The Student Room Group

2016 OCR Biology A Breadth - Unofficial Mark Scheme

Scroll to see replies

I think that the answer to the SA:V ration multiple choice was B) 2cm side length
Does anyone disagree with my logic here for the evidence one on the back page? Can't remember the precise wording or letters attributed to the evidence.

Evidence that it's an active process
- Metabolic inhibitors stop translocation (i.e. it requires energy to take place, poisons prevent this energy production and therefore it will stop).
- High temperatures stop/slow the process (requires carrier proteins to load the phloem).

Evidence that it's from source to sink
- Whichever one said they import the assimilates was probably a good shout.
- T'other one.

Irrelevant (i.e. not written in answer)
- **** the aphids, they prove cock all. (it only told you they can be used to analyse sap in the phloem vessel).
- The one about movement from leaf into vessel (sure, it goes into a vessel, nothing about the net movement in this context is suggested though).

roast me
(edited 7 years ago)
Original post by Charlotte.P
I think that the answer to the SA:V ration multiple choice was B) 2cm side length


I agree.

SA : V

(22x6) : (23) = 24:8 = 3:1
(edited 7 years ago)
Original post by Simbak6
There was a 1 mark question about how zoo's prevent the rhinos becoming extinct other than captive breeding (which hadn't worked).

As an answer for this I wrote that zoo's have no poachers so the rhinos cannot be killed e.g. for their horns.
I did originally write about how zoo's have vets which can help ill animals and prevent them from dying, I changed it last minute because i wasnt sure but i'm pretty sure that could have been a potential answer since it was one a 1 marker.


I think it was looking for more about conservation though education e.g donations and awareness and that kind of thing, I do AQA environmental studies, and questions that are worded like that have those kind of things on the mark scheme, although you may be right!

Hope you did well!
Reply 84
Avatar for VivianaG
VivianaG
I put Bohr shift would I still get the mark?
Original post by jbman690
if 0.3 was the original then it would be 6600% but if 20.1 was the original it would be 98.5%


Since it said percentage increase, not percentage decrease, it's 6600% I think
Original post by MsDanderson
Since it said percentage increase, not percentage decrease, it's 6600% I think


Any positive value of percentage change is still an increase, regardless of if it is less than 100% (i.e. if it is 100% it is doubled, if it is 0% there is no change => his value is still a percentage increase).
Original post by jbman690
its not 98.5% larger, the difference between 20.1 and 0.3 as a percentage of 20.1 is 98.5%


The original was not 20.1, the original is 0.3. Hence percentage increase. If you're going from 20.1 to 0.3 that's decreasing
Original post by DoubleDoors
Any positive value of percentage change is still an increase, regardless of if it is less than 100% (i.e. if it is 100% it is doubled, if it is 0% there is no change => his value is still a percentage increase).


Yes, I know that. You've misunderstood what I've said.
Original post by VivianaG
I put Bohr shift would I still get the mark?


Hope so, I put that as well; here's some references to old OCR spec mark schemes which say 'bohr shift':
http://www.ocr.org.uk/Images/63763-mark-scheme-unit-f211-cells-exchange-and-transport-june.pdf


http://www.ocr.org.uk/Images/58194-mark-scheme-unit-f211-cells-exchange-and-transport-january.pdf

http://www.ocr.org.uk/Images/235464-mark-scheme-unit-f211-cells-exchange-and-transport-june.pdf
What did everyone out as to why red blood cells don't use up any of the oxygen that they carry?? I out that they don't respire because they don't have a flagellum to move so they don't require ATP. They don't respire so they don't need oxygen. I'm not too sure about it hough since it was a bit of a last minute answer.
(edited 7 years ago)
Original post by Charlotte.P
What did everyone out as to why red blood cells don't use up any of the oxygen that they carry?? I out that they don't respire because they don't have a flagellum to move so they don't require ATP. They don't respire so they don't need oxygen. I'm not too sure about it hough since it was a bit of a last minute answer.


The more immediate answer would be that they do not have mitochondria, therefore do not use up oxygen during aerobic respiration.
Original post by VivianaG
I put Bohr shift would I still get the mark?


I put that too, hopefully
Original post by Yukio.X
The % increase was defo 98.5% 6600 dosnt make sense at all...


Posted from TSR Mobile


THANK GOD SOMEONE ELSE GOT 98.5%! 6600% is FAR too big of an increase, i swear?! (got that initially)
Original post by typicalvirgo
THANK GOD SOMEONE ELSE GOT 98.5%! 6600% is FAR too big of an increase, i swear?! (got that initially)


If you think of 100% as one lot of 0.3, 6600/100 = 66 lots of 0.3

66*0.3=19.8 (which is the increase from 0.3)

The large value looks odd just because OCR like to **** with us for crack.
I'll shove this on a google docs later on and tidy it up a bit; in the meantime if people could recall question numbers and have any more questions they remember that'd be great.
Original post by VivianaG
I put Bohr shift would I still get the mark?


I put this, I guess so
Reply 97
Avatar for oweymo
oweymo
Did anyone put for the water potential, you know its between 0.2 and 0.3 so take furher readings between those two values
For the % change question i got 6600% at first BUT I read the question again and i'm sure it said 'calculate % change from BLOOD to PLASMA' i.e (0.3-20.1/20.1 x 100) so i did that and got (-) 98.5%

Was plasma 0.3 and blood 20.1?
Original post by oweymo
Did anyone put for the water potential, you know its between 0.2 and 0.3 so take furher readings between those two values


I did! I said repeat the experiment with concentration between those two values though in hindsight I should have talked about the graph

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you