OCR Biology F211 resit - 16th May

Yes. Therefore the question did not ask about setting up equipment or using soda lime, but rather the calculation to do in order to measure oxygen uptake.

Reply 381

Groat

13

Original post by _Jasmine

Yes. Therefore the question did not ask about setting up equipment or using soda lime, but rather the calculation to do in order to measure oxygen uptake.

Yes, nor did I say you have to talk about setting up soda lime. But you haven't shown the examiner that you know why the decrease in air equals the oxygen uptake, which I assume will be a mark.

Reply 382

fran598

Can someone please post a unoffical mark scheme <3 :smile:

Reply 383

puddleduck

16

With the rate of Oxygen uptake spirometer question, was it right to calculate the total volume of oxygen used (from the y axis) then divide that by time taken? I genuinely had no idea what to do :s-smilie:

And has anyone decided whether the gaseous exchange question wanted goblet cells, cilia, cartilage, smooth muscle, elastic etc. or alveoli, one cell thick capillaries etc?

Reply 384

paulbridger

6

Original post by Groat

I think a lot of people may have missed the mark in saying that carbon dioxide exhaled = oxygen inhaled yet the carbon dioxide is absorbed by the soda lime. Therefore the volume lost in the air chamber is the oxygen uptake. :eek:

No, you didn't need to write that, it said "How can the oxygen uptake be measured using the spirometer TRACE" .. not the spirometer itself ;]

Edit: someone's already said this...

(edited 12 years ago)

Reply 385

paulbridger

6

For the measuring oxygen uptake using the spirometer trace I wrote something like:

"You calculate the total volume in the air chamber at the beginning, then you find out how much is left after a set time unit (I.e. a minute)
You subtract the final volume from the initial volume to calculate how much oxygen has been used up"

Does that sound ok? enough for 3 marks? :tongue:

Reply 386

paulbridger

6

Original post by puddleduck

And has anyone decided whether the gaseous exchange question wanted goblet cells, cilia, cartilage, smooth muscle, elastic etc. or alveoli, one cell thick capillaries etc?

I wrote about alveoli, goblet cells, ciliated epithelium, smooth muscle, elastic tissue, alveolar epithelium, and capillary endothelium, and about the large surface area of the alveoli, and the short diffusion distance between the alveoli and capillaries. :smile:

Reply 387

Groat

13

Original post by paulbridger

No, you didn't need to write that, it said "How can the oxygen uptake be measured using the spirometer TRACE" .. not the spirometer itself ;]

Edit: someone's already said this...

Knowing Biology there'll be a number of ways to get the 3 marks, so there's no point arguing. :colone:

However I still think there will be a mark for saying that the oxygen intake = carbon dioxide exhaled therefore the decrease in the volume of air = oxygen intake as carbon dioxide is absorbed.

Reply 388

kazx

Original post by Groat

Yes, but you've just made an assumption out of nowhere that the difference in peaks of the first breath and the last breath is the oxygen uptake. Therefore, it made sense to say that oxygen intake = carbon dioxide exhaled, yet as the carbon dioxide is absorbed, this is also equals the reduction in the volume of air.

I got scared then that I had written about completely the wrong thing then :P

Reply 389

arcticwombats

yo, i explained that oxygen uptake is equal to the amount of co2 absorbed by the soda lime, and then i said that you should minus the lowest mark on the first breath on the trace from the lowest mark on the last breath on the trace, which equalls amount of o2 gone from the tank

didn't do any calculations, as i just thought it was asking HOW you would find the oxgen uptaken

how many marks would i get for what i wrote, or was i just talking absolute sh*t

Reply 390

Straight up G

this thread shud be closed

Reply 391

levantine

12

Original post by sixthformer

this paper had stupid questions on it tbh.

i think it will be 44/60 for an A

even so, i doubt i'll get that

where'd you get that from??? you know I think it will be 58/60 for an A...oh sorry I thought we were playing a game of "lets just say random numbers and pretend to know what weare on about when actually we're just talking bull****"

You have no idea what the boundaries will be just like everyone else who took the exam

Reply 392

sixthformer

Original post by BradfordCityJoss

I put root (tip) cells and in-between xylem and phloem in the stem. I don't know whether or not you need to put Cambium which is right ofc, but there is definitely meristematic tissue in root tip cells and between xylem and phloem in the stem.

It really depends on the mark scheme.

yes you're right

did it ask which organs the stem cells are found i thought? :s-smilie:

like i wrote in brackets cambium in the stem, but yeah

Reply 393

sixthformer

Original post by levantine

where'd you get that from??? you know I think it will be 58/60 for an A...oh sorry I thought we were playing a game of "lets just say random numbers and pretend to know what weare on about when actually we're just talking bull****"

You have no idea what the boundaries will be just like everyone else who took the exam

the grade boundaries are 42-48, never seen it higher or lower
i assumed they'd be somewhere in the middle

the paper was not easy, nor was it the hardest

but you're right, the lower the better i guess

time to focus on next exam

Reply 394

Straight up G

Original post by sixthformer

the grade boundaries are 42-48, never seen it higher or lower
i assumed they'd be somewhere in the middle

the paper was not easy, nor was it the hardest

but you're right, the lower the better i guess

time to focus on next exam

It was 40 for the exam that we did in January, and I don't remember them being 48. Enlighten me please? 46 was the highest I've seen. 48 would mean raw marks % = UMS marks %, which is total crap really.

Reply 395

sixthformer

Original post by Straight up G

It was 40 for the exam that we did in January, and I don't remember them being 48. Enlighten me please? 46 was the highest I've seen. 48 would mean raw marks % = UMS marks %, which is total crap really.

check the boundary for june 2010 IGNORE ME! YOU'RE TOTALLY RIGHT, INFACT, THE BOUNDARY WAS 41/60 LAST YEAR

i did badly in that exam dropping around 20 marks, and i want to apply to medicine, and i know this exam counts for hardly anything lol, it's unit 2 that counts

BUT

=/ yeah maybe ur right

(edited 12 years ago)

Reply 396

puddleduck

16

Original post by sixthformer

i did badly in that exam dropping around 20 marks, and i want to apply to medicine, and i know this exam counts for hardly anything lol, it's unit 2 that counts

Of course this exam counts! It's 30% of your total grade... without it the maximum you'd get is 70%... presuming you've already got 100% in your practicals...

Reply 397

levantine

12

Original post by sixthformer

check the boundary for june 2010 IGNORE ME! YOU'RE TOTALLY RIGHT, INFACT, THE BOUNDARY WAS 41/60 LAST YEAR

i did badly in that exam dropping around 20 marks, and i want to apply to medicine, and i know this exam counts for hardly anything lol, it's unit 2 that counts

BUT

=/ yeah maybe ur right

where you from...(nice prifle picture)