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Biochemistry

The document consists of a series of questions related to biochemistry, photosynthesis, enzyme activity, and the structure of DNA. It includes tasks such as describing relationships between variables, calculating percentages, and explaining biochemical processes. The questions are designed to assess knowledge in biology, particularly in areas like plant physiology, enzyme function, and molecular biology.

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0% found this document useful (0 votes)

13 views258 pages

Biochemistry

Uploaded by

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We take content rights seriously. If you suspect this is your content, claim it here.

Available Formats

Download as RTF, PDF, TXT or read online on Scribd

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1

1. Many elements are necessary to form biochemicals required by living

organisms. For each element below, state the name of one molecule containing
the element and state the function of the molecule.

(a) Iron:

Molecule .........................................................................

Function ..........................................................................

..................................................................................
.......
(2)

(b) Phosphorus:

Molecule .........................................................................

Function ..........................................................................

..................................................................................
.......
(2)
(Total 4 marks)

2. There are many abiotic factors that affect the rate of photosynthesis in terrestrial
plants. Wheat is an important cereal crop in many parts of the world. Wheat
seedlings were grown at three different concentrations of carbon dioxide (in
parts per million) and the rate of photosynthesis was measured at various light
intensities.

2
50

–1
m in 2
40

R a te o f p h o to s y n th e s is /  l C O 30 k ey :
1300 ppm C O 2
20 500 ppm C O 2
280 ppm C O 2
10

0
0 5 10 15 20
L ig h t in ten sity / × 1 0 3 lu m en m – 2

[Source: Adapted from J P Kimmins, 1997 Forest Ecology, (2nd edition) page 161]

3
(a) Describe the relationship between the rate of photosynthesis and light
intensity for wheat seedlings grown at a CO2 concentration of 500 ppm.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(b) Outline the effect of CO2 concentration on the rate of photosynthesis of the
wheat seedlings.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(c) The normal atmospheric concentration of CO2 is 370 ppm. Deduce the
effect of doubling the CO2 concentration to 740 ppm on the growth of
wheat plants.

.......................................................................................................................
..............

.......................................................................................................................
..............
4
.......................................................................................................................
..............
(2)

5
Leaf area and chlorophyll levels were measured in sun leaves and shade
leaves of Hedera helix (English Ivy) and Prunus laurocerasus (Cherry Laurel).
Sun leaves developed under maximal sunlight conditions while shade leaves
developed at reduced sunlight levels in the shadow of other leaves.

Specie Leaf Type Chlorophyll/ Leaf Area/

s g ml-1 cm2
Ivy Shade 4.3 72.6
Sun 3.8 62.9
Laurel Shade 4.7 38.7
Sun 4.2 25.7

[Source: D Curtis, Plant Ecology independent project, 1990]

(d) Calculate the percentage increase in the amount of chlorophyll in shade

leaves of ivy compared to sun leaves of ivy

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(e) Suggest a reason for the differences in chlorophyll concentration and leaf
area in sun and shade leaves in these two species.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 10 marks)

6
3. Draw a diagram of the molecular structure of a portion of DNA.
(Total 4 marks)

4. Describe the consequence of a base substitution mutation with regards to sickle

cell anaemia.
(Total 7 marks)

5. Outline the production of a dipeptide by a condensation reaction. Include the

structure of a generalized dipeptide in your answer.
(Total 5 marks)

6. Explain the process of translation.

(Total 9 marks)

7. List four functions of proteins, giving an example of each.

(Total 4 marks)

8. The diagram below shows possible pathways for the breakdown of glucose in
various cells.
G lu co se

P ro cess Q P ro cess R
(n o o x y g en p resen t) (o x y g en p resen t)

B C+D D +E

(a) State the names of processes Q and R.

Q: ..............................................................................................................
.............
(1)

7
R: ..............................................................................................................
.............
(1)

8
(b) Deduce the names of substances A and D.

A: ..............................................................................................................
.............
(1)

D: ..............................................................................................................
.............
(1)

(c) State the organelle in which process R takes place.

.......................................................................................................................
..............
(1)
(Total 5 marks)

9. Describe the significance of water to living organisms.

(Total 6 marks)

10. Outline the role of condensation and hydrolysis in the relationship between
amino acids and dipeptides.
(Total 4 marks)

9
11. At the start of glycolysis, glucose is phosphorylated to produce glucose 6-
phosphate, which is converted into fructose 6-phosphate. A second
phosphorylation reaction is then carried out, in which fructose 6-phosphate is
converted into fructose 1,6-bisphosphate. This reaction is catalyzed by the
enzyme phosphofructokinase. Biochemists measured the enzyme activity of
phosphofructokinase (the rate at which it catalyzed the reaction) at different
concentrations of fructose 6-phosphate. The enzyme activity was measured
with a low concentration of ATP and a high concentration of ATP in the reaction
mixture. The graph below shows the results.

L o w AT P co n cen tratio n

E n zy m e activ ity
H ig h AT P co n cen tratio n

F ru cto se 6 -p h o sp h ate co n cen tratio n

(a) (i) Using only the data in the above graph, outline the effect of
increasing fructose 6-phosphate concentration on the activity of
phosphofructokinase, at a low ATP concentration.

..............................................................................................................
.............

..............................................................................................................
.............
(2)

(ii) Explain how increases in fructose 6-phosphate concentration affect

the activity of the enzyme.

..............................................................................................................
.............

..............................................................................................................
.............
10
..............................................................................................................
.............

..............................................................................................................
.............
(2)

11
(b) (i) Outline the effect of increasing the ATP concentration on the activity
of phosphofructokinase.

..............................................................................................................
.............

..............................................................................................................
.............
(2)

(ii) Suggest an advantage to living organisms of the effect of ATP on

phosphofructokinase.

..............................................................................................................
.............

..............................................................................................................
.............
(1)
(Total 7 marks)

12. The complex structure of proteins can be explained in terms of four levels of
structure, primary, secondary, tertiary and quaternary.

(a) Primary structure involves the sequence of amino acids that are bonded
together to form a polypeptide. State the name of the linkage that bonds
the amino acids together.

.......................................................................................................................
..............
(1)

(b) Beta pleated sheets are an example of secondary structure. State one
other example.

.......................................................................................................................
..............
(1)

12
(c) Tertiary structure in globular proteins involves the folding of polypeptides.
State one type of bond that stabilizes the tertiary structure.

.......................................................................................................................
..............
(1)

13
(d) Outline the quaternary structure of proteins.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 5 marks)

13. Explain the reasons for

(a) a large area of thylakoid membrane in the chloroplast.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(b) low rates of photosynthesis in plants growing beneath trees, where the
light has already passed through the trees’ leaves.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

14
15
(c) large amounts of RuBP carboxylase in the chloroplast;

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

14. Which of the following reactions occurs when a dipeptide is formed from amino
acids?

A. Hydrolysis

B. Denaturation

C. Condensation

D. Oxidation
(Total 1 mark)

15. What is the function of helicase?

A. It forms bonds between DNA nucleotides.

B. It adds new nucleotides to the DNA helix.

C. It forms the DNA helix.

D. It separates DNA strands.

(Total 1 mark)

16
16. What is removed to form mature eukaryotic mRNA?

A. RNA primers

B. Exons

C. RNA polymerases

D. Introns
(Total 1 mark)

17. (a) Define the term active site of an enzyme.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(b) Outline how enzymes catalyze biochemical reactions.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) Explain the effect of pH on enzyme activity.

.......................................................................................................................
..............

.......................................................................................................................
17
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

18
(d) State three functions of lipids.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 8 marks)

18. Explain the process of aerobic respiration including oxidative phosphorylation.

(Total 8 marks)

19. The graph below shows the variation in the concentration of atmospheric
carbon dioxide since 1970.
375
370
365
360
355
CO 2
350
co n cen tratio n
/ ppm 345
340
335
330
325
320
1970

1975

1980

1985

1990

1995

2000

[Source: C D Keeling and T P Whorf, Atmosphere CO2 concentrations (ppm) derived from in situ air
samples, collected at Mauna Loa Observatory, Hawaii]

The annual fluctuation is mainly the result of changes in the levels of

photosynthesis associated with the seasons in Northern Hemisphere forests.

19
(a) (i) Describe the overall trend shown in the graph.

..............................................................................................................
.............

..............................................................................................................
.............
(1)

(ii) Suggest a cause for the overall trend throughout the period 1970–
1999.

..............................................................................................................
.............

..............................................................................................................
.............
(1)

(b) (i) Using a clear label, identify any one point on the graph which shows
the CO2 level in mid-summer.
(1)

(ii) Explain why the concentration of CO2 varies with the seasons.

..............................................................................................................
.............

..............................................................................................................
.............
(2)

.......................................................................................................................
..............
(1)
(Total 6 marks)

20. Draw a diagram showing the molecular structure of a section of the DNA

20
molecule.
(Total 5 marks)

21
21. Outline the process of translation.
(Total 5 marks)

22. Explain the effects of temperature, pH and substrate concentration on enzyme

activity.
(Total 8 marks)

23. List the functions of membrane proteins.

(Total 4 marks)

24. The unicellular green alga Phaeodactylum tricornutum is photosynthetic. Cell

biologists genetically modified this organism by adding a glucose transporter
gene. The modified and unmodified algae were grown in a nutrient medium
under a series of different conditions and the growth rate of the cells was
measured.
12
K ey :
U n m o d ified alg ae M o d ified alg ae = lig h t an d n o g lu co se
10
in th e m ed iu m
8
C ell d en sity / = lig h t an d g lu co se
1 0 7 cells cm – 3 6 in th e m ed iu m
4 = d ark an d g lu co se
in th e m ed iu m
2
0
0 2 4 6 8 0 2 4 6 8
Tim e / d ay s
[Source: L A Zaslavskaia, et al., Adapted (2001) Science, 292, pages 2073–2075]

(a) State the role of glucose in the metabolism of cells.

.......................................................................................................................
..............
(1)

22
(b) Deduce where you would expect to find the glucose transporter protein in
the modified algae cells.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

Commercially, unmodified algae are grown in shallow sunlit ponds or illuminated

containers. The cells only grow in the top few centimetres. However, the
modified algae can grow at any depth.

(d) Explain why the modified algae can grow at any depth whereas the
unmodified algae can only grow at the surface.

.......................................................................................................................
..............

23
.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 8 marks)

24
25. (a) State one named example of a fibrous protein and one named example of
a globular protein.

Fibrous: ........................................... Globular: ...........................................

(2)

(b) Outline the effect of enzymes on the reactions they catalyse.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) The rate of cellular respiration is controlled by the allosteric inhibition of

phosphofructokinase by ATP. Phosphofructokinase is the first enzyme in
the respiration pathway. Explain the meaning of allosteric inhibition using
this example.

.......................................................................................................................
..............

.......................................................................................................................
..............
(4)

25
(Total 8 marks)

26. State two products of the light dependent reaction of photosynthesis.

...............................................................................................................................
................
(Total 2 marks)

27. What is the composition of the backbone of DNA?

A. Alternating sugar and phosphate molecules

B. Complementary base pairs

C. Alternating sugar and base molecules

D. A polysaccharide
(Total 1 mark)

28. A certain gene codes for a polypeptide that is 120 amino acids long.
Approximately how many nucleotides long is the mRNA that codes for this
polypeptide likely to be?

A. 30

B. 40

C. 360

D. 480
(Total 1 mark)

29. Of the following products, which is produced by both anaerobic respiration and
aerobic respiration in humans?

I. Pyruvate

II. ATP

III. Lactate

26
A. I only

B. I and II only

C. I, II and III

D. II and III only

(Total 1 mark)

27
30. Which enzyme removes the RNA primer during replication?

A. RNA primase

B. DNA polymerase I

C. DNA ligase

D. Helicase
(Total 1 mark)

31. Consider the metabolic pathway shown below.

1 2 3 4
A B C D E

If there is end-product inhibition, which product (B to E) would inhibit which

enzyme (1 to 4)?

Product Enzyme
A. C 4
B. B 3
C. B 4
D. E 1
(Total 1 mark)

32. Which is not a primary function of protein molecules?

A. Hormones

B. Energy storage

C. Transport

D. Structure
(Total 1 mark)

28
33. Which two colours of light does chlorophyll absorb most?

A. Red and yellow

B. Green and blue

C. Red and green

D. Red and blue

(Total 1 mark)

34. Which is not a product of the Krebs cycle?

A. CO2

B. NADH + H+

C. Pyruvate

D. ATP
(Total 1 mark)

35. How many ATP molecules (net yield) are produced per molecule of glucose as a
direct result of glycolysis?

A. 2

B. 4

C. 10

D. 38
(Total 1 mark)

29
36. What happens during muscle contraction?

A. Both actin and myosin filaments shorten.

B. Na+ ions are taken up by the sarcoplasmic reticulum.

C. The actin and myosin filaments slide over each other.

D. Cross bridges remain attached to the filaments.

(Total 1 mark)

37. (a) State the main photosynthetic pigment in plants.

.......................................................................................................................
..............
(1)

(b) State the two materials used to convert carbon dioxide to organic
molecules in plants.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

.......................................................................................................................
..............

30
.......................................................................................................................
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(4)
(Total 7 marks)

38. Explain the similarities and differences in anaerobic and aerobic cellular
respiration.
(Total 8 marks)

39. Describe the use of carbohydrates and lipids for energy storage in animals.
(Total 5 marks)

40. During photosynthesis in plants, light energy is absorbed by chlorophyll. This

energy is then used to carry out photolysis, which supply substances that are
needed to convert carbon dioxide into organic molecules such as glucose.

(a) State the names of two products of photolysis in photosynthesis.

