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8/12/2019 2bio-ex-2008-bk12
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2008 BIOLOGY
Monday 10 November: 9 a.m.
Time: 3 hours
Section A and Part 1 of Section B
Examination material: Question Booklet 1 (20 pages)Question Booklet 2 (11 pages)one 8-page script bookone multiple-choice answer sheetone SACE registration number label
Approved dictionaries and calculators may be used.
Instructions to Students
1. You will have 10 minutes to read the paper. You must not write in your question booklets or script book, oron your multiple-choice answer sheet, or use a calculator during this reading time but you may make notes onthe scribbling paper provided.
2. This paper is in three sections: Section A and Part 1 of Section B are in Question Booklet 1; Part 2 of Section Band Section C are in Question Booklet 2.
Section A: Multiple-choice Questions(Questions 1 to 25)Answer Section A on the separate multiple-choice answer sheet, using black or blue pen.
Answerallquestions in Section A.
Section B: Short-answer Questions(Questions 26 to 35)Answer Part 1 of Section B (Questions 26 to 30) in the spaces provided in Question Booklet 1.Write on page 20 of Question Booklet 1 if you need more space.
Answer Part 2 of Section B (Questions 31 to 35) in the spaces provided in Question Booklet 2.Write on page 10 of Question Booklet 2 if you need more space.
Section C: Extended-response Questions(Questions 36 and 37)
Answerbothquestions in Section C in the separate script book.
3. In Section B there is no need to fill all the space provided; clear, well-expressed answers are required. If youdelete part or all of an answer you should clearly indicate your final answer and label it with the appropriatequestion number.
4. The allocation of marks and suggested allotment of time are as follows:
Section A 50 marks 40 minutesSection B 120 marks 110 minutesSection C 30 marks 30 minutes
Total 200 marks 3 hours
5. Attach your SACE registration number label to the box at the top of this page. Copy the information fromyour SACE registration number label into the boxes on your multiple-choice answer sheet and on the frontcovers of Question Booklet 2 and your script book.
6. At the end of the examination, place Question Booklet 2, your script book, and your multiple-choice answersheet inside the back cover of Question Booklet 1.
External Examination 2008
ATTACH SACE REGISTRATION NUMBER LABEL
TO THIS BOX
FOR OFFICE
USE ONLY
SUPERVISOR
CHECK
RE-MARKED
QUESTION
BOOKLET
120 pages, 30 questions
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STUDENTS DECLARATION ON THE USE OF
CALCULATORS
By signing the examination attendance roll I declare that:
my calculators have been cleared of all memory;
no external storage media are in use on these calculators.
I understand that if I do not comply with the above conditions
for the use of calculators I will:
be in breach of the rules;
have my marks for the examination cancelled or amended;
be liable to such further penalty, whether by exclusion from
future examinations or otherwise, as the SACE Board of
South Australia determines.
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SECTION A: MULTIPLE-CHOICE QUESTIONS(Questions 1 to 25)
(50 marks)
Answerallquestions in this section.
Each of the twenty-five multiple-choice questions in Section A involves choosing from four
alternative answers. Read each question carefully. Then indicate the onealternative that you
consider best answers the question by shading the bubble by the appropriate letter alongside
the question number on the multiple-choice answer sheet. Use black or blue pen. It is in your
interest to give an answer to every question in this section of the paper, as no marks are deducted
for incorrect answers. Each question is worth 2 marks. You should spend about 40 minutes on
this section.
1. Carcinogens are chemicals that
J. increase the rate of cell division by causing harmful mutations.K. decrease the rate of cell division by causing beneficial mutations.
L. increase the rate of cell division by causing beneficial mutations.
M. decrease the rate of cell division by causing harmful mutations.
2. William and Mary are brother and sister and they are twins.
Ignoring mutations, which one of the following cells is genetically identical to a liver cell from
William?
J. A liver cell from Mary.
K. A sperm cell from William.
L. A muscle cell from William.
M. An egg cell from Mary.
3. Mangrove swamps occur in the sheltered intertidal zone of South Australias Spencer Gulf and
Gulf St Vincent. These mangrove swamps are the breeding grounds for many species of fish,
including King George whiting (Sillaginodes punctata) and yellow-eyed mullet
(Aldrichetta forsteri).
King George whiting and yellow-eyed mullet are members of the same
J. biosphere but not the same population.
K. community but not the same ecosystem.
L. ecosystem but not the same biosphere.
M. population but not the same community.
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4. Which one of the following characteristics must a cell have in order to be classified as a
eukaryotic cell?
