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Hannah_Boot
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#2581
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#2581
Also can someone tell me what we need to know about glycogen and do we need to know anything about lipids/ fatty acids??? I'll be eternally grateful!

:love:
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Jimmy20002012
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#2582
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#2582
Does DNA half in mitosis?


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VigneshSB
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#2583
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#2583
(Original post by Liam2404)
Could someone just clarify if this is right about water transport in plants:
1) The Root:
- Ions are actively transported into the xylem
- This reduces water potential in the xylem
- Water moves down a water potential gradient from the soil to the root hair cells by osmosis
- This creates root pressure
2) The Routes:
- The symplast pathway involves travelling through living parts of the cell - the cytoplasm
- Cells are connected by plasmodesmata
- The apoplast pathway involves travelling through the non-living parts of the cell - the cell wall.
- Once endodermis cells are reached, a waxy casparian strip prevents the water from moving through the cell wall, so its forced to travel through the cell membrane (which allows for more control over water movement)
- Water molecules then reach the xylem
3) The Xylem:
- Water evaporates at the leaf of the plant
- This creates tension (suction) which forces more water molecules into the leaf
- Water molecules are cohesive due to hydrogen bonding, so when one is sucked up, a whole column follows
- As water enters via the roots, it pushes water already in the xylem further upwards (root pressure)

Much appreciated, need to get this!
That is absolutely beautiful, but I would recommend you say WATERPROOF casparian strip over 'waxy', because that word has been rejected in the past!
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senz72
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#2584
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#2584
(Original post by iamNatasha)
I second that...
The problem is I dropped bio (parents want an A in AS) and so it's like learning everything as new content.
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F1's Finest
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#2585
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#2585
(Original post by FatHeadedKing)
I wish I were DNA helicase...then I could unzip your genes.
:rofl:

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hali123
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#2586
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#2586
(Original post by ibmb24)
does anyone have a mnemonic for learning the taxonomy groups
Kevins
Poor
Cow
Only
Feels
Good
Sometimes
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Liam2404
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#2587
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#2587
(Original post by VigneshSB)
That is absolutely beautiful, but I would recommend you say WATERPROOF casparian strip over 'waxy', because that word has been rejected in the past!
Ahh thank you so much! hope this is the 6 marker now :L
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FatHeadedKing
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#2588
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#2588
(Original post by James A)
:rofl:

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Zebrajess
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#2589
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#2589
(Original post by Liam2404)
Could someone just clarify if this is right about water transport in plants:
1) The Root:
- Ions are actively transported into the xylem
- This reduces water potential in the xylem
- Water moves down a water potential gradient from the soil to the root hair cells by osmosis
- This creates root pressure
2) The Routes:
- The symplast pathway involves travelling through living parts of the cell - the cytoplasm
- Cells are connected by plasmodesmata
- The apoplast pathway involves travelling through the non-living parts of the cell - the cell wall.
- Once endodermis cells are reached, a waxy casparian strip prevents the water from moving through the cell wall, so its forced to travel through the cell membrane (which allows for more control over water movement)
- Water molecules then reach the xylem
3) The Xylem:
- Water evaporates at the leaf of the plant
- This creates tension (suction) which forces more water molecules into the leaf
- Water molecules are cohesive due to hydrogen bonding, so when one is sucked up, a whole column follows
- As water enters via the roots, it pushes water already in the xylem further upwards (root pressure)

Much appreciated, need to get this!
Just to add at the end, water molecules also stick to the xylem walls. This is called adhesion. The force is so strong it pulls the walls of the xylem inwards.
And when you talk about cohesion and tension use the phrase 'cohesion-tension'. You often get a mark just for that before you explain it the rest seems right

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F1's Finest
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#2590
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#2590
(Original post by FatHeadedKing)
Only kidding pal, I'll positive rep you
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VigneshSB
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#2591
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#2591
Could someone redirect me to the Biology Analysis pdf? I forgot what page it's on
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denteddental
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#2592
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#2592
(Original post by Jimmy20002012)
Does DNA half in mitosis?


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Nope, only halves during meiosis.
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hali123
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#2593
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#2593
Does anybody have any notes for how science works or common questions that come up?
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ImAz
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#2594
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#2594
(Original post by VigneshSB)
They won't ask you that amigo. All you need to know is that the chromosomes line up at the equator in homologous pairs. At this point, crossing over(rare) and independent segregation occur that increase variation. You don't need to really explain the stages of meiosis
Are independent assortment and independent segregation the same thing?


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pushkin_
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#2595
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#2595
  • Hello !
    Could you explain me question 4 (a) in June 2009 on mitosis ? This table really confuses me, apparantely my knowledge about mitosis is still quite weak. In the answers the said that nr of chromosomes in the telophase of mitosis is 26, but I thought that number of chromosomes halves after two new cells (gametes If I'm not mistaken) are formed. And then sperm cell has half of the original chromosome number (therefore I understand this point) . However why in telophase it's 26 not 13 ?
    And also , shouldn't mass of DNA be proportional to nr of chromosomes ? Why at telophase they say it's 30 not 60 ??

    Please , help me, I'm really confused now...
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lorobolorolo
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#2596
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#2596
(Original post by Hannah_Boot)
Also can someone tell me what we need to know about glycogen and do we need to know anything about lipids/ fatty acids??? I'll be eternally grateful!

:love:
Glycogen:
It is made up of alpha glucose monomers
Join together by condensation reaction to produce a large chain
It is highly branched
It is used as storage in animals but not in plants

I don't think we need to know about lipids and fatty acids for unit 2.

Glad I could help
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Simran Mars Foster
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#2597
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#2597
Do we have know about maternal and foetal hameoglobin. If so please explain!
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Zebrajess
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#2598
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#2598
(Original post by Jimmy20002012)
Does DNA half in mitosis?


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DNA replicates during interphase. So when the cell divides they both have the diploid number of chromosomes. So technically it doubles and then halves, so it ends up with the same number

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Liam2404
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#2599
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#2599
(Original post by Zebrajess)
Just to add at the end, water molecules also stick to the xylem walls. This is called adhesion. The force is so strong it pulls the walls of the xylem inwards.
And when you talk about cohesion and tension use the phrase 'cohesion-tension'. You often get a mark just for that before you explain it the rest seems right

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Thank you!!
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denteddental
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#2600
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#2600
Guys, question 5dii on the June 2010 paper, why is it 8?
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