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AQA AS BIO Unit 2 OLD SPEC RESIT Tue 7th June (pm) 2016

Post me with alternative answers i'm happy to put next to it.
_{Thanks guys for posting your answers and revise for Unit 4 next Thursday! And good luck!} :h:

Unofficial Mark scheme

What is phylogenetic group? [1 mark]
(Groups based on) evolutionary history/relationship

What is species? [2 marks]
Group of similar organisms able to produce fertile offspring
Notice if you put 'produce fertile offspring' = 2 marks

Label the missing order of taxonomy [1 mark]
Phylum, Order, Genus, Species

Draw addition circles and label them [2 marks]
Two circles -1 for each genus then 1 circle inside each of those for the species

Suggest how this related ????? [2 marks]
Nucleotide sequence: Two species (can't remember names of the tigers) have the same nucleotide sequence for part of a gene so they are more closely related species. The other species has a different nucleotide sequence for part of a gene so it is less closely related to the other two species.

What do you call two or more than of polypeptide chains? [1 mark]
Quaternary (structure)

What is the minimum number of DNA bases in alpha-polypeptide (141 amino acids)? [1 mark]
141 amino acids so 141 x 3 = 423

Explain what happened at K in Cell A. [2 marks]
Crossing over (of the chromatids in the homologous pair of chromosomes)
Forms new combination/variety of alleles

The person with Anemia advantage [3 marks]
Haemoglobin has a lower affinity for oxygen at a higher pO2
So haemoglobin readily unloads to respiring tissues for more respiration

Describe how to use temporary mounts [2 marks]
Cut through leaf for cross-sectional area?
Put nail vanish on slide
Put sellotape on specimen (leaf)????

Find the length between F and G? [2 marks]
Use scale bar as shown - 1.6 cm = 50 micrometers so whole length is 6.4cm/1.6cm = 4 then x 50
200 (micrometers)

What is genetic diversity? [1 mark]
total number of different alleles in a population

What is species diversity? [1 mark]
total number of different species in a community

What measurements needed to calculate index of diversity? [2 marks]
(total) number of organisms of each species
(total) number of organisms of all species

Explain how do sewage reach to river come to scientist's findings? [3 marks]
(high density of organisms but low index of diversity)
Sewage is poisonous to most of the organisms?
Most species died due to lack of oxygen/nutrients = Low index diversity;
Fewer food sources?
Only some species adapted to survive and reproduce;
So population increase = high density of organisms;

Name the structure where gases enter and leave in insect. [1 mark]
Spiracles
Could accept phonogenic spelling (e.g spirale, spiricle)

Name the structure that gases brought directly to respiring tissues. [1 mark]
Tracheoles
Could accept phonogenic spelling (e.g tracheaole, trachiole)

Describe how oxygen reaches to respiring cells. [3 marks]
Oxygen enters through spiracles --> trachea --> tracheoles.
Down the diffusion gradient;
Low oxygen concentration in tissues;
Oxygen diffuses down the gradient;

The mesenteric advantage during vigorous exercise [3 marks]
More blood containing more oxygen // Less blood goes to small intestine
More oxygen to respiring tissues
More respiration
More energy released (from ATP) for muscle contraction

Scientists recommend not to exercise vigorously after eating meals. Do Table 6 and Figure 7 support this conclusion? [4 marks]
(YES)
Blood flow increased for at least 15 mins after consumption.
the sample/data was representative;

(NO)
Table 6 regarding the different meals taken did not specify who the subjects were, how many of them there were and if their meal size was consistent.
The figure didn't specify when the volunteers have last had their meals and if they had done the same 'vigorous exercise'.
No data indicating rate at which blood flow decreased etc. only data done on one artery, blood flow to other areas not measured so hard to draw overall conclusion;
One sample;
Volunteers have different volume of blood;

Name of structure of many different cells for different functions in leaf [1 mark]
Organ

Percentage difference [1 mark]
56(%)

Why do some cells ??? abruity 1 and 2? [1 mark]
Some cells were undergoing DNA replication whilst other cells had finished/not started it

Describe the patterns of blood circulation from Kidney and then return back to Kidney [6 marks]
1. Blood exits kidney through renal vein
2. into vena cava into heart
3. pulmonary artery (reoxygenates)
4. pulmonary vein back to heart
5. heart to aorta
6. aorta to renal artery (back to kidney)

Alternative:
Blood in vena cave goes to right atrium;
Right atrium to right ventricle. Then pulmonary artery to lungs to be oxygenated;
Then pulmonary vein to left atrium then to left ventricle;
Then left ventricle pumps it down the aorta;
Renal artery goes back to the kidney;

The scientists followed strict safety guidelines when collecting samples of faeces. Apart from the risk of contamination from e.coli, this was especially important when collecting human faeces. Explain why.
[1 mark]
Bacteria in human faeces more likely to spread and infect other humans than bacteria in animal faeces as strains may be different

Describe and explain one way how have the scientists increased the reliability of their results? [2 marks]
46 farms so large sample size
more representative (results)

Describe how you investigate nicotrigen-resistant bacteria to be identical to other strain of bacteria from birds? [2 marks]
Determine the DNA sequence and compare.

