2015

Question 1

What is the function of the coronary arteries?

[2 marks]

Answer 1

(Carry) oxygen/glucose;
2. (To) heart
muscle/tissue/cells/myocytes;

Question 2

The rise and fall in blood pressure in the aorta is greater than in the small arteries.
Suggest why. [3 marks]

Answer 2

(Aorta)
1. (is) close/directly linked to to the
heart/ventricle / pressure is higher/is
very high;
2. (Aorta has) elastic tissue;
3. (Aorta has) stretch/recoil;

Question 3

Give two differences in the variation in body length of male and female thorny lizards.
[2 marks]

Answer 3

1. Females are (generally)
longer/larger/bigger/up to 115(mm) /
males are (generally)
shorter/smaller/up to 100(mm);
2. Females show a greater
range/variation / males show a
narrower range/variation;

Question 4

The ecologists also determined the index of diversity of lizards in an oil palm plantation
next to the woodland area. They found fewer species of plant in the oil palm plantation.
Lizards feed on plants and insects.
Explain why fewer species of plant would lead to fewer species of lizard in the oil palm
plantation.
[3 marks]

Answer 4

(Fewer plant species) – no mark
1. (So) few(er) habitats/niches;
2. (So) lower diversity of insects / fewer
insect species/fewer insect types;
3. (So) fewer food sources / less
variety of food;

Question 5

Give two ways in which the structure of starch is similar to cellulose.
[2 marks]

Answer 5

1. Are polymers/polysaccharides/ are
made of monomers/of
monosaccharides;
2. Contain glucose/carbon, hydrogen
and oxygen
3. Contain glycosidic bonds;
4. Have 1–4 links;
5. Hydrogen bonding (within structure);

Question 6

Give two ways in which the structure of starch is different from cellulose.
[2 marks]

Answer 6

1. Contains α/alpha glucose;
2. Helical/coiled/compact/branched/not
   straight;
3. 1,6 bonds/ 1,6 branching;
4. Glucoses/monomers same way up;
5. No H-bonds between molecules;
6. No (micro/macro) fibres/fibrils;

Question 7

suggest and explain one other way in which sieve cells are adapted for
mass transport.
[2 marks]

Answer 7

1. No/few organelles / very little
cytoplasm / cytoplasm at edge /
more room/hollow/large
vacuole/large space/thick walls;
2. (So) easier/more flow/
(thick/strong walls) resist pressure;

Question 8

suggest and explain one other way in which companion cells are
adapted for the transport of sugars between cells.
[2 marks]

Answer 8

1. Mitochondria release energy/ ATP/
site of respiration;
2. For active transport/uptake against
concentration gradient;
OR:
3. Ribosomes/roughendoplasmic
reticulum produce(s) proteins;
4. (Proteins) linked to transport eg
carrier proteins/enzymes;

Question 9

Describe the role of DNA polymerase in DNA replication.

[1 mark]

Answer 9

Joins nucleotides (to form new strand);

Question 10

Other than being smaller, give two ways in which prokaryotic DNA is different from
eukaryotic DNA.
[2 marks]

Answer 10

(Prokaryotic DNA)
1. Circular/non-linear (DNA);
2. Not (associated) with proteins/
histones;
3. No introns / no non-coding DNA;

Question 11

Humans and grasshoppers have very similar percentages of each base in their DNA but
they are very different organisms.
Use your knowledge of DNA structure and function to explain how this is possible.
[2 marks]

Answer 11

1. Have different genes;
2. (Sobases/triplets) are in a different
   sequence/order;
3. (So) different amino
   acid(sequence/coded for) / different
   protein/different polypeptide/different
   enzyme;

Question 12

The DNA of the virus is different from that of other organisms.
Use Table 2 and your knowledge of DNA to suggest what this difference is.
Explain your answer.
[2 marks]

Answer 12

(Virus DNA)
1. A does not equal T / G does not
equal C;
2. (So) no base pairing;
3. (So) DNA is not double stranded/is
single stranded;

Question 13

Give three ways in which courtship behaviour increases the probability of successful
mating.
[3 marks]

Answer 13

1. Recognise/identify/attract same
species;
2. Stimulates/synchronises
mating/production/release of
gametes;
3. Recognition/attraction of
mate/opposite sex;
4. Indication of (sexual)
maturity/fertility/receptivity/readiness
to mate;
5. Formation of a pair bond/bond
between two organisms (to
have/raise young);

Question 14

The scientists wanted to know if the recorded natural song was less effective than the
natural song in stimulating courtship behaviour.
Suggest how the scientists could determine if the recorded natural song (L) was less
effective than the natural song.
[2 marks]

Answer 14

1. Use a (real) male (with intact
   wings/no wing removed);
2. Determine (percentage) response
   (of females compared withL)

Question 15

A student concluded from Table 3 that the number of chirps and ticks is essential for
successfully stimulating courtship behaviour.
Do these data support this conclusion? Explain your answer.
[4 marks]

Answer 15

1. Lowest/only 30% courtship with no
song/K/
(or) courtship still occurred when no
song played/K;
2. Reducedcourtship when no ticks/M /
there is some courtship when no
ticks/M;
3. Reduced courtship when no chirps/N
/ there is some courtship when no
chirps/N;
4. (So) courtship must involve a visual
stimulus/other factor involved;
5. Chirps more important as lowest
courtship when none/N / ticks less
important as similar courtship when
changed/M;
6. Data only show presence and
absence of chirps/0 and 7 chirps;

Question 16

The events that take place during interphase and mitosis lead to the production of two
genetically identical cells. Explain how.
[4 marks]

