Aqa biol 4 june 2015 unofficial mark scheme

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Xx1CALUM1xX
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#1
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#1
Changes to death and birth rates along DTM (1)
High the start in both, decrease, DR decreases more rapidly than BR, both decrease to low levels
Changes to population along DTM (1)
Low, rapid rise, stabilises
Calculate the % difference between male average life expectancy and female average life expectancy (2)
Find pop size at median
84-79 = 5
5/84 x100 = 5.95 (approx 6%)
I hear I am wrong on this?
Suggest why % average life expectancy for males is lower (1)
Males more risk of CHD, less HDL in blood than females
More men smoke
Men go to war
.... anything that is valid, will depend on AQA MS hugely
What process involves nitrification (1
R
One other process by which ammonium ions are released into the soil (2)
Saprobiotic decomposition
Nitrogen in organic matter of plants, animals (e.g. in protein) converted to ammonium/ammonia
Good things about ploughing
Aeration , aids nitrification
Prevents dentrification, prevents loss of nitrates, fertility thus increases
Two advantages of crop rotation (2)
Legumious plants, fix N2, fertilise soil for next crop
Dig waste parts of plant into soil, decomposition...
Perhaps about certain pests present at certain times
Certain harvest times
will depend on AQA MS hugely

Units for gross productivity (1)
KJm-2Yr-1
Why does gross productivity decrease as succession occurs (2)
Taller trees, dense leaves in canopy,
Less light to producers on forest floor
Less energy conversion (gross prod)
Less energy for all organisms in food chain that eat producers...
Why does biomass increase as succession continues (3)
Pioneer species, hostile to less hostile, allows new species to colonise, env changes, abiotic changes, competition, increase biodiversity, niches, more organisms etc.
Why does net productivity decrease (2)
N=G-R
Wasnt sure... Gross became smaller? Resp stays about the same?
Why conservation (1)
Prevent extinction of endangered species,
Medicines,
Natural landscape
Resources
Habitats, niches retained

Define co-dominant alleles (1)
Equally dominant,, neither recessive, both alleles expressed
Why are males less likely to have the condition (1)
Only have one allele, on X chromo, can’t show co dominance
Genotypes, Phenotypes, Ratio (3)
Draw cross
Get tortoise female, black male, black female and ginger male
Ratios: i thought 1;1;1;1 apparently its 1;2;1. Not sure, isn’t the gender classed in phenotypes?
Hardy-Weinburg (2)
2pq+p^2 = their number?
So do 1-2pq+p^2=0.81=q^2
Square root
To get q=0.9
What happens to the proportion of homozygous alleles (1)
Homozygous dominant freq increases
Recessive selected against and lost?

What measurement for photosynthesis experiment (1)
Rate of O2 produc
Name two other factors (beside temperature and pH) that need to be kept constant (2)
Light int, co2 conc
What happens to the pH of the solution (2)
Debated: I said decrease as H+ increases acidity and CO2 produced via resp which is acidic. Also algae cannot absorb all wavelengths so respire more?
Or increase as CO2 absorbed for photo, CO2 acidic, so increases alkalinity
I think second version is correct

Why does the rate of photosynthesis drop (graph) (2)
Cannot absorb wavelength, not correct range, cholorphyll
Reflected
Less e excited, ETC
Less photolysis, less O2 releases (we are measuring O2 production)
How is acetylcoenzyme A prodcued in the link reaction (2)
Pyruvate oxidised to acetate
Decarboxylation
One NAD to red NAD
Acetate + CoA = Acetly Coa
How does oxocotalase (forgive spelling) allow acetylcoenzyme A to bind with citrase enzyme (2)
Non comp inhib
Allosteric site
Changes AS, makes complimentary to CoA to bind
E-S complex
How does another enzyme regulate cycle (Competitive Inhibition) (2)
Comp inhib
Binds to enzy AS, saturates
Prevent binding of the other CoA molecules
Less ES complex
Role of pyruvate in anaerobic respiration allowing continued glycolysis (2)
Red NAD to NAD which is recycled
Glycolysis
2 net atp
Advantage of converting some lactate back to pyruvate (1)
Can go onto link, krebs, make reduced coenzymes and ATP (in krebs) and thus in ETC
Why does climate change increase soil salinity (2)
Evaporation
Salt less diluted in soil, increase salt conc
Also heard about sea levels rising, and deposit salts
Why plant growth is lower at higher salt salinity
Low WP in soil,
Water moves out of roots via osmosis or less absorbed for photsyn
Less photo means less proteins, carbs etc.
Less growth
Why did they isolate fungus and do exp in same soil salinity
To prevent spread of fungus
Representative, as doing in same soil salinity cucumber grows in
Evaluate the biological control (4)Purpose of control A (2)
THIS WAS HORRIBLE AS I DIDNT HAVE TIME TO READ AND FULLY UNDERSTAND QUE
Basically compare SE values,
Overlap = non sig diff
Non overlap = sig diff
Not sure... here I HATE HSW
Suggest how the bacteria increase growth (1)
Kill pests fungus (not sure here, i wrote second point)
Respire aerobically, release CO2 used in photosynthesis
Nitrogen fixing, nitrogen into ammonium
Why were weeds removed from the pot (2)
Interspecific comp (may not need to write interspecific)
Reduce comp
For nutrients, light , water, space, increase growth of cucumber

Speciation (6)
1. No interbreeding / gene pools are separate / geographic(al) isolation;
2. Mutation; variation
3. Different selection pressures / different foods/niches/habitats;
4. Adapted organisms survive and breed / differential reproductive success;
5. Change/increase in allele frequency/frequencies;
cannot produce fertile offspring
over a long time, speciation

