Aqa as biology paper 2 2017 unofficial markscheme
If you could remember any questions post them here so I can put together the markscheme
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to monitor temperature (1 mark)
-use a thermometer
Drawing a curve (1 mark)
Go through all points
affect of higher temperature on light absorption value (2 marks)
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
-carry out biuret test
-find value using colorimeter
-plot graph with reading on y-axis & concentration on x-axis
difference in male & female (1 mark)
6 (i think)
rate of decrease in males (2 mark)
5/35 = 0.143
why a large number of AMY1 genes was advantageous (3 marks)
more colloisions between enzyme & substate so more e-s complex formed
natural selection of large number of amylase genes (3 marks)
why old people are more likely to catch infectious disease (1 mark)
-have less antibody in blood
working out ratio (1 mark)
-number below 1 (dont remember exact value)
why substance helps plants that live in dry conditions (3 marks)
-stomatal openings decrease, so less transpiration
-helps conserve water
why substance helps things from entering through stomata (2 marks)
Reduces diameter size so cannot enter down the concentration gradient into the plant & cause infection
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
why conclusion is not valid (3 marks)
Why there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis to form clones
how an s-shaped dissociation curve is formed (2 marks)
-binding of first oxygen molecule changes shape, making it easier for the other oxygen molecules to bind
advantage of having adult haemoglobin (3 marks)
-lower affinity,so more oxygen unloaded at respiring cells so greater rate of respiration
Why an increase in fetus haemoglobin is advantageous (3 marks)
question on monoclonal antibodies (1 mark)
-will bind to antigen, preventing it from binding to receptors on nerve cells
why antibody is specific (4 marks)
-specific base sequence so specific primary structure
-particular hydrogen-ionic bonds in tertiary structure so specific tertiary structure
-binding site only complementary to antigen to form antibody-antigen complex
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
-water evaporates from mesophyll cells by transpiration
-this lowers wp
-water enters by xylem
-creates tension
-water is cohesive so forms a continuous column
-water is pulled upwards from the roots to the stem
How mRNA is formed in plants (5 marks)
-an enzyme breaks h-bonds between polynucleotide stands
-strands can act as templates
-free flowing nucleotide join exposed bases by complementary base pairing
-this reaction is catalysed by enzyme polymerase
-splicing occurs to remove introns, allowing exons to join together
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to monitor temperature (1 mark)
-use a thermometer
Drawing a curve (1 mark)
Go through all points
affect of higher temperature on light absorption value (2 marks)
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
-carry out biuret test
-find value using colorimeter
-plot graph with reading on y-axis & concentration on x-axis
difference in male & female (1 mark)
6 (i think)
rate of decrease in males (2 mark)
5/35 = 0.143
why a large number of AMY1 genes was advantageous (3 marks)
more colloisions between enzyme & substate so more e-s complex formed
natural selection of large number of amylase genes (3 marks)
why old people are more likely to catch infectious disease (1 mark)
-have less antibody in blood
working out ratio (1 mark)
-number below 1 (dont remember exact value)
why substance helps plants that live in dry conditions (3 marks)
-stomatal openings decrease, so less transpiration
-helps conserve water
why substance helps things from entering through stomata (2 marks)
Reduces diameter size so cannot enter down the concentration gradient into the plant & cause infection
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
why conclusion is not valid (3 marks)
Why there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis to form clones
how an s-shaped dissociation curve is formed (2 marks)
-binding of first oxygen molecule changes shape, making it easier for the other oxygen molecules to bind
advantage of having adult haemoglobin (3 marks)
-lower affinity,so more oxygen unloaded at respiring cells so greater rate of respiration
Why an increase in fetus haemoglobin is advantageous (3 marks)
question on monoclonal antibodies (1 mark)
-will bind to antigen, preventing it from binding to receptors on nerve cells
