2012
YEAR 12 HALF YEARLY
E X A M I N AT I O N
Biology
General Instructions
• Reading time – 5 minutes
• Working time – 2 hours
• Board-approved calculators
may be used.
• Write using blue or black pen.
• Draw diagrams using pencil.
SECTION 1
Total marks (93)
This section has two parts, Part A and
Part B
Part A
Total marks (20)
• Attempt Questions 1 – 20
• Allow about 25 minutes for this part
Part B
Total marks (73)
• Attempt Questions 20 – 28
• Allow about 1 hour and 35 minutes
for this part.
Student Number:___________________________
Question
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
A
B
C
D
Section I
Total marks (93)
Part A
Total marks (20)
Attempt Questions 1 – 20
Allow about 25 minutes for this part
Use the multiple-choice answer sheet.
Select the alternative A, B, C or D that best answers the question.
Question 1
The DNA in plants and animals is composed of the same chemical components.
What is the biological significance of this statement?
(A) Plants and animals can interbreed.
(B) Plants and animals share common ancestry.
(C) Plants and animals are genetically identical.
(D) Plants and animals are composed of identical proteins.
Question 2
Which substance is mainly bound to proteins when it is carried in mammalian
blood?
(A) Nitrogenous waste
(B) Carbon dioxide
(C) Lipid
(D) Salt
Question 3
In organisms, the maintenance of a constant internal environment is
(A) necessary because organisms must have a constant body temperature.
(B) necessary because enzyme activity is highest at specific temperatures.
(C) unnecessary because organisms are found in environments with a broad
range of temperatures.
(D) unnecessary because the nervous system detects and responds to changes
in ambient temperature.
Question 4
The presence of freckles is a dominant characteristic. A child’s mother has no
freckles and its father is heterozygous for freckles. What is the probability that
this child will have freckles?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
Question 5
The diagram represents one current theory for the movement of materials in
phloem.
In the process illustrated in the diagram, water from xylem
(A) causes a build up of pressure.
(B) allows adhesion for capillarity.
(C) provides water for photosynthesis.
(D) dilutes sucrose for active transport.
Question 6
An Australian insect produces uric acid and no other form of nitrogenous waste.
What is the purpose of this adaptation?
(A) To increase salt loss
(B) To reduce water loss
(C) To increase its toxicity to predators
(D) To reduce the chance of attracting predators
Question 7
Which diagram best explains changes to the composition of blood in the lungs?
Question 8
African ostriches, South American rheas and Australian emus are all large extant
flightless birds. These observations provide evidence for the theory of evolution.
This evidence for evolution belongs to
(A) biochemistry.
(B) biogeography.
(C) paleontology.
(D) comparative embryology.
Question 9
The pedigree shows the inheritance of a trait controlled by a pair of alleles.
Which Punnett square correctly represents the cross between the parents in
generation I?
Question 10
Diagrams of blood vessels are shown (not to scale).
Which of the following correctly lists the names of the blood vessels shown? (on
the next page)
Question 11
How does the fossil record provide evidence to support the concept of
punctuated equilibrium?
(A) The fossil record is incomplete.
(B) The fossil record shows that some organisms have become extinct.
(C) The fossil record shows that there are short periods of rapid change in fossil
forms.
(D) The fossil record shows that some organisms change gradually over geologic
time.
Question 12
What is the role of enzymes in metabolism?
(A) They slow down chemical reactions so that more product is formed.
(B) They produce chemical reactions that would not normally occur.
(C) They improve the absorption of nutrients in the body.
(D) They reduce the activation energy needed for chemical reactions.
Question 13
Observe the flow diagram below.
Which body mechanism is described by this flow diagram?
(A) Enantiostasis
(B) Excretion
(C) Positive reinforcement
(D) Homeostasis
Question 14
Observe the following image of human blood, as seen under a light microscope.
What are the three large objects, in the middle of picture, most likely to be?
(A) Red cells, as they are large and carry more oxygen than white cells
(B) Dust contamination from a dirty slide
(C) Platelets, as they have dark clotting material inside them
(D) White cells, as they are larger than the other cells and have a nucleus
Question 15
Under which of the following conditions is pulse oximetry used?
(A) When pulse rate or blood flow is slow, during cardiac failure
(B) when monitoring oxygenation and pulse rates throughout anaesthesia
(C) when blood pressure needs to be determined, during surgery
(D) When levels of energy being used by the patient needs to be determined
Question 16
The diagram below compares the length of “loop of Henle” for a beaver, human
and kangaroo rat. The Loop of Henle is located in the nephrons of kidney
tubules.
Based on this information, which organism is suited to survive in hot dry desert
conditions?
(A) The beaver, because it has a short loop of Henle and so loses less water in
its urine
(B) The kangaroo rat, because it has a longer loop of Henle and can reabsorb
more water back into its bloodstream
(C) The human, because it has a medium length loop of Henle and can cope with
a larger range of water availability
(D) Neither organism, as water reabsorption occurs mainly in Bowmans capsule,
not the Loop of Henle
Question 17
What is the role of anti-diuretic hormone?
(A) It controls the amount of water reabsorbed in the nephron of the kidney.
(B) It controls water balance by regulating the transfer of potassium and sodium
ions in the kidney.
(C) It is released during stress to increase heart rate and provide glucose to
muscles.
