OCR F211 May 25th Biology

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Reply 100

sohinder

for the mesosome i put releases energy in bacteria :s-smilie:

Reply 101

TougherThanYSZ

Prokaryotic question- put naked dna, they'd probably accept- nucleoid (area naked dna is), circular dna and bacterial dna. Any of those are fine.

For mesosome q', I put, site of atp production - it's in text book, so it's right.

Staining question - to distinguish between cells and/or highlight specific organelles.
TEM SEM questions - TEM can see lysosomes (or any other organelle present in white blood cell) SEM - 3-d surface structure of erythrocyte, biconcave disc etc.

Really annoyed about the methylene blue and yeast questions. Lost a ridiculous amount of marks in my opinion due to stupid questions asking virtually the same thing. For f211 you don't have to know about a proteins tertiary structure being denatured at higher temperatures, so I can only assume it was focused on plasma membranes and how they become leaky. But yeah, really badly written exam to be honest.

For cell budding question i wrote mitosis, stated the four phases (pmat) and then said that cell budding begins after these. Was only a 2 mark question, shouldn't need much detail.

Comparing animal and plant cell questions, really easy one this, just put - cellulose cell wall in plant cell, whereas it isn't present in animal cell, and cell vacuole " " ...

Heart rate Q, got 60/0.8 = 75.
Digitalis question, said bpm was lowered and diastole was significantly longer. Isn't in text book, so as long as you described the electrocardiograms you should be fine.

Xylem question was about "Water uptake up the Xylem" so features here- Transpiration pull (tension in water, transpiration stream), capillary action (cohesion between water molecules and adhesion to xylem walls) and root pressure, endodermis causes root pressure by pumping nutrients into xylem, so not much else about the roots was needed. Apoplast, symplast and vacuolar pathways needn't be mentioned as water uptake occurs in the xylem alone- dead cells.

Fetal haemoglobin, pretty easy, has a lower affinity to oxygen and must "take up" oxygen in an environment which causes maternal oxyhaemoglobin to dissociate with oxygen.
Bohr shift curve should have been lower and to the right of the standard oxyhaemoglobin dissociation cure - when carbon dioxide is present in respiring tissues oxygen dissociates from oxyhaemoglobin more readily. However, I think I forgot to explain why, as in, Hydrogen ion competing with Oxygen molecule etc.

Meiosis question stumped me as it's more of an A2 question. But I circled 2 sister chromatids joined by the centromere (1 of them) but reading up about it I am unsure whether this is correct, probably should have been 2 which are the same size (so 2 of them).
Next part, sister chromatids should have been drawn as singular seperate strands.

Grade boundaries WILL be lower than 48 out of 60 for this exam easily, it just depends by how much. In my opinion, 40 will be an A if they're really strict, probably just 42 out of 60 marks will be an A.

Now for F212...

Reply 102

LittlestTurner

I have check through the OCR F211 Syllabus and as far as I can see there is nothing about yeast cells and methylene blue. That question was really unfair, I mean methylene blue to do with microscopes or mitosis would be fine but the yeast one was odd. I guess they would say it was to do with plasma membranes which I did write about and they would probs put it down to 'stretch and challenge' which seems to be their favourite phrase. Yep bring on F212!

Reply 103

sapphire23X

LittlestTurner

I only knew a tiny bit about the yeast thing because it was in my CGP textbook, there is NOTHING in the official OCR book :/
Humm, I found some of this exam really easy but there were a few questions that I thought were extremely unfair, and they were the questions that yielded higher marks. Arrr.

Reply 104

---hamza---

I read somewhere that the grade boundary for an A in a previous f211 was 40. And i did that in class as a mock and found it slightly easier than this one. i got 50/60 in that i think. so its all good for me aneways. gud luk the rest of u people with therest of ur exams.

