[The Assassin]

Didn't mind this paper, although it seems there were many ambiguous questions.

; denotes a mark point. There are obviously more answers and I've missed out many questions - so please help!

Thanks to TheBigDog, iAre Teh Lejend and some other people for some help

1)

a) Diffusion. (1 mark)

b) Thin so short diffusion pathway; large surface area (2 marks)

c) A collection of tissues joined to serve a common/specific function. (1 mark)

d) Diffusion; through stomata; diffusion gradient set up(3 marks)

2)

a) The sugar beet had: (4 marks)

Larger leaves; more surface area for photosynthesis

Larger root; allows more sugar storage/more water storage for photosynthesis.

b) How does the farmer profit? (more answers) (1 mark)

More rapid growth in a shorter time;
saves on fertilisers;

c) How would growing the sugar beet affect the diversity of the sugar roots?
(2 marks)

Grown on large scale;
using the same specific allele;
for more yield of sugar (in shorter time);
(so) diversity reduced;

3) a) Monomers of cellulose (1 mark)

Beta glucose

b) What bond is shown? (1 mark)

Glycosidic

c) What group is Z?

OH/Hydroxyl

d) 2 reasons - Differences between cellulose and starch (2 or 4 marks?)

Starch is made up of alpha glucose; but cellulose beta
starch forms purple complex with iodine; cellulose doesn't form colour;
storage role for starch; structural role for cellulose;
starch has flexible chains; cellulose had straight chains;
starch forms helix; cellulose forms microfibrils

e) Describe structure of cellulose related to function
(2 marks)

long straight chains;
can form microfibrils;
provide rigidity to cell walls;
so they resist osmotic pressure;
held together by hydrogen bonds;
difficult to break bonds;
resists digestion / enzyme activity


4)

a) How do you know this is a polymer? (1 mark)

Joined by many nucleotides / has sugar phosphate backbone / units are repeating

b) Name the molecules.
(Don't remember the order) (3 marks)

Hydrogen bonds
Deoxyribose/Pentose Sugar (the pentagon)
Phosphate (circle)

c) Adenine; Guanine & Cytosine; 16 and 16 each (I think?) (2 marks)

d) Minimum number required

51*3 = 153

e) Introns / junk DNA.

5) a) Why is mitosis essential?


Growth;
Quick cell restoration/repair/regeneration;
asexual reproduction;

b) Stage the two stages in A and B
Ambiguous - I believe they'll be generous.

A -

Prophase; because the chromosomes were condensed and visible

OR

Metaphase; chromsomes were lining up in the equator

B-

Anaphase; chromosomes move to the opposite ends of the cell.

b) 2 hours. Interphase was 90%. 100-90 = 10%. 10% of 20 hours is 2.



6) Index of diversity questions

a 1.285-1.3

b) Would the index of diversity for the wheat field be less or more? (2 marks)

less;
every species apart from oak aphids had a lower number or organisms than the organisms found in the wood;
many species have 0 organisms;

c) A journalist mentioned that farming reduces the diversity. (2 marks)

No - farming wasn't mentioned;
yes - farmers clear out woodland/other plants to make room for wheat fields;

d) How would shrubs help? (2 marks)

Increase diversity;
more habitats;
more food sources;

7)

a) Kingdom / Phylum / Class (1 mark)

b) Family

c) (2 marks)

Standard deviation measures variation;
if overlap, whether due to chance/coincidence

d)

Courtship identifies members of same species;
male species different colour to other male species;
likewise for female;

e) The question of Protein sequence.

Compared same protein;
same species will have similar base sequences
DNA Hybridisation;
more hydrogen bonds form;
more heat required indicates relationship;
amount of precipitate from both species indicates relationship

8) a) Explain the changes in the graph (3 marks)

(Xylem pressure low during the night) as stomata closed and there’s less transpiration;
(During day it increases) because rate of water movement increases;
because of more sunlight;
This puts the water column under pressure so the xylem is drawn in so diameter is reduced

b) Why are the pressure values negative? (1 mark)

Transpiration pull/xylem pulled in by tension

0)

a) Explain why the artery has the thickest wall? (1 mark)

Artery has thicker walls because pressure is higher.

b) Why is the thickness of the aorta different every time?
(3 marks)

Different surges in pressure;
streches;
recoils;

c) Which showed the greatest variation in wall thickness? (2 marks) Bitch of a question - ambiguous.

