A2 Biology OCR June 2015 Revision Thread Watch

danwilliams33
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Just thought I'd set up this thread so that we can start building a group of people for the exam in June.

If you do A2 Biology then please join in on this. Share past papers or questions etc so that we can start to get our grades higher.

A revision thread really helped for my AS so I think this will also be beneficial if we use this for revision aswell. ))))))
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luce'
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I will be doing this exam :/
How far through the content are you, out of interest?
My school is notorious for not finishing the course until like a week before the exam!
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danwilliams33
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(Original post by luce')
I will be doing this exam :/
How far through the content are you, out of interest?
My school is notorious for not finishing the course until like a week before the exam!
F214 - Communication and homeostasis (half of it done)
- Excretion (done)
- Photosynthesis (done)
- Respiration (done)

F215 - Cellular control (half done)
- Biotechnology (not done)
- Ecosystems (done)
- Responding to the environment (not done)

Lol, how much have you covered???
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kendalll
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I'm doing it too!!
I've finished F214 (not learned yet tho)
and only done Cellular control in F215!!

Does anyone have June 2014 papers???
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luce'
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(Original post by danwilliams33)
F214 - Communication and homeostasis (half of it done)
- Excretion (done)
- Photosynthesis (done)
- Respiration (done)

F215 - Cellular control (half done)
- Biotechnology (not done)
- Ecosystems (done)
- Responding to the environment (not done)

Lol, how much have you covered???
Done f214, started cellular control (mind****), and did ecosystems (so bloody dull!) but haven't done many controlled assessments yet
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luce'
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(Original post by kendalll)
I'm doing it too!!
I've finished F214 (not learned yet tho)
and only done Cellular control in F215!!

Does anyone have June 2014 papers???
Did June 2014 for my mock- it's awful...so many suggest questions! Won't be getting the paper back for a couple weeks, but can remember some question. Depends why you want it to whether I can help you? :/
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ChoccyPhilly
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I dunno about you guys but the official revision book for this is crap
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Puddles the Monkey
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Just popped this in the biology exam forum :yy: Good luck with it all guys! Check out the threads in the rest of the forum for last years' threads, they might come in handy. I'll try and find them at some point tomorrow and post here.
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danwilliams33
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(Original post by kendalll)
I'm doing it too!!
I've finished F214 (not learned yet tho)
and only done Cellular control in F215!!

Does anyone have June 2014 papers???
F214 june 2014 unofficial mark scheme:
(Unfinished)
These are by no means, entirely correct, they are just brief indications of what I wrote and a few points from other people.
I personally thought it was a hard paper.

Q1)
Name the pigment at the reaction centre (1)


  • chlorophyll a


Name an accessory pigment (1)

  • carotene/xanthophyll/chlorophyll b (POSSIBLY carotenoids)


Purpose of accessory pigments (1)

  • absorb a range of wavelengths not well absorbed by chlorophyll and pass on that energy
  • maybe protect chlorphyll from very intense light


Name of compound formed (1)

  • adenosine triphosphate (ATP)


Enzyme that fixes CO2 in calvin cycle (1)

  • rubisco


stable intermediate formed (1)

  • Glycerate-3-phosphate


Compound regenerated (1)

  • Ribulose bisphosphate (RuBP)


Polysaccharides that can be formed (1)

  • Cellulose and starch/(amylose/amlyopectin)



Q2)
Why is it a transducer? (1)

  • converts one form of energy to another (pressure stimulus converted to electrical energy of nerve impulse)



Suggest how membrane made more permeable to Na+ (1)


  • Gate of sodium ion channel forced open/ deformation by pressure


What is the all or nothing law? (1)

  • action potentials do not vary in size, either happens or doesn't (if reaches threshold potential (-50mV))


How intensity of stimulus signalled to brain? (2)

  • frequency of action potentials indicates strength
  • greater frequency = more intense
    OR
    All action potentials same magnitude but stronger stimuli produce more action potentials


Why do the impulses generated stop? (1)

  • acclimitisation/runs out of vesicles/fatigued


Role of synapses (3)

  • Ensure one direction only
  • Intergration (convergence/divergence)
  • Summation (temporal/spatial)
  • memory and conscious thought
  • Filter out low level signals


Q3)
Condition tested for (1)

  • diabetes mellitus


Why was he fasting? (1)

  • Needs to have a high blood glucose concentration so effect of insulin can be seen


Calculate % increase (2)

  • 18.6%


Explain when a glucagon injection is needed (1)

  • blood glucose concentration low/hypoglacaemia


Hb complex thing why not useful after 8-12 weeks? (2)

  • red blood cells broken down and recycled in liver
  • therefore less Hb complex thing than there should be



Explain why blood glucose was higher in test than over 8 week period (1)

