(Original post by 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 and some other people for some help
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)
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?
Grown on large scale;
using the same specific allele;
for more yield of sugar (in shorter time);
(so) diversity reduced;
a) Monomers of cellulose
b) What bond is shown?
c) What group is Z?
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
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
a) How do you know this is a polymer?
Joined by many nucleotides / has sugar phosphate backbone / units are repeating
b) Name the molecules.
(Don't remember the order) (3 marks)
Deoxyribose/Pentose Sugar (the pentagon)
c) Adenine; Guanine & Cytosine; 16 and 16 each (I think?) (2 marks)
d) Minimum number required
51*3 = 153
e) Introns / junk DNA.
a) Why is mitosis essential?
Quick cell restoration/repair/regeneration;
b) Stage the two stages in A and B
Ambiguous - I believe they'll be generous.
Prophase; because the chromosomes were condensed and visible
Metaphase; chromsomes were lining up in the equator
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.
Index of diversity questions
b) Would the index of diversity for the wheat field be less or more?
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.
No - farming wasn't mentioned;
yes - farmers clear out woodland/other plants to make room for wheat fields;
d) How would shrubs help?
more food sources;
a) Kingdom / Phylum / Class (1 mark)
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
more hydrogen bonds form;
more heat required indicates relationship;
amount of precipitate from both species indicates relationship
a) Explain the changes in 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;
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?
Transpiration pull/xylem pulled in by tension
a) Explain why the artery has the thickest wall?
Artery has thicker walls because pressure is higher.
b) Why is the thickness of the aorta different every time?
Different surges in pressure;
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
At (arteriole) end of capillary;
Hydrostatic / blood pressure;
Forces out soluble / small molecules;
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;
a) i) Why were the bacteria incubated at 35 degrees?
Similar temperature to body; optimum temperature for bacterial growth.
a) ii) Why was the same amount of bacteria used?
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?
To show that it was only the antibiotic that affected the results
ii) Describe the changes shown on the graph
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?
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?
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.
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
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