J. A single circular chromosome in the cytoplasm.
K. No membrane-bound organelles.
L. A cytoskeleton attached to the cell membrane.M. A cell wall made of cellulose.
5. Refer to the following diagram, which shows a part of two DNA molecules from the same type of
bacterium grown in different media:
a part of
two DNA
molecules
from thesame type
of bacterium
grown in medium containing
non-radioactive nitrogen (14N)
grown in medium containing
radioactive nitrogen (15N)
Bacteria were grown for several generations in a medium containing non-radioactive nitrogen.
The medium was then replaced with a medium containing radioactive nitrogen.
Which one of the following diagrams best represents the DNA molecules produced when the
bacteria were allowed to divide oncein the medium containing radioactive nitrogen?
+ + + +
J. K. L. M.
6. Thyroxine is a hormone that is involved in the regulation of body temperature in human beings.
Which one of the following responses will result from an increase in body temperature?
J. An increased release of thyroxine, resulting in a decreased cell metabolism.
K. A decreased release of thyroxine, resulting in a decreased cell metabolism.
L. A decreased release of thyroxine, resulting in an increased cell metabolism.
M. An increased release of thyroxine, resulting in an increased cell metabolism.
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7. The exponential growth of the human population is not sustainable because
J. on average, a woman produces 2.9 children during her lifetime.
K. the input and the output of energy on the Earth are almost equal.
L. the resources of the biosphere are limited.
M. most of the energy that enters a community is lost as heat.
8. Refer to the following diagrams, which show the components of a nucleotide in a DNA molecule:
sugar phosphate basenitrogenous base
(adenine, cytosine,
guanine, or thymine)
S P
Which one of the following diagrams shows the arrangement of these components in a nucleotide
that will pair in a DNA molecule with a nucleotide that contains guanine?
adenine
S
Pcytosine
P
S
J. K.
adenine
P
S cytosine
S
P
L. M.
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9. Refer to the following electronmicrograph, which shows a section of an organelle:
1m
The main function of this organelle is
J. semi-conservative replication.
K. photosynthesis.
L. translation.
M. aerobic respiration.
10. The synthesis of ATP from ADP and inorganic phosphate results
J. from an input of energy from the breakdown of glucose.
K. in an output of energy from the breakdown of glucose.
L. in an output of energy from the synthesis of glucose.
M. from an input of energy from the synthesis of glucose.
11. Evidence suggests that until about 8000 years ago all human beings had brown eyes.
Which one of the following combinations correctly matches the process by which the gene for
blue eyes originated and the process by which the gene for blue eyes increased in frequency?
Process by which the gene for
blue eyes originated
Process by which the gene for
blue eyes increased in frequency
J. speciation natural selection
K. speciation geographical isolationL. mutation geographical isolation
M. mutation natural selection
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12. A length of DNA that codes for part of a polypeptide is known to contain 633 base pairs.
Which one of the following combinations of number of codons and number of amino acids in the
polypeptide is most likely to be associated with this length of DNA?
Number of codons Number of amino acids in
the polypeptide
J. 1266 422
K. 633 211
L. 422 422
M. 211 211
13. Four pieces of rhubarb from the same plant were weighed separately to determine their mass.
Solutions A, B, C, and D, each with a different salt concentration, were poured into four identical
beakers, each containing one of the pieces of rhubarb. After 20 minutes the pieces of rhubarb wereremoved from the beakers, dried with paper towelling, and reweighed. The results are summarised
in the table below:
SolutionMass of piece of rhubarb (g)
Before the experiment After 20 minutes
A 10.2 9.8
B 10.6 10.9
C 9.8 10.9
D 10.2 9.2
Source:www.adventuresinshaw.
wordpress.com
Which one of the following conclusions is consistent with the information above?
J. The solute concentration of solution A is higher than that of solution D.
K. The solute concentration of solution C is higher than that of solution B.
L. The solute concentration of solution A is higher than that of solution C.
M. The solute concentration of solution B is higher than that of solution D.
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14. Which one of the following nerve pathways represents the reflex response to the stimulus of
stepping on a sharp object?
J. Receptor motor nerve spinal cord sensory nerve muscle in foot.
K. Receptor motor nerve brain sensory nerve muscle in leg.
L. Receptor sensory nerve brain motor nerve muscle in foot.M. Receptor sensory nerve spinal cord motor nerve muscle in leg.
