Jih
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The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
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Ecds
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How many marks is it and which exam board?
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Daddy Dagoth
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(Original post by Jih)
The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
All about that surface area my dude
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umbrellala
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(Original post by Jih)
The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
Think about the structure of the alveoli and how red blood cells are adapted to their job
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Arima
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think about elasticity of alveoli. think about surface area. think about the distance between blood + alveoli. there's a lot to write about
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Jih
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(Original post by Ecds)
How many marks is it and which exam board?
It is 6 marks and I am not sure which exam board as the question was given to me by my teacher who made the exam paper up by choosing different sets of questions and combining them into one exam paper.
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FarhanChughtai
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(Original post by Jih)
The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
Think Fick's Law:
ALVEOLI
- very large surface area for efficient gaseous exchange
- rich blood supply to maintain a favourable concentration gradient
- short diffusion distance to make gaseous exchange easier
BLOOD
- biconcave shape to increase surface area
- no nucleus to provide more space to carry oxygen/CO2
- filled with lots of haemoglobin so lots of oxygen/CO2 can be carried

Any question that states "adapted" ensures the idea of an application of Fick's Law
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Nurani61105
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- large surface area to vol
- well vascularised
- one cell thick walls
- low CO2 and high O2 conc

These are the only ones I can think of now but remember to link it to its main fuctions, so about faster oxygen diffusion.
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Ukvoltaire
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(Original post by Jih)
The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
Well alveoli are found at the ________. They increase the ______ . The blood has a _____ _____ _____. This makes gas exchange quicker.

Try to fill the gaps and expand a bit more on the answer. Then you should be able to find out what you need for the answer.
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Ecds
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Ah okay; well I finished biology A level in June but I'll see if I can give it a go.

Alveoli:
- 1 cell thick wall consisting of squamous cells in order to reduce the diffusion distance
- the alveoli cells produce a surfactant to prevent the alveoli from sticking together when it collapses during exhalation
- the alveoli are 3D and there are many of them resulting in a larger surface area to volume ratio
- (not specific to alveoli as such but I always included this in my answers for this kind f question) there is a steep concentration gradient due to oxygen and carbon dioxide constantly being removed via ventilation and also the movement of the blood

Blood:
- there are many small capillaries covering the surfaces of the alveoli in order to maximise the surface for diffusion
- the endothelial cells of capillaries reduce the diffusion distance
- blood flow maintains a steep concentration gradient

If you're doing the new A levels and are going to be doing OCR then the marking scheme is no longer a mark per point. Instead you will have levels which correspond to different marks.
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AJ Nwagwu
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Alveoli:
- Large SA:V ratio which allows more gases to be exchanged at a time.
- Thin membrane (1 cell thick) which reduces diffusion distance.
- Good blood supply and ventilation; so carbon dioxide is brought to the alveoli and oxygen is taken away quickly, maintaining a constant high diffusion gradient.

Red Blood Cells:
- Biconcave disc shape to provide a large SA for gas exchange.
- Only slightly larger than capillary diameter and flexible, so cells pass in a single file line through capillaries, reducing the speed of blood flow and allowing more time for gas exchange.
- Has haemoglobin- which has a higher affinity for oxygen, the greater the partial pressure of oxygen. So takes in oxygen to form oxyhaemoglobin where oxygen concentration is high and releases oxygen where oxygen concentration is low. (Works the same way for Carbon Dioxide)
- No nucleus so there is more room for haemoglobin.

All of these increase the rate of diffusion and exchange of gases.
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Jih
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(Original post by FarhanChughtai)
Think Fick's Law:
ALVEOLI
- very large surface area for efficient gaseous exchange
- rich blood supply to maintain a favourable concentration gradient
- short diffusion distance to make gaseous exchange easier
BLOOD
- biconcave shape to increase surface area
- no nucleus to provide more space to carry oxygen/CO2
- filled with lots of haemoglobin so lots of oxygen/CO2 can be carried

Any question that states "adapted" ensures the idea of an application of Fick's Law
Thank you so much!!!!
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Beth286
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(Original post by Jih)
The question is to 'Explain how the alveoli and blood are adapted to ensure efficient gas exchange'
How much of a step up is it from gcse and do you enjoy it?? How much work does it involve?? Can you do all your work in frees or not?? Sorry for all the questions haha
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Jih
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(Original post by Beth286)
How much of a step up is it from gcse and do you enjoy it?? How much work does it involve?? Can you do all your work in frees or not?? Sorry for all the questions haha
Personally, I found that in GCSE if you learn the textbook or the spec you can get an A but with A levels its more detailed and you won't get a high mark by just learning the content, you must understand and use appropriate terminology otherwise you could lose a lot of marks.

I do definitely enjoy it and i find it a lot more interesting than i did GCSE biology. You definitely can't leave the work to the last minute because there is a lot but it is manageable so don't stress over it, just make sure you do your work on time and do some revision after your lesson as well. Sometimes i'll start my Homework in my frees so that i don't have to do it at home but i don't always finish and i find that i rush to get it done, so i use my free periods to revise and make notes.

Hope this helps
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Beth286
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(Original post by Jih)
Personally, I found that in GCSE if you learn the textbook or the spec you can get an A but with A levels its more detailed and you won't get a high mark by just learning the content, you must understand and use appropriate terminology otherwise you could lose a lot of marks.

I do definitely enjoy it and i find it a lot more interesting than i did GCSE biology. You definitely can't leave the work to the last minute because there is a lot but it is manageable so don't stress over it, just make sure you do your work on time and do some revision after your lesson as well. Sometimes i'll start my Homework in my frees so that i don't have to do it at home but i don't always finish and i find that i rush to get it done, so i use my free periods to revise and make notes.

Hope this helps
Thank you so much for your help!! I’m doing it with Spanish and psychology I think so as long as I use my frees and don’t talk I should be fine (hopefully) good luck in your exams
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LN05
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(Original post by Arima)
think about elasticity of alveoli. think about surface area. think about the distance between blood + alveoli. there's a lot to write about
I read some where that mentioning about elasticity is incorrect?
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