Reply 105

eddie90

well for the mesosomes bit, its defo the site of production for ATP.

for the active transport bit, i said that at lower temperatures , because active transport only works 1 way (due to change in carrier protein through use of ATP), the blue stain in the cell would remain there until the membrane became leaky in which the blue stain would then move out membrane at higher temperatures as could move freely.

i got 75 for heartbeat (in previous test(S) it had been 75 so thought most probably right, considering average heartbeat is between 60-80 per min i think)

for budding i said it reproduces by mitosis to produce 2 genetically identical cells to each other and parent cell (it also says this on wikipedia i think - checked after exam)

put 3D images to shows biconcave shape for both SEM and TEM lol. safe bet one is right (i hope) XD

for the weird heart thing i put that it had increased ventricular systole and diastole casue both were over a longer period of time.

and for the fetal haem. i put it has higher affinity than adult haem, and it cant get oxygen from outside so needs to get from the blood in placenta and needs area which has a low enough oxygen tension for the maternal haem. to disociate with the oxygen molecules. sounded right to me but who knows lol.

na im pretty sure grade boundaires will be pretty low, cause all other past papers were really easy compared to this and this test was based on mainly pictures in the OCR text book and hardly on the actual information in them.

Reply 106

TougherThanYSZ

Let's hope the grade boundaries are lower. It's got me slightly worried about f212, however, if you look at the past papers there's some content which hasn't been covered yet in the new specification, same with f211, you can bet your life that the content which hasn't been covered will come up. Also, hopefully they get some feedback from f211 and use a back up paper instead if they were going to use similar styled baffling questions.

Reply 107

bex_1_2_1

pauljoseph

Fetal haemoglobin, pretty easy, has a lower affinity to oxygen and must "take up" oxygen in an environment which causes maternal oxyhaemoglobin to dissociate with oxygen.

isnt it higher?

Reply 108

There will be Particles

bex_1_2_1

isnt it higher?

Fetal Haemoglobin has a higher affinity to Oxygen than the mother's (adult) at lower partial pressures of Oxygen.

Reply 109

Andygunner93

Does anyone no what you needed to get out of 40 for an A in the practilcal assesment?

Reply 110

iloverocknroll

Andygunner93

Does anyone no what you needed to get out of 40 for an A in the practilcal assesment?

32 FOR AN A :smile:

Reply 111

TougherThanYSZ

Originally Posted by pauljoseph

Fetal haemoglobin, pretty easy, has a lower affinity to oxygen and must "take up" oxygen in an environment which causes maternal oxyhaemoglobin to dissociate with oxygen.

isnt it higher?/QUOTE]

Yeh it has a higher affinity for oxygen. Sorry was rushing that lengthy post

Reply 112

merrmerr

what did everyone draw for the chromosome question with the haploid number??

Reply 113

merrmerr

i drew 3 single separate strands! cos it says at the top it was in prophase...so doesnt that mean the chromosomes had already been replicated?? so didnt you have to divide by 4 and then draw separate strands....all my friends drew 3 sister chromatids (so they drew 3 crosses so 6 chromosomes all together)...im the only one who just drew 3 singular i think i am wrong!!!

Reply 114

lmfw

Marshmellow.

BIG BLOODY OOPS.

Was the question how does it travel up the roots and out through the leaves or how does it travel through the xylem and out through the leaves?

'Cause if it was root, I should get some credit because I talked about the active transport of minerals changing the water potential in the different layers of cells and thereby creating a transpiration movement across the entire root cortex..

I was sure it was Root-Xylem? I said nothing about movement in the actual xylem and everything about water potential/ions etc like you?

Reply 115

Marshmellow.

LisaWilliams

I was sure it was Root-Xylem? I said nothing about movement in the actual xylem and everything about water potential/ions etc like you?

I'm 100% it said how is it transported through the roots to the leaves. So I only talked about the transport through the roots.. and then just said as soon as it gets to the leaves this and this happens. But the transport up the xylem is how it reaches the leaves. :o:

However, there wasn't enough room to write about the role of the root cortext and the role of the xylem?

Reply 116

Marshmellow.

Andygunner93

Does anyone no what you needed to get out of 40 for an A in the practilcal assesment?

I think it's 35. Because I only just managed to get a B and got 30/40.. Although it might be something like 32 or 33. So somewhere in the 30-35 range I'd imagine