1. ...................................................................................................................
..............

2. ...................................................................................................................
..............
(2)

(b) Explain briefly one method for measuring the rate of photosynthesis in a
plant.

.......................................................................................................................
..............

.......................................................................................................................
..............
31
.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

32
(c) The rate of photosynthesis is affected by light intensity. Draw a line on the
graph below to show the relationship between light intensity and the rate
of photosynthesis.

rate o f p h o to sy n th esis

lig h t in ten sity

(2)

(d) State two factors in the environment of a plant, apart from light intensity,
that can affect the rate of photosynthesis in the plant.

1. ...................................................................................................................
..............

2. ...................................................................................................................
..............
(2)
(Total 8 marks)

33
41. The diagrams below show various molecular structures.
I. II. O
O
HOH 2C H
CH 3 (C H 2 ) n C
C C
OH H H
H OH
C C

OH OH

III. CH 2OH IV. R

H O
C O H
H N C C
H
C OH H C H OH
H
OH C C OH

H OH

(a) Identify which of the diagrams represent

(i) the structure of glucose;

..............................................................................................................
.............
(1)

(ii) the structure of amino acids;

..............................................................................................................
.............
(1)

(iii) the structure of fatty acids.

..............................................................................................................
.............
(1)

34
(b) Discuss which of the molecules are most similar in structure.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 6 marks)

42. Sickle cell anemia is a serious disease caused by a single base substitution
mutation. Explain how a single base substitution mutation can have significant
consequences for an individual.
(Total 6 marks)

35
43. The rate of carbon dioxide uptake by the green succulent shrub Aeonium
goochiae can indicate the amount of photosynthesis taking place in the plant.
This rate was measured at 15°C and 30°C over a 24-hour period. The units of
carbon dioxide absorption are mg CO2 h–1.

The results are shown below. The centre of the graph corresponds to –2 mg
CO2 h–1 and the outer ring is +2.5 mg CO2 h–1.

K ey :
3 0 ºC
2 4 0 0 (m id n ig h t) 1 5 ºC
2300 2 .5 0100
2200 2 0200
1 .5
2 1 0 0 (late ev en in g ) 0 3 0 0 (early m o rn in g )
1
2000 0 .5
0400
0
– 0 .5
1900 0500
–1
– 1 .5
1 8 0 0 (ev en in g ) –2 0 6 0 0 (m o rn in g )

1700 0700

1600 0800

1 5 0 0 (early aftern o o n ) 0 9 0 0 (late m o rn in g )

1400 1000
1300 11 0 0
1 2 0 0 (m id -d ay )

[Source: adapted from www.biologie.uni-hamburg.de/b-online/e24/9.htm]

(a) Identify a time that carbon dioxide uptake was the same at both
temperatures.

.......................................................................................................................
..............
(1)

(b) State the maximum rate of carbon dioxide uptake at 15°C.

.......................................................................................................................
..............
(1)

36
37
(c) Compare the rate of carbon dioxide uptake at each temperature in daylight
and darkness.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(d) Suggest why the carbon dioxide uptake may at times be negative.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)
(Total 6 marks)

44. (a) (i) Identify the cell organelle shown in the micrograph below.

38
..............................................................................................................
.............
(1)

39
(ii) Identify the structure labelled I above and explain how it is adapted
for the organelle to function efficiently.

..............................................................................................................
.............

..............................................................................................................
.............
(3)

(b) Describe the role of acetyl CoA in the metabolism of lipids.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

45. (a) Explain the significance of secondary structure to the structure of a

protein.

.......................................................................................................................
..............

.......................................................................................................................

40
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

41
(b) State the name of a competitive enzyme inhibitor.

.......................................................................................................................
..............
(1)

(c) Outline the difference between competitive and non-competitive enzyme

inhibitors.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

46. Lipids are essential nutrients that must be included in the diet.

(a) State one food rich in lipids suitable for a vegan diet.

.......................................................................................................................
..............
(1)

(b) Outline two functions of lipids in the body.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

42
(c) Discuss the possible health problems associated with diets rich in lipids.

.......................................................................................................................
..............

.......................................................................................................................
..............
(4)
(Total 7 marks)

47. Alcohol dehydrogenase is an enzyme that catalyses the reversible reaction of

ethanol and ethanal according to the equation below.

NAD+ + CH3CH2OH CH3CHO + NADH + H+

ethanol ethanal

The initial rate of reaction can be measured according to the time taken for
NADH to be produced.

43
In an experiment, the initial rate at different concentrations of ethanol was
recorded (no inhibition). The experiment was then repeated with the addition of
l mmol dm–3 2,2,2-trifluoroethanol, a competitive inhibitor of the enzyme. A third
experiment using a greater concentration of the same inhibitor (3 mmol dm–3)
was performed. The results for each experiment are shown in the graph below.
1 .2
1 .1
1 .0
0 .9
0 .8
0 .7
In itial rate o f reactio n 0 .6
/ arb itrary u n its 0 .5
0 .4
0 .3 n o in h ib itio n
0 .2 1 m m o l d m – 3 in h ib ito r
0 .1 3 m m o l d m – 3 in h ib ito r
0 .0
0 10 20 30 40 50 60 70 80 90 100
–3
E th an o l co n cen tratio n / m m o l d m
[Source: R Taber, Biochemical Education, (1998) 26, pages 239-242]

(a) Outline the effect of increasing the substrate concentration on the control
reaction (no inhibition).

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(b) (i) State the initial rate of reaction at an ethanol concentration of 50

mmol dm–3
in the presence of the inhibitor at the following concentrations.

1 mmol dm–3:
............................................................................................
.........

44
3 mmol dm–3:
............................................................................................
.........
(1)

(ii) State the effect of increasing the concentration of inhibitor on the

initial rate of reaction.

..............................................................................................................
.............

..............................................................................................................
.............
(1)

(c) Explain how a competitive inhibitor works.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 7 marks)

48. Anaerobic respiration occurs in the absence of oxygen while aerobic respiration
requires oxygen.

(a) State one final product of anaerobic respiration.

.......................................................................................................................
..............

45
(1)

(b) Complete the table showing the differences between oxidation and
reduction.

Oxidation Reduction
Electrons gained or
lost
Oxygen or hydrogen
gained or lost
(2)

46
(c) The structure of a mitochondrion is shown in the electron micrograph
below.

Name the parts labelled A, B and C and state the function of each.

Part A:

Name: ..............................................................................................
............

Function: ..........................................................................................
............

Part B:

Name: ..............................................................................................
.............

Function: ..........................................................................................
............

Part C:

Name: ..............................................................................................
.............

Function: ..........................................................................................
............
(3)
(Total 6 marks)

47
49. (a) State the site of the light-independent reactions in photosynthesis.

.......................................................................................................................
..............
(1)

48
The absorption spectrum of chlorophyll a and chlorophyll b are shown in the
graph below.

ch lo ro p h y ll b

ch lo ro p h y ll a

A b so rb an ce

400 500 600 700

W av elen g th / n m

(b) On the graph above, draw the action spectrum of photosynthesis for a
green plant.
(1)

(c) Explain photophosphorylation in terms of chemiosmosis.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 5 marks)

49
50
50. Which of the following are connected by a hydrogen bond?

A. The hydrogen and oxygen atoms of a water molecule

B. A base pair of a DNA molecule

C. Two amino acid molecules of a dipeptide

D. Two glucose molecules in a disaccharide

(Total 1 mark)

51. Which molecule represents ribose?

A. B.
CH 2OH O

H C O H H C H

H C O
C C
OH H H
OH C OH N
C
H H
H OH

C. H 2C OH D. O
H OH 2C H

HC OH C C
H H
H 2C OH H OH
C C

OH OH
(Total 1 mark)

51
52. Which way do the protons flow when ATP is synthesized in mitochondria?

A. From the inner matrix to the intermembrane space

B. From the intermembrane space to the inner matrix

C. From the intermembrane space to the cytoplasm

D. From the cytoplasm to the intermembrane space

(Total 1 mark)

53. What can reduce the effect of a competitive inhibitor of an enzyme?

A. Decrease the temperature at which the reaction takes place.

B. Increase the temperature at which the reaction takes place.

C. Increase the substrate concentration.

D. Add a non-competitive inhibitor.

(Total 1 mark)

54. What accumulates in the inter-membrane space of the mitochondrion during

electron transport?

A. ATP

B. Electrons

C. Protons (hydrogen ions)

D. Oxygen
(Total 1 mark)

55. (a) Define the term degenerate as it relates to the genetic code.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

52
53
(b) Apart from international cooperation, outline two positive outcomes of the
Human Genome Project.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) State the catalytic activity of reverse transcriptase.

.......................................................................................................................
..............
(1)

(d) State one use of monoclonal antibodies in diagnosis and one use in
treatment.

Diagnosis: ...................................................................................................
...........

Treatment: ...................................................................................................
...........
(2)
(Total 6 marks)

56. Outline enzyme-substrate specificity.

(Total 5 marks)

57. Explain how allosteric control of metabolic pathways by end-product inhibition

includes negative feedback and non-competitive inhibition.
(Total 8 marks)

54
58. Distinguish between fibrous and globular proteins, giving one example of each.
(Total 5 marks)

59. State a role for each of four different named enzymes in DNA replication.
(Total 6 marks)

60. Explain how the light-independent reactions of photosynthesis rely on light-

dependent reactions.
(Total 8 marks)

61. Outline the effect of temperature, light intensity and carbon dioxide
concentration on the rate of photosynthesis.
(Total 6 marks)

62. The structure of the DNA double helix was described by Watson and Crick in
1953. Explain the structure of the DNA double helix, including its subunits and
the way in which they are bonded together.
(Total 8 marks)

63. Compare DNA transcription with translation.

(Total 4 marks)

64. Explain the reactions involving the use of light energy that occur in the
thylakoids of the chloroplast.
(Total 8 marks)

55
56
65. Draw the structure of a fatty acid.

(Total 1 mark)

¢ à66. Outline how monosaccharides are converted into polysaccharides.

...............................................................................................................................
................

...............................................................................................................................
................
(Total 2 marks)

57
67. Explain the effect of substrate concentration on enzyme activity.

...............................................................................................................................
................

...............................................................................................................................
................
(Total 3 marks)

68. Distinguish between the structure of DNA and RNA.

DNA RNA

...................................................... ......................................................
........ ........

...................................................... ......................................................

58
........ ........
(Total 3 marks)

69. Explain, with reference to its properties, the significance of water as a coolant, a
means of transport and as a habitat.
(Total 8 marks)

70. Biosphere 2, an enormous greenhouse built in the Arizona desert in the USA,
has been used to study five different ecosystems. It is a closed system so
measurements can be made under controlled conditions. The effects of different
factors, including changes in carbon dioxide concentration in the greenhouse,
were studied. The data shown below were collected over the course of one day
in January 1996.
1200 1600

1400
1000
1200
C O 2 / 800 lig h t /
ppm 1 0 0 0 m o l m – 2 s – 1

600 800

600
400
400
200 K ey : CO 2
L ig h t 200

0 0
0 1 .5 3 4 .5 6 7 .5 9 1 0 .5 1 2 1 3 .5 1 5 1 6 .5 1 8 1 9 .5 2 1 2 2 .5 2 4
Tim e / h o u rs
[Source: http://www.Ideo.columbia.edu/martins/climate_water/labs/lab6/labinstr6/html]

(a) (i) Identify the time of day when the sun rose.

..............................................................................................................
.............
(1)

(ii) Identify the time of minimal CO2 concentration.

..............................................................................................................
59
.............
(1)

(b) Determine the maximum difference in the concentration of CO2 over the
24-hour period.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 5 marks)

71. (a) State two functions of proteins with a named example of each.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

60
(b) Explain chemiosmosis as it occurs during cell respiration.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 4 marks)

72. (a) Outline the induced fit model of enzyme activity.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(b) (i) State two products of the light-dependent reactions of

photosynthesis.

..............................................................................................................
.............

61
..............................................................................................................
.............
(2)

62
(ii) Explain the light-independent reactions in photosynthesis.

..............................................................................................................
.............

..............................................................................................................
.............
(4)
(Total 9 marks)

73. Which structure represents an amino acid?

A. H B. H
H O H O
N C C N C C

H H H SH
H OH

C. H D. H
H O H O
N C C N C C

H H H OH
OH H

63
(Total 1 mark)

64
74. The diagram below shows a short section of DNA molecule before and after
replication. If the nucleotides used to replicate the DNA were radioactive, which
strands in the replicated molecules would be radioactive?
I
G C T A C
C G A T G
II
G C T A C
C G A T G
III
G C T A C
C G A T G
IV

A. II and III only

B. I and III only

C. I and II only

D. I, II, III and IV

(Total 1 mark)

75. What is needed in photosynthesis to convert carbon dioxide into organic

molecules?

A. Light and hydrogen from the splitting of water

B. Light and oxygen from the splitting of water

C. ATP and hydrogen from the splitting of water

D. ATP and oxygen from the splitting of water

(Total 1 mark)

65
76. The diagram below shows a channel protein in a membrane. Which parts of the
surface of the protein would be composed of polar amino acids.

A. I and II only

B. II and III only

C. III and IV only

D. I and IV only
(Total 1 mark)

77. What effect do enzymes have on the activation energy of exergonic and
endergonic reactions?

Activation Activation
energy of energy of
exergonic endergonic
reactions reactions
A. increases increases
B. decreases decreases
C. increases decreases
D. decreases increases
(Total 1 mark)

66
78. What is the sequence of stages during the conversion of glucose into pyruvate
in glycolysis?