why antibody is specific (4 marks)
-specific base sequence so specific primary structure
-particular hydrogen-ionic bonds in tertiary structure so specific tertiary structure
-binding site only complementary to antigen to form antibody-antigen complex
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
-water evaporates from mesophyll cells by transpiration
-this lowers wp
-water enters by xylem
-creates tension
-water is cohesive so forms a continuous column
-water is pulled upwards from the roots to the stem
How mRNA is formed in plants (5 marks)
-an enzyme breaks h-bonds between polynucleotide stands
-strands can act as templates
-free flowing nucleotide join exposed bases by complementary base pairing
-this reaction is catalysed by enzyme polymerase
-splicing occurs to remove introns, allowing exons to join together
(edited 6 years ago)
Scroll to see replies
Il just add those here
Cellulose- beta glucose, hydrogen bonding, microfibrils, unbranched
Glycogen- alpha glucose, branched
Starch good for storage- amylopectin branched ( 1,4 and 1,6) help give it a very compact shape, lot of energy stored, insoluble-doesnt affect osmotic potential
Mutation question- non disjunction is failure of separation of chromosomes in meiosis meaning one cell has an extra copy and one is missing one-can lead to e.g downs and turner respectively ( i dont think this was the question btw)
Cohesion tension theory- cohesion between water molecules, delta negative oxygen attracts delta positive hydrogen and drives transpiration stream, adhesion also adds to this effect as cell wall molecules repel water, allows water to travel as a stream, purely passive process, when water removed from leaf by transpiration, osmosis causes water molecule to replace it and cohesion tension causes whole stream to rise from roots to leaves.
mRNA produced when a cistron unwinds exposing bases (unwinds with the help of dna helicase and RNA polymerase) , attracts free complementary bases/ nucleotides which join up to it, Uracil is attracted to adenine,not thymine. Mrna strand then separates and is used as template in translation, 3 bases code for one amino acid, codon on it pairs with anticodon to make proteins.
Glycogen- alpha glucose, branched
Starch good for storage- amylopectin branched ( 1,4 and 1,6) help give it a very compact shape, lot of energy stored, insoluble-doesnt affect osmotic potential
Mutation question- non disjunction is failure of separation of chromosomes in meiosis meaning one cell has an extra copy and one is missing one-can lead to e.g downs and turner respectively ( i dont think this was the question btw)
Cohesion tension theory- cohesion between water molecules, delta negative oxygen attracts delta positive hydrogen and drives transpiration stream, adhesion also adds to this effect as cell wall molecules repel water, allows water to travel as a stream, purely passive process, when water removed from leaf by transpiration, osmosis causes water molecule to replace it and cohesion tension causes whole stream to rise from roots to leaves.
mRNA produced when a cistron unwinds exposing bases (unwinds with the help of dna helicase and RNA polymerase) , attracts free complementary bases/ nucleotides which join up to it, Uracil is attracted to adenine,not thymine. Mrna strand then separates and is used as template in translation, 3 bases code for one amino acid, codon on it pairs with anticodon to make proteins.
Original post by Lazybutmotivated
If you could remember any questions post them here so I can put together the markscheme
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to maintain constant temperature (1 mark)
-use a water bath
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
Where there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
How mRNA is formed in plants (5 marks)
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to maintain constant temperature (1 mark)
-use a water bath
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
Where there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
How mRNA is formed in plants (5 marks)
All body cells have mutations because of mistakes made in DNA replication, insertion/deletion/substitution etc, different amino acid made ( if mutation large enough), different proteins made. Mutation can also be hereditary or environmental. Then cells divide by mitosis so mutated DNA replicated
Original post by GCShElpme
How did you guys find it? I'll type up what I can remember in a minute!
