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# OCR Biology F212 Revision [3rd June 2013] (Now Closed) watch

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1. Hey guys!! im doing a past paper at the minute, can someone help me out with a calculation question please? its May 2011 paper. Question 2cii) The answer is 2 but im a bit confused on how they got that answer. The mark scheme doesn't show the calculations
2. Can anybody tell me why cellulose are not coiled? Do they not have 1-6 glycosidic bond? What kind of bond do they have???? Thank you

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3. (Original post by Beni24)
Hey guys!! im doing a past paper at the minute, can someone help me out with a calculation question please? its May 2011 paper. Question 2cii) The answer is 2 but im a bit confused on how they got that answer. The mark scheme doesn't show the calculations
You do 3/1.5=2

At 15'C the rate of reaction is 1.5
At 25'C the rate of reaction is 3
Just basically read it off the graph

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4. (Original post by wndms)
Can anybody tell me why cellulose are not coiled? Do they not have 1-6 glycosidic bond? What kind of bond do they have???? Thank you

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They don't have 1-6 glycosidic bonds, they have beta 1,4 glycosidic bonds
This means that molecules of beta glucose are joined by a 1-4 glycosidic bond, but in order for this to happen, ever other molecule needs to be rotated 180 degrees. (as in beta glucose the OH on C1 is above the ring) This makes a straight chain and therefore glucose cannot coil up. Hydrogen bonds then form between adjacent parallel molecules to create a microfibril
5. (Original post by kited4)
They don't have 1-6 glycosidic bonds, they have beta 1,4 glycosidic bonds
This means that molecules of beta glucose are joined by a 1-4 glycosidic bond, but in order for this to happen, ever other molecule needs to be rotated 180 degrees. (as in beta glucose the OH on C1 is above the ring) This makes a straight chain and therefore glucose cannot coil up. Hydrogen bonds then form between adjacent parallel molecules to create a microfibril
Oh thank you so much!
So for Alpha glucose, they have 1-4 glycosidic bond but they are not rotated 180' so it's coiled right?

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6. hey please can anyone help me with this learning obejctive_
explain how the structures of triglyceride, phospholipid and cholesterol molecules relate to their functions in living organisms;

thanks
7. (Original post by wndms)
You do 3/1.5=2

At 15'C the rate of reaction is 1.5
At 25'C the rate of reaction is 3
Just basically read it off the graph

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Ah right, that makes sense! Thank you!!
8. What are structures and functions of triglycerides, phospholipids and cholesterol? Looking through all my notes and that was where I got confused.

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9. (Original post by wndms)
Oh thank you so much!
So for Alpha glucose, they have 1-4 glycosidic bond but they are not rotated 180' so it's coiled right?

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Depends what molecule. For starch which contains Amylose and amylopectin, they are made of alpha, amylose containing all 1-4, and amylopectin containing some of both I think. Then there's glycogen, which is made of alpha glucose, again both 1-4&1-6, and then you have cellulose

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10. (Original post by RyanMarshall94)
What are structures and functions of triglycerides, phospholipids and cholesterol? Looking through all my notes and that was where I got confused.

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11. (Original post by RyanMarshall94)
What are structures and functions of triglycerides, phospholipids and cholesterol? Looking through all my notes and that was where I got confused.

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Triglyceride - One glycerol and three fatty acids, contains three ester bonds, and mainly used for long term energy storage, insulation/protection of organs, form HDL and LDL's.

Phospholipid - one glycerol, one phosphate head, two fatty acids bonded to glycerol molecule by ester bonds. Composes plasma membrane of cells. It's important to remember that the tails are HYDROPHOBIC, and the head is HYDROPHILIC, hence why the bilayer forms in water.

Cholesterol - structure is always given, don't need to know about its structure, although its used to make hormones and steroids, as well as regulate fluidity of cell surface membranes, more cholesterol, the less fluid it is.

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12. (Original post by wndms)
Oh thank you so much!
So for Alpha glucose, they have 1-4 glycosidic bond but they are not rotated 180' so it's coiled right?

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yeah! hence amylose in starch
13. I just did January 2011's paper and one of the questions said 'Other than biochemical evidence, what can taxonomists use to group organisms?'
So my answers were morphology (anatomy) and behaviour
But in the mark scheme it grouped anatomy and behaviour into one marking point.
Does anyone have any idea of their reasoning behind this, when other years they were separate marking points?
14. Is anyone bothering to remember all the trash in the last module? Like international cooperation. God its dull
15. Can someone tell me about the three domains because I have no notes on it and text book doesn't give much info. Thanks!
Is anyone bothering to remember all the trash in the last module? Like international cooperation. God its dull
What is that again? ;p
17. Are disulfide bonds always double bonds?

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Is anyone bothering to remember all the trash in the last module? Like international cooperation. God its dull
Its dull but there's frequent questions on it. I haven't learned them off by heart but a basic knowledge, for example CITES aim to regulate trade, Biological Convention aim to encourage efficient use of resources and EIA aims to reduce the impact of development. Most of the time you can use common sense in answering the questions.

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19. Wheres Disupfide bonds found?
20. Can anyone help me with this please?
You know how two alpha glucose makes maltose and more than two alpha glucose makes amylose.

How about beta glucose? What happens if two beta glucose join together? Is there a name for it?
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