OCR Biology F211 resit - 16th May Watch

b41nzy
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#81
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anybody know of a good way to remember the stages of Mitosis? like a mnemonic or something?
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jemma2805
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#82
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Posh Men Always Trump :L Prophase Metaphase Anaphase Telophase
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abi.tanner
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#83
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channel proteins = charged molecules e.g. sodium ions. can be gated to allow only certain molecules through.
carrier proteins = large molecules e.g. glucose. use ATP to actively change shape, allowing the large molecule to pass through the membrane, complementary shape.
they are both facilitated diffusion.
is this right?
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earthisearthis
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#84
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our teacher taught us P MAT (pro,meta,ana,telo)
and imagined it as a cat/dog whatever peeing on the mat.

or, for the more sophisticated:
pro = before, so it prepares itself for the division eg centrioles move to poles, envelope disappears etc
meta = m = middle, the chromatids line up in the middle and attach to the spindle fibres
ana = a = after, the chromatids split at the centromere and get pulled etc etc etc
telo = like watching it afterwards on telo-vision, the envelope reforms etc etc



also: does anyone have the 2 or 3 mark definitions for Resolution and Magnification?
and, why is staining necessary for light microscopes and electron microscopes?
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hopes
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(Original post by earthisearthis)
our teacher taught us P MAT (pro,meta,ana,telo)
and imagined it as a cat/dog whatever peeing on the mat.

or, for the more sophisticated:
pro = before, so it prepares itself for the division eg centrioles move to poles, envelope disappears etc
meta = m = middle, the chromatids line up in the middle and attach to the spindle fibres
ana = a = after, the chromatids split at the centromere and get pulled etc etc etc
telo = like watching it afterwards on telo-vision, the envelope reforms etc etc



also: does anyone have the 2 or 3 mark definitions for Resolution and Magnification?
and, why is staining necessary for light microscopes and electron microscopes?
because alot of biological molecules are colourless therefore its hard to distinguish and intepreth their detail so staining uses certain chemicals which bind onto the components of the cell making it visible.

Magnification is the degree to which the size of an image is larger then the actual image itself.

Resolution is the ability to distinguish between two different points identifying detail.
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caiti_lewis92
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#86
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Hey guys, I am re-sitting this for the second time. I think there will be a bit on organelles and the heart (including the bohr shift) as none of this appeared last time. Anyone else got any ideas? xx
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b41nzy
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(Original post by abi.tanner)
channel proteins = charged molecules e.g. sodium ions. can be gated to allow only certain molecules through.
carrier proteins = large molecules e.g. glucose. use ATP to actively change shape, allowing the large molecule to pass through the membrane, complementary shape.
they are both facilitated diffusion.
is this right?
yep thats it
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simmyxx
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(Original post by b41nzy)
anybody know of a good way to remember the stages of Mitosis? like a mnemonic or something?
I have been taught to remember it as:

Please = Prophase
Make = Metaphase
Another = Anaphase
Two = Telophase

hope it helps

...

can anyone explain the xylem and phloem =/ really don't understand it

xx
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levantine
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#89
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three questions.

using channel proteins and carrier proteins are they passive or active processes?.

and whats difference between normal and facilitated diffusion?

and also WHY does the casparian strip block the apoplast route?? whats the point???
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rish515
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#90
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The grade boundaries have been quite low. been ranging from 40-45 out of 60 to get an A
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harmony.
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#91
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(Original post by b41nzy)
if you're using the ocr textbook. pg 23 bottom right theres a table.

channel proteins 'ions like sodium ions and calcium ions'

carrier proteins 'larger molecules like glucose and amino acids'
However on page 19 it says the complete opposite of what it says on page 23
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b41nzy
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(Original post by levantine)
three questions.

using channel proteins and carrier proteins are they passive or active processes?.

and whats difference between normal and facilitated diffusion?

and also WHY does the casparian strip block the apoplast route?? whats the point???
i think they are only active processes if its going AGAINST the concentration gradient.

Diffusion: net movement of molecules or ions in a gas or liquid from an area of high concentration to low concentration. Facilitated diffusion:Passive movement of molecules across membranes DOWN their concentration gradient aided by transport (carrier) protein molecules.

the casparian strip blocks the apoplast pathway so that the water and dissolved nutrients MUST go through the symplast pathway (ensuring that water and dissolved NITRATE ions have to pass into the cell cytoplasm through cell membranes). the transporter proteins in the cell membranes mean that nitrate ions can be actively transported from the cytoplasm to the cortex cells (into the xylem). This lowers water potential in the xylem so water from cortex cells enter the xylem via osmosis.
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b41nzy
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#93
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(Original post by harmony.)
However on page 19 it says the complete opposite of what it says on page 23
oh yeahh :/ damn. well it think its because you can have different types of channel proteins. page 19 is talking about glucose channels and pg 23 ion channels.
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VisualKiddy
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(Original post by levantine)
three questions.

using channel proteins and carrier proteins are they passive or active processes?.

and whats difference between normal and facilitated diffusion?

Channel proteins can be used either passively or actively.

When used passively, they transport large molecules with teh concentration gradient.

When used actively, they transport specific molecules against the concentration gradient.


Normal diffusion can be performed by lipid soluble (ie, non-polar, small) molecules, directly passing through the plasma membrane. This is passive.

Facilitated diffusion uses channel proteins to transport polar, water soluble molecules, and carrier proteins to transport large molecules. These are passive.


Afaik.
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b41nzy
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(Original post by hopes)
because alot of biological molecules are colourless therefore its hard to distinguish and intepreth their detail so staining uses certain chemicals which bind onto the components of the cell making it visible.

Magnification is the degree to which the size of an image is larger then the actual image itself.

Resolution is the ability to distinguish between two different points identifying detail.
actual object itself*
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b41nzy
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#96
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translocation going to come up??
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michelleabelle
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#97
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I am so screwed
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Signed Solution
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#98
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I have a funny feeling a question about microscopes are going to come up, but that's just me.

I've spent so much time doing maths past papers the last month that when I do biology papers it just seems so wordy. I'm bad with words, so that doesn't help either.

My 3rd time sitting this exam. Wish us all good luck.
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aedai
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someone seriously needs to give me a good definition of resolution.
Whenever I write one, I always get it wrong.
I've never seen a good explanation of it.

Is this right?
The ability to distinguish two seperate points clearly.

As for magnification can you just say the ratio between the size of an object and its image?

I have no idea how I'd answer a 3 mark resolution question.

also for magnification for TEM and SEM.
in the books it says TEM = 250000x and in exams its been 500,000x
for SEM= 100000x in books. and 150000x in exams. Really confused. I guess I stick to what the examboard wants right?

I'm going to go through xerophytes and transpiration before I go to bed. and maybe a bit of the heart.

I'm actually quite relaxed
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b41nzy
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(Original post by aedai)
someone seriously needs to give me a good definition of resolution.
Whenever I write one, I always get it wrong.
I've never seen a good explanation of it.

Is this right?
The ability to distinguish two seperate points clearly.

As for magnification can you just say the ratio between the size of an object and its image?

I have no idea how I'd answer a 3 mark resolution question.

also for magnification for TEM and SEM.
in the books it says TEM = 250000x and in exams its been 500,000x
for SEM= 100000x in books. and 150000x in exams. Really confused. I guess I stick to what the examboard wants right?

I'm going to go through xerophytes and transpiration before I go to bed. and maybe a bit of the heart.

I'm actually quite relaxed
resolution: is the degree to which it is possible to distinguish between two objects that are very close together. the higher the resolution, the greater detail you can see.
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