OCR Biology F214

OP

Original post by otrivine

correct

is it because in mammanals urea is toxic which has to be broken before causing harm to other organs. Fish can excrete starighway as they are simple and do have complex bodies containing many organs ?

Partly correct, fish can use lots of water to dilute the ammonia so that it is not toxic for them. The dilute ammonia solution is released straight away. But mammals need to conserve water, they cannot release too much water in the urine. Mammals also release concentrated urine, and is kept in the bladder to be stored. So mammals need to convert ammonia to a less toxic compound, urea, so that it is transported more safely.

I hope that make sense lol
This was posted from The Student Room's Android App on my HTC Desire HD A9191

Reply 42

Original post by ds4143

Partly correct, fish can use lots of water to dilute the ammonia so that it is not toxic for them. The dilute ammonia solution is released straight away. But mammals need to conserve water, they cannot release too much water in the urine. Mammals also release concentrated urine, and is kept in the bladder to be stored. So mammals need to convert ammonia to a less toxic compound, urea, so that it is transported more safely.

I hope that make sense lol
This was posted from The Student Room's Android App on my HTC Desire HD A9191

oh clever one nice
do you think they will accept this answer as it is 1 mark?

Reply 43

OP

Original post by otrivine

oh clever one nice
do you think they will accept this answer as it is 1 mark?

Well i guess if the question was out of two marks, you would atleast get one because you did mention urea being toxic in mammals which is true.
Ooh btw i dont think urea is broken down, i think it combines with carbon dioxide to form urine. Correct me if im wrong

This was posted from The Student Room's Android App on my HTC Desire HD A9191

Reply 44

andrew_c

Original post by otrivine

hey do you want to revise for both units ?

Sure why not :smile:

.

Reply 45

Original post by andrew_c

Sure why not :smile:

.

ok you start :wink:

Reply 46

Original post by ds4143

Well i guess if the question was out of two marks, you would atleast get one because you did mention urea being toxic in mammals which is true.
Ooh btw i dont think urea is broken down, i think it combines with carbon dioxide to form urine. Correct me if im wrong

This was posted from The Student Room's Android App on my HTC Desire HD A9191

yes i think wait is it not remove toxic amino acids in liver then moves to plasma all the way to kidney ready for it to be excreted ?

Reply 47

OP

Original post by otrivine

yes i think wait is it not remove toxic amino acids in liver then moves to plasma all the way to kidney ready for it to be excreted ?

Sorry i dont wuite ubderstand what you mean there but I know that amino acid cannot be stored so it is broken down into ammonia and keto acid ... ammonia is toxic so it combines with carbon dioxide to form urea which now can travel safely in the blood to the kidneys where it is excreted.

This was posted from The Student Room's Android App on my HTC Desire HD A9191

Reply 48

OP

What is the difference between synaptic convergence and summation :/?

This was posted from The Student Room's Android App on my HTC Desire HD A9191

Reply 49

tamitm

Ok anyone revisin for f214?? After the horrid f215 this retake is either gonna make me or break me!
So i thought it's a good idea to revise here!

Reply 50

Horchata

11

Can someone help clear up ultrafiltration for me? this is what I have written down using the textbook and my teacher:

Blood flows into the glomerulus from the afferent arteriole which splits into capillaries to ensure the blood is under increased pressure. Pressure is also increased by the efferent arteriole being narrower than the afferent arteriole.
Blood flows from the higher pressure in the glomerulues to lower pressure in the Bowman's capsule.
The blood containing small soluble molecules pass through the narrow gaps in the endothelium of the capillaries (??) of the glomerulus through gaps in the basement membrane (??) which filts out large molecules of molecular mass greater than 69,0000. The molecules then pass through gaps in the podocytes ensured by major processes.

Does anyone know if all those gaps exist and can anyone make that description better?

Reply 51

Horchata

11

Original post by ds4143

What is the difference between synaptic convergence and summation :/?

This was posted from The Student Room's Android App on my HTC Desire HD A9191

Summation - lots of action potentials in one neurone will lead to many vesicles of transmitter substance being released and depolarisation in the next neurone is more likely to cause an action potential

Convergence - several presynaptic neurones converge to one postsynaptic neurone, allowing signals from different parts of the nervous system to create the same response

Reply 52

sarahbellazir

Ds4143 & otrivine you guys don't stop quizzing each other coz I'm stalking you two on the thread and testing myself with your random questions as I revise haha.. Merci!

This was posted from The Student Room's iPhone/iPad App

Reply 53

Original post by sarahbellazir

Ds4143 & otrivine you guys don't stop quizzing each other coz I'm stalking you two on the thread and testing myself with your random questions as I revise haha.. Merci!

This was posted from The Student Room's iPhone/iPad App

khoesh mikonam :wink:

Reply 54

OP

Original post by sarahbellazir

Ds4143 & otrivine you guys don't stop quizzing each other coz I'm stalking you two on the thread and testing myself with your random questions as I revise haha.. Merci!

This was posted from The Student Room's iPhone/iPad App

Haha

Glad it helps someone >=]

Reply 55

OP

Original post by Horchata

Summation - lots of action potentials in one neurone will lead to many vesicles of transmitter substance being released and depolarisation in the next neurone is more likely to cause an action potential

Convergence - several presynaptic neurones converge to one postsynaptic neurone, allowing signals from different parts of the nervous system to create the same response

OOOOHHHH wow thanks for clearing that up for me :biggrin:

!!

Reply 56

Original post by ds4143

OOOOHHHH wow thanks for clearing that up for me :biggrin:

!!

hi want to revise for f214 :wink:

how did u find f215?

Reply 57

OP

Original post by Horchata

Can someone help clear up ultrafiltration for me? this is what I have written down using the textbook and my teacher:

Blood flows into the glomerulus from the afferent arteriole which splits into capillaries to ensure the blood is under increased pressure. Pressure is also increased by the efferent arteriole being narrower than the afferent arteriole.
Blood flows from the higher pressure in the glomerulues to lower pressure in the Bowman's capsule.
The blood containing small soluble molecules pass through the narrow gaps in the endothelium of the capillaries (??) of the glomerulus through gaps in the basement membrane (??) which filts out large molecules of molecular mass greater than 69,0000. The molecules then pass through gaps in the podocytes ensured by major processes.

Does anyone know if all those gaps exist and can anyone make that description better?

I guess there are gaps in the basement membrane and capillaries...but I wouldnt say gaps to be honest, I would say it passes through. It defo passes through the gaps in the PODOCYTE cells ensured my the major processes. I know they definetly do have gaps. Also it does not filter out molecular mass GREATER than 69,0000. It filters out molucules with a mass less than 69,000 (three zeros, not four :smile:

) Things like proteins and red blood cells which are larger than 69,000 cannot pass through, everything else smaller, like water, urea, amino acids, glucose, and inorganic ions can pass through :smile:

You explained the first part well :smile:

but just the second part you got a itny bit muddled up in :smile:

Hope this helped!!

Reply 58

OP

Original post by otrivine

hi want to revise for f214 :wink:

how did u find f215?

Omg dont even bother asking me about f215 LOL I failed that big time -.- I HATE application questions. I literally know the text book of by heart, but that did not help me in the slightest. I needed to understand application -.- UGH oh well Im over it. How did you find it?

And yup lets do f214

Reply 59