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# OCR Biology A Exam Thread (Breadth - May 26, 2016 and Depth - June 7, 2016) watch

1. You too, hopefully it goes well
(Original post by Carrot_Cake_13)
Ah ok. Well good luck with the exams tmrw :')
2. What would happen if I drink red bull before tomorrows exam?
3. perhaps tachycardia
(Original post by IXxi HIIDA ixXI)
What would happen if I drink red bull before tomorrows exam?
4. (Original post by kaykaayy)
A quick brief comparison of the microscopes anyone? Magnification, resolution, adv, disadvantages etc.
Optical microscope magnification: x 1500 resolution: 0.2micrometres
Advantages: Cheap, easy to use and portable

TEM magnification: Up to x 1000000 resolution: 0.0002micrometres

SEM magnfication: Up to x100 000 resolution: 0.002micrometres
Advantages of Electron microscopes: Higher resolution & magnification.
5. Man, I'm so ****ed, so many people mention things I haven't learnt 😂
6. (Original post by OddFuturez)
Man, I'm so ****ed, so many people mention things I haven't learnt 😂
Same
7. Any predictions anyone? My teacher said this:
-heart/ cardiac cycle
-enzymes/inhibition
-evolution/darwin etc
-cell membranes/ cell signalling
8. Anyone know what this means? "the importance of sampling the range of organismsin a habitat."
9. Can someone please explain how to do Q3c(i) on the depth practice paper. Its the one with the percentage change. I don't get how they got -14(+-)1
10. What is tachycadia and the other two ?
11. (Original post by 4nonymous)
Can someone please explain how to do Q3c(i) on the depth practice paper. Its the one with the percentage change. I don't get how they got -14(+-)1
find how long one beat lasts for using the trace
Do 60 divided by 1 beat to get the beats per minute
you are given that the dioxin rate was 75bpm
75 - (bpm of normal heart)
divide by 75 and times by 100, as using percentage change formula ((original - difference)/difference) * 100
as the heart rate decreased, put a - in front of the change.

eg. if it doesn't make sense

1 beat = 0.94
60/0.94 = 63.829... = 63.8 bpm
75 - 63.8 = 11.2
11.2/75 = 0.1493... * 100 = 14.93 ≈ 15
≈ -15 as decrease
12. (Original post by sugi10)
What is tachycadia and the other two ?
Tachycardia is when your heart rate is too fast (eg 100bpm)
Ectopic heart beats are when the heart beats too early, followed by a long pause
Fibrillation is when there is an irregularly timed heart beat

and that's all you need to know
13. (Original post by bp_22)
perhaps tachycardia
Wow
14. (Original post by James3000117)
find how long one beat lasts for using the trace
Do 60 divided by 1 beat to get the beats per minute
you are given that the dioxin rate was 75bpm
75 - (bpm of normal heart)
divide by 75 and times by 100, as using percentage change formula ((original - difference)/difference) * 100
as the heart rate decreased, put a - in front of the change.

eg. if it doesn't make sense

1 beat = 0.94
60/0.94 = 63.829... = 63.8 bpm
75 - 63.8 = 11.2
11.2/75 = 0.1493... * 100 = 14.93 ≈ 15
≈ -15 as decrease
TY. I was doing it right up to the point where you do ((original - difference)/difference) * 100 I didnt know this formula.
15. How did people do on the depth paper on the OCR website?
16. (Original post by Desouza123)
Plants have active and passive defences. Passive defences are already present before infection and will prevent the entry of any pathogen.
Passive defences include physical barriers such as cellulose cell wall, waxy cuticle, lignin, stomatal closure, tylose and callose. Chemicals include terpernoids, phenols, alkaloids & hydrolytic enzymes. These are only produced when a pathogen is detected as they require a lot of energy.

Active defences just fortify passive defences e.g. extra cellulose and callose. Active defences also include necrosis which is deliberate cell suicide of a part of the plant that is infected and canker which is death of cambium tissue in the bark.
Thank you!!
17. (Original post by IXxi HIIDA ixXI)
What would happen if I drink red bull before tomorrows exam?
Just done an all nighter, had 2 cans of Emerge, 1 of Monster, 1 Red Bull and am drinking my 2nd Red Bull now. Got another 2 Red Bulls to finish before the exam. I've done this for every exam I had so far

You'll be fine, good luck!
18. Can someone help with this question?

4a) Some single-celled organisms live in estuaries where the concentration of salt changes regularly

Explain, in terms of water potential, the problem faces by these organisms (2 marks)

-I know it's a relatively easy question, & however there are only 3 lines and my explanation takes up more than that. Is there an easier way to sum it up?
19. (Original post by SGHD26716)
How did people do on the depth paper on the OCR website?
59%
20. Can someone explain the phospholipid bilayer and the components please

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