Aorta; greatest (difference in) standard deviation

Pulmonary veins beacuse the standard deviation for that was highest relative to what the actual mean value was.

d) Explain the formation of tissue fluid (6 marks)

At (arteriole) end of capillary;
Hydrostatic / blood pressure;
Forces out soluble / small molecules;
And water;
Protein remains in blood / plasma;
Molecules too large;
More negative / lower water potential at (venule) end;
Water drawn in by osmosis / diffuses in;
lymphatic system collects excess tissue fluid;
Some fluid/lymph returned to blood by lymphatic system;


10) a) i) Why were the bacteria incubated at 35 degrees? (1 mark)
Similar temperature to body; optimum temperature for bacterial growth.

a) ii) Why was the same amount of bacteria used?
(1 mark)

So you can compare / there'd be more bacteria at the end for different concentrations / decreases validity / results affected

b) i) Why was a control used? (1 mark)

To show that it was only the antibiotic that affected the results

ii) Describe the changes shown on the graph (2 marks)

Rapid decrease up to 5; slight decrease from 5-10; steady but slow decrease from 10-50; extremely slow decrease/levels off from 50-100

iii) The scientists concluded that 50 micrograms was the most efficient concentration. Do you agree?
(3 marks)

Correlation doesn't mean causation;
may be other factor involved;
graph supports this because most amount of bacteria were killed then;
not much difference from above 50 so can save on cost/less risk of resistant bacteria replicating (?);


c) How does bacteria develop resistance? (2 marks)

Random mutation;
Gene transmission

d) Why were the people similar ages

Increases reliablity / more age representitive / affects different ages in different ways

e) The scientists said that taking antibiotics was the right thing to do. Does the information in b c and d support this? (4 marks) Really weird question.

No -

Could wipe out competition and leave resistant strain;
strain divides and gives genes via vertical gene transmission;
there wasn't much difference between the volunteers in 2 months;
both values were the same in 3 months;
antibiotic testing showed that there was still 40% of bacteria despite 100% concentration of antibiotics

Yes -

antibiotics destroy bacteria anyways and can reduce risk of heart disease;



Predicted grade boundaries

70/85 - 140 UMS
60/85 - A
55/85 - B
49/85 - C
44/85 - D

[IAmMclovin]

for 9 a)i) could you say 35 degrees = optimum temp for enzyme action therefore optimum rate of metabolic/enzyme catalysed reactions so more growth?

[xDesertRose]

(Original post by IAmMclovin)
for 9 a)i) could you say 35 degrees = optimum temp for enzyme action therefore optimum rate of metabolic/enzyme catalysed reactions so more growth?

Correct me if im wrong but i dont think it talked about enzymes...
why neg me u prick

[Richyp22]

[QUOTE=The Assassin;37673755]Didn't mind this paper, although it seems there were many ambiguous questions.



For the xylem question its, Xylem was pulled in by tension. Confirmed


Getting negged because I gave an answer ppl got wrong, Just lol.

[renegadeprime]

post exam discussion http://www.scriblink.com/index.jsp?a...DA5D6B2E88CD3D

[IAmMclovin]

(Original post by xDesertRose)
Correct me if im wrong but i dont think it talked about enzymes...

It didnt mention enzymes but most cellular reactions are catalysed by enzymes

[IAmMclovin]

(Original post by Richyp22)
For the xylem question its, Xylem was pulled in by tension. Confirmed

Did it ask about xylem being pulled in? I thought it asked to explan the relationship between pressure/tension and rate of water movement in xylem, not about diameter of root etc.

[Richyp22]

(Original post by IAmMclovin)
Did it ask about xylem being pulled in? I thought it asked to explan the relationship between pressure/tension and rate of water movement in xylem, not about diameter of root etc.

No im on about the one were it said. Why is the pressure negative

[IAmMclovin]

(Original post by Richyp22)
No im on about the one were it said. Why is the pressure negative

Ah right, sorry

[RosieH7]

after labelling the dna molecule it asked you to label Z which was alchohol group/ OH?

[LemonLattes]

Why did I come here, Ive just depressed myself.

[IAmMclovin]

Damn, for the "why negative pressure?" question i put something like the water column is under tension as water bein pulled up so its negative pressure?
That probably wont have got the mark :/

[clairelouise444]

(Original post by RosieH7)
after labelling the dna molecule it asked you to label Z which was alchohol group/ OH?

