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username5741284
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Hi has anyone sat the 2020 paper 1? could you please help us by trying to make an unofficial mark scheme?
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this is what I remember :

1.1. function of app hydrolase? catalyses the hydrolysis of ATP into ADP+Pi (M1) to release energy needed for transport of substance by carrier proteins, process is active transport which requires energy (M2) ,you can write the equation

1.2. explain movement of Na+? not sure about M1, low conc of Na+ in cell so Na+ moves from lumen to cell carrying glucose with it, co-transport (M2)

1.3. 2 features in cells specialised for absorption? (2)
1.4. drawing of phospholipid (2)
1.5. how amino acids join to form a polypeptide so there is always NH2 at one end and COOH at the other(2)
M1 peptide bond M2:
2.1. explain differences in table 1: (3)
2.2. explain why (2)
2.3. describe the role of micelles in the absorption of fats into the cells lining the ilium (3)
Micelles increase the surface area for lipase to act on, which means faster hydrolysis action by lipase. Micelles are water soluble vesicle and so deliver fatty acids and glycerol to the epthelial cells of the ileum for absorption .
3.1. explain why (3)
3.2. there is a small increase in pressure and in rate of blood flow in the aorta. explain how this happens and its importance(2)
3.3. describe one way in which the student's curve would be similar to and one way it would be different from the curve shown. (2)
3.4 calculate heart rate (1)
4.1. tick box 2
4.2. two variables to keep constant: water temperature, concentration of acid
4.3 membrane structure (4)
4.4. describe a method to prepare colour standards and use them to give data for the total... (3)
5.1. describe role of DNA polymerase (2) joins free floating nucleotides by comp base pairing, forms phosphodiester bond, its a bond reaction
5.2. calculate time diff as a percentage (2)
5.3. describe how an enzyme can be phosphorylated (2)
5.4. why higher conc could cause a tumor? (2)
cells go through DNA rep earlier, more DNA rep, rep is uncontrollable, results in a mass of cells

6.1. why death of alveolar epithellium cells reduces gas exchange in human lungs(3)

10.1 describe how mRNA is formed by transcription in eukaryotes(5)
DNA helicase unwinds DNA strands breaking hydrogen bonds between them(M1). One of the strands acts as a template strand. Free RNA bases attach to complementary bases on template strand forming complementary base pairing. DNA polymerase joins the nucleotides together forming phosphodiester bonds between them(M6). This forms pre mRNA. Pre mRNA undergoes splicing(M7), removing non-coding DNA which is introns and exons remain. Mature mRNA is formed.

10.2. describe how a polypeptide is formed by translation of mRNA (6)

10.3. define gene mutation and explain how it can have no effect on an individual and a positive on. (4)
Gene mutation is a change in DNA base sequence(M1). Dna is degenerate and so more than one codon can code for the same amino acid, so base substitution will have not effect(M2). However, base addition and deletion can cause an effect as it changes the amino acid being coded for and therefore can produce non functional proteins
Last edited by username5741284; 1 month ago
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zoey101xo
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function of ATP hydrolase- catalyses the hydrolysis of ATP to release energy needed for transport of substance by carrier proteins, process is active transport which requires energy
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zoey101xo
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Did u sit the paper, if u did can u also write the answers as well
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zoey101xo
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(Original post by mmask3)
I did but I don't have the markscheme so I need other people's help to write them
Ok do u remember what u wrote and we can go from there
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username5741284
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(Original post by zoey101xo)
Ok do u remember what u wrote and we can go from there
I didn't get much marks but I'll add what I know
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zoey101xo
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(Original post by mmask3)
I didn't get much marks but I'll add what I know
Ok lets do it
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zoey101xo
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10.1. DNA helicase unwinds DNA strands breaking hydrogen bonds between them. One of the strands acts as a template strand. Free RNA bases attach to complementary bases on template strand forming complementary base pairing. DNA polymerase joins the nucleotides together forming phosphodiester bonds between them. This forms pre mRNA. Pre mRNA undergoes splicing, removing non-coding DNA which is introns and exons remain. Mature mRNA is formed.
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zoey101xo
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10.3. Gene mutation is a change in DNA base sequence. Dna is degenerate and so more than one codon can code for the same amino acid, so base substitution will have not effect. However, base addition and deletion can cause an effect as it changes the amino acid being coded for and therefore can produce non functional proteins
Last edited by zoey101xo; 1 month ago
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zoey101xo
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What was the qs for 3.2 and 3.3
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zoey101xo
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(Original post by guji_1193)
Has anybody sat 2020 paper 2?
No not yet
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zoey101xo
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Not sure about this but kinda seems right:
2.3. Micelles increase the surface area for lipase to act on, which means faster hydrolysis action by lipase. Micelles are water soluble vesicle and so deliver fatty acids and glycerol to the epthelial cells of the ileum for absorption .
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zoey101xo
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(Original post by jadarose)
My school gave us the actual markschemes and papers for 2020 so we can practise but I don't think I can share them online
OH your sooo lucky but u can help us with the unofficial markscheme pls, any help would be great
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username5741284
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(Original post by zoey101xo)
No not yet
I have and I can try and help
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username5741284
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(Original post by zoey101xo)
Not sure about this but kinda seems right:
2.3. Micelles increase the surface area for lipase to act on, which means faster hydrolysis action by lipase. Micelles are water soluble vesicle and so deliver fatty acids and glycerol to the epthelial cells of the ileum for absorption .
I'll add it now but lets hope someone else joins us so we can have more answers/opinions
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zoey101xo
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(Original post by mmask3)
yes of course! thank you for interacting with this post
You're very welcome, hope others can help as well !!
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guji_1193
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(Original post by mmask3)
I have and I can try and help
Can you try and advise what the key topics/subtopics to revise for 2020 paper 2 are?
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username5741284
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(Original post by guji_1193)
Can you try and advise what the key topics/subtopics to revise for 2020 paper 2 are?
I'll make a thread for it
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guji_1193
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(Original post by mmask3)
I'll make a thread for it
Thank you very much!
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username5741284
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(Original post by guji_1193)
Thank you very much!
its okay, remind me to do so by the end of the week
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hongchayoung
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where's the 2019 paper 2 unofficial ms ??
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