A2 Biology OCR June 2015 Revision Thread

Original post by danwilliams33

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????

I've finally found something.
'The amygdala appears to be a center of emotions (e.g., fear). It sends signals to the hypothalamus and medulla which can activate the flight or fight response of the autonomic nervous system.'
Source: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CNS.html

So this seems to suggest the medulla oblongata is in fact stimulated in the fight/flight response and so impulses are transmitted along the accelerator nerve to increase the heart rate.

It's still strange that this isn't mentioned on wikipedia or other sources and everything tries to imply the hypothalamus coordinates the response... However this makes more sense!

Reply 22

Original post by Hilton184

I've finally found something.
'The amygdala appears to be a center of emotions (e.g., fear). It sends signals to the hypothalamus and medulla which can activate the flight or fight response of the autonomic nervous system.'
Source: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CNS.html

So this seems to suggest the medulla oblongata is in fact stimulated in the fight/flight response and so impulses are transmitted along the accelerator nerve to increase the heart rate.

It's still strange that this isn't mentioned on wikipedia or other sources and everything tries to imply the hypothalamus coordinates the response... However this makes more sense!

The medulla oblongata is responsible for coordination of the unconscious functions of the body, such as breathing and heart rate.
The cardiovascular centre is a region in the medulla oblongata which receives sensory inputs about levels of physical activity blood pressure and blood carbon dioxide concentrations and sends nerve impulses to the SAN to alter the frequency of excitations waves.

Reply 23

Original post by jjblok

The medulla oblongata is responsible for coordination of the unconscious functions of the body, such as breathing and heart rate.
The cardiovascular centre is a region in the medulla oblongata which receives sensory inputs about levels of physical activity blood pressure and blood carbon dioxide concentrations and sends nerve impulses to the SAN to alter the frequency of excitations waves.

Thanks for your reply. Yeah I know that, but what I'm essentially asking is: is the medulla oblongata responsible for is the increase in heart rate during the fight/flight response, or is the increase in heart rate solely due to the action of adrenaline.

And if the medulla oblongata is involved, why do texts quote the hypothalamus as 'controlling the fight/flight response'. 😊

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Reply 24

Original post by Hilton184

Thanks for your reply. Yeah I know that, but what I'm essentially asking is: is the medulla oblongata responsible for is the increase in heart rate during the fight/flight response, or is the increase in heart rate solely due to the action of adrenaline.

And if the medulla oblongata is involved, why do texts quote the hypothalamus as 'controlling the fight/flight response'. ��

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My findings on the almighty internet, this is the best explanation I could find however it may be a little too detailed.

The hypothalamus is a bit like a command centre. This area of the brain communicates with the rest of the body through the autonomic nervous system, which controls such involuntary body functions as breathing, blood pressure, heartbeat, and the dilation or constriction of key blood vessels and small airways in the lungs called bronchioles. The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system functions like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system acts like a brake. It promotes the "rest and digest" response that calms the body down after the danger has passed.
After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream. As epinephrine circulates through the body, it brings on a number of physiological changes. The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs. Pulse rate and blood pressure go up. The person undergoing these changes also starts to breathe more rapidly. Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper. Meanwhile, epinephrine triggers the release of blood sugar (glucose) and fats from temporary storage sites in the body. These nutrients flood into the bloodstream, supplying energy to all parts of the body.

Reply 25

Original post by jjblok

My findings on the almighty internet, this is the best explanation I could find however it may be a little too detailed.

The hypothalamus is a bit like a command centre. This area of the brain communicates with the rest of the body through the autonomic nervous system, which controls such involuntary body functions as breathing, blood pressure, heartbeat, and the dilation or constriction of key blood vessels and small airways in the lungs called bronchioles. The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system functions like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system acts like a brake. It promotes the "rest and digest" response that calms the body down after the danger has passed.
After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream. As epinephrine circulates through the body, it brings on a number of physiological changes. The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs. Pulse rate and blood pressure go up. The person undergoing these changes also starts to breathe more rapidly. Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper. Meanwhile, epinephrine triggers the release of blood sugar (glucose) and fats from temporary storage sites in the body. These nutrients flood into the bloodstream, supplying energy to all parts of the body.

Hey
Yeah I keep seeing articles like that, so that's suggesting that it is adrenaline responsible for the increase in heart rate in fight/flight response and has nothing to do with the medulla oblongata? But then a mark scheme says award marks for 'correct reference to medulla oblongata' so this continues to confuse me.

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Reply 26

Original post by Hilton184

Hey
Yeah I keep seeing articles like that, so that's suggesting that it is adrenaline responsible for the increase in heart rate in fight/flight response and has nothing to do with the medulla oblongata? But then a mark scheme says award marks for 'correct reference to medulla oblongata' so this continues to confuse me.

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Yes it is all confusing, and was that mark scheme from official ocr paper?