15. Which one of the following processes doesnotrequire energy?
J. The uptake of oxygen by red blood cells.
K. The growth of a bacterial cell.
L. The movement of the flagellum of a sperm cell.
M. The asexual reproduction of a yeast cell.
16. A cell with a diploid number of six is undergoing a type of cell division.
Which one of the following diagrams could represent the arrangement of chromosomes in
the cell?
J. K. L. M.
represents a maternal chromosome represents a paternal chromosome
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17. Refer to the following diagram, which represents a map of human chromosome number 1.
The labels show the abbreviations and names of medical conditions associated with the
information coded for at four different places on the chromosome:
UROD
(Porphyria cutanea tarda)
GBA
(Gaucher disease)
HPC1
(prostate cancer)
PS2
(Alzheimers disease)
The segment of human chromosome number 1 labelled GBArepresents a
J. disease.
K. gene.L. base triplet.
M. polypeptide.
18. Kelp is a marine alga, which grows to about 1 metre in height and lives for about 10 years.
Kelp forests, which are found in temperate waters such as those off the coast of Adelaide, provide
a habitat for fish.
The kelp forests are being destroyed by stormwater discharged from metropolitan Adelaide
into the coastal waters. The stormwater contains high levels of nutrient, such as nitrogen andphosphorus compounds, and high levels of sediment. Turf-forming species of alga, which grow
to less than 5 millimetres in height and live for about 1 year, are replacing the kelp forests.
Which one of the following statements is consistent with the information above?
J. The impact of high levels of sediment on the kelp forests is greater than the impact of
high levels of nutrient.
K. The discharge of stormwater results in an increase in the population of K-selected species.
L. A reduction in fishing off the coast of Adelaide would result in the re-establishment of
the kelp forests.
M. More r-selected strategies are shown by the turf-forming species of alga than by the kelpforests.
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19. The eastern brown snake (Pseudonaja textilis) and the common death adder (Acanthophis
antarcticus) are species of snake found throughout Australia.
The following table provides information, for each of these species, about habitat(s), food, method
of obtaining food, and change in population size since European settlement of Australia:
Eastern brown snake Common death adder
Habitat(s)cleared land with little
vegetationcoastal dune and mallee
Food lizards, frogs, and mice lizards and birds
Method of obtaining foodactively searches for
prey
lies, covered by leaves, and
waits for prey
Change in population
size since European
settlement of Australia
increased decreased
Since European settlement, coastal dune and mallee habitats have been extensively cleared.
The clearing of the remainingcoastal dune and mallee habitats should
J. proceed because the common death adder serves no useful purpose in these habitats.
K. not proceed because it will prevent competition between the eastern brown snake and the
common death adder.
L. not proceed because these habitats provide all the conditions necessary for the survival of
the common death adder.
M. proceed because it will assist the survival of the eastern brown snake in these habitats.
20. In 2005New Scientistmagazine reported that green tea contains the compound epigallocatechin
gallate (EGCG). This compound blocks the enzyme dihydrofolate reductase, which is essential to
the growth of gastric and oesophageal tumours.
The shape of a part of the EGCG molecule is
J. similar to the shape of the dihydrofolate reductase molecule.
K. similar to the shape of the active site of the dihydrofolate reductase molecule.
L. complementary to the shape of the dihydrofolate reductase molecule.
M. complementary to the shape of the active site of the dihydrofolate reductase molecule.
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21. Which one of the following combinations correctly matches a type of capillary in the human body,
a material that moves into the capillary, and the process of movement of this material into the
capillary?
Type of capillary in the
human body
Material that moves into
the capillary
Process of movement of this
material into the capillary
J.blood capillary in small
intestinecarbon dioxide active transport
K.blood capillary in epithelial
tissueglucose endocytosis
L.lymph capillary in epithelial
tissuewater osmosis
M.lymph capillary in small
intestineamino acids exocytosis
22. Which one of the following features doesnotincrease the surface area of an exchange surface?
J. Microvilli on the epithelial cells of the small intestine.
K. Capillary walls being one cell thick.
L. Alveoli in lung tissue.
M. The length of the nephron tubule.
23. Which one of the following statements about experimental results is correct?
J. An increase in the number of samples will decrease random errors.
K. Results are less accurate when there is more scatter.
L. A decrease in random errors will increase accuracy.
M. Results are more precise when there is less scatter.
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24. Which one of the following diagrams shows a possible sequence of the processes involved in the
life cycle of a sexually reproducing eukaryotic organism?
mitosis
fertilisationmeiosis
haploid
diploid
haploid
mitosis
fertilisationmeiosis
diploid
diploid
haploid
J. K.
meiosis
fertilisationmitosis
haploid
diploid
haploid
meiosis
fertilisationmitosis
diploid
haploid
haploid
L. M.
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25. Refer to the following diagram, which shows possible evolutionary relationships based on DNA
evidence:
0
50
100
150
200
250
300
350
lizards snakes crocodiles
dinosaurs(extinct)
birds turtles
Millions ofyears ago
It is reasonable to conclude from the information in the diagram above that there
J. would be more similarity between dinosaur DNA and bird DNA than between dinosaur
DNA and snake DNA.
