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AQA BIOL2~3rd June 2013~AS Biology (Now Closed)

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Reply 4060

nerd1

Original post by Starlight94

I was going to put this but i didn't think humans had cell walls? :frown:

unless it wasn't talking about humans lol, i can't remember

OMG YOU MIGHT BE RIGHT

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Reply 4061

Matt_dragon

About the 6 marker, I didnt include the root pressure but did everything else. How many marks do you reckon I'd lose?
Also, this paper was INCREDIBLY hard, the hardest paper for unit 2 I've done

Reply 4062

sar-egy

Original post by bad8oy

you would have to say deletion of 3 bases and i think that would be 3 mutatuions though?? I dont know man see whats on the mark scheme its no big deal. Its either right or wrong lol cant change it now.
chill out

Not sure if this was right but I thought that a base could mutate into a non coding base- intron. So triplet code for one amino acid is no longer present?

Reply 4063

GTSwattsy

Original post by nerd1

OMG YOU MIGHT BE RIGHT

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It was a question about bacteria, bacteria have cell walls as they are usually prokaryotic

Reply 4064

nerd1

Original post by GTSwattsy

It was a question about bacteria, bacteria have cell walls as they are usually prokaryotic

Ok I was just freaking out for no reason, thanks

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Reply 4065

Futuristicmedic

Original post by sar-egy

Not sure if this was right but I thought that a base could mutate into a non coding base- intron. So triplet code for one amino acid is no longer present?

Introns is correct

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Reply 4066

Blobar

If Chemistry is full of HSW then fml.

Reply 4067

Liam2404

Original post by Matt_dragon

About the 6 marker, I didnt include the root pressure but did everything else. How many marks do you reckon I'd lose?
Also, this paper was INCREDIBLY hard, the hardest paper for unit 2 I've done

Possibly none, there usually 8 or 9 points you can make for the 6 marker, so if you've got 6 points from other explanations you can still get full marks or 5/6 :smile:

And i agree, it was hard, not as hard as the jan 2010 paper though, should be lower grade boundaries than jan 2013, so in the 50s for an A :smile:

Reply 4068

laithmo96

Is inhibiting protein synthesis wrong for the bacterial growth question?

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Reply 4069

Blobar

Anyone got the paper they can upload?

Reply 4070

username984585

Original post by Blobar

If Chemistry is full of HSW then fml.

Agreed!

Reply 4071

Blobar

Original post by laithmo96

Is inhibiting protein synthesis wrong for the bacterial growth question?

Yeah that can be correct too. Thats how Tetracyclines work.

Reply 4072

MintCrepz

Is introns accepted for the amino acid removal ?

Reply 4073

username984585

Original post by laithmo96

Is inhibiting protein synthesis wrong for the bacterial growth question?

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I said that it inhibits the enzymes that are needed for bacterial cell wall formation and hence osmotic lysis occurs. :smile:

Reply 4074

Blobar

Original post by Nav_Mallhi

I said that it inhibits the enzymes that are needed for bacterial cell wall formation and hence osmotic lysis occurs. :smile:

Thats right too, remember there's more than 1 right answer to some questions!

Reply 4075

Matt_dragon

Original post by Liam2404

Possibly none, there usually 8 or 9 points you can make for the 6 marker, so if you've got 6 points from other explanations you can still get full marks or 5/6 :smile:

And i agree, it was hard, not as hard as the jan 2010 paper though, should be lower grade boundaries than jan 2013, so in the 50s for an A :smile:

Splendid

I did jan 2010 the day before the actual exam and got 63% which was basically about 3 marks over an A grade so I was surprised the grade boundaries were that low. This paper was so hard, I have no idea what to think now, and I've got chemistry tomorrow -.-

Reply 4076

The_Blade

for control i put amount of time the snakes was in cage/...

Reply 4077

1144876

I put temperature (And amount of lipid) for things you must keep the same. What do you think then, does the temperature affect the hornyness of snakes?

Reply 4078

laithmo96

Do we get marked down for not rounding up our values for the index of diversity and the percentage increase question ?

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Reply 4079

walkers38

BIOL2 UNOFFICIAL MARK SCHEME

1a(i) Centromere [1]
a(ii) attaches to spindle fibres; and splitting during anaphase [2]
b) different alleles [1]
c) the chromosomes had divided into chromatids [1]
d) three chromosomes drawn; different shape [2]
d) Crossing over [1]
2a) groups of organisms; that interbreed to produce fertile offspring [2]
b) 6.98/7;; [2]
c) less plants; less habitat; less food variety [3]
3a) groups within groups; no overlap [2]
b) shows evolutionary relationship [1]
c) least different/most similar amino acids sequence; most similar base pairs; more a.a seq= more closely related [2]
d) B and C had different differences so different amino acid sequences [1]
e) all organisms have it [1]
4a) Sample 1: 15N only;
Sample 2: 14N/15N;
Sample 3: 14N/15N and 14N only [3]
b) breaks H bonds in DNA; between complementary base pairs; unzips the strand [2]
c) binds with guanine; complimentary base pair can’t form; DNA can’t zip back [2]
d) cancer cells as they divide more frequently [1]
e) prevents formation of cell wall; osmotic lysis [1]
5a) vertical gene transmission; passes resistant gene to next generation [2]
b) (The scientists used many patients) to make results more reliable [1]
c) (True) Hypochlorite had most no. of bacteria killed;
(False) SD overlap so no real difference/more likely to be chance; no control dish used; need to test on more disinfectants [3]
d) Mutated; resistant gene; [2]
6a) Quaternary: Haemoglobin only
Condensation: All 3;
Nitrogen: Haemoglobin only [3]
b) 16%. [1]
c) (The fetal haemoglobin had) a higher affinity; associates/loads oxygen more readily [2]
d) respiration occurs; haemoglobin has lower affinity; oxygen unloaded easily for respiration. [2]
e) (no symptoms because) adult haemoglobin present [1]
7a) (Founder effect is when) few/30 individuals from Swiss population colonised a new region; fewer different allele/reduced gene pool; (making it) less genetically diverse; inbreeding; [3]
b) 250,000. [1]
c) mutation; three bases removed [2]
d) amino acid sequence changes; tertiary structure changes; non functional active site, e-s complex can’t form [2]
8a) mineral ions actively transported to xylem; WP gradient in xylem reduced; water enters xylem by osmosis; water evaporates/transpires via stomata; WP in leaf cells reduced; water drawn up from xylem (by osmosis); creates tension; water molecules cohere/H bonding; continuous column of water [6]
b) (abdominal musle movement) ventilates air; maintains concentration gradient; O2 diffuses in/CO2 diffuses out [2]
c) (small insects have) large SA:Vol ratio [1]
d) 6.7;; [2]
e) 342 % ;; [2]
f) (removal of water) increases O2 conc. in tracheoles/shortens diffusion pathway [1]
9ai) age; species; health conditions? [2]
aii)) (different males used) so previous tests did not influence results; [1]
aiii) Avoid bias [1]
aiv) Paper with no lipid from female [1]
b) (Conclusion was that) length of female was more influential than lipid...? [2]
c) (2 benefits of longer females) more eggs; better predator; successful mating; [2]
d) longer the female, greater the unsaturated fatty acid %; males attracted to high fatty acid% so more attracted to longer females (who have that) [2]
ei) Draw line of best fit; extrapolate [2]
eii) (beyond 75cm) exceeds 100% (so unlikely); [1]
f) (female) won’t recognise/respond [1]

(edited 10 years ago)