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

I was going to put that but then it said males choosen at random so not sure tbh.

And for ppl wondering what full ums will be. For jan13 full ums was 70/85 that paper was way easier than the one today. Full ums will be 67/68 no higher.

So was the answer for insects ventilation per minute 6 or 6.7?

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]

Sorry if someone has already mentioned this, but how did u get 6 for the spiracle question?

Seems plausible seeing 140 UMS is max. Lol.

So full marks you reckon? thanks

I think I marked myself humbly, only gave myself 3 marks in the 6 mark questions, and left out some marks I wasn't sure about, got 62... I just want to get an A lool!

Let try to help here...

5 b) I said they used different patients as the bacteria could have different strains.
9 a) also said age and species
9 b) I think the bar of the paper was the same height as long snakes. So I said they could have a poor vision and depend more on their oth
heheer senses like smell. And they couldn't distinguish between paper and snakes
9 d) you might be right.. But I said the longer the snake the better they could protect the eggs and the longer they are the older they are (prob) and more mature so ready to breed

If in January 60 was an A, and this one many people found it hard, hope the boundaries are lower... A "B" would disappointing xD

Now, it's time to eat the chemistry book

graph repeated every 10 seconds.

In a minute, thats 60/10 = 6

Probably 145+

Posted from TSR Mobile

I think I got around 50 marks. I really fluffed up in the haeomoglobin question! Anybody have any ideas what 50 marks would be?

Sorry if someone has already mentioned this, but how did u get 6 for the spiracle question?

In the one saying why is cytochrome better than haemoglobin, what did you put?
I was gonna say they all have it but then again wouldnt they all have haemoglobin?


Posted from TSR Mobile

I said haemoglobin changes shape and then crossed it out and said haemoglobin is made of many proteins

What was the actual answer?




Posted from TSR Mobilehh

I said haemoglobin changes shape and then crossed it out and said haemoglobin is made of many proteins

What was the actual answer?




Posted from TSR Mobilehh

I said haemoglobin changes shape and then crossed it out and said haemoglobin is made of many proteins

What was the actual answer?


Posted from TSR Mobilehh

I said it has a slightly different shape in different organisms since some organisms have a higher affinity for O2 and some have a lower affinity...no idea if it is right though.