  • nervous before taking exam = increased blood glucose levels/had just been exercising


Describe role of glucagon (5)

  • detected by alpha cell receptors
  • glucaon secreted binds to complementary receptor cells in liver plasma membrane
  • gluconeogenesis (making glucose from fats/amino acids)
  • glycogenolysis(breaking down glycogen to glucose)
  • more fatty acids used in respiration
  • role of adenyl cylase/cyclic AMP
  • glucose leaves cells by faciliated diffusion
  • reference to inhibitory effect of hormone (stops insulin secretion)


Explain why concentration of NAQ thing builds up (2)

  • the glutathione runs out
  • enzymes become saturated, cannot work quickly enough


Name a neurotransmitter (1)

  • acetylcholine


Where are the receptors located on the neurone and explain (2)

  • either pre or post synaptic membrane
  • stop secretion/stop binding


Diagram of liver (5)

  • sinusoid
  • bile duct
  • hepatic portal vein (branch of)
  • hepatic artery (branch of)
  • hepatic vein (branch of)


Liver cells that divide are called and how they do (1)

  • hepatocytes and mitosis


Describe how respiration rate of cauliflower changes with temperature (2)

  • rate increases as temperature increases
  • figures quoted, trend (5 to 10 degrees rate doubles)


What are the best conditions from table? (1)

  • low temperature (0 degrees)


Which is the best fruit/vegetable to store and explain (3)

  • Onion as slowest rate of respiration at all temperatures
  • possibly potato at 0 degrees? unknown rate of respiration
  • really don't know what else to put for this one


Which is the worst one and why? (1)

  • asparagus as has highest rate at all temperatures


Why do parasites in blood respire anaerobically? (2)

  • oxygen tightly held to haemoglobin
  • no oxygen was the selection pressure for natural selection
  • can't kill host, so cannot use their oxygen
  • travel in deoxygenated areas of body (in veins) (possibly)


Why is anaerobic respiration in animals reversible? (3 + QWC)

  • In mammals pyruvtae turned into lactate
  • lactate converted back to pyruvate in liver
  • in yeast CO2 released
  • Maybe doesn't have enzymes for conversion back?
    possibly lactate/ethanol dehydrogenase catalyse both directions, pryruvate carboxylase cannot


Where is glucose reabsorbed? (1)

  • PCT ( I think the label was Q)


Parts of the nephron in cortex (1)

  • All of them except the loop of henle and lower part of the collecting duct


Where are podocytes found? (1)

  • Renal capsule label


how long loop of henle helps desert mouse (2)

  • greater salt concentration in medulla
  • more water reabsorbed by osmosis from collecting duct
  • maybe ref. to mechanism, impermeable ascending walls, greater countercurrent mechanism


Substance tested for in urine (1)

  • anabolic steroids
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danwilliams33
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(Original post by ChoccyPhilly)
I dunno about you guys but the official revision book for this is crap
Is it the book with the brain on the front??
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danwilliams33
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(Original post by kendalll)
I'm doing it too!!
I've finished F214 (not learned yet tho)
and only done Cellular control in F215!!

Does anyone have June 2014 papers???
F215 june 2014 unofficial mark scheme:

Continuous variation example (1)

Body Length
Weight

Discontinuous variation example (1)

Eye colour
Gender

Frequency of dominant allele (3)

The answer is 0.5

45/60 are brown. (75%)
because brown is dominant this means that p^2 + 2pq = 0.75
1 - 0.75 = 0.25. Therefore q^2 = 0.25
Root . 25 = 0.5. Therefore q = 0.5
1 - 0.5 = 0.5. Therefore p = 0.5
Therefore allele frequency of p (dominant) = 0.5

How a gene is expressed (7)

Helix untwists
Hydrogen bonds break between bases
Chain unzips
Free nucleotides bind to template strand
mRNA complementary to template strand peels away
mRNA leaves through the nuclear pore
mRNA binds to small subunit of a ribosome
mRNA is exposed to the large subunit
1st tRNA brings an amino acid and attaches to the 1st codon
2nd...
3rd...
1st leaves to collect another
Continues until the ribosome reaches a stop codon
Polypeptide has now been assembled

Discuss the advantages and disadvantage of making ethanol via yeast fermentation compared to the chemical method (6 + 1 QWC)

ADVANTAGES//

Low temperature for enzymes to work at their optimum so cheaper energy costs
Low pressure so don't need expensive and strong equipment to withstand high pressures
Renewable source of sugar so better for the environment as don't need to use fossil fuels

DISADVANTAGES//

Slower rate of reaction as lower temperature
Batch process so less efficient - have to stop the reaction to clean out the batch and distill product
Lower volume of product produced as have to stop the reaction, whereas ethene --> ethanol is a continuous reaction.