In UK, few animals feed on antibiotics. Suggest why. [4 marks]
Less resistant bacteria survive and reproduce;
Reduced spread of infection;
Prevents horizontal/vertical gene transmission/conjugation;
Fewer animals die due to infection caused by bacteria;

Alternative:
Antibiotic food is much more expensive so not viable for farmers trying to make profits etc.
Other techniques used such as selective breeding

(edited 7 years ago)

Scroll to see replies

Reply 1

username1084917

what books do you use to revise with?

I use the Tool and Tool and the CGP textbook.

I do all the past papers too.

Anything else you people do?

Do you do the old spec papers?

Reply 2

amina126

Ahh, after the BIOL1 resit, i just dont feel like doing unit 2 anymore 😧

Reply 3

Ordo

Original post by Kira Yagami

what books do you use to revise with?

I use the Tool and Tool and the CGP textbook.

I do all the past papers too.

Anything else you people do?

Do you do the old spec papers?

Textbook by Nelson Thornes.
I haven't done any past papers yet lol. From 2010 to 2015.
Will write down the list of two questions (5/6 marks) soon.

(edited 7 years ago)

Reply 4

h133ma

Has anyone got any predictions for AS bio unit 2?

Reply 5

icexcity_

What is the best/ effective way to revise for unit 2 bio knowing there's only a week left of the exam?

Posted from TSR Mobile

Reply 6

Ordo

Original post by icexcity_

What is the best/ effective way to revise for unit 2 bio knowing there's only a week left of the exam?

Posted from TSR Mobile

Do past papers and make condensed notes. Then test yourself by writing on a blank page in each topic - so you can see how much you can remember. This is what im doing now. Hope this helps

(edited 7 years ago)

Reply 7

emma_1111

6 marker predictions?

Reply 8

dont leave blank

Original post by emma_1111

6 marker predictions?

mitosis..?

Reply 9

downton-abbie

Majorly regretting leaving starting revision till today thinking it's 'just a resit' lol

Reply 10

username1539513

Best of luck to everyone doing this paper; if anyone is feeling hopeless, take comfort in the fact I did about 2 days worth of revision for this unit after not doing it since 2011 (I sat it in 2015) and I came out with a C. If I can do that in 2 days you can do better

Reply 11

username1084917

Original post by downton-abbie

Majorly regretting leaving starting revision till today thinking it's 'just a resit' lol

Yeah. There is a lot to learn in biology, you need to revise at-least 4/5 days before even if it's a resit.

Reply 12

97Y

Hey guys! I don't want to sound like an ass, but I've done four past papers now and come out with 140 UMS each time
Do you think that it'll be as easy on Tuesday? I really don't understand the whole plant stuff and know nothing about the heart but here is to hoping

How's it all going?

Apparently unit 1 bio was a killer and I'm worried that this one will be too :frown:

Reply 13

emma_1111

Any other predictions for 6 markers?

Reply 14

username1084917

Original post by emma_1111

Any other predictions for 6 markers?

Xerophytes adaptations.

Do you do old spec papers too? Or do you do the all the current spec papers and read tool and tool?

Reply 15

miradordelmar

Original post by 97Y

whats 140 in raw marks I did 2 ppapers and got 64 for both oddly out of 85 ???

Reply 16

97Y

Original post by miradordelmar

whats 140 in raw marks I did 2 ppapers and got 64 for both oddly out of 85 ???

Nooo! UMS, that's the UMS convertion. I always convert because I'm after the UMS not the mark 😅

Reply 17

97Y

Go to 'AQA UMS converter' and type in the year etc. And it'll come up 😚

Reply 18

username1084917

140 UMS usually at-least 68 marks according to recent grade boundaries so it should be around 68-70 ish this year too because they don't usually change much.

Reply 19

username1084917

Hey guys, how do you lot revise? Do you do ALL the current spec past papers or do you do old spec papers too?

do you do the questions in tool and tool or just read it?

Could you guys please tell me what you do exactly to revise for AQA A level biology.

Do you guys use those booklet questions which are meant to be old spec questions?

I use tool and tool and CGP textbook. I do all the questions in these books too and do all the current spec past papers.