K. has been no change in lizard DNA in 350 million years.
L. is more variation in turtle DNA than in bird DNA.
M. is less similarity between snake DNA and lizard DNA than between snake DNA and
crocodile DNA.
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SECTION B: SHORT-ANSWER QUESTIONS(Questions 26 to 35)
(120 marks)
You should spend about 110 minutes on this section. Answers may be in note form. The allocation of
marks is shown in brackets at the end of each part of each question. Answerallquestions in the spaces
provided.
Part 1(Questions 26 to 30)
(60 marks)
26. Refer to the following diagram, which represents part of a cellular structure:
ATPADP + Pi
X
Y
Z
(a) Name molecule Z.
____________________________________________________________________________________________(2 marks)
(b) Name the process by which molecule Ymoves through structure X.
____________________________________________________________________________________________(2 marks)
(c) Explain how cyanide, a poison that inhibits aerobic respiration, could affect the
movement of molecule Y through structure X.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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27. Human beings use microscopic organisms such as yeasts and bacteria in a variety of ways.
Early Europeans used fermentation by yeasts to sterilise water. Similar methods are used today in
the production of beer and wine.
(a) Name the substrate required for fermentation by yeasts.
____________________________________________________________________________________________(2 marks)
Yeasts are eukaryotic cells that can reproduce by budding, which results in genetically identical
offspring.
(b) Name the type of cell division that yeasts use to reproduce by budding.
____________________________________________________________________________________________(2 marks)
(c) State one disadvantage that producing genetically identical offspring has for yeasts.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
Human beings use bacteria for genetic engineering.
(d) Selected genes can be transferred between species, using bacterial plasmids as vectors.Bacterial plasmids that contain a selected gene are called recombinant plasmids.
Explain how a bacterial plasmid can be cut open so that a specific selected gene can be
inserted, to form a recombinant plasmid.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
(e) Explain one advantage that the genetic manipulation of organisms has for society.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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28. Three species of beetle living on an island are thought to have evolved from a common ancestral
species that inhabited the island millions of years ago.
It is thought that the rising sea level caused the island to become three separate islands. In the long
period of isolation that followed, the three species of beetle (one species on each island) evolved
from the common ancestral species.
When the sea level fell, the islands re-formed into one island. The beetles remained as three
distinct species, each with its own gene pool.
(a) State the meaning of the term gene pool.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(b) (i) What observation would lead biologists to be sure that two populations of beetlebelong to different species?
__________________________________________________________________________________________________
_______________________________________________________________________________________(2 marks)
(ii) State one mechanism that maintains the reproductive isolation of two species.
__________________________________________________________________________________________________
_______________________________________________________________________________________(2 marks)
(c) Explain how geographical isolation led to the evolution of the three species of beetle.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
(d) Describe one method that biologists could use to determine which two of the three
species of beetle are the more closely related.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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29. Drugs that are used in general anaesthetics bring about a reversible loss of consciousness during
surgery.
During anaesthesia:
the metabolic rate is decreased by approximately 15%;
anaesthetic drugs act as vasodilators;
the shivering response is inhibited.
As a result of the effects listed above, the patient experiences a mild case of hypothermia in which
the body temperature decreases by about 3C.
(a) Describe how vasodilation and the inhibition of shivering result in a decrease in
a patients body temperature during anaesthesia.
Vasodilation: ________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
Inhibition of shivering: ____________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
(b) State one benefit and one harmful effect of drugs that are used in general anaesthetics.
Benefit: ______________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
Harmful effect: _____________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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30. Ecowash BBandAddcoolare commercially produced enzymes.Ecowash BBis used to pre-fade
denim, whereasAddcoolpolishes fibres and improves the durability of the fabric.
The effectiveness of each of these enzymes on its own substrate was tested at a range of
temperatures. For each enzyme, ten test-tubes were set up. Each test-tube contained 30 millilitres
of the substrate and 2 millilitres of the same concentration of enzyme. Each test-tube was held at a
constant temperature.
