OCR BIOLOGY - F211 AS Jan 2013 Revision (Group)

Can anyone help me with transpiration? the exam questions on it are always so hard! :'(

it is the respiration ( or loss of water ) by evaporation from the aerial parts of a plant ( the leaves in this case)
basically the leaves "sweat" they lose water and there are many factors that affect theloss of water.
read this .,might help
https://www.youtube.com/watch?v=jHNRSBi3CBo :smile:

Reply 41

Sid101

Original post by R10T_N0_B0UNTY

So firstly the root takes in minerals and ions by active transport. This lowers the water potential of the cells in the plant. Because the water potential in the root hair cell, water moves in via osmosis into the root hair cell.

From here the water can move either these pathways:

Apoplast pathway- water moves in the cell wall, but when reaches the casparian strip it is forced to go the symplast pathway.
Symplast pathway- water moves by the cytoplasm.
Vacuolar pathway ( not sure this is called this) - water moves through by vacuoles.

From these pathways the water enters the xylem by osmosis also as it “moves down a conc. Gradient“ ..... (or is it simply diffusion) what do you think?

Hope this helps and happy revising.

This was posted from The Student Room's Android App on my GT-I9100

It did make it easier to understand, but I don't understand the bit about the different pathways; how does that work?! How does the water know which pathway to go through?

Help? :frown:

Reply 42

JamesNeedHelp2

5

Anyone who wants to do Q/A session Qoute me!

Reply 43

SomePotential

4

Original post by Sid101

It did make it easier to understand, but I don't understand the bit about the different pathways; how does that work?! How does the water know which pathway to go through?

Help? :frown:

It goes through both. Water is moving from an area of high water potential to an area of low water potential as fast as it can. This involves going through both pathways as going through only one would decrease the water potential gradient. I don't think you need to know which is faster/more efficient, just that there are two pathways water takes to get from the roots to the Xylem.

Reply 44

morvenrkr

COMPLETELY PANICKING ABOUT THIS EXAM :confused:

:'(

Reply 45

R10T_N0_B0UNTY

OP

12

Original post by morvenrkr

COMPLETELY PANICKING ABOUT THIS EXAM :confused:

:'(

Do not panick. At the end of the day, when you go to the exam despite you knowing or not knowing your stuff. Think of a logical and most likely response/ answer the question wants you to give.... Think like the examiner. Thats an option when your stuck.

P.S You will be fine :smile:

This was posted from The Student Room's Android App on my GT-I9100

Reply 46

morvenrkr

Original post by R10T_N0_B0UNTY

Do not panick. At the end of the day, when you go to the exam despite you knowing or not knowing your stuff. Think of a logical and most likely response/ answer the question wants you to give.... Think like the examiner. Thats an option when your stuck.

P.S You will be fine :smile:

This was posted from The Student Room's Android App on my GT-I9100

Thank you, I really hope so! I've been revising like crazy, I'm OK on cells, confident of mammal transport and hopeless with plant transport! Any tips on plants would be must appreciated :-).

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Reply 47

morvenrkr

Please can someone explain the transport of carbon dioxide via hydrocarbonic ions? :s-smilie:

Reply 48

morvenrkr

Original post by JamesNeedHelp2

Anyone who wants to do Q/A session Qoute me!

I do :-)

Posted from TSR Mobile

Reply 49

SomePotential

4

Original post by morvenrkr

Please can someone explain the transport of carbon dioxide via hydrocarbonic ions? :s-smilie:

This is an excellent post on Oxygen and Carbon Dioxide transport:
http://www.thestudentroom.co.uk/showpost.php?p=40638313&postcount=16

Reply 50

Hannah196

1

can someone explain to me how to work out heart rate from electrocardiograph?

like question 6a on this past paper?
http://www.ocr.org.uk/images/59664-question-paper-unit-f211-cells-exchange-and-transport.pdf

pleasee help!

Reply 51

morvenrkr

Original post by Hannah196

can someone explain to me how to work out heart rate from electrocardiograph?

like question 6a on this past paper?
http://www.ocr.org.uk/images/59664-question-paper-unit-f211-cells-exchange-and-transport.pdf

pleasee help!

Its the distance from one point for example P to the next one. So from P to P it takes 0.80seconds
Which means 1 beat per 0.80s
60 (one minute) / 0.80 (one beat) = 75 beats per minute
Hope this helped J

Reply 52

R10T_N0_B0UNTY

OP

12

Original post by Hannah196

can someone explain to me how to work out heart rate from electrocardiograph?

like question 6a on this past paper?
http://www.ocr.org.uk/images/59664-question-paper-unit-f211-cells-exchange-and-transport.pdf

pleasee help!