Ah I wrote hydroxyl group

[clairelouise444]

(Original post by IAmMclovin)
Damn, for the "why negative pressure?" question i put something like the water column is under tension as water bein pulled up so its negative pressure?
That probably wont have got the mark :/

I wrote that too

[mulac1]

do you think for the sugar plant question, it would be ok to say shorter stem, so shorter distance for water to get to the leaves up the xylem?

[Mocking_bird]

(Original post by clairelouise444)
Ah I wrote hydroxyl group

Hydroxyl group is correct.

[Mocking_bird]

(Original post by mulac1)
do you think for the sugar plant question, it would be ok to say shorter stem, so shorter distance for water to get to the leaves up the xylem?

Are you talking about the high yield one?

If so, that doesnt really relate to how there is a high yield.

[TheBigDog]

Q1 7 Marks


1a) diffusion
b) thin – short diffusion pathway
curled – more surface area for diffusion
c) Whats an organ? Group of tissues working together to carry out function
d) How does CO2 get in mesophyll cells? Stomata, diffuse, down conc grad.


Q2 7 Marks


2a) Difference – sugar beet has larger root Expl. - can store more sugar
Difference – sugar beet has larger leaves Expl. – more surface area for photosynthesis to make sugar.
b) faster growth = more photosynthesis = more sugar
c) monoculture, less variation of alleles.


Q3 7 Marks


3a) beta glucose,
ii) glycosidic bonds
iii) OH
b) Starch – alpha glucose, branched chains
Cellulose – beta glucose, unbranched chains
c) Myofibrils give mechanical and structural support – prevents osmosis.


Q4 9 Marks


4a) why mitosis is necessary – growth and repair.
b) Why 200? 200 is good sample size
c) Prophase – chromatids visible/distinct but not lined up on equator attached to centromere
Anaphase – pulled apart to opposite ends as spindle contracts
d) Apparently 2 hours?


Q5 8 Marks


5a) Why is DNA a polymer? More than 1 nucleotide joined together
b) H-Bonds
ii) Deoxyribose sugar
iii) Phosphate
c) 16,34,16 and adenine
d) 153
ii) Why more than 153 bases? Introns


Q6 8marks


6a) Why random selection? Random avoids bias/representative
b) 1.3
c) Lower – fewer species and apart from one species they were present in smaller numbers than the wood
d) Yes good conclusion as data supports it
However only one study – more required.
e) Increase animal diversity as more food sources/habitats/niche


Q7 8marks


7a) Class/Kingdom/Phylum
ii) Family
b) What does SD do? shows spread around the mean and shows how reliable they are
Can see if difference between two mean values are statistically significant.
c) The fiery and copaz have different throat colour so different courtship behaviour so less similar/ not as closely related
d) How does studying amino acid sequence determine species? Amino acid sequence determined by DNA, similar DNA = more closely related.


Q8 15 Marks


8a) Explain the graph - Xylem pressure low during the night as stomata closed and there’s less transpiration.
During day it increases because rate of water movement increases. This puts the water column under pressure so the xylem is drawn in so diameter is reduced therefore pressure increases.
b) Why is xylem pressure negative? Because pressure outside is lower.
c) Artery has thicker walls because pressure is higher.
ii) Why does Aorta wall thickness vary? systole pressure is high so elastic layer stretches and at diastole pressure is lower so elastic layer recoils to even out pressure changes.
iii) Aorta walls had highest SD
d) Tissue fluid question
- Hydrostatic Pressure bigger at Arteriole end
- water, oxygen, glucose forced out
- plasma proteins too big – ultrafiltration
- at venule end Hydrostatic pressure is lower and osmotic pressure is higher so water moves back in via osmosis into capillary back to the heart.
- Rest is drained via the lymphatic system
- muscle contractions push it up to circulation


Q9 15 Marks


9a) Why 35? Optimum temp for enzymes, won’t denature
ii) Why same bacteria volume? Allows comparison
iii) What does control do? Make sure it was the antibiotic ONLY having an effect on S. Aureus concentration
b) Describe graph – falls then levels out blah blah
c) Conclusion evaluation. Good – data supports it ( only falls a little after 50)
- There was a control group
Bad – only one study. More needed for proper conclusion.
d) How do bacteria become resistant? Horizontal gene transmission and mutations.
ii) Age should be similar to control variable – pensioners more susceptible to infection

e) NO idea. What a rubbish question.

[lmacknold20]

for the question on what is the chemical molecule i wrote HO instead of OH is this still right?

[Guilz94]

For question 5)a) did you have to put all three taxonomic groups (kingdom, phylum, class) or did you only have to name one of the groups that they all belong to?