Answer 16

1. DNA replicated;
2. (Involving)
   specific/accurate/complementary
   base-pairing;
3. (Ref to) two identical/sister
   chromatids;
4. Each chromatid/ moves/is separated
   to(opposite) poles/ends of cell;

Question 17

The student cut thin sections of tissue to view with an optical microscope.
Explain why it was important that the sections were thin.
[2 marks]

Answer 17

1. To allow (more) light through;
2. A single/few layer(s) of cells to be
   viewed;

Question 18

What does Figure 5 show about the growth of roots?
Use the data to explain your answer.
[2 marks]

Answer 18

1. More/faster mitosis/division near
tip/at 0.2 mm;
2. (Almost) no mitosis/division at/ after
1.6 mm from tip;
3. (So) roots grow by mitosis/adding
new cells to the tip

Question 19

This classification system consists of a hierarchy as there are small groups within larger
groups.
Give one other feature of a hierarchy that is shown in Figure 6.
[1 mark]

Answer 19

No overlap;

Question 20

Complete colour blindness occurs at a higher frequency on Pingelap than in the USA.
Use the information provided to explain why.
[3 marks]

Answer 20

1. Genetic bottleneck;
2. Less genetic diversity / small(er)
   gene pool / less variety of alleles;
3. Individuals breed within group /
   do not breed with outsiders;
4. High(er) chance of inheriting
   allele/high(er) frequency of allele
   in offspring;

Question 21

A mutation can lead to the production of a non-functional enzyme. Explain how.
[6 marks]

Answer 21

1. Change/mutation in base/nucleotide
sequence (of DNA/gene);
2. Change in amino acid
sequence/primary structure (of
enzyme);
3. Change in hydrogen/ionic/disulfide
bonds;
4. Change in the tertiary
structure/shape;
5. Change in active site;
6. Substrate not complementary/cannot
bind (to enzyme/active site) / no
enzyme-substrate complexes form;

Question 22

One way in which the stringent response gives resistance to this antibiotic is by stopping
cell division.
The scientists concluded that stopping cell division is not the only way in which the
stringent response gives resistance to this antibiotic.
Explain how Figure 7 supports this conclusion.
[2 marks]

Answer 22

1. Division stopped (of both strains by
   scientist);
2. SR strain still more resistant/fewer
   die/none die (at higher
   concentrations of antibiotic);

Question 23

The stringent response involves a number of enzyme-catalysed reactions.
Explain how scientists could use this knowledge to design drugs that make the treatment
of infections caused by the SR strain more successful.
[2 marks]

Answer 23

1. Make a competitive/non-competitive
inhibitor;
2. Competitive competes with/blocks
active site/non-competitive inhibitor
affects/changes active site;
OR
3. (Make a drug) that
inhibits/denatures/destroys
enzyme/stringent response;
4. Give at the same time as/before an
antibiotic

Question 24

Use the information provided and Figure 8 to suggest an explanation for the greater
resistance of the SR strain to this antibiotic.
[3 marks]

Answer 24

SR strain)
1. Fewer free radicals (than non-SR);
2. Produces more catalase (than nonSR);
3. Catalase (might be) linked to
production of fewer free radicals /
breaking down/removing free
radicals;

Question 25

The scientists removed the ovaries from the mice for the investigation. They also gave
the mice injections of the substrate of aromatase each day.
Explain why these steps were necessary.
[2 marks]

Answer 25

1. Removes (main/largest) source of
oestrogen / (different) mice produce
different amounts of oestrogen;
2. (Allows) oestrogen to be
controlled/oestrogen to be made by
aromatase only / only oestrogen
made in lungs to be involved;

Question 26

The scientists predicted that fulvestrant would be more effective when given with
anastrozole than when given alone.
Use the information provided to suggest why they predicted this.
[2 marks]

Answer 26

1. (Anastrozole) prevents/reduces
oestrogen production;
2. (Fulvestrant) stops remaining
oestrogen binding /less oestrogen
binds to receptors;

Question 27

The scientists concluded that both drugs should be used together to reduce the risk of
lung cancer in women exposed to tobacco products.
Do you agree? Explain your answer.
[5 marks]

Answer 27

(Yes for Group T)
1. Least tumours per animal (from fig.
9)
2. Lowest (mean) tumour area/size
(from fig. 10);
3. Lowest top of range;
(But)
4. Means (tumour area) are similar;
5. Ranges overlap/share values so
differences may not be
real/treatments may be just effective
in reducing tumour;
6. Range affected by outliers/ SD’s
would be better;
7. Done on mice / not done on
women/humans;
8. Only 10 mice used per group/small
sample size so may not be
representative/reliable;
9. Might be side effects ;
10. Only did for 15 weeks somaximum
effect of drugs may not have been seen

Question 28

The scientists used tumour area as an indicator of tumour size.
Explain why tumour area may not be the best indicator of tumour size and suggest a
more reliable measurement.

Answer 28

1. Tumours may be different depths /
area does not take depth into
account / tumours are 3-D/are not 2-
D;
2. (Measure) tumour volume/mass/ weight

Question 29

The scientists repeated the investigation but this time they did not give the drugs until
week 9.
Suggest why they gave the drugs at week 9, rather than at week 5.
[2 marks]

Answer 29

1. Allows tumours to
grow/develop/form;
2. (So) can investigate treatment rather
than prevention (of tumours)/ when
tumour/cancer is more advanced;

Question 30

Another group of scientists is currently using these drugs in human trials. However, the
control group is not being given a placebo.
Suggest why a placebo is not being given and what is being given to this group instead.
[2 marks]

Answer 30

1. Unethical (not to treat patients) /
   may increase probability of patients
   dying/getting more ill;
2. Use normal cancer drugs/treatment;