Hello

So firstly heart rate is the number of heart beats per minute.

So the general rule is :
From one point to of the elecrtogram to the same point.
ie. Peak of P to the next peak of P.
Fine the time it takes/ time difference ( this is one heart beat)

In the question 6. It would be from the first P to the second P is aprox. 0.88 - 0.80 = 0.80 seconds

Therefore to find heart rate how many times can 0.80 s take place in 60 seconds- 1 minute.

60/0.8 =
78 beats per minute.

Hope this helped

This was posted from The Student Room's Android App on my GT-I9100

Reply 53

Gotzz

13

What changes does a stem cell undergo to become a neutrophil?

Reply 54

R10T_N0_B0UNTY

OP

12

Original post by Gotzz

What changes does a stem cell undergo to become a neutrophil?

Im not too sure, but I know a stem cell has to differentiate for it to become a specialized cell. :rolleyes:

In this case I would write:
The stem cell has to differentiate to become a neutrophil. The cell keeps its nuclues, their cytoplasm becomes granular due to the large numbers of lysosomes produced. Making the cell -neutrophil- specialized for killing microorganisms.

However, I do not know whether this is sufficient for you to gain any marks.
This is from reference from the OCR book page 35. :smile:

Reply 55

Gotzz

13

Original post by R10T_N0_B0UNTY

Im not too sure, but I know a stem cell has to differentiate for it to become a specialized cell. :rolleyes:

In this case I would write:
The stem cell has to differentiate to become a neutrophil. The cell keeps its nuclues, their cytoplasm becomes granular due to the large numbers of lysosomes produced. Making the cell -neutrophil- specialized for killing microorganisms.

However, I do not know whether this is sufficient for you to gain any marks.
This is from reference from the OCR book page 35. :smile:

I couldn't find anything better than the info on that page either, so I guess that'll do.
Thanks :smile:

Reply 56

Gotzz

13

How can a spirometer be used to measure vital capacity and breathing rate?

Reply 57

Zahra00

Reading through the OCR book and I got a bit confused...

It says: The ability of haemoglobin to take up and release oxygen depends on the amount of oxygen in the surrounding tissues.
At low oxygen tension, the haemoglobin does not readily take up oxygen molecules.
As the oxygen tension rises, the diffusion gradient into the haemoglobin molecules increases.

Shouldn't the oxygen tensions be the other way around? If the oxygen tension is the amount of oxygen in the surrounding tissues then shouldn't there be a higher oxygen tension before the oxygen diffuses into the red blood cell? Because there would be a higher amount of oxygen in the surrounding tissues such as the lungs? And lower oxygen tension when oxygen diffuses into the red blood cell as the amount of oxygen in the surrounding tissues has decreased?

So confused :/

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Reply 58

SomePotential

4

Original post by Zahra00

Reading through the OCR book and I got a bit confused...

It says: The ability of haemoglobin to take up and release oxygen depends on the amount of oxygen in the surrounding tissues.
At low oxygen tension, the haemoglobin does not readily take up oxygen molecules.
As the oxygen tension rises, the diffusion gradient into the haemoglobin molecules increases.

Shouldn't the oxygen tensions be the other way around? If the oxygen tension is the amount of oxygen in the surrounding tissues then shouldn't there be a higher oxygen tension before the oxygen diffuses into the red blood cell? Because there would be a higher amount of oxygen in the surrounding tissues such as the lungs? And lower oxygen tension when oxygen diffuses into the red blood cell as the amount of oxygen in the surrounding tissues has decreased?

So confused :/

Posted from TSR Mobile

Your paragraph confused me. :rolleyes:

Your book is right, when there is a low Oxygen tension (I prefer to use 'partial pressure'), the area surrounding the red blood cells is low on Oxygen so it is harder for Haemoglobin to 'take it up'. At higher Oxygen tensions, where there is a lot of Oxygen available, it's easier for the Oxygen to attach to the haem groups.

This seems to be same thing your book describes, and what you (I think) described.

"If the oxygen tension is the amount of oxygen in the surrounding tissues then shouldn't there be a higher oxygen tension before the oxygen diffuses into the red blood cell"

That's what the book says too,
"As the oxygen tension rises, the diffusion gradient into the haemoglobin molecules increases. "
At higher oxygen tensions is when the oxygen diffuses into the red blood cell, down a diffusion gradient.