After 20 minutes the reaction mixture was tested and the percentage of the original quantity of
substrate that remained was recorded. The results of this experiment are shown in the table below:
Percentage of substrate remaining in
solution after 20 minutes
Temperature (C) Ecowash BB Addcool
5 100 100
15 100 88
25 100 38
35 98 1
45 17 58
55 2 99
65 26 100
75 71 100
85 96 100
95 100 100
(a) Graph the data for Ecowash BB and for Addcoolon one set of axes on the grid below.
Label each graph.
(6 marks)
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(b) State the independent variable in this experiment.
____________________________________________________________________________________________(2 marks)
(c) State a conclusion that is consistent with the data in the table.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(d) State why the enzymes are ineffective at:
(i) 5C. _____________________________________________________________________________________________
_______________________________________________________________________________________(2 marks)
(ii) 95C. ___________________________________________________________________________________________
_______________________________________________________________________________________(2 marks)
(e) State the temperature at which Addcool is 99% effective in this experiment.
___________C. (2 marks)
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SACE Board of South Australia 2008
You may write on this page if you need more space to finish your answers to any questions in
Part 1 of Section B. Make sure to label each answer carefully (e.g. 29(a) continued).
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2008 BIOLOGY
Monday 10 November: 9 a.m.
Part 2 of Section B, and Section C
Write your answers to Part 2 of Section B in this question booklet.
Write your answers to Section C in the separate script book.
External Examination 2008
FOR OFFICE
USE ONLY
SUPERVISOR
CHECK
RE-MARKED
QUESTION
BOOKLET
211 pages, 7 questions
SACE REGISTRATION NUMBER
FIGURES
BIOLOGY
CHECK
LETTER
SEQ BIN
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SECTION B: SHORT-ANSWER QUESTIONS
Part 2(Questions 31 to 35)
(60 marks)
Answerallquestions in the spaces provided.
31. The urine that two normal, healthy people produced over 12 hours on a hot day was analysed to
determine the effect of water consumption on the average concentration of urea in the urine. All
other factors were kept constant. The results of this experiment are shown in the following table:
Person A Person B
Water consumption over 12 hours (L) 3 0.5
Average concentration of urea in the
urine produced over 12 hours (%)0.5 4
(a) With reference to the data in the table, describe the relationship between the water
consumption and the average concentration of urea in the urine.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
(b) Explain the process that resulted in the difference between the average concentration of
urea in the urine of person A and the average concentration of urea in the urine of
person B.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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(c) State one weakness in the design of this experiment and explain how it would affect the
reliability of the data.
Weakness in the design: __________________________________________________________________________
_______________________________________________________________________________________________________
Explanation: _________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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32. Micro RNA (miRNA) molecules are RNA molecules that are about 21 to 23 nucleotides long.
These miRNA molecules are transcribed from DNA but are not translated. In bacteria they are
known to be complementary to part of one or more messenger RNA (mRNA) molecules to which
they can bind.
(a) State one structural difference between DNA and mRNA.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(b) State the complementary mRNA nucleotide sequence for the following miRNA
nucleotide sequence by writing the appropriate letters in the boxes below.
miRNA nucleotidesequence
A G G C
complementary mRNA
nucleotide sequence
(2 marks)
(c) Explain how the binding of an miRNA molecule to an mRNA molecule will affect the
role of the mRNA.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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33. Eukaryotic cells evolved about 1.5 billion years ago in an environment that is thought to have
been very different from todays environment.
(a) State one piece of evidence to support the hypothesis that prokaryotic cells probably
existed before eukaryotic cells.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(b) State and explain one piece of evidence to support the hypothesis that the evolution of
eukaryotic cells probably involved endosymbiotic events.
Evidence: ____________________________________________________________________________________________
Explanation: _________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
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34. The beaver (Castor canadensis) is a large rodent that is found mainly in North American forests.
With their chisel-like teeth, beavers cut down trees, which they use to build dams in streams and
ponds. These dams play a major role in succession as they create new wetland environments
for other species. The wetlands slow the erosion of soil and purify the water, but can also cause
flooding in low-lying areas.
Source: http://animals.nationalgeographic.com
(a) Describe how the dams built by beavers can lead to a change in the mixture of species
over time.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
The by-products of decomposers in North American forests are mainly carbon dioxide and
methane (CH4), the two largest components of greenhouse emissions. It is estimated that, over a
120-day period, decomposers in the dams built by beavers produce 678 g/m2of CO2and
11.3 g/m2of CH4.