A. Lysis phosphorylation of sugar oxidation

B. Lysis oxidation phosphorylation of sugar

C. Phosphorylation of sugar lysis oxidation

D. Phosphorylation of sugar oxidation lysis

(Total 1 mark)

79. How is the proton gradient generated in chloroplasts during photosynthesis?

A. Flow of electrons from carrier to carrier in the thylakoid membrane causes

pumping of protons across the thylakoid membrane.

B. Light causes protons to flow through protein channels in the thylakoid

membrane.

C. Light splits water molecules in the stroma, causing the release of protons.

D. Protons are pumped across the thylakoid membrane using energy from
ATP.
(Total 1 mark)

80. Why is the action spectrum for photosynthesis similar to the absorption spectra
of photosynthetic pigments?

A. Photosynthetic pigments have the same optimum temperature as the

enzymes used in photosynthesis.

B. Plants absorb the same photosynthetic pigments for use in

photosynthesis.

C. Only wavelengths of light absorbed by pigments can be used in

photosynthesis.

D. The amount of energy absorbed by photosynthetic pigments is equal to

the activation energy for photosynthesis.
(Total 1 mark)

67
81. It had always been assumed that eukaryotic genes were similar in organization
to prokaryotic genes. However, modern techniques of molecular analysis
indicated that there are additional DNA sequences that lie within the coding
region of genes. Exons are the DNA sequences that code for proteins while
introns are the intervening sequences that have to be removed. The graph
shows the number of exons found in genes for three different groups of
eukaryotes.
P ercen tag e o f g en es
100
80 S acch a rom yces cerevisia e (a yea st)
60
40
20
0
40

30 D ro so ph ila m ela n og a ster (fru it fly )

0
20

15 M am m als

0
1 2 3 4 5 6 7 8 9 1 0 11 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 < 3 0 < 4 0 < 6 0 > 6 0
N u m b er o f ex o n s
[Source: Benjamin Lewin, (1999) Genes VII, OUP, page 55]

(a) Calculate the percentage of genes that have five or less exons in
mammals.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

68
(b) Describe the distribution of the number of exons and the percentage of
genes in
D. melanogaster.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

..............................................................................................................
.............

..............................................................................................................
.............
(2)

(ii) Suggest one reason for the differences in the numbers of exons
found in genes of
S. cerevisiae and mammals.

..............................................................................................................
.............

..............................................................................................................
.............
(1)

69
Human DNA has been analysed and details of certain genes are shown in the
table below.

Gene Gene size / mRNA size / kb Number of

kb* introns
Insulin 1.7 0.4 2
Collagen 38.0 5.0 50
Albumin 25.0 2.1 14
Phenylalanine 90.0 2.4 12
hydroxylase
Dystrophin 2 000.0 17.0 50

*kilobase pairs
[Source: William S Klug and Michael R Cummings, (2002), Concepts of Genetics, 7th edition, Prentice Hall, page 314]

(d) Calculate the average size of the introns for the albumin gene.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(e) Analyse the relationship between gene size and the number of introns.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

70
(f) Determine the maximum number of amino acids that could be produced
by translating the phenylalanine hydroxylase mRNA.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

Hemoglobin is a protein composed of two pairs of globin molecules. During the

process of development from conception to adulthood, human hemoglobin
changes in composition. Adult hemoglobin consists of two alpha- and two beta-
globin molecules. Two globin genes occur on chromosome 16: alpha- and zeta-
globin. Four other globin genes are found on chromosome 11: beta, delta,
epsilon and gamma. The graph below illustrates the changes in expression of
the globin genes over time.

50
K ey :
40 alp h a-g lo b in
P ercen tag e o f g am m a-g lo b in
h em o g lo b in 3 0 b eta-g lo b in
d elta-g lo b in
20 ep silo n -g lo b in
zeta-g lo b in
10

0
10 20 30 40 2 4 6
w eek s o f g estatio n b irth m o n th o f ag e

[Source: adapted from M Cummings, Human Heredity, 4th edition, West/Wadsworth Publishing Company]

(g) State which globin genes are the first to be expressed after fertilization.

.......................................................................................................................
..............
(1)

71
(h) Compare the expression of the gamma-globin gene with the beta-globin
gene.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(i) Deduce the composition of the hemoglobin molecules

at 10 weeks of gestation;
.........................................................................................

..................................................................................
........

2 months after birth.

................................................................................
..........

..................................................................................
........
(2)
(Total 17 marks)

82. Outline the significance to organisms of the different properties of water.

(Total 5 marks)

83. Living organisms produce a wide variety of organic compounds.

(a) Define the term organic.

72
.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

Organic compounds are made of chemical elements, which are therefore

essential to living organisms.

(b) State the three most commonly occurring elements.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(i) nitrogen;

..............................................................................................................
.............
(1)

(ii) phosphorus.

..............................................................................................................
.............
(1)
(Total 4 marks)

84. Living organisms use DNA as their genetic material. Explain how DNA is
replicated within the cells of living organisms.
(Total 8 marks)

73
85. Describe the genetic code.
(Total 6 marks)

86. Outline two examples of the commercial application of enzymes in

biotechnology.
(Total 6 marks)

74
87. State one function for each of the main four elements in organisms.
(Total 4 marks)

88. The respiratory quotient (RQ) is a measure of the metabolic activity of an

animal. It is the ratio of CO2 produced to O2 consumed. In general, the lower the
RQ value the higher the energy yield. The RQ is dependent on the diet
consumed by the animal. The following table lists the typical RQ values for
specified diets.

Diet RQ
Lipid 0.71
Carbohydrate 1.00
Protein 0.74

[Source: Walsberg and Wolf, Journal of Experimental Biology, (1995), 198, pages 213–219.
Reproduced by permission of The Company of Biologists Ltd]

In an experiment to assess RQ values for house sparrows, the birds were fed a
diet of pure mealworms (beetle larvae) or millet (a type of grain).

The graph below shows the RQ values of a house sparrow fed on a high
carbohydrate diet (millet) and a high lipid diet (mealworms).

1 .0

K ey :
0 .9 M illet
M ealw o rm s
R esp irato ry q u o tien t

0 .8

0 .7

0 .6
0 1 2 3 4 5 6 7
Tim e after feed in g / h

[Source: Walsberg and Wolf, Journal of Experimental Biology, (1995), 198, pages 213–219.
Reproduced by permission of The Company of Biologists Ltd]

75
(a) Compare the RQ values for millet and mealworms between 1 hour and 6
hours after feeding.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

The expected RQ value for house sparrows metabolizing millet is 0.93. The
expected value when metabolizing mealworms is 0.75.

(b) Explain why the expected RQ values for millet and mealworms are
different.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) Suggest reasons for

(i) the high initial RQ values for house sparrows fed on millet;

..............................................................................................................
.............

..............................................................................................................

76
.............
(1)

77
(ii) the rapid fall in RQ values for house sparrows fed on millet.

..............................................................................................................
.............

..............................................................................................................
.............
(1)
(Total 6 marks)

89. (a) State one type of secondary structure of a protein.

.......................................................................................................................
..............
(1)

(b) Outline the differences between globular and fibrous proteins, giving a
named example of each.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

.......................................................................................................................
..............

.......................................................................................................................
78
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

79
90. (a) State where, in the chloroplast, the enzymes of the Calvin cycle are
located.

.......................................................................................................................
..............
(1)

(b) Explain how the proton gradient in the chloroplast is generated by

chemiosmosis.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

80
(Total 6 marks)

81
91. The enzyme aspartate carbomyltransferase (ACTase) is a key regulatory
enzyme in nucleotide metabolism in bacteria. The activity of this enzyme was
studied in the bacterium Helicobacter pylori, an important human pathogen.
ACTase activity and the growth of H. pylori were measured at different
concentrations of carbomoyl aspartate (CAA), the end product of the reaction
catalysed by ACTase.

100 100

75 75

A C Tase activ ity / 5 0 50 G ro w th /

% o f co n tro l % o f co n tro l
K ey :
25 A C Tase activ ity 25
H . p ylo ri g ro w th
0 0
0 10 20 30 40 50 60
C o n cen tratio n o f carb am o y l asp artate / m m o l d m – 3

[Source: Burns, et al, Biological Procedures Online, (1998), http://www.biologicalprocedures.com]

(a) (i) State the growth of H. pylori at a CAA concentration of 30 mmol dm–
3
.

..............................................................................................................
.............
(1)

(ii) Calculate the change in ACTase activity between CAA concentrations

of 20 and 40 mmol dm–3.

..............................................................................................................
.............

..............................................................................................................
.............
(1)

82
(b) Compare the effect of increasing CAA concentration on the growth of H.
pylori and ACTase activity.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) Explain the effect of CAA on ACTase activity.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(d) Suggest a direct medical application of this information.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)
(Total 7 marks)

92. (a) State two products of the process of glycolysis.

.......................................................................................................................
83
..............

.......................................................................................................................
..............
(1)

84
(b) Explain the significance of polar and non-polar amino acids within the cell.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 4 marks)

93. (a) Draw and label the structure of the chloroplast as seen in the electron
microscope.

(3)

85
(b) Explain the relationship between the structure of the chloroplast and its
function.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) Outline the process of chemiosmosis.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 7 marks)

86
94. The graph below shows the effect of changing the substrate concentration on
an enzyme controlled reaction.

4 0 % su b strate
2 0 % su b strate
1 0 % su b strate
A m o u n t o f p ro d u ct fo rm ed
5 % su b strate

2 .5 % su b strate

0 % su b strate
Tim e

What is the correct interpretation of these data?

A. The rate of reaction increases continuously with increase in substrate

concentration.

B. The rate of reaction decreases continuously with increase in substrate

concentration.

C. The rate of reaction increases up to a point and then remains constant.

D. The rate of reaction is not affected by any change in the substrate

concentration.
(1)

95. Pigments are extracted from the leaves of a green plant. White light is then
passed through the solution of pigments. What effect do the leaf pigments have
on the white light?

A. Green wavelengths are absorbed and red and blue wavelengths are
transmitted.

B. Red and blue wavelengths are absorbed and green wavelengths are
transmitted.

C Blue wavelengths are absorbed and green and red wavelengths are
transmitted.

D. Green and red wavelengths are absorbed and blue wavelengths are
transmitted.
(1)

87
88
96. To which parts of the deoxyribose molecule do phosphates bind in DNA?

V CH2 OH
I
O H

IV
H H H OH

OH H
III

A. I and V

B. III and IV

C. II and III

D. III and V
(1)

97. In the enzyme controlled pathway shown below, which compound is most likely
to inhibit enzyme (w)?

enzyme enzyme enzyme enzyme

w x y z
Precursor  I  II  III  IV

A. I

B. II

C. III

D. IV
(1)

89
98. How many molecules of acetyl CoA (ethanoyl CoA) does the oxidation of the
fatty acid stearic acid produce?
CH 3
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
S tearic acid
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
CH 2
COOH

A. 2

B. 6

C. 9

D. 18
(1)

90
99. Which of the following could cause denaturation of an enzyme?

A. Substrate concentration

B. A competitive inhibitor

C. High temperature

D. Low salt concentration

(1)

100. Where do transcription and translation occur in eukaryotic cells?

Transcription Translation
A. Cytoplasm Cytoplasm
B. Cytoplasm Mitochondria
C. Nucleus Cytoplasm
D. Nucleus Nucleus
(1)

101. A biochemist isolated and purified molecules needed for DNA replication. When
some DNA was added replication occurred, but the DNA molecules formed
were defective. Each consisted of a normal DNA strand paired with segments of
DNA a few hundred nucleotides long. Which of the following had been left out of
the mixture?

A. DNA ligase

B. Helicase

C. Nucleotides

D. DNA polymerase
(1)

91
102. Which of the following produce ATP in mitochondria?

A. The movement of protons from the matrix to the intermembrane space

B. The movement of protons from the intermembrane space to the cytoplasm

C. The splitting of water molecules and the movement of electrons to oxygen

D. The movement of protons from the intermembrane space to the matrix

(1)

103. Enzymes are used by living organisms to catalyse reactions. Some of these
reactions occur in the cytoplasm of cells. Other reactions take place outside
cells, for example the digestion of foods in the human gut.

(a) State the name used by biochemists for the chains and cycles of reactions
that occur inside cells.

.......................................................................................................................
..............
(1)

92
(b) Enzymes of digestion in humans are secreted by glands. They have a
pH optimum which allows them to work efficiently in the part of the gut into
which they are secreted.

(i) In the table below, identify the missing enzyme, the two glands, and
the pH optimum

Name of Gland Substrate Products pH optimum

enzyme secreting
the enzyme
amylase starch maltose
triglyceride fatty acids 7
s and
glycerol
(4)

(ii) Outline the effect of pH values above and below the optimum on
enzyme structure.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

(c) Enzymes that work inside cells are sometimes affected by non-competitive
inhibitors. Explain how a non-competitive inhibitor affects the activity of an
enzyme.

.......................................................................................................................
..............

93
.......................................................................................................................
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 10 marks)

94
104. The process of translation involves the use of transfer RNA (tRNA) and amino
acids. Outline the structure of tRNA.
(Total 5 marks)

105. Draw the basic structure of an amino acid, and label the groups that are used in
peptide bond formation.
(Total 4 marks)

106. Explain the process of translation.

(Total 9 marks)

107. Outline two examples of the commercial application of named enzymes in

biotechnology.
(Total 6 marks)

108. Explain competitive and non-competitive inhibition, including allostery.

(Total 8 marks)

109. Outline the use of carbohydrates and lipids in energy storage.

(Total 5 marks)

110. Explain the process of aerobic cellular respiration.

(Total 8 marks)

95
111. Which is the structure of glycerol?

