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Reply 180
yhh sure. that would help me revise
you can start :smile:
I miss the F211. It wasn't a lot to learn. plus I enjoyed the body stuff, like lungs, gas exchange system and the heart. But this F212, is really too much to know. Still have biodiversity, conservation, evolution, food production to go.
Original post by Future_Dr
I miss the F211. It wasn't a lot to learn. plus I enjoyed the body stuff, like lungs, gas exchange system and the heart. But this F212, is really too much to know. Still have biodiversity, conservation, evolution, food production to go.


Good luck, its a trial I know! :smile:
Original post by Axion
tis :P the heart would do .

Anyone want to do a question exchange. whreby every post you write, has to end with a question and a set number of marks and the next person has to answer it?


Describe and explain the main features of the gas exchange system (lungs) and how it ensures effcient gas exchange? (6-8)

Why do large organisms need a specialised gas exchange system? (4)

Outline the mechanism for inspiration and expiration? (8)

Which of these structures have a squamous epithelium? - trachea, bronchus, bronchiole, alveolus (1)

How do you measure Oxygen uptake by using a spirometer? (4)
(edited 11 years ago)
Does anyone have the recent january 12 F211 Paper? Please!!!:smile:
Reply 185
Original post by Future_Dr
Does anyone have the recent january 12 F211 Paper? Please!!!:smile:


here you go
http://www.thestudentroom.co.uk/showthread.php?t=1943168
:smile:
Reply 186

Get the person to breathe in and out at rest

compelete this for about 1 minute

obtain the trace and draw a line against all the peaks during the first minute recorded

measure the total decrease from the first peak to the last peak

this is representative of the oxygen uptake


Original post by skylight17
Describe and explain the main features of the gas exahcnage system and how it ensures effcient gas exchange? (6-8)

Why do large organisms need a specialised gas exchange system? (4)

Outline the mechanism for inspiration and expiration? (8)

Which of these structures have a squamous epithelium? - trachea, bronchus, bronchiole, alveolus (1)

How do you measure Oxygen uptake by using a spirometer? (4)


Is question 1 referring to the lungs? you said 'the' gas excahgen system

large organisms need one because

they are mobile are have large requirements

the need to be able to remove waste products quickly

they have a small surface area to volume ratio

therefore diffusion is not enough



alveolus have squamous epithelium

Inspiration

diaphragm and ICM contract

ribs up and out, diaphragm flattens

volume thorax up

pressure thorax down

air flows in down pressure gradient



I'll let someone else do expiration :P
Reply 187
Describe the structure of ribosomes (1 mark)
Original post by Axion
Describe the structure of ribosomes (1 mark)


do we need to know this? :redface:
Original post by skylight17
Describe and explain the main features of the gas exchange system (lungs) and how it ensures effcient gas exchange? (6-8)

Why do large organisms need a specialised gas exchange system? (4)

Outline the mechanism for inspiration and expiration? (8)

Which of these structures have a squamous epithelium? - trachea, bronchus, bronchiole, alveolus (1)

How do you measure Oxygen uptake by using a spirometer? (4)



I'll do the expiration one, if you two don't mind?:smile:

Diaphragm relaxes and is pushed up by the digestive organs.
The intercostal muscles relax and the ribs fall.
Volume of chest cavity decreases.
Pressure in lungs is below atmospheric pressure, hence the air moves into the lungs.
Reply 190
Original post by TaraBelle
do we need to know this? :redface:


Yep.

Ok I'll ask another one.

List 3 functions of cystoskeletons
Reply 191
can someone please help me with calculating the actual length i never get it right.
in the jan 2009 paper Q1aiii, you are meant to go 20x15 divided by 80
but where does the 80 come from :s

helpppppp
Reply 192
And here is one question you you BEAUT.

list the resolution and magnifications of the light, TEM and SEM
Reply 193
Original post by SHAH :)
can someone please help me with calculating the actual length i never get it right.
in the jan 2009 paper Q1aiii, you are meant to go 20x15 divided by 80
but where does the 80 come from :s

helpppppp


cell image length is 80mm, real cell length = 20micrometres

therefore 1mm = 0.25 micrometres

Therefore 0.25 micrometres x 15 (the length of the mitochondrion)

=3.75micrometres
(edited 11 years ago)
Original post by Axion
Describe the structure of ribosomes (1 mark)


it has a large subunit and a small subunit.Why is imporant that during mitosis, the length of time the the chromosomes are supercoiled is as short as possible? Explain what happens during G1, G2 and the S-phase during interphase.
(edited 11 years ago)
Original post by Axion
And here is one question you you BEAUT.

list the resolution and magnifications of the light, TEM and SEM


Light - 200nm / 1500x
TEM - 0.1nm / 500 000x
SEM - 0.1nm / 100 000x

I'll give you a question in a second.:smile:
Reply 196
Original post by sumsum123
it has a large subunit and a small subunit.Why is imporant that during mitosis, the length of time the the chromosomes are supercoiled is as short as possible? Explain what happens during G1, G2 and the S-phase during interphase.


but what is in composed of?

cell growth, organelle replication, checking and copying of genetic material
Reply 197
Original post by ohmyBEAUT
Light - 200nm / 1500x
TEM - 0.1nm / 500 000x
SEM - 0.1nm / 100 000x

I'll give you a question in a second.:smile:


really?? I thought TEM and SEM was 1nm :confused:

I also thought SEM was x300000 :confused:
Question for Axion - Define the term passive transport and explain one process which is passive. (5)

Question for anyone else - Explain the need for staining samples used in light microscopy and electron microscopy. (3)
Original post by Axion
really?? I thought TEM and SEM was 1nm :confused:

I also thought SEM was x300000 :confused:


For the TEM/SEM resolution anything from 0.05 - 1.0nm is accepted.
For the magnification I'm not sure.