(b) State the function of decomposers.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(c) Using chemical formulae, write the chemical equation for the aerobic reaction that would
occur in the decomposers and produce carbon dioxide.
____________________________________________________________________________________________(2 marks)
This photograph cannot be reproduced here for copyright reasons.
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North American forests have been studied over long periods of time and are known as carbon
sinks. This means that they remove carbon dioxide from the air and fix carbon in the tissues
of plants.
(d) Describe how carbon sinksfi
x carbon in the tissues of plants.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________(4 marks)
(e) Explain how a decline in the number of beavers could affect the levels of atmospheric
carbon dioxide in these forests.
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________
(4 marks)
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35. Refer to the following graph and diagram, which relate to the regulation of the cell cycle by the
proteins MPF, cyclin, and cyclin-dependent kinase (Cdk). Cyclin and Cdk combine to form MPF.
The times shown on the diagram correspond to the times shown on the graph.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34
concentration
of cell cycleproteins
(arbitrary units)
time (hours)
MPF cyclin cyclin-dependent kinase (Cdk)
one cell cycle
G1 phase
(6 hours)
S phase(6 hours)
mitosis andcytokinesis
(1 hour)
G2 phase
(3 hours)
checkpoint G2
checkpoint M
checkpoint R
Time
0 hours 16 hours
Cell cycle
[This diagram is not drawn to scale.]
(a) Choose one external factor and describe its role in the regulation of the cell cycle.
External factor: _____________________________________________________________________________________
Role: ________________________________________________________________________________________________
_______________________________________________________________________________________________________
____________________________________________________________________________________________
(4 marks)
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9 PLEASE TURN OVER
In 1997 researchers conducted an experiment, which showed that the chemical olomoucineacts as
an inhibitor of Cdk in lung cancer cells grown in a cell culture.
In the experiment it was shown that various concentrations of olomoucine resulted in a
concentration-dependent inhibition at checkpoint G2 in the cell cycle. At the highest concentration
of olomoucine tested, the cell cycle was completely blocked.
(b) State one hypothesis that this experiment may have been designed to test.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(c) State why lung cancer cells were used for this experiment.
_______________________________________________________________________________________________________
____________________________________________________________________________________________(2 marks)
(d) State two factors that would need to be kept constant in this experiment.
Factor 1: ____________________________________________________________________________________________
Factor 2: _________________________________________________________________________________(2 marks)
(e) (i) Using information from the graph and the diagram opposite, describe what happensto the concentrations of cyclin and MPF that enables the cell to move past
checkpoint G2 and checkpoint M.
Checkpoint G2: ________________________________________________________________________________
__________________________________________________________________________________________________
__________________________________________________________________________________________________
Checkpoint M: _________________________________________________________________________________
__________________________________________________________________________________________________
_______________________________________________________________________________________(4 marks)
(ii) Explain how olomoucine blocks the cell cycle.
__________________________________________________________________________________________________
__________________________________________________________________________________________________
__________________________________________________________________________________________________
__________________________________________________________________________________________________
_______________________________________________________________________________________(4 marks)
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10
You may write on this page if you need more space to finish your answers to any questions in
Part 2 of Section B. Make sure to label each answer carefully (e.g. 34(a) continued).
Do not answer Section C on this page.
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SECTION C: EXTENDED-RESPONSE QUESTIONS (Questions 36 and 37)
(30 marks)
Answerbothquestions in this section.
Write your answers in the separate script book provided. Begin each answer on a new page.
You should spend about 30 minutes on this section, 5 to 10 minutes planning and
20 to 25 minutes writing. Credit will be given for clear, well-expressed answers that are well
organised and relevant to the questions.
36. The well-being of an ecological community is dependent on its level of productivity and the
continued survival and reproduction of its organisms.
Describe:
how energy is captured and made available to organisms in a community;
how two factors could influence the productivity of the community;
two processes that occur in sexually reproducing organisms and that provide the
genetic variation necessary for their continued survival and reproduction.
(15 marks)
37. Human stem cells have the potential to develop into a range of different cell types. One of the
uses of cell culture could be to grow stem cells that are stimulated into making functional human
tissues and organs.
Describe the conditions that would be necessary to grow human cells in cell culture.
Using examples, describe the hierarchical structure within multicellular organisms.
Explain how genetically identical human stem cells could develop into different human
tissues and organs.
(15 marks)
SACE Board of South Australia 2008