A. H H H B. H H H

H C C C H H C C C H

OH OH OH H H OH

C. H H D. H H

H C C H H C C H

OH OH H OH
(Total 1 mark)

112. Which substance is a base that is found in DNA?

A. Adenosine

B. Cytokinin

C. Guanine

D. Uracil
(Total 1 mark)

113. Aerobic respiration involves conversion of glucose into pyruvate and conversion
of pyruvate into carbon dioxide and water. Where do these processes occur in a
eukaryotic cell?

Where pyruvate is broken

Where glucose is broken
down
down
into carbon dioxide and
into pyruvate
water
A. Cytoplasm Cytoplasm
B. Cytoplasm Mitochondrion
C. Mitochondrion Cytoplasm
D. Mitochondrion Mitochondrion
(Total 1 mark)

96
114. Studies were carried out on the leaves of the wild type of the flowering mustard
plant (Arabidopsis thaliana) to determine the pigment composition of the
thylakoid membrane. The results were compared with the leaves of a mutant
strain of the plant. These studies were repeated using thylakoid membranes
from leaves grown in cultures deficient in either iron or magnesium.

Carotenoids
Strain of Mineral Chlorophyll /
/
Plant Deficiency g g–1 leaf –1
g g leaf
None 454 16
Wild Type Iron 441 71
Magnesium 317 64
None 387 67
Mutant Iron 317 81
Magnesium 172 95

[Source: Lu et al, (1995), Botanical Bulletin of Academia Sinica, 36, pages 175–179]

(a) State the concentration of chlorophyll found in the leaves of the mutant
strain of plant when deficient in iron.

.......................................................................................................................
.............
(1)

(b) (i) Calculate the percentage increase in carotenoids found in the wild
type when magnesium is deficient.

..............................................................................................................
............
(1)

(ii) Suggest why magnesium deficiency causes the changes shown in

the pigment content of the leaves.

..............................................................................................................
............

97
..............................................................................................................
............
(2)

98
(c) Using the data in the table, outline the effects of iron deficiency on the
pigment content of the leaves.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 6 marks)

115. In an electron micrograph, a DNA molecule appears 1 mm wide. The

magnification of the micrograph is 500 000. What is the width of the DNA
molecule?

A. 0.5 nm

B. 2 nm

C. 0.5 m

D. 2 m
(Total 1 mark)

116. What is a difference between the sense and antisense strands of DNA?

A. Nucleotides are linked to the sense strand by hydrogen bonding during

transcription, but not to the antisense strand.

B. The sense strand has the same base sequence as tRNA, but the
antisense strand does not.

C. Nucleotides are linked to the antisense strand by hydrogen bonding during

transcription, but not to the sense strand.

D. The antisense strand has the same base sequence as mRNA but the
sense strand does not.
(Total 1 mark)

99
100
117. The graphs below show the energy changes during endergonic and exergonic
reactions, with and without enzymes.

Which line represents an endergonic reaction, without an enzyme?

A. I

B. II

C. III

D. IV
(Total 1 mark)

101
118. Which diagram represents the process of cyclic photophosphorylation?

(Total 1 mark)

119. What is the advantage of having a small volume inside the thylakoids of the
chloroplast?

A. A high proton concentration is rapidly developed.

B. A high electron concentration is rapidly developed.

C. Photosynthetic pigments are highly concentrated.

D. Enzymes of the Calvin cycle are highly concentrated.

(Total 1 mark)

102
120. The information needed to make polypeptides is carried in the mRNA from the
nucleus to the ribosomes of eukaryotic cells. This information is decoded during
translation. The diagram below represents the process of translation.

(a) Annotate the diagram to show the direction in which the ribosome moves
during translation.
(1)

(b) State the name of the next amino acid which will attach to the polypeptide.

.......................................................................................................................
.............
(1)

103
(c) Explain how the amino acid was attached to the tRNA.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)

(d) Identify two locations within a eukaryotic cell where translation occurs.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)
(Total 6 marks)

121. What determines the specificity of an enzyme for its substrate?

A. The temperature at which it is operating

B. The optimum pH of the enzymes

C. The concentration of the substrate

D. The structure of the enzyme molecule

(Total 1 mark)

104
122. The diagram below represents a DNA nucleotide. What could the part labelled X
represent?

A. Ribose

B. Uracil

C. Guanine

D. Phosphate
(Total 1 mark)

123. In the structure of DNA what binds with cytosine?

A. Deoxyribose

B. Ribose

C. Thymine

D. Adenine
(Total 1 mark)

124. What would be the effect of increasing temperature on the rate of

photosynthesis in a green plant?

A. It increases constantly.

B. It increases up to a point and then remains constant.

C. It increases up to a point and then decreases.

D. It remains constant.
(Total 1 mark)

105
125. The diagram below represents an animal cell.

Which processes occur in the locations labeled?

Transcription Translation Respiration

A. II III I
B. III II I
C. II III IV
D. III II IV
(Total 1 mark)

126. Which molecule is a monosaccharide?

A. Ribose

B. Glycogen

C. Amylase

D. Glycerol
(Total 1 mark)

106
127. Which of the following is an organic compound found in both plant and animal
cells?

A. Cellulose

B. Carbonate

C. Water

D. Pyruvate
(Total 1 mark)

128. Which of the following features are correct for hydrogen bonding?

I. It is involved in the cohesion of water.

II. It results in the thermal properties of water.

III. It is a bond within the water molecule.

A. I and II only

B. II and III only

C. I and III only

D. I, II and III
(Total 1 mark)

129. What is a role of carbohydrates in animal cells?

A. As channels for passive transport

B. As enzymes

C. As energy storage

D. As components of the animal cell wall

(Total 1 mark)

107
130.

Which of the following terms correctly describe(s) the molecule above?

I. Monosaccharide

II. Glucose

III. Component of triglyceride

A. I only

B. I and II only

C. II and III only

D. I, II and III
(Total 1 mark)

131. In which part of the digestive system is most water re-absorbed?

A. The kidneys

B. The stomach

C. The small intestine

D. The large intestine

(Total 1 mark)

108
132. (a) State why each step in a biochemical pathway often requires a separate
enzyme.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

(b) Explain the effects of either changing temperature or pH on enzyme

activity.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 5 marks)

133. (a) Determine the strand of mRNA that is transcribed from the DNA strand
below.

109
ATCCAGGTCAAG

.......................................................................................................................
.............
(1)

110
(b) List three of the other molecules, apart from mRNA, required for
transcription.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 4 marks)

134. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw a labelled diagram showing stages of the carbon cycle.

(5)

(b) Explain how the rate of photosynthesis can be measured.

(7)

111
135. Plants that grow in the desert have many adaptations that enable them to cope
with full sunlight and low water availability, such as thicker leaves with reduced
surface area. Researchers have also observed that leaf pubescence
(presence of white leaf surface hairs) may be another adaptation to dry
environments. A study was done to evaluate the effects of leaf pubescence on
two species of Californian plants, Encelia farinosa, a desert species with
pubescent leaves and Encelia californica, a native of the moist coast with non-
pubescent leaves.

The graph below shows the absorption spectrum of intact leaves of both
species in the photosynthetically active spectrum between the wavelengths 400
nm (blue light) and 800 nm (red light) of light.

100 K ey :
90 E . californica
80
E . farinosa
70
60
A b so rp tio n 5 0
/%
40
30
20
10
0
400 450 500 550 600 650 700 750 800
B lu e G reen Yello w O ran g e R ed
Wav elen g th / n m

[Source: From J. Ehleringer et al., “Leaf Pubescence: Effects on Absorptance and Photosynthesis in a Desert Shrub”,
Science (23 April 1976), vol. 192, issue 4237, pp. 376-377. Reprinted with permission from AAAS]

(a) Calculate the difference in absorption between E. farinosa and E.

californica at 600 nm.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

(b) Suggest a possible explanation for the decrease in absorption at 550 nm

for E. californica.

.......................................................................................................................
.............

112
.......................................................................................................................
.............
(1)

The following graph shows the rate of CO2 uptake of three leaves of Encelia
farinosa with different absorbance coefficients (x) (proportion of light absorbed)
which is related to the degree of pubescence of the leaf. The higher the
coefficient the more light is absorbed.

4 .0 x = 0 .8 2

3 .5
x = 0 .6 5
3 .0

2 .5
R ate o f C O 2 u p tak e / x = 0 .5 3
2 .0
n m o l C O 2 cm – 2 sec – 1
1 .5

1 .0

0 .5

0 .0

0 50 100 150 200 250

L ig h t in ten sity / m o l cm – 2 sec – 1

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

(d) (i) Using the data, deduce the relationship between pubescence and
light absorption.

113
..............................................................................................................
............

..............................................................................................................
............
(1)

114
(ii) Evaluate the relationship of leaf pubescence and CO2 uptake.

..............................................................................................................
............

..............................................................................................................
............
(1)

(e) Suggest how natural selection may have caused the difference in leaf
pubescence between E. farinosa and E. californica.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

Further research was carried out to evaluate the relationship between leaf
pubescence during the growing season of E. farinosa and its water use
efficiency. Water use efficiency is defined as the amount of CO2 uptake divided
by the amount of water lost by transpiration from the leaf. The graph below
shows the seasonal change in leaf pubescence and water use efficiency of E.
farinosa. The period of maximum growth is indicated on the graph. During the
course of the year the optimum temperature for photosynthesis remains at 30C
while the air temperature fluctuates from a high of 38C in the summer months
(May–September) to a low of 8C during the winter months (December–
February).

6 0 .3 5 K ey :

0 .3 0 Water u se effcien cy
5
W a te r u s e e ffc ie n c y / a rb itra ry u n its

P u b escen ce T h ick n ess /m m

0 .2 5 P u b escen ce th ick n ess

4
0 .2 0
3
0 .1 5
2
0 .1 0

1 0 .0 5

0 0 .0 0
M J J A S O N D J F M A M
Tim e o f th e y ear / m o n th m ax im u m g ro w th p erio d
n ew leav es em erg e

115
[Source: Ecology by William K. Smith and Park S. Nobel. Copyright 1977 by Ecological Society of America. Reproduced
with permission of Ecological Society of America in the format of CD-Rom via Copyright Clearance Center.]

116
(f) State the month with the highest water use efficiency.

.......................................................................................................................
.............
(1)

(g) Outline the changes in leaf pubescence of E. farinosa during the year.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

(h) Analyse the change in the level of water use efficiency between July and
December for E. farinosa.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 11 marks)

117
136. The following diagram represents replication in DNA.

A B

[Freeman, Scott, Biological Science, 1st,  2002. Electronically reproduced by permission of Pearson Education, Inc.,
Upper Saddle River, New Jersey]

(a) State the name and describe the function for the enzymes labelled A and
B on the diagram.

(i) A: Name:
..........................................................................................

Function:
..........................................................................................

(ii) B: Name:
..........................................................................................

Function:
..........................................................................................
(2)

(b) Identify the cellular location of DNA replication in eukaryotic cells.

.......................................................................................................................
.............
(1)

.......................................................................................................................
.............

118
(1)

119
(d) Explain the significance of complementary base pairing during DNA
replication.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 6 marks)

137. The hydrolysis of inorganic phosphate (PPi) by phosphatase enzyme provides

energy for a wide range of reactions. A phosphatase (PPase) occurs bound to
thylakoid membranes. This enzyme was purified from the thylakoid membranes
of spinach leaves using chromatography. The activity of the membrane bound
enzyme and the purified enzyme was measured.

The effect of the concentration of magnesium ions (Mg2+) on the relative activity
of these enzymes was determined using different concentrations of magnesium
chloride. The concentration of inorganic phosphate used in both cases was of 1
mmol dm–3.

Activity of phosphatase (arbitary

units)
Membrane bound Purified
12 618 1215

120
P u rifed
M em b ran e
bound
R elativ e activ ity
/%

m ag n esiu m ch lo rid e co n cen tratio n / m m o l d m – 3

[Reprinted from Po-Yin Cheung et al., “Thiols Protect the Inhibition of Myocardial Aconitase by Peroxynitrite”, Archives of
Biochemistry and Biophysics, vol. 350, issue 1, pp. 104-108 © 1998, with permission from Elsevier.]

121
(a) State the percentage of relative activity of the purified enzyme when the
concentration of magnesium chloride is

(i) 1 mmol dm–3 ...................................

(ii) 2 mmol dm–3 ...................................

(2)

(b) Outline the effect of magnesium chloride on the relative activity of the
membrane bound enzyme.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

(c) Calculate the approximate ratio of inorganic phosphate to magnesium

chloride concentration needed to achieve maximum activity in membrane
bound enzymes.

.......................................................................................................................
.............
(1)

(d) (i) State the difference in phosphatase activity when membrane bound
and when purified.

..............................................................................................................
............

..............................................................................................................
............
(1)

(ii) Suggest a reason for this difference.

122
..............................................................................................................
............

..............................................................................................................
............
(1)
(Total 7 marks)

138. The diagram below shows some features of ATP synthetase.

(a) Identify in which cell organelle the process below occurs?

.......................................................................................................................
.............

(1)

(b) Explain the process represented by the diagram.

.......................................................................................................................
.............

.......................................................................................................................

123
.............

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 4 marks)

124
139. Copepods are very small crustaceans and an important component of plankton
in the Arctic sea ice. The distribution of copepods, which feed on microalgae,
can be related to the food and predators. The biomass of microalgae was
measured and the concentration of chlorophyll a was calculated. The graphs
below show how the concentration of chlorophyll a and copepods change with
depth.

