nuclear division stopped at metaphase
so you just needed to add interphase + prophase

rekon they'll give me a mark :frown:

?

Reply 272

Groat

13

Original post by arcticwombats

Can someone please check my answers and give an estimate how many marks i got on the questions that i'm not sure about?

- the active transport question: i said it's a non passive process used to bring large substances, or polar substances in to the cell that are too big too diffuse through the phospholipid bi layer (forgot about ATP and against conc gradient... feel like an idiot)

- the one where you had to say what transports etc - i said - blood transports, exchange surface is the lungs, and valves control pressure ( i think all of these are wrong, fml )

- and for how seive elements are adapted - i just wrote they have no organelles, allowing transport of assimilates, do you think i'll get any marks for that

- also the calculation question, if you just put 18% and not18.00 % do you think you'll lose a mark????

cheers whoever answers this!

EDIT: oh, and for the where are meristems located, is root tips and stem tips enough for the 2 marks!??

Why would you lose a mark for putting 18%. :eek:

I also put roots and stem tips for that question and after checking the OCR textbook that's exactly where they say meristem cells are.

I think you're right with the transport medium being the blood

Reply 273

Original post by Shabba101

surely if you get chemistry related the H+ ions would come from the water moving out due to the increase in water potential?

:P

It is in fact the hydrolysis of ATP to ADP that releases the H+ ions which then can be actively pumped out of the companion cell.

Reply 274

Original post by Shabba101

Oh oh and for the mitosis question instead of writing 18% i put 82%!!
But i wrote a note on the side stating that i was aware nuclear division stopped at metaphase
so you just needed to add interphase + prophase

rekon they'll give me a mark :frown:

?

But surely nuclear division means mitosis (i.e. PMAT), so calc. would be 100-12=88?

Reply 275

Groat

13

Original post by Ivo

But surely nuclear division means mitosis (i.e. PMAT), so calc. would be 100-12=88?

Yeah, nuclear division is mitosis. The table listed interphase then the stages of mitosis, so the working was either 100 - 82 = 18% or add the other stages.

Reply 276

arcticwombats

Original post by Ivo

But surely nuclear division means mitosis (i.e. PMAT), so calc. would be 100-12=88?

nah it was how much percent is made up of the nuclear divis (pmat) which was only 18%, with the rest being like G1 and G2 or something like that

... i think

Reply 277