Mark-release-recapture (4)

1. Capture sample, mark and release;
2. Appropriate method of marking suggested / method of marking does not harm lizard;
3. Take second sample and count marked organisms;
4. Large sample, allow mixing, marking do not harm or reduce survival chance
5. Do when Population changes small, e.g. not in breeding season
6. No in No in Population = (sample1 × sample2) divided by Number marked in sample2;

Carbon dioxide concentration question (duplicate of a question from a past paper in the last few years) (5)
1. High concentration of carbon dioxide linked withnight/darkness;
2. No photosynthesis in dark/night / light required forphotosynthesis/light-dependent reaction;
3. (In dark) plants (and other organisms) respire;
4. In light net uptake of carbon dioxide by plants/plants usemore carbon dioxide than they produce/ rate ofphotosynthesis greater than rate of respiration;
5. Decrease in carbon dioxide concentration with height;
6. At ground level fewer leaves/less photosynthesising tissue/more animals/less light
6
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Xx1CALUM1xX
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#2
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#2
Overall, not a terrible exam.
Lots of horrible "suggest" que, which concerns me about MS
Lots of wierd questions where you could say a lot of different stuff
Good range of questions
THE CUCUMBERS WAS A JOKE, NO WAY ENOUGH TIME TO READ AND FULLY UNDERSTAND UNLESS YOU STARTED WITH IT.
Don't know what to think
My MS is only my answers and other peoples answers, from what I heard anyway.
Yep, good luck with BIOL 5 the BEAST guys!
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xMystics
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#3
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#3
(Original post by Xx1CALUM1xX)
Overall, not a terrible exam.
Lots of horrible "suggest" que, which concerns me about MS
Lots of wierd questions where you could say a lot of different stuff
Good range of questions
THE CUCUMBERS WAS A JOKE, NO WAY ENOUGH TIME TO READ AND FULLY UNDERSTAND UNLESS YOU STARTED WITH IT.
Don't know what to think
My MS is only my answers and other peoples answers, from what I heard anyway.
Yep, good luck with BIOL 5 the BEAST guys!
pretty much had the same answer as u, i was concerned that i was the only one with 5.95% increase ( i rounded it up to 6.0%) in my school, everyone else had 6.3% or something
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Uberphuq
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#4
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#4
(Original post by Xx1CALUM1xX)
Overall, not a terrible exam.
Lots of horrible "suggest" que, which concerns me about MS
Lots of wierd questions where you could say a lot of different stuff
Good range of questions
THE CUCUMBERS WAS A JOKE, NO WAY ENOUGH TIME TO READ AND FULLY UNDERSTAND UNLESS YOU STARTED WITH IT.
Don't know what to think
My MS is only my answers and other peoples answers, from what I heard anyway.
Yep, good luck with BIOL 5 the BEAST guys!
I wrote the sames for8a but hearing it's different? I didn't i was wrong
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TashJacobs
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#5
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#5
Thank you for this! Was wondering what you thought the grade boundaries may be? Hoping that 56ish would be an A... what do you think?
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ibz100
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#6
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#6
Im thinking way lower, that could even be close to full UMS imo
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Xx1CALUM1xX
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#7
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#7
(Original post by TashJacobs)
Thank you for this! Was wondering what you thought the grade boundaries may be? Hoping that 56ish would be an A... what do you think?
Its okay!
As for grade boundaries, it was:
58 for an A*,
54 for an A,
50 for a B last year.
I'm thinking either last year boundaries or slightly lower.
Lowest boundaries, from what I remember from that horrid june 10 paper were:
39 A*
35 A
31 B
I doubt they will be this low.
From what I hear from others in my class, a lot of people really hated the paper (I don't blame them). So i'm thinking maybe like 55 for an A*, 50-55 for an A, 46-50 for a B? Maybe?
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TashJacobs
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#8
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#8
That would be great, crossing my fingers!


(Original post by Xx1CALUM1xX)
Its okay!
As for grade boundaries, it was:
58 for an A*,
54 for an A,
50 for a B last year.
I'm thinking either last year boundaries or slightly lower.
Lowest boundaries, from what I remember from that horrid june 10 paper were:
39 A*
35 A
31 B
I doubt they will be this low.
From what I hear from others in my class, a lot of people really hated the paper (I don't blame them). So i'm thinking maybe like 55 for an A*, 50-55 for an A, 46-50 for a B? Maybe?
0
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Xx1CALUM1xX
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#9
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#9
(Original post by TashJacobs)
That would be great, crossing my fingers!
Yep, good luck with Biol 5...the beast that is going to kill me off.
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TashJacobs
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#10
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#10
Thank you, and you too! I cant eveb start revising for it until friday because of other exams 😑
(Original post by Xx1CALUM1xX)
Yep, good luck with Biol 5...the beast that is going to kill me off.
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elliemoriartyell
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#11
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#11
That mark scheme seems pretty spot on to me, I definitely think phenotypic ratio is 1:1:1:1 though. It was a tough paper but I think I managed, the general consensus for my college was just time was a problem (and HSW is a b*tch but what's new there). My stab at grade boundaries is A* 56, A 52, B 48, C 43, D 38, E 33.
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Xx1CALUM1xX
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#12
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#12
(Original post by TashJacobs)
Thank you, and you too! I cant eveb start revising for it until friday because of other exams 😑
same here chem4,5 core 3,4 coming up
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princessBG
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#13
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#13
(Original post by Xx1CALUM1xX)
same here chem4,5 core 3,4 coming up
I cant until tuesday ..imagine 😧
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