M icro a lg a e C o p ep o d s

C h lo ro p h y ll a / m g m – 3 R elativ e n u m b ers

D e p th / m
D e p th / m

[Source: Martin Fortier, et. al., Visual predators and the diel vertical migration of copepods under Arctic sea ice during the
midnight sun” (2001), vol. 23, issue 11, pp. 1263–1278, by permission of Oxford University Press]

(a) State the amount at a depth of 30 m below sea level of

(i) chlorophyll a;

..............................................................................................................
............

(ii) copepods.

..............................................................................................................
............
(2)

125
(b) Describe the distribution of microalgae.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

(c) Discuss factors that could affect the distribution of copepods.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 7 marks)

126
140. The electron micrographs below show mitochondria in longitudinal section. The
mitochondrion in A is from a bat pancreas cell and that in B is from a mouse
liver cell.

[Source: Tribe and Whittaker, Chloroplasts and Mitochondria, (1972), 31, pp 28–29]

(a) Annotate the micrographs to show two similarities in the structure of the
mitochondria.
(2)

(b) The mitochondria differ in size. State two other differences that are visible
in the mitochondria.

1. ..............................................................................................................
............

2. ..............................................................................................................
............
(2)

127
(c) Predict, with two reasons, which of the mitochondria would have been
able to produce ATP at a greater rate.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 7 marks)

141. What is one role of the element phosphorus?

A. It forms part of the structure of amino acids.

B. It forms part of the structure of fatty acids.

C. It forms part of the structure of ribose.

D. It forms part of the structure of nucleotides.

(Total 1 mark)

128
142. The reaction below shows the energy changes in a chemical reaction.

What would happen to the changes in energy if this reaction was controlled by
an enzyme?

A. I would increase.

B. II would decrease.

C. I and IV would decrease.

D. II and III would decrease.

(Total 1 mark)

143. Which of the following reactions is an oxidation reaction?

A. Pyruvate  Acetate + CO2

B. FAD + 2H+ + 2e–  FADH2

C. Ribulose bisphosphate + CO2  2  Phosphoglycerate

D. NADP+ + 2H+ + 2e–  NADPH + H+

(Total 1 mark)

129
144. The average surface area for the inner membranes of mitochondria in a
epithelial cell is 40 m2 g–1. The surface area of the inner membrane of
mitochondria from heart muscle cells is over 200 m2 g–1.

What is the reason for the large surface area of the inner membranes of the
mitochondria in the heart muscle cells?

A. They contain enzymes to hydrolyse ADP and inorganic phosphate to

ATP.

B. They contain enzymes to oxidize ADP and inorganic phosphate to ATP.

C. They contain enzymes to reduce ADP and inorganic phosphate to ATP.

D. They contain enzymes to condense ADP and inorganic phosphate to

ATP.
(Total 1 mark)

145. According to the induced fit model of enzyme function, which of the following
statements is correct?

A. Active sites on enzymes are specific to a single substrate.

B. The shape of the active site can be changed by the binding of an allosteric
inhibitor.

C. The binding of the substrate changes the shape of the active site slightly.

D. Competitive inhibitors can change the shape of enzymes.

(Total 1 mark)

146. During which process are oxygen molecules directly involved during cellular
respiration?

A. Glycolysis

B. Krebs cycle

C. Oxidation of pyruvate to acetyl CoA

D. Accepting electrons at the end of the electron transport chain

(Total 1 mark)

130
147. Where is an anti-codon located?

A. tRNA

B. mRNA

C. DNA

D. Ribosomes
(Total 1 mark)

148. Up to two additional marks are available for the construction of your answers.
(2)

(a) Outline the structure of DNA.

(5)

(b) Describe the effects of polygenic inheritance using two specific examples.
(5)

(c) Explain the process of transcription in eukaryotes.

(8)
(Total 20 marks)

131
149. Studies have been carried out on the consumption of oxygen by mammals
under different conditions. The graph below shows the oxygen consumption of a
pigmy possum (Cercaertus nanus) at various air temperatures.

3
O x y g en
co n su m p tio n
/ m l O 2 g - 1 h -1 2

0
0 5 10 15 20 25 30 35 40
A ir tem p eratu re /  C
Knut Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, 5ed (Cambridge:
Cambridge University Press, 1997). Reprinted with permission.

(a) Estimate the oxygen consumption at 20C.

.......................................................................................................................
.............
(1)

(b) Outline the effect of temperature on oxygen consumption.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

132
(c) An air temperature of 32C is the lower critical temperature for a pigmy
possum. Deduce the meaning of lower critical temperature.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

The graph below shows the metabolic rates of various mammals in relation to
air temperatures. Metabolic rate refers to the rate of use of energy by an animal
and may be measured indirectly by oxygen consumption. The basal metabolic
rate (BMR) for each animal, in the absence of stress, is given the value of
100. This occurs at different temperatures for different animals. The changes
in metabolic rate as the temperature falls are expressed as a percentage of the
BMR for each animal.

[Knut Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, 5ed (Cambridge: Cambridge University Press,
1997). Reprinted with permission.]

(d) (i) Identify the mammal with the greatest increase in metabolic rate per
degree of temperature, as the temperature decreases.

..............................................................................................................
............
(1)

133
(ii) Calculate the average change in the metabolic rate, per degree of
temperature, of a weasel as the temperature decreases from 17C to
–20C. Show your workings.

..............................................................................................................
............

..............................................................................................................
............
(2)

(e) Suggest one reason for the increase in metabolic rate of mammals at
lower temperatures.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

(f) Discuss the differences between tropical and arctic mammals regarding
the changes in their metabolic rates as the temperature decreases.

.......................................................................................................................
.............

134
.......................................................................................................................
.............
(3)

135
Other studies were carried out to see the relationship of the thickness of fur in
mammals to its value as an insulator. A good insulator prevents heat loss from
the animals to their environment. The graph below shows the relationship of the
fur thickness to fur insulation in different mammals. Symbols represent the
transfer of heat from fur to air or fur to ice water.

4 .0

3 .5 w h ite fo x d all sh eep

3 .0 w o lf
rein d eer g rizzly b ear
p o lar b ear
2 .5 red fo x
rab b it
dog
F u r in su latio n 2 .0 b eav er
v alu e / W d m – 2

1 .5 seal

sq u irrel lem m in g
1 .0
seal in ice w ater
w easel
0 .5 sh rew
b eav er in ice w ater p o lar b ear in ice w ater
0 .0
0 10 20 30 40 50 60 70 80
F u r th ick n ess / m m

Key : ♦ = the rate of transfer of heat from fur to air

◊ = the rate of transfer of heat from fur to ice water
[Source: K Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, (1978), CUP, pp 321]

(g) (i) Calculate the difference in fur thickness between a reindeer and a
grizzly bear.

..............................................................................................................
............

..............................................................................................................
............
(1)

(ii) Suggest a reason for their similar fur insulation value.

..............................................................................................................
............

136
..............................................................................................................
............
(1)

(h) (i) Calculate the change in the insulation value for a beaver when it
enters ice water.

..............................................................................................................
............

..............................................................................................................
............
(1)

(ii) Suggest an adaptation that allows a mammal to maintain its body

temperature while in ice water.

..............................................................................................................
............

..............................................................................................................
............
(1)

(i) Discuss the relationship between metabolic rate and fur thickness in
mammals.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 18 marks)

137
138
150. A study was conducted on how cattle grazing affects the water content of soils.
One area studied was a pasture of alfalfa (Medicago sativa). A special probe
was used to take measurements of soil water to depths of 300 mm. The range
of measurements obtained were used to calculate the total soil water content
expressed in mm. Results from part of the study during the growing season for
the year 2000 are shown below.

125 K ey : g razed
u n -g razed

100

To tal so il w ater
/ mm 75

25
120 140 160 180 200 220 240 260 280

D ay o f th e y ear

[Source: Mapfumo et al., Canadian Journal of Soil Science, (2003), 83, pp 601–614]

139
(a) State the overall trend in total soil water content during the study period.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

140
(b) Identify the day on which the difference in total soil water content of grazed
and un-grazed areas was greatest.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

141
(c) Discuss the effects of grazing on the total soil water content.

.......................................................................................................................
.............

.......................................................................................................................
.............
(4)
(Total 6 marks)

142
151. Identify the atoms and ions from the table below.

Atoms Ions
A. H+ Na+ OH– Cl–
B. Fe K CH3COO– H2O
C. Fe H2O Ca2+ N3 –
D. Na C I– NO3 –
(Total 1 mark)

143
152. Which compounds are both organic and found in living organisms?

Carbon Calcium
Glucose Urea
Dioxide Carbonate
C6H12O6 OC(NH2)
CO2 CaCO3
A.
B.
C.
D.

Key: = present = absent

(Total 1 mark)

144
153. What is an active site?

A. The part of an enzyme that binds only to the product molecules.

B. The sequence of amino acids responsible for the catalytic activity of

enzymes.

C. The sequence of amino acids responsible for the structure of an enzyme.

D. The specific area responsible for the activity of all proteins.

(Total 1 mark)

145
154. What is responsible for the conservation of the base sequence during DNA
replication?

A. DNA polymerase working on one strand at the same time.

B. Unpaired bases always attracting their complementary nucleotides.

C. DNA helicase and polymerase are complementary.

D. Both strands are identical to each other.

(Total 1 mark)

146
155. Which graph shows the effect of increasing carbon dioxide concentration (CO2)
on the rate of photosynthesis?

147
(Total 1 mark)

148
156. Which types of enzyme are found in the human digestive system?

I. Amylases

II. Proteases

III. Lipases

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

149
157. Magellanic penguins (Spheniscus magellanicus) live and breed near the coast
of Argentina. However, their colonies are a long way from the open sea where
they hunt for fish. They cannot fly so have to swim to the feeding grounds. A
study investigated how the water currents due to high and low tides affected
their journey to and from their colonies. The results are shown below.

C u rren t fro m C u rren t to C u rren t fro m

co lo n y co lo n y co lo n y
70
60
50
40
P enguins / num ber
30
20
10
0
0 6 :0 0 1 2 :0 0 1 8 :0 0 2 2 :0 0
M o rn in g E v en in g
Tim e o f d ay / h o u r

K ey : d ep artin g fro m co lo n y arriv in g at co lo n y

[Source: R. P. Wilson, “Magellanic Penguins Spheniscus magellanicus commuting through San Julian Bay;
do current trends induce tidal tactics?”, Journal of Avian Biology (Oct 30 2003), vol. 32, issue 1, pp. 83-89.
Copyright © 2003. Reprinted with permission of Blackwell Publishing Ltd.]

150
(a) (i) Identify the number of penguins departing from the colony at 06:00
hours.

..............................................................................................................
............
(1)

151
(ii) Identify the time of day when most penguins arrive at the colony.

..............................................................................................................
............
(1)

152
(b) Describe the pattern of movement of penguins departing from the colony
between 06:00 hours and 22:00 hours.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

153
(c) Suggest why there is little movement in either direction between 14:00
hours and 16:00 hours.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

154
The study also investigated the range of swim speed for one penguin when out
hunting in the open sea.

4 .0

3 .5

3 .0

2 .5

S w im sp eed / m s -1 2 .0

1 .5

1 .0

0 .5

0 .0
0 6 :0 0 11 :0 0 1 6 :0 0
Tim e o f d ay / h o u r

[Source: R. P. Wilson, “Magellanic Penguins Spheniscus magellanicus commuting through San Julian Bay; do current
trends induce tidal tactics?”, Journal of Avian Biology (Oct 30 2003), vol. 32, issue 1, pp. 83-89. Copyright © 2003.
Reprinted with permission of Blackwell Publishing Ltd.]

155
(d) Calculate the greatest difference in swim speed during the study.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

156
(e) Suggest two reasons for the changes in swim speed of the penguin during
the period of time of the study.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

157
The diagram below shows part of the coastline.

p o in t Y L an d O p en sea

w alk in g d istan ce 1 7 5 m

p o in t X

[Source: R. P. Wilson, “Magellanic Penguins Spheniscus magellanicus commuting through San Julian Bay; do current
trends induce tidal tactics?”, Journal of Avian Biology (Oct 30 2003), vol. 32, issue 1, pp. 83-89. Copyright © 2003.
Reprinted with permission of Blackwell Publishing Ltd.]

158
(f) A penguin uses 88 joules of energy to walk one metre. Calculate the
energy used to walk from point X to point Y.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

159
(g) The penguin uses more energy swimming. Suggest one reason why most
penguins actually swim rather than walk from point X to point Y.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)

160
(h) Explain why penguins have many mitochondria in the muscles used for
swimming.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 13 marks)

161
158. (a) Explain how photosynthesis can be measured both directly and indirectly.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)

162
(b) Outline two uses of absorbed carbohydrates in humans.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

163
(c) The diagram below represents an energy pyramid and four trophic levels.

III

1 0 0 0 0 0 k J m –2 y r–1 I

[Source: adapted from www.bio.miami.edu/dana/160/pyramid.gif]

(i) Identify the trophic level of the organisms indicated below.

I. ......................................................................................................
.........

IV. ......................................................................................................
.........
(2)

164
(ii) Calculate the approximate amount of energy in kilojoules transferred
in m–2 yr–1 from trophic level I to trophic level II.

..............................................................................................................
....... kJ
(1)
(Total 8 marks)

165
159. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label a diagram to illustrate the fluid mosaic model of biological
membranes.
(5)

(b) Using a table, compare aerobic and anaerobic respiration in a eukaryotic

cell.
(5)

(c) Explain the process of translation.