The way I think about it, is that the medulla oblongata changes heart rate when it receives sensory inputs about physical activity, CO2 concentration and blood pressure. But adrenaline changes heart rate in response to stress, so adrenaline is the main factor in fight-or-flight. But as the mark scheme says I guess the medulla oblongata is also used in the fight-or-flight, because it sends action potentials to the adrenal glands to excrete the adrenaline. So its cell signalling between the two, so they work together to bring about the the response.

Reply 27

Original post by jjblok

Yes it is all confusing, and was that mark scheme from official ocr paper?

The way I think about it, is that the medulla oblongata changes heart rate when it receives sensory inputs about physical activity, CO2 concentration and blood pressure. But adrenaline changes heart rate in response to stress, so adrenaline is the main factor in fight-or-flight. But as the mark scheme says I guess the medulla oblongata is also used in the fight-or-flight, because it sends action potentials to the adrenal glands to excrete the adrenaline. So its cell signalling between the two, so they work together to bring about the the response.

Yeah, it's F215 Jan 2011 question 2e, a 9 mark question on the fight/flight response.
Yeah I agree the medulla oblongata changes heart rate in response to change in blood pressure/pH of blood.
And the heart rate also increases when adrenaline is secreted from the adrenal medulla. However note it's the hypothalamus that stimulates the adrenal medulla to secrete adrenaline.

So basically:
Textbooks say hypothalamus controls fight/flight response, which is correct in most respects.
But in addition, mark scheme gives 'AVP' mark for 'correct reference to medulla oblongata' so I presume that the medulla oblongata also acts to increase the heart rate in the fight/flight response? Oh well at least it's nothing too major, would be nice to know a definite answer though!

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Reply 28

ChoccyPhilly

13

Can't wait for this thread to explode come April/may

Reply 29

danwilliams33

OP

1

Original post by ChoccyPhilly

Can't wait for this thread to explode come April/may

yk

Reply 30

Another nervous system related question, F215.

Specification says 'describe the role of the brain and nervous system in the coordination of muscular movement'

Does this question want something along the lines of...
'Nerve impulses transmitted from cerebellum to motor areas of cerebrum in order to adjust/fine tune motor area output to effectors/muscles.
This ensures motor area output is coordinated in such a way to ensure movement is precise and accurately timed, and balance and posture is maintained. Hence muscular movement is coordinated.'

I mean its not really clear in the official textbook what exactly is required to answer this question if it came up, which I'm sure it could do for 3 or 4 marks. Most revision guides don't really go into any detail at all that links to this specification point. How would you go about answering this question, anybody?

Reply 31

When amino acids are used in respiration, do the keto acids enter the krebs cycle directly, or is it the amino acid? The excretion chapter of the book says the keto acids enter the krebs cycle, but the respiration chapter says that the amino acid does (maybe by amino acids, they mean without the amine group).

Reply 32

Beni24

Hey guys, I've created a thread for the OCR F215 June exam, Thought it might help each other with revision help and share questions to help achieve higher grades. We can start building a group of people who will be taking this exam in June :smile:

Here it is:
http://www.thestudentroom.co.uk/showthread.php?t=3120025&p=53345149#post53345149

Reply 33

Asif_m96

1

Anyone here do AQA chemistry A2? If so check out my chem thread. Also this bio thread is very useful.

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Reply 34

nik345

5

Hey guys, I'm gonna be resitting the F214 paper in the summer. Are the modules the same as last year? Are there any changes?

Reply 35

hkka2323

Hi guys,
I need some advice if anyone could help it would be great I am going to do F212, F214 and F215 in june 2015 and in my mock exams I got U's do you think that 4 months is enough to revise for these exams and get a B overall in biology. FYI I got a B in F211 and F213
please help!

Reply 36

Original post by hkka2323

Hi guys,
I need some advice if anyone could help it would be great I am going to do F212, F214 and F215 in june 2015 and in my mock exams I got U's do you think that 4 months is enough to revise for these exams and get a B overall in biology. FYI I got a B in F211 and F213
please help!

If you are revising like normal, then no. If you want to push them U grades into B or higher then you are going to have to work really hard. You may not believe me, but I know a guy who got EUUU at AS, then in year 13 he worked extremely hard, he had little of his sanity remaining, he was retaking almost everything from AS so he would study like 45 hours + a week outside of school. He gave up his social life and his hobbies, but in the end he got A*A*A*a. So he proved that with hard work you can get the grades you want. 4 months is enough in my opinion, it took me just 2 weeks to go over all of F214. Just make sure you do lots of questions and all of the past papers.

Reply 37

Beni24

Can someone help me with this question( F214)

Respiration can be aerobic and anerobic.

Certain parasites live in the blood of mammals. Suggest why, even though blood carries oxygen, these parasites are adapted to respire anerobically? (2 marks)

Reply 38