Year 12s: what will be the first way you research your future options? >>

A2 Biology OCR June 2015 Revision Thread

Scroll to see replies

June 10 F214 Q5aiii - when is the membrane most permeable to potassium ions.

Apparently the answer is D. But the potassium ion channels open at C, so this is when the concentration gradient will be greatest, so surely this is when the membrane is most permeable to potassium ions no? I don't understand how it could possibly be half way into re-polarisation, when clearly by this point there is a much lower electrochemical gradient.

I made the same mistake , I think C is meant to be showing closing of the sodium channel ....

Reply 961

maisie__x

Original post by TheLegalDealer

I made the same mistake , I think C is meant to be showing closing of the sodium channel ....

I think it's because C is meant to show when sodium ion channels are full open, the cell becomes positively charged, then D is when potassium ion channels open due to the change in potential difference and the cell becomes re polarised :smile:

Reply 962

TheLegalDealer

Original post by maisie__x

Yup , that makes sense cheers !

Reply 963

Hilton184

Hmm yeah I can see what you mean. Pretty poor diagram really if that's what they are trying to imply, because the sodium ion channels close and potassium ion channels open when +40mV is reached, not sodium ion channels close at +40mV and then half way back to resting potential potassium ion channels suddenly open.

Posted from TSR Mobile

Reply 964

Ahsen2015

does anyone know what to get for full UMS on f214?

Reply 965

AnnekaChan173

Original post by Ahsen2015

does anyone know what to get for full UMS on f214?

I posted this up some time ago on the chemistry thread I think

Reply 966

Ahsen2015

Thanks, how is everyone revising for Biology?

Posted from TSR Mobile

Reply 967

Ahsen2015

Cos I'm really worried, I've had awful biology teachers this year and haven't gone through the last 2 modules of f215, so what's the best way to go over it etc

Posted from TSR Mobile

Reply 968

PinkElephant16

Can someone pls help me with this question?? Screenshot from 2015-05-29 04:20:34.png

(It's june 2010 2bii)

Reply 969

huniibehi

Use A2 biology 101 notes there quick and simple, also Mr BioTom on YouTube has some great explanation videos, and deffo look through past papers so you get the hang of things!

Posted from TSR Mobile

Reply 970

huniibehi

Original post by PinkElephant16

Can someone pls help me with this question?? Screenshot from 2015-05-29 04:20:34.png

(It's june 2010 2bii)

First just do the cross to make it clear, as you can see the phenotypic ratio is 1:1 for red eyed and white eyed if the red eyed parent is heterozygous, so that cannot be a good explanation. as we know the probability of male:female is also 1:1 so a male with red eyes should be equally as likely to get white eyes

Posted from TSR Mobile

1432880771188.jpg84.2KB

Reply 971

huniibehi

Original post by PinkElephant16

Can someone pls help me with this question?? Screenshot from 2015-05-29 04:20:34.png

(It's june 2010 2bii)

Hopefully this makes sense

Posted from TSR Mobile

1432881496566.jpg49.1KB

Reply 972

bbadonde2

Original post by huniibehi

Use A2 biology 101 notes there quick and simple, also Mr BioTom on YouTube has some great explanation videos, and deffo look through past papers so you get the hang of things!

Posted from TSR Mobile

Past papers are literally the key to success with these exams!

Reply 973

HappyCheesecake

Original post by Ahsen2015

does anyone know what to get for full UMS on f214?

I made excel spreadsheets for F214 and F215 grade boundaries (including raw marks needed for full UMS). Here they are:

(edited 8 years ago)

That's really helpful! Good job :top:

Reply 975

hameesh

Original post by Ahsen2015

Cos I'm really worried, I've had awful biology teachers this year and haven't gone through the last 2 modules of f215, so what's the best way to go over it etc

Posted from TSR Mobile

First time posting so I'm not sure how much help I will be. I would recommend going through some key areas in the spec.

For Animal responses I would:
- Know why animals need to respond to their environment (same as why plants to)
- Ensure you know the difference in the Central Nervous system and the peripheral
- Know what/where the Cerebrum, cerebellum, oblongata and hypothalamus do/are in the brain
- Give a detailed account of how muscle contraction is produced (make a flowchart of the steps and keep going over it)
- Know how a neuromuscular junction is different to a synapse (neurotransmitters/structure)
- Differences in structure/function between voluntary, involuntary and cardiac (a lot of questions go for comparative tables so make a meaty one with as many as you can)
- Explain how hormones and nerves are involved in flight/fight (often in longer QWC questions)

For Animal behaviour:
- List advantages of innate behaviour (+ some characteristics and examples)
- Know what escape reflexes, taxes and kineses do (+ one example for each)
- Define learned behaviour
- Know what habituation, imprinting, classical and operant conditioning, latent and insight learning are (+ again use examples)
- Examples and definition of social behaviour in primates (NEVER use humans as examples though as mark schemes are haters on it)
- Know about dopamine receptor DRD4 and abnormal behaviour

For animal behaviour you might have picked up the vibe that you need examples. Most mark schemes tend to give another mark if you give an example with a definition.

My teacher for this had a mare so we ended up teaching ourselves. Hope this helps you out, not a clue if its what you were after

Reply 976

TheLegalDealer

Can someone explain to me how to produce Golden Rice + do we have to learb the exact species involved ?

Reply 977

games211

Original post by TheLegalDealer

we have to know that ?! I just use Viruses on Qs about gene therapy

How can you tell what vector to use ? I remember a question and the possible options were: liposomes. bacs, viruses etc etc ;/

Reply 978

George444

Hi guys, anyone got any revision notes/resources for the synoptic element of F214 and F215?

Reply 979

cr7alwayz

Could someone kindly describe the stucture of the sliding filament model and explain how the sliding filament model works. The diagrams in the textbook look complicated.