(8)
(Total 20 marks)

166
160. The cyanobacterium (Calothrix elenkenii) is cultivated as a source of
photosynthetic pigments for use in research and industry. The chart below
shows the quantity of two of the pigments produced when exposed to a day of
continuous dark, a day of 16 hours light and 8 hours dark and a day of
continuous light. This was repeated in both aerobic and anaerobic conditions.

K ey : C h lo ro p h y ll
D ark β-C aro ten e
A ero b ic
L ig h t – D ark

L ig h t

D ark
A n aero b ic
L ig h t – D ark

L ig h t

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5 5 .0 5 .5 6 .0
A m o u n t o f P ig m en t / μ g cm – 3

[Source: Reprinted from Journal of Plant Physiology, Vol 161, Parsanna et al., “Modulation of pigment…” pages 1125–
1132,
 copyright (2002), with permission from Elsevier.]

167
(a) Identify the light conditions that cause most chlorophyll to be made when
the cyanobacterium is cultivated anaerobically.

.......................................................................................................................
.............
(1)

168
(b) Calculate the percentage increase in chlorophyll grown anaerobically in
the light, compared with anaerobically in the dark.

.......................................................................................................................
.............
(1)

169
(c) Compare pigment production in different aerobic conditions.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

170
(d) Discuss why having more than one photosynthetic pigment is an
advantage to cyanobacterium.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 7 marks)

171
161. (a) State the net gain of ATP molecules during glycolysis of one glucose
molecule.

.......................................................................................................................
.............
(1)

172
(b) State where in the mitochondrion the enzymes of the Krebs cycle are
found.

.......................................................................................................................
.............
(1)

173
(c) Compare the process of chemiosmosis in both respiration and
photosynthesis.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 5 marks)

174
162. Which graph shows the effect of increasing carbon dioxide concentration (CO2 )
on the rate of photosynthesis?

175
(Total 1 mark)

176
163. What is the function of DNA polymerase I?

A. To add appropriate nucleotides in the 3′  5′ direction

B. To remove the RNA primers and replace them with DNA

C. To join together the Okazaki fragments

D. To join together both strands of DNA to the histones

(Total 1 mark)

177
164. Which statement describes how allosteric enzymes work?

End-
Competitive Active and
Reversible product
inhibition inactive forms
inhibition
A.
B.
C.
D.

Key: = yes = no
(Total 1 mark)

178
165. Which diagram shows how enzymes change the activation energy in an
endergonic reaction?

A. B. Y
X
X
Y

E n erg y E n erg y

P ro g ress o f reactio n P ro g ress o f reactio n

C. D. Y
X
X
Y
E n erg y E n erg y

P ro g ress o f reactio n P ro g ress o f reactio n

Key: X = without enzyme Y = with enzyme

(Total 1 mark)

166. What is the “link reaction” in eukaryotic respiration?

A. Pyruvate joining with coenzyme A to produce CO2 and NADH + H+

B. Oxidation of NADH to yield electrons and protons

C. Acetyl coenzyme A combining or joining with a C4 compound to give C6 +

coenzyme A

D. Passage of acetyl coenzyme A through the mitochondrial membrane

(Total 1 mark)

179
167. How are photosynthesis and aerobic respiration similar?

ATP synthetase Electron transport

enzyme chain NADH + H+

A.
B.
C.
D.

Key: = both have or use this = both do not have or use this
(Total 1 mark)

168. In the graph below which line shows an action spectrum of photosynthesis?

B D
A
C

R elativ e rate o f
p h o to sy n th esis

400 500 600 700

Wav elen g th / n m
(Total 1 mark)

180
169. Phenylketonuria (PKU) is a disease caused by a gene mutation that makes too
much phenylalanine which may cause brain damage. The enzyme
phenylalanine ammonia lyase (PAL), converts phenylalanine into harmless
products. Mice with PKU were injected with PAL. The levels of phenylalanine in
blood plasma were measured immediately after the injection (0 hour) and every
hour for the next three hours. Different groups of mice with PKU were injected
with three different doses of PAL. The results are shown below as a percentage
of the levels of phenylalanine before the PAL injection.

100

10 p lasm a
p h en y lalan in e
/%

0
1 1
tim e /
2 100
hour
3 20
2
d o ses o f PA L / u n its
[Source: C. Sarkissian et al., “A different approach to treatment of phenylketonuria: Phenylalanine degradation with
recombinant phenylalanine ammonia lyase”, Proceedings of the National Academy of Sciences (1999), vol. 96, pp.
2339–2344.
Copyright (1999) National Academy of Sciences, U.S.A.]

(a) Calculate the approximate percentage reduction in phenylalanine at 0 hour

when the mice were injected with a dose of two units of PAL.

................................................................................... 
(1)

(b) Outline the effect of a dose of twenty units of PAL on phenylalanine levels.

.......................................................................................................................
.............

.......................................................................................................................
181
.............
(2)

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)

(d) Outline how the type of mutation that causes PKU differs from Klinefelter’s
syndrome.

.......................................................................................................................
.............

.......................................................................................................................
.............
(1)
(Total 7 marks)

170. Which of the following could be a function of a membrane protein?

A. Energy storage

B. Enzymatic activity

C. Oxygen uptake
182
D. Thermal insulation
(Total 1 mark)

183
171. During the process of replication, which bond(s) in the diagram of DNA below
is/are broken?

3 6
4
1
7

A. 3

B. 4, 5

C. 1, 2, 6, 7

D. 1, 7, 4, 5
(Total 1 mark)

172. What is the maximum number of fatty acids that can be condensed with
glycerol?

A. One

B. Two

C. Three

D. Four
(Total 1 mark)

184
173. Which row in the table describes the first stage of cellular respiration?

Substrate Location Product Product

A. pyruvate mitochondri oxygen water
a
B. pyruvate cytoplasm carbon ATP
dioxide
C. glucose mitochondri pyruvate water
a
D. glucose cytoplasm pyruvate ATP

(Total 1 mark)

174. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label a simple diagram to show how DNA is constructed from sugars,
phosphates and bases.
(6)

(b) Define the terms gene and gene mutation.

(4)

(c) Genetic modification involves the transfer of DNA from one species to
another. Discuss the potential benefits and possible harmful effects of one
example of genetic modification in a named organism.
(8)
(Total 20 marks)

175. (a) Outline why the transparency of water is important to organisms living in an aquatic
habitat.

.......................................................................................................................
............

.......................................................................................................................
............
(2)

185
(b) The diagram below shows a simplified food web for a lake.

[Source: Water on the Web (2004), Monitoring Minnesota Lakes on the Internet and Training Water
Science
Technicians for the Future – A National On-line Curriculum using Advanced Technologies and Real-Time
Data,
www.waterontheweb.org/under/lakeecology/11_foodweb.html,
reprinted with the permission of Water on the Web project, University of Minnesota, Duluth, MN 55812]

(i) State the initial energy source for the above food web.

..............................................................................................................
...........
(1)

(ii) Define the term trophic level.

..............................................................................................................
...........

..............................................................................................................
...........
(1)

(iii) Deduce the trophic level of the immature game fish.

..............................................................................................................

186
...........
(1)

(iv) In the food web shown, identify one heterotroph and one autotroph.

heterotroph: ..................................................................................
..................

autotroph: ............................................................................................
........
(1)
(Total 6 marks)

176. Diatoms are unicellular algae which live as plankton in fresh water and oceans.
Biochemists investigated two species of diatom, Thalassiosira oceanica which
lives in the open ocean where the water is clear and Thalassiosira weissflogii
which lives in coastal waters where the water is often cloudy. Iron is an
important part of a number of molecules involved in photosynthesis. Iron
however is often deficient in the waters of the open ocean. The scientists
investigated the amount of iron present in the cells of the diatoms when they
were grown at different intensities of light, in both high and low iron conditions.
T h ala ssio sira o cea n ica T h ala ssio sira w eissflo g ii
1000
K ey :
h ig h iro n co n d itio n s
800
lo w iro n co n d itio n s
Iro n 600
co n cen tratio n
in cells /
m o l d m –3 400

200

0 100 200 300 0 100 200 300

L ig h t in ten sity / relativ e u n its

[Source: Reprinted with permission from Macmillan Publishers Ltd: Robert F. Strzepek and Paul J. Harrison,
“Photosynthetic architecture differs in coastal and oceanic diatoms”, Nature (7 October 2004), vol. 431, issue 7009,
p. 689, © 2004]

(a) Compare the iron concentrations in the cells of T. oceanica and T. weissflogii under high
iron conditions.

.......................................................................................................................
............

187
.......................................................................................................................
............

.......................................................................................................................
............

.......................................................................................................................
............
(2)

188
(b) Suggest a reason for the response of T. weissflogii to low light intensities.

.......................................................................................................................
............

.......................................................................................................................
............
(2)

When the growth of these two species was compared in the two iron conditions
it was found that the growth of T. oceanica was not affected by low iron
concentrations but the growth of T. weissflogii was reduced by about 20%.

(c) Explain how T. oceanica is adapted to oceanic waters.

.......................................................................................................................
............

.......................................................................................................................
............
(3)

(d) Predict what would be the effect on the populations of these diatoms if
atmospheric pollution reduced light intensities over the oceans.

.......................................................................................................................
............

189
.......................................................................................................................
............
(1)
(Total 8 marks)

190
177. (a) Explain the secondary and tertiary levels of protein structure.

..................................................................................................................
...........

..................................................................................................................
...........
(4)

(b) Outline the induced fit model for enzyme action.

.......................................................................................................................
...........

.......................................................................................................................
...........
(2)
(Total 6 marks)

191
192
178. Scientists have long been concerned about the effect of heavy metals in foods
that we eat. Aquatic filter feeders including bivalves, such as mussels and
oysters, are especially prone to accumulation of heavy metals.

Calcium is taken into bivalves through protein channels, but other non-essential
elements may also be taken in.

To investigate the relationship between the uptake of calcium and other

elements, the bivalves Hyridella depressa and Velesunio ambiguous were
placed in solutions containing ten times the normal level of calcium (Ca). The
elements manganese (Mn), lead (Pb), cadmium (Cd) and cobalt (Co) were also
present in the solutions at normal concentrations. The results are shown below.

H . dep ressa
12
10
8

F acto r o f 6
in crease / 4
red u ctio n
2
0
C a in w ater C a in tissu e
–2
M n in tissu e P b in tissu e C d in tissu e C o in tissu e
–4
M etal

V. a m big uo us
12
10
8
6
F acto r o f
in crease / 4
red u ctio n 2
0
C a in w ater C a in tissu e
–2
M n in tissu e P b in tissu e C d in tissu e C o in tissu e
–4
M etal

[Source: Reprinted from Markich Scott J. and Jeffree Ross A., “Absorption of divalent trace metals as analogues of
calcium by Australian freshwater bivalves: an explanation of how water hardness reduces metal toxicity”, Aquatic
Toxicology (August 1994), vol. 29, issue 3–4, pp. 257–290, © 1994 with permission from Elsevier]

193
(a) (i) Outline the effect of increasing calcium levels in the water on calcium
levels in the tissue of the bivalves.

..............................................................................................................
...........

..............................................................................................................
...........
(1)

(ii) Outline the effect of increasing calcium levels in the water on metals
other than calcium in the tissue of the bivalves.

..............................................................................................................
...........

..............................................................................................................
...........
(1)

(b) Suggest reasons for the effects of calcium on the levels of the other metals
in the tissues.

.......................................................................................................................
............

.......................................................................................................................
............
(2)

.......................................................................................................................
............

194
.......................................................................................................................
............

.......................................................................................................................
............

.......................................................................................................................
............
(3)
(Total 7 marks)

195
179. The mitochondrion carries out key reactions in the cells of eukaryotes.

[Source: D S Friend, Brigham and Women’s Hospital, www.nigms.nih.gov/ news/science_ed/mito1.html]

(a) (i) State the name of label A and label B in the photomicrograph above.

A: ......................................................................................................
.........

B: ......................................................................................................
.........
(1)

(ii) State the processes that occur at label A and label B.

A: ......................................................................................................
.........

B: ......................................................................................................
.........
(1)

196
(b) Explain the relationship between the structure of the mitochondrion and its
function.

.......................................................................................................................
............

.......................................................................................................................
............
(3)
(Total 5 marks)

180. (a) Draw and label the structure of a chloroplast as seen in electron micrographs.
(3)

(b) Explain the relationship between the absorption spectrum and the action
spectrum of photosynthetic pigments.

.......................................................................................................................
............

.......................................................................................................................

197
............

.......................................................................................................................
............
(3)
(Total 6 marks)

198
181. The drawing below shows a short section of a DNA molecule. What is labelled
by I, II and III?

III

I II III
A. 3′ end purine hydrogen bond
B. 5′ end pyrimidine covalent bond
C. 3′ end pyrimidine hydrogen bond
D. 5′ end purine covalent bond

(Total 1 mark)

182. Which combination of changes describes biological oxidation?

Electrons Oxygen Hydrogen

A. loss gain loss
B. loss loss gain
C. gain loss gain
D. gain gain loss
(Total 1 mark)

199
183. Within the mitochondria, what compound is produced through oxidation of fatty
acids?

A. Acetyl-CoA

B. Acetylcholine

C. Oxaloacetate

D. Pyruvate
(Total 1 mark)

184. Which of the following features is/are present in mitochondria but not in
chloroplasts?

I. DNA and ribosomes

II. Outer and inner membranes

III. Cristae

A. I only

B. II only

C. III only

D. I and III only

(Total 1 mark)

200
185. Which diagram represents the action spectrum of photosynthesis?