Enzyme that turns mRNA into DNA (1)

Reverse transcriptase

Question about muscles with blank spaces (5)

1. Mitochondria
2. Oxidative Phosporylation
3. Creatine Phospate
4. Cross Bridge
5. Myosin Head

Neuromuscular junction labels (3)

1. Protein
2. Synaptic cleft
3. Acetylcholinesterase

Difference between Pioneer Community/Climax Community (2)

Primary: Living organisms which first begin to colonise bare ground (e.g sea rocket close to water line on a sand dune)
Climax: The stable community that emerges at the end of succession

Difference between preservation and Conservation (2)

Preservation is leaving a habitat alone, (non-intrusive)
Conservation is active maintenance of a habitat, e.g. coppicing felling

Difference between Decomposition and denitrification (2)

Decomposition is the decay of recently dead organisms, (decomposers are saproprhytic bacteria), Denitrification is the conversion of nitrates to Nitrogen by bacteria.

Difference between Nitrogen fixation and Nitrification (2)

Nitrogen fixiation is conversion of Nitrogen to ammonia ions and nitrates by lightning, haber provess and Rhibozium bacteria
Nitrification is oxidation of ammonia ions to nitrates and nitrites.
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Asif_m96
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The June 2014 paper was bad. It had very low boundaries though (42 was an A)


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s23t
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do you have the full MS this seems to be only 36 marks
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danwilliams33
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(Original post by s23t)
do you have the full MS this seems to be only 36 marks
I didn't make it so no I don't.

SORRYYY
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s23t
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does ANYONE have the MS for june 2014 f215 please i have a mock tomorrow afternoon
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WesterosWildling
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(Original post by s23t)
does ANYONE have the MS for june 2014 f215 please i have a mock tomorrow afternoon
Snap me too. I think I'll let it be a surprise though, no one's got it anyways.

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danwilliams33
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(Original post by WesterosWildling)
Snap me too. I think I'll let it be a surprise though, no one's got it anyways.

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Scroll up, ive put one in here 18 hours ago!!!
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WesterosWildling
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(Original post by danwilliams33)
Scroll up, ive put one in here 18 hours ago!!!
Sorry I thought it was another f214 I haven't done that unit yet.

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Hilton184
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Hey

So the OCR textbook says in the key definition that the hypothalamus is 'effectively in control of the autonomic nervous system '

And yet it also says in a box that the medulla oblongata is 'effectively in control of the autonomic nervous system'

Now i understand that the medulla oblongata is in control of heart rate and respiration rate, which are autonomically regulated, and the hypothalamus is in control of other autonomic pathways.

My problem lies with what is in control of the fight or flight response. The textbook says it's the hypothalamus, every internet resource says it's the hypothalamus.
In the fight or flight response the heart rate and respiratory rate increase. However this is solely due to the action of adrenaline I believe and not impacted by the medulla oblongata increases them?

However, a question on the fight or flight response had marks under AVP for 'correct reference to medulla oblongata', which leads me to believe that the medulla oblongata does increase the heart/respiratory rate in the fight/flight response... But then why do no sources about the fight/flight response even mention the medulla oblongata?

Sorry for the long post but this is really bugging me! I know it's probably quite pedantic but I feel like it's something they could ask!


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danwilliams33
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(Original post by Hilton184)
Hey

So the OCR textbook says in the key definition that the hypothalamus is 'effectively in control of the autonomic nervous system '

And yet it also says in a box that the medulla oblongata is 'effectively in control of the autonomic nervous system'

Now i understand that the medulla oblongata is in control of heart rate and respiration rate, which are autonomically regulated, and the hypothalamus is in control of other autonomic pathways.

My problem lies with what is in control of the fight or flight response. The textbook says it's the hypothalamus, every internet resource says it's the hypothalamus.
In the fight or flight response the heart rate and respiratory rate increase. However this is solely due to the action of adrenaline I believe and not impacted by the medulla oblongata increases them?

However, a question on the fight or flight response had marks under AVP for 'correct reference to medulla oblongata', which leads me to believe that the medulla oblongata does increase the heart/respiratory rate in the fight/flight response... But then why do no sources about the fight/flight response even mention the medulla oblongata?

Sorry for the long post but this is really bugging me! I know it's probably quite pedantic but I feel like it's something they could ask!


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Im really not sure how to help with this question because I agreewith you and I guess in this case we just have to assume the mark scheme isincorrect.


Ive done my research also and it says that the ANS is in themedulla oblongata so I guess that’s where the oblongata reference may havestemmed from.
Also, research the adrenal medulla because there was a fewsources on that which may help.
Other than that I think we just have to ignore the ‘dodgy’mark scheme and assume that it is the hypothalamus that stimulates the fight orflight response
Yh????
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