I found it easier than the first paper
Old people are more likely to suffer from infectious diseases. suggest why this may mean they have less protein in the blood? [1 mark]explain AMY1 gene adaptation in those with high starch diet in terms of natural selectionUse your knowledge of protein synthesis and enzymes to explain why extra AMY1 copies are advantage(i think) hese are probably worded wrong lol but was the jist
98% is hbF but by 6 months almost all hbA - explain why this is an advamtage for the baby
Original post by unimatrix79
I wrote because there are less antibodies
So many people saying that was better than the first paper 
I found the first one quite good but there was so many in this that I was unsure about!! The calibration one I had no clue , and the one on natural selection due to the genes, I was confused because surely you're not more likely to survive if you can digest starch better? And I accidentally missed out the one to calculate the rate 
I found the first one quite good but there was so many in this that I was unsure about!! The calibration one I had no clue , and the one on natural selection due to the genes, I was confused because surely you're not more likely to survive if you can digest starch better? And I accidentally missed out the one to calculate the rate 
Original post by unimatrix79
Old people are more likely to suffer from infectious diseases. suggest why this may mean they have less protein in the blood? [1 mark]explain AMY1 gene adaptation in those with high starch diet in terms of natural selectionUse your knowledge of protein synthesis and enzymes to explain why extra AMY1 copies are advantage(i think) hese are probably worded wrong lol but was the jist
For the first question I thought it was - Old people have less protein in the blood how does this lead to more infections?
Original post by Lazybutmotivated
If you could remember any questions post them here so I can put together the markscheme
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to maintain constant temperature (1 mark)
-use a water bath
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
Where there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
How mRNA is formed in plants (5 marks)
Differences between glycogen & cellulose (2 marks)
-cellulose has microfibrils
-cellulose has beta glucose monomers
Why glycogen is a good storage molecule (2 marks)
-helical structure
-large molecule
-branched
-insoluble
Chemical test for starch (1 mark)
Iodine/potassium iodine
Magnification (1 mark)
40 micrometers
Type of microscope used & explanation (2 marks)
SEM - 3D image formed
Why volume water was kept constant (2marks)
How to maintain constant temperature (1 mark)
-use a water bath
Calibration & colorimetry question (4 marks)
-makes solutions of known concentrations
How to work out diameter of stomata (3 marks)
-measure length with graticule & calibrate against something of known length
Where there was a Mutation (2 marks)
-non-disjunction
Why all body cells have mutation (3 marks)
-body cell divide by mitosis
Why children may die with the disease (3 marks)
-less blood in aorta so less oxygenates blood to respiring tissues so less respiration
Cohesion-tension theory (5 marks)
How mRNA is formed in plants (5 marks)
I thought the question was how do you make sure the temperature is constant not 'How to maintain constant temperature' I literally wrote check the temperature at regular intervals but now im thinking you're right - facepalm-
Original post by jazz_xox_
...surely you're not more likely to survive if you can digest starch better?
I put in the event of a famine where non-starch foods were eliminated, individuals who could digest more starch and form more amylose (by extension energy) would have a better chance at survival than those who could not digest as much. Therefore the individuals with more copies of the gene would survive, and those without as many would die.
(edited 6 years ago)
Makes sense, I wasn't thinking of the sense of a life or death thing lol, I did say they're more likely to be healthier, survive and reproduce and would pass on the their allele more often? Is it an allele that would cause the more production? Threw me right off .. hope I can still get an A, hated that paper
Original post by brrrigid
I put in the event of a famine where non-starch foods were eliminated, individuals who could digest more starch and form more amylose (by extension energy) would have a better chance at survival than those who could not digest as much. Therefore the individuals with more copies of the gene would survive, and those without as many would die.
Original post by jazz_xox_
Makes sense, I wasn't thinking of the sense of a life or death thing lol, I did say they're more likely to be healthier, survive and reproduce and would pass on the their allele more often? Is it an allele that would cause the more production? Threw me right off .. hope I can still get an A, hated that paper
It said it was a AMY1 gene, and some populations have more copies of it. Yeah, the passing on of the gene I think was key to it.
I didn't really like either of the papers - they were not terrible by any means, but they weren't easy either. Glad I have this experience for next year (:
And for the microscope question I put SEM because it was a 3D image.
Original post by FabStudent
I thought the question was how do you make sure the temperature is constant not 'How to maintain constant temperature' I literally wrote check the temperature at regular intervals but now im thinking you're right - facepalm-
I thought this too!!!!
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