A. B.
100 100
80 80

R elativ e rate o f
p h o to sy n th esis
R elativ e rate o f
p h o to sy n th esis

60 60
40 40
20 20
0 0
400 500 600 700 400 500 600 700
W av elen g th W av elen g th

C. D.
100 100
80 R elativ e rate o f 80
R elativ e rate o f

p h o to sy n th esis
p h o to sy n th esis

60 60
40 40
20 20
0 0
400 500 600 700 400 500 600 700
W av elen g th W av elen g th
(Total 1 mark)

186. (a) State two differences between the structure of DNA and RNA.

1. ..............................................................................................................
...........

..............................................................................................................
...........

2. ..............................................................................................................
...........

..............................................................................................................
...........
(2)

201
The diagram below shows the structure of a ribosome during protein synthesis.

II p o ly p ep tid e

I III

(b) State the names of the structures labelled above.

I. ..............................................................................................................
............

II. ..............................................................................................................
............

III. ..............................................................................................................
............

IV. ..............................................................................................................
............
(2)

.......................................................................................................................
.............
(1)

(d) Explain why the process used during protein synthesis in cells is called
translation.

.......................................................................................................................
.............

202
.......................................................................................................................
.............

.......................................................................................................................
.............
(2)

203
(e) Explain briefly how termination of translation occurs.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 9 marks)

187. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label a diagram showing the structure of a glomerulus and associated nephron.
(4)

(b) Explain how water balance is maintained in the blood.

(8)

(c) Describe the process of water uptake and movement in roots.

(6)
(Total 20 marks)

188. Which substance is a base found in RNA?

A. Ribose

B. Thymine

C. Adenosine

D. Uracil
(Total 1 mark)

204
189. What type of bond holds the complementary base pairs together in a double
helix of DNA?

A. Covalent bonds

B. Peptide bonds

C. Glycosidic bonds

D. Hydrogen bonds
(Total 1 mark)

190. During the process of translation which of the following statements describes
the relationship between nucleic acids?

A. Anticodons on mRNA bind to complementary codons on DNA.

B. Anticodons on tRNA bind to complementary codons on mRNA.

C. Bases on DNA bind to complementary bases on mRNA.

D. A single strand of mRNA is produced from the DNA in the nucleus.

(Total 1 mark)

191. What chemical substances are used during the manufacture of organic
molecules in photosynthesis?

I. Hydrogen

II. ATP

III. Carbon dioxide

A. I and III only

B. I and II only

C. II and III only

D. I, II and III
(Total 1 mark)

205
192. The graph below shows the effect of light intensity on photosynthesis at 0.1%
carbon dioxide concentration.

R ate o f p h o to sy n th esis /
arb itrary u n its

L ig h t in ten sity / arb itrary u n its

(a) On the graph above, draw the results obtained at 0.01% carbon dioxide.
(1)

(b) Outline the fate of the oxygen and hydrogen which are produced in the
photolysis of water during photosynthesis.

Oxygen: ....................................................................................................
...........

....................................................................................................
...........

Hydrogen ....................................................................................................
...........

....................................................................................................
...........
(2)

(c) The energy produced in photosynthesis can enter a food chain. Explain
how this energy can be lost before it reaches the last link in the chain.

.......................................................................................................................
.............

.......................................................................................................................
.............
(2)
(Total 5 marks)

206
207
193. The eastern oyster (Crassostrea virginica) is a marine mollusc that lives in
estuaries. The environmental surroundings of the eastern oyster, such as the
temperature and concentration of trace elements, are constantly changing. The
trace element cadmium affects the mitochondria and prevents them from
carrying out their function efficiently. Investigators isolated mitochondria from
the oysters to study how the respiration rate changed while varying the water
temperature and the cadmium ion concentration.
3 .0 K ey : 1 5 °C
2 5 °C
2 .5 3 5 °C

R esp iratio n
rate / arb itrary 1 .5
u n its
1 .0

0 .5

0 .0
0 1 5 10 15 20
C ad m iu m io n co n cen tratio n / µ m o l d m –3
[Source: I M Sokolova, (2004), The Journal of Experimental Biology, 207, pages 2639–2648.
With permission of the Company of Biologists Ltd.]

(a) State the relationship between the concentration of cadmium ions and
respiration rate at 35C.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(b) Compare the respiration rate of the mitochondria at cadmium ion

concentrations of 0mol dm–3 and 50mol dm–3.

.......................................................................................................................
..............

208
.......................................................................................................................
..............
(2)

209
(c) Suggest one other environmental property of the water, apart from
temperature and mineral concentration, that may show daily changes.

.......................................................................................................................
..............
(1)

(d) The investigators concluded that seasonal and global warming might
make the eastern oysters more likely to suffer from trace element
poisoning.

Using the data, evaluate this hypothesis.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 7 marks)

194. (a) State where in the chloroplast the enzymes of the Calvin cycle are located.

.......................................................................................................................
..............
(1)

(b) Outline the fate of ribulose biphosphate (RuBP) during photosynthesis

.......................................................................................................................
..............

210
.......................................................................................................................
..............
(2)

211
(c) A green plant is not photosynthesizing at its maximum rate when the light
intensity is increased.

Suggest why there is no increase in the rate of photosynthesis

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 5 marks)

195. (a) State the function of a named protein.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(b) Outline the significance of the primary structure in a protein.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

212
213
(c) Discuss the statement, “Enzyme inhibitors function by binding to the active
site of the enzyme”.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 6 marks)

196. Which of the following diagrams is the structure of ribose?

A. H O H 2C O B. C H 2O H
H
C C C O
H H H H
H OH H
C C
C C OH OH H OH
OH OH C C
H OH

C. H O H 2C O D. H O H2C O
OH H
C C C C
H H OH C H 2O H H H H OH

C C C C
OH H OH H
(Total 1 mark)

214
197. The graph below shows enzyme activity plotted against temperature. What is
happening at point I?

E n zy m e activ ity / arb itrary u n its

Tem p eratu re / C

A. The enzyme is being denatured.

B. pH changes are slowing the reaction.

C. The concentration of the substrate remains constant.

D. The reaction is increasing in speed.

(Total 1 mark)

215
198. The diagram below shows the bases on a short section of DNA during
replication. Identify the sequence of bases on the new complementary strand
labelled I in the diagram.

C
T
I

A
G
A

A. CTAG

B. CUAG

C. TCGA

D. AGCT
(Total 1 mark)

199. What are the end products of aerobic cell respiration?

A. Carbon dioxide and ethanol

B. Lactate and ATP

C. Water, ATP and oxygen

D. Water, carbon dioxide and ATP

(Total 1 mark)

216
200. What occurs in the induced fit model for enzyme catalysed reactions?

A. There is an exact fit between a specific substrate and a specific enzyme.

B. The enzyme can change shape to accommodate the substrate.

C. The substrate can change its shape to fit a number of enzymes.

D. Other substrates can bind away from the active site.

(Total 1 mark)

201. What is a nucleosome?

A. The protein core of a chromosome

B. Histone proteins and DNA

C. A chain of ribosomes

D. The material within the nuclear membrane

(Total 1 mark)

202. What is an intron?

A. The 3  5 strand of a DNA double helix

B. The 5  3 strand of a DNA double helix

C. A section of mRNA removed before translation

D. A tRNA with a start anticodon

(Total 1 mark)

217
203. The diagram below shows the light independent stage of photosynthesis (the
Calvin Cycle).
G lu co se R ib u lo se
b isp h o sp h ate
(R u B P )
I CO2

Trio se P h o sp h ate II
(T P )
G ly cerate 3 – P h o sp h ate
(G P )

III

Where is energy, from ATP generated during the light dependent stage, used in
this cycle?

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

204. What is the key function of acetyl CoA in cellular respiration?

A. Involved in carbohydrate and fatty acid metabolism

B. Used in anaerobic respiration to oxidize pyruvate

C. Introduces amino acids into the Krebs cycle

D. Used as a hydrogen carrier in the link reaction

(Total 1 mark)

218
205. (a) The table below compares prokaryotic and eukaryotic cells. Place a tick ( ) wherever the
organelle is present.

Organelle Prokaryotic Eukaryotic

Nucleus
Mitochondrio
n
Ribosomes
(2)

(b) (i) The graph below shows the energy changes in a reaction.
E n erg y

P ro g ress o f reactio n

On the above graph draw the result you would obtain in this same
reaction if an enzyme that catalyses this reaction were added.
(1)

(ii) Explain how the enzyme produces this effect.

..............................................................................................................
.............

..............................................................................................................
.............
(3)

219
220
(c) Outline the process of glycolysis.

.......................................................................................................................
.............

.......................................................................................................................
.............
(3)
(Total 9 marks)

206. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label the action spectrum of photosynthesis.

(4)

(b) Explain the relationship between the structure of the chloroplast and the
light-dependent reactions of photosynthesis.
(8)

(c) Outline the potential harmful effects of increased carbon dioxide

concentration on the ecosystem and state one measure that could be
taken to reduce the amount of carbon dioxide in the atmosphere.
(6)
(Total 20 marks)

207. What role does iron play in living organisms?

A. As a component in nucleic acids

B. As a component of lipids

C. As a component of carbohydrates

D. As a component of proteins
(Total 1 mark)

221
208. Which diagram correctly illustrates a dipeptide?

A. H O H H B. H H O H H O
H O
N C C N C C N C C N C C
H H H OH H OH
H H

C. H H H H H O D. H H O H H O

N C C N C C N C C N C C

H H H OH H H H OH
(Total 1 mark)

209. What are the components of a DNA nucleotide?

A. Deoxyribose, a phosphate and one of the bases: adenine, cytosine,

guanine or thymine

B. Ribose, a phosphate and one of the bases: adenine, cytosine, guanine or

uracil

C. Deoxyribose, a nitrate and one of the bases: adenine, cytosine, guanine or

thymine

D. Ribose, a nitrate and one of the bases: adenine, cytosine, guanine or

thymine
(Total 1 mark)

210. What is the correct sequence of chemicals produced in the anaerobic

respiration pathway?

A. Lactate → pyruvate → ethanol

B. Ethanol → pyruvate → glucose

C. Glucose → lactate → pyruvate

D. Glucose → pyruvate → lactate

(Total 1 mark)

222
211. Why do leaves of plants look green?

A. Most of the green light is absorbed by chlorophyll and most of the red and
blue light is reflected.

B. Most of the blue light is absorbed by chlorophyll and most of the red and
green light is reflected.

C. Most of the red light is absorbed by chlorophyll and most of the green and
blue light is reflected.

D. Most of the red and blue light is absorbed by chlorophyll and most of the
green light is reflected.
(Total 1 mark)

212. How would the following DNA sequence, ACGTTGCATGGCA, be transcribed?

A. UGCAACGUACCGU

B. TGCAACGTACCGT

C. ACGTTGCATGGCA

D. ACGUUGCAUGGCA
(Total 1 mark)

213. What causes water to have a relatively high boiling point?

A. Hydrogen bonds between water molecules

B. Hydrogen bonds between hydrogen and oxygen within water molecules

C. Cohesion between water molecules and the container in which the water
is boiled

D. Covalent bonds between hydrogen and oxygen within water molecules

(Total 1 mark)

223
214. Which of the following substances are organic?

I. Lipids
II. Water
III. Carbon dioxide

A. I only

B. II and III only

C. I and II only

D. I, II and III
(Total 1 mark)

215. The diagram below represents DNA replication. Some of the bases are
indicated.

In which direction is the replication fork moving and which bases would be
needed to replicate the section of DNA shown?

Direction of movement of Bases needed

replication fork
A. Left to right U, G and C
B. Right to left U, G and C
C. Left to right T, G and C
D. Right to left T, G and C
(Total 1 mark)

224
216. Where in eukaryotic cells is glucose broken into pyruvate, to release energy for
use in the cell?

A. Chloroplast

B. Cytoplasm

C. Mitochondrion

D. Nucleus
(Total 1 mark)

217. (a) Explain the properties of water that allow living organisms to use it as a
habitat.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(b) List two end products of aerobic cell respiration.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

.......................................................................................................................
225
..............
(1)
(Total 6 marks)

226
218. Up to two additional marks are available for the construction of your answers.
(2)

(a) Explain why enzymes are substrate specific and why their activity is
affected by substrate concentration.
(8)

(b) Outline the use of restriction enzymes (endonucleases) and DNA ligase in
gene technology.
(6)

219. Mitochondrial electron transport defects (called mitochondrial myopathy) causes

tiredness at low levels of exercise and varies from mild to severe. Scientists
measured oxygen delivery to cells and oxygen use in cells of thirty-five patients
with mitochondrial myopathy. The results were compared to a control group of
thirty-two healthy individuals. The results are shown in the two charts below.
O x y g en d eliv ery to cells O x y g en u se in cells

400 50
45
350
40
35
R ate/m l K g – 1 m in – 1

R ate/m l K g – 1 m in – 1

300
30
250 25
20
200
15
10
150
5

K ey : m ito ch o n d rial m y o p ath y g ro u p co n tro l g ro u p

[Source: adapted from T. Taivassalo and R. G. Haller, (2006), ‘Exercise and training in mitochondrial myopathies’,
Medicine and Science in Sports and Exercise, 37 (12) 2094-2101, © Lippincott Williams & Wilkins, USA]

227
(a) State the mean value for oxygen delivery to cells in patients suffering from
mitochondrial myopathy.

.......................................................................................................................
...............
(1)

(b) Calculate the percentage difference of the oxygen use in cells by the
control group compared to oxygen use in cells of patients with
mitochondrial myopathy.

................ %
(1)

.......................................................................................................................
...............

.......................................................................................................................
...............
(3)
(Total 5 marks)

220. (a) State the name and function of

(i) a fibrous
protein ................................................................................................

..............................................................................................................
..............
(1)

(ii) a globular
protein ..............................................................................................

..............................................................................................................
..............
(1)

228
(b) Annotate the graph representing an exergonic enzyme catalysed reaction.

(2)

(c) Explain how end-product inhibition controls metabolic pathways.

.......................................................................................................................
...............

.......................................................................................................................
...............
(3)
(Total 7 marks)

221. (a) Photosynthesis consists of two sets of reactions. State the names of these
two sets.

.......................................................................................................................
...............

.......................................................................................................................
...............
(1)

229
(b) Outline how one specific limiting factor affects the rate of photosynthesis.

.......................................................................................................................
...............

.......................................................................................................................
...............
(2)

(c) Explain the production of ATP by chemiosmosis during photosynthesis.

.......................................................................................................................
...............

.......................................................................................................................
...............
(3)
(Total 6 marks)

230
222. Fruits remain alive for a period of time after harvesting. Cellular respiration
continues and it can greatly influence the maturation (ripening) process in the
fruits. The rate of respiration depends on many factors such as the type, quality,
degree of ripeness and water content of the fruits, temperature and air
composition. Respiration that continues after harvesting may sometimes lead to
the over-ripening and eventual loss of an entire cargo of fruit during transport.

Studies of the maturation process in bananas are summarized in the following

graph.

R elativ e rate

g reen g reen /y ello w y ello w

Tim e/arb itrary u n its (sh o w in g co lo u r ch an g es in b an an as)
K ey :
ch lo ro p h y ll b reak d o w n
starch b reak d o w n
w ater release
C O 2 fo rm atio n
S u g ar fo rm atio n
[Source: www.containerhandbuch.de/chb_e/scha/index.html?/chb_e/scha/scha_15_02_03_02.html]

(a) (i) State two chemical products released as gases during cellular
respiration.

1 ...........................................................................................................
.............

2 ...........................................................................................................
.............
(1)

(ii) State one non-chemical product of respiration.

..............................................................................................................
.............
(1)

231
(b) Using the data, analyse the events that occur when maturation begins in
bananas.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

223. (a) Compare the structure of a mitochondrion with a chloroplast.

Mitochondrion Chloroplast

..................................................... .....................................................
........ ........

..................................................... .....................................................

232
........ ........

..................................................... .....................................................
........ ........

..................................................... .....................................................
........ ........
(3)

233
(b) Explain the role of chemiosmosis in oxidative phosphorylation.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)
(Total 6 marks)

224. (a) Photosynthesis consists of two groups of reactions. State the names of the
two groups of reactions.

.......................................................................................................................
..............

.......................................................................................................................
..............
(1)

(b) Draw and label the action spectrum of photosynthesis.

(3)

234
(c) Explain the concept of limiting factors with reference to light intensity.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

225. Which events take place in DNA replication?

I. Formation of messenger RNA

II. Unwinding of DNA double helix
III. Formation of complementary strands by DNA polymerase

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

226. Which combination measures the rate of photosynthesis?

Direct measurement Indirect measurement

A. Oxygen production Biomass increase
B. Carbon dioxide uptake Biomass decrease
C. Oxygen uptake Biomass increase
D. Carbon dioxide production Biomass decrease
(Total 1 mark)

235
227. Which are the correct directions of the following processes?

Replication Transcription Translation

A. 5’ to 3’ 3’ to 5’ 3’ to 5’
B. 3’ to 5’ 5’ to 3’ 5’ to 3’
C. 5’ to 3’ 5’ to 3’ 5’ to 3’
D. 3’ to 5’ 3’ to 5’ 3’ to 5’
(Total 1 mark)

236
228. Which stage of translation is illustrated by the diagram below?

A. Termination

B. Initiation

C. Translocation

D. Elongation
(Total 1 mark)

237
229. The diagram below shows the energy levels of a reaction in the presence or
absence of an enzyme. What is the best explanation of the different energy
levels labelled I, II and III?

II
E n e rg y le v e l

E n erg y o f
reactan ts
III

E n erg y o f p ro d u cts

P ro g ress o f reactio n

I II III
A. Absence of an Presence of an Endergonic reaction
enzyme enzyme
B. Presence of an Absence of an Exergonic reaction
enzyme enzyme
C. Absence of an Presence of an Exergonic reaction
enzyme enzyme
D. Presence of an Absence of an Endergonic reaction
enzyme enzyme
(Total 1 mark)

238
230. In the diagram of a chloroplast below where will the Calvin cycle take place?

III

II
IV

A. I

B. II

C. III

D. IV
(Total 1 mark)

239
231. The diagram below shows the three stages of glycolysis. Which processes are
indicated by I, II and III?

6 -carb o n g lu co se

6 -carb o n g lu co se p h o sp h ate

3 -carb o n 3 -carb o n
su g ar p h o sp h ate su g ar p h o sp h ate

III

3 -carb o n 3 -carb o n
p y ru v ate p y ru v ate

-
I II III
A. Lysis Phosphorylation Oxidation and ATP
formation
B. Oxidation and ATP Phosphorylation Lysis
formation
C. Phosphorylation Lysis Oxidation and ATP
formation
D. Phosphorylation Oxidation and ATP Lysis
formation

240
(Total 1 mark)

232. Which limiting factor of photosynthesis is shown below?

R ate o f p h o to sy n th esis

A. Increasing carbon dioxide concentration

B. Increasing temperature

C. Increasing light intensity

D. Increasing humidity
(Total 1 mark)

241
233. Which of the following molecules is ribose?
A. B.

C. D.

(Total 1 mark)

234. Why are the messenger RNA molecules received by eukaryotic ribosomes
shorter than the messenger RNA molecules formed by transcription of DNA?

A. Base deletion mutations make the mRNA shorter.

B. Start codons are not at the end of the mRNA molecule.

C. Introns are removed before the RNA is translated.

D. Bases are removed from the ends of the mRNA each time it is translated.
(Total 1 mark)

242
235. What happens during end product inhibition of the pathway shown below?
S u b stan ce W

en zy m e I

S u b stan ce X

en zy m e II

S u b stan ce Y

en zy m e III

S u b stan ce Z

A. Enzyme I is inhibited by substance X.

B. Enzyme I is inhibited by substance Z.

C. Enzyme III is inhibited by substance W.

D. Enzyme III is inhibited by substance Y.

(Total 1 mark)

236. What substance is moved into the thylakoids of the chloroplast using energy
derived from light?

A. Carbon dioxide (CO2 )

B. Protons (H+)

C. Glycerate 3-phosphate (GP)

D. Adenosine triphosphate (ATP)

(Total 1 mark)

243
237. What colours of light give the two peaks on the graph of the action spectrum of
photosynthesis shown below?

% ab so rp tio n

w av elen g th o f lig h t

A. Red and infrared

B. Green and red

C. Blue and green

D. Blue and red

(Total 1 mark)

238. Up to two additional marks are available for the construction of your answers.
(2)

(a) Outline the first three levels of protein structure, including the types of
bonding within each and the significance of each level.
(5)

(b) Using a table, compare competitive and non-competitive inhibition and

give one named example of each.
(5)

(c) Explain the production of antibodies.

(8)
(Total 20 marks)

244
239. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label a mitochondrion as seen in electron micrographs.

(4)

(b) Outline the cellular locations of different named processes in both

photosynthesis and cell respiration.
(6)

(c) Explain the energy flow in a food chain as exemplified by a pyramid of

energy.
(8)
(Total 20 marks)

240. Carbon, hydrogen, nitrogen and sulphur are elements found in living cells.
Which is the least common?

A. Carbon

B. Hydrogen

C. Nitrogen

D. Sulphur
(Total 1 mark)

245
241. Which of the following terms correctly describe the molecule below?
H
H OH
C

C O
H H
H
C C
OH H
OH OH
C C

H OH

I. Monosaccharide

II. Ribose

III. Carbohydrate

A. I only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

242. A certain gene in a bacterium codes for a polypeptide that is 120 amino acids
long. How many nucleotides are needed in the mRNA to code for this
polypeptide?

A. 30

B. 40

C. 360

D. 480
(Total 1 mark)

246
243. What enzyme is used in transcription but not in translation?

A. DNA polymerase

B. Helicase

C. Protease

D. RNA polymerase
(Total 1 mark)

244. Humans can respire aerobically and anaerobically. Which are products of both
aerobic cell respiration and anaerobic cell respiration in humans?

A. Pyruvate and ATP

B. Pyruvate and lactate

C. ATP and carbon dioxide

D. Lactate and carbon dioxide

(Total 1 mark)

245. Which two colours of light does chlorophyll absorb most?

A. Red and yellow

B. Green and blue

C. Red and green

D. Red and blue

(Total 1 mark)

247
246. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw and label a diagram of the digestive system.

(4)

(b) Discuss factors that affect enzyme activity.

(9)

(c) Outline one industrial use of lactose.

(5)
(Total 20 marks)

247. Inflammation of human tissues often causes pain. Cyclooxygenases (COX) are
a group of enzymes that play a role in causing inflammation. Analgesics are
drugs that can reduce pain. The graph below shows how increasing
concentrations of the analgesic drug dipyrone, affects the activity of three
different cyclooxygenases, COX-1, COX-2 and COX-3.
K ey:
C O X -1
120 C O X -2
E n zy m e activ ity / arb itrary u n its

C O X -3
100
80

0
0 1 10 100 1000 10 000
D ip y ro n e co n cen tratio n / μ m o l d m – 3

[Source: Adapted from N V Chandrasekharan, et al, (2002), Proceedings of the National Academy of Sciences, USA, 99,
(21),
pages 1392613931]

(a) Outline the relationship between dipyrone concentration and COX-3

activity.

.......................................................................................................................
..............

.......................................................................................................................
..............
248
.......................................................................................................................
..............
(2)

(b) Deduce whether dipyrone is an inhibitor of COX-2.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 6 marks)

248. (a) List two examples of fibrous proteins.

1. ...................................................................................................................
..............

2. ...................................................................................................................
..............
(1)

(b) (i) State one protein involved in oxidative phosphorylation.

249
..............................................................................................................
.............
(1)

250
(ii) Outline the role of this protein in oxidative phosphorylation.

..............................................................................................................
.............

..............................................................................................................
.............
(2)
(Total 4 marks)

249. (a) Explain why carbon dioxide concentration is a limiting factor of

photosynthesis.

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

(b) Explain the relationship between the structure of the chloroplast and its
function.

.......................................................................................................................
..............

.......................................................................................................................

251
..............

.......................................................................................................................
..............

.......................................................................................................................
..............
(3)

252
(c) State two products of the light-dependent reactions.

.......................................................................................................................
..............

.......................................................................................................................
..............
(2)
(Total 8 marks)

253
250. The diagram shows part of a molecule produced by replication of DNA. What is
the significance of the shaded and the unshaded regions?

A. The shaded parts are DNA and the unshaded parts are mRNA.

B. The shaded parts contain adenine and thymine and the unshaded parts
contain guanine and cytosine.

C. The shaded part is a codon and unshaded part is an anticodon.

D. One of the parts has been newly synthesized and the other was part of a
pre-existing DNA molecule.
(Total 1 mark)

251. If mRNA has a codon CAU, what is the corresponding anticodon on the tRNA
molecule?

A. CAT

B. GUA

C. CAU

D. GTA
(Total 1 mark)

254
252. Which graph shows the relationship between the substrate concentration and
the rate of an enzyme controlled reaction?
A. B.

reactio n
R ate o f
reactio n
R ate o f

S u b strate S u b strate
co n cen tratio n co n cen tratio n

C. D.

(Total 1 mark)

253. What are pyrimidines in DNA?

A. Types of nucleotides

B. Types of base pairs

C. Types of sugars

D. Types of bases
(Total 1 mark)

255
254. Which enzyme removes the RNA primer during replication?

A. RNA primase

B. DNA polymerase I

C. DNA ligase

D. Helicase
(Total 1 mark)

255. Consider the metabolic pathway shown below.

1 2 3 4
V W X Y Z

If there is end-product inhibition, which product would inhibit which enzyme?

Produc Enzym
t e
A. X 4
B. W 3
C. W 2
D. Z 1
(Total 1 mark)

256. What is the net production of ATP, per molecule of glucose during the
fermentation of glucose to lactate?

A. 36 molecules

B. 4 molecules

C. 2 molecules

D. None
(Total 1 mark)

256
257. The diagram below summarizes the light-dependent reactions in
photosynthesis. What is occurring at X?

E lectro n s
X

E lec tro n s

L igh t
P h otosystem I

L igh t
P h otosystem II

A. ADP + phosphate  ATP

B. NADP+NADPH + H+

C. H2O  O2– + 2H+

D. NADPH + H+  NADP+
(Total 1 mark)

258. What is the first identifiable product of carbon dioxide fixation in

photosynthesis?

A. Ribulose bisphosphate (RuBP)

B. Glycerate3-phosphate (GP)

C. Triose phosphate (TP)

D. Acetyl CoA
(Total 1 mark)

257
259. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw a labelled diagram showing the structure of a plasma membrane.

(4)

(b) Outline the role of chlorophyll and the effects of temperature, light intensity
and carbon dioxide concentration on the rate of photosynthesis.
(6)

(c) Explain the production of energy during aerobic respiration from pyruvate
that has been produced by glycolysis.
(8)
(Total 20 marks)

260. Up to two additional marks are available for the construction of your answers.
(2)

(a) Draw a labelled diagram showing the structure of the digestive system.
(4)

(b) Outline the need for enzymatic hydrolysis in the digestive process.
(6)

(c) Explain how the kidney prevents the body from losing important materials
absorbed from the digestive system.
(8)
(Total 20 marks)

258

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