(D) It is released before meals to stimulate hunger and the secretion of saliva.
Question 18
This Punnet square represents a cross between a yellow pea plant and a green
pea plant. (code: Y : yellow; y: green. Yellow is dominant.)
What will be the expected ratio of phenotypes in the offspring?
(A) One yellow : one green
(B) Three yellow : one green
(C) All green
(D) One yellow : three green
Question 19
Human blood group is controlled by three alleles, IA, IB, and i. The IA and IB alleles
are co-dominant, and the i allele is recessive. The table illustrates the genotype
and resulting phenotype of the different human blood groups.
What would be the possible blood types n offspring from a mother with type AB
blood and a father with type O?
(A) All AB
(B) All type O
(C) Type A or type B
(D) Type AB or type O
Question 20
Why do scientists often use models to describe the process by which DNA
controls the production of polypeptides?
(A) Models show chemical interactions more accurately.
(B) Models give a better visual representation of relationships and processes.
(C) Models are cheaper to produce than the real thing.
(D) Models are easier to make than complex biochemical reactions.
Section 1
Part B
Total Marks (73)
Attempt Questions 21- 31
Allow about 1 hour and 40 minutes for this part
Maintaining A Balance Questions
Question 21 (16 marks)
Six students performed a trial experiment on enzyme activity. The enzyme they
were studying acts on a cloudy suspension, breaking it down into a soluble form.
The lesson ended and students were asked to stop their experiment. They then
recorded the time the experiment had run and their observations. These data are
collated in the table.
(a) What is the purpose of this experiment? (1 mark)
(b) Describe TWO changes that would improve the validity of the data
collected in the experiment. (2 marks)
1.
2.
(c) Another student completed an experiment on the effect of change in pH on
the activity of the enzyme catalase. The student recorded the following
results.
Test Tube
pH
1
2
3
4
3
6
8
11
Rate of Reaction
Height/reaction time
(mm/second)
14.6
30.1
56.7
39.3
I. Graph the students results. A piece of graph paper is attached to the
end of the exam paper. (5 marks)
II. Explain the shape of the graph. (2 marks)
III. What is pH? (2 marks)
IV. Does repetition of an experiment give validity? Explain your answer.
(2 marks)
V. What is meant by ‘accuracy’ in an experiment? (2 marks)
Question 22 (5 marks)
A diagram of a nephron is shown.
(a) Label each of the two boxes on the diagram using A, B, C or D to identify
the processes that take place at this location. (2 marks)
(b) Which one of the above processes (A, B, C or D) occurs due to active
transport? (1 mark)
(c) Outline the effect of aldosterone on the control of body fluids. (2 marks)
Question 23 (5 marks)
You are required to plan and perform a first-hand investigation to demonstrate
the effect of dissolved carbon dioxide on the pH of water.
Complete the following table for your investigation.
Dependent Variable
Independent
Variable
Control
Safe work practices
to be followed.
Question 24 (5 marks)
Scientists recorded the body temperature of 50 reptiles of the same species on
the same day. They were kept in small cages in the shade in a hot desert habitat.
Technology X was used to measure skin temperature. This was linked to
technology Y and then to a computer as shown in the diagram. The graph on the
next page shows the averaged data generated by the computer from this
experiment.
(a) Identify technology X and technology Y. (2 marks)
X:
Y:
(b) The scientists concluded that the body temperature of this species of
reptile is only controlled by the ambient temperature. Construct an
argument against this conclusion, based on the information provided. (3
marks)
Question 25 (6 marks)
Assume that the following equipment has been supplied to you:
 100 toothpicks stained with bright red food colouring
 100 toothpicks stained with dark green food colouring (the same colour as
the grass).
 Stopwatch
 5 metre roped square of long green grass in a nearby park
(a) Describe how you would use the materials to design an experiment, to
model the Darwin/Wallace theory of natural selection. (3 marks)
(b) Explain a way you could improve the reliability of your results. (1 mark)
(c) Justify the use of models in explaining scientific theories such as natural
selection. (1 mark)
Blueprint of Life
Question 26 (3 marks)
Several scientists were involved in determining the structure of DNA. Complete
the table of information about these scientists.
Scientist
Year
What they
researched
1866
Pea Plants
Showed that
chromosomes are
not all the same.
1902
1902
Thomas Hunt
Morgan
1910
George Beedle
1941
1941
What they
discovered
Grasshoppers
Question 27 (6 marks)
The flow diagram below represents the stages in meiotic division.
(a) Label on the diagram where you would you find the following?
a. Crossing over occurring.
b. Random segration of chromosomes
c. Production of haploid gametes (3 marks)
(b) Explain how EACH of he processes mentioned in part (a) increases
variability in the offspring. (3 marks)
Question 28 (5 marks)
James Watson, Francis Crick, Rosalind Russell and Maurice Wilkins were
important scientists in determining the structure of DNA. With reference to their
work, discuss the role of collaboration and effective communication in scientific
research.
Question 29 (4 marks)
(a) White eyes is a recessive X sex-linked trait in the fruit fly Drosophila
melanogaster. Normal eye colour is red. In Drosophilia, males are XY and
females are XX.
What would be the genotypes and phenotypes of the offspring of a cross
between a white-eyed male fruit fly and a heterozygous red-eyed female?
(b) In cattle a cross between a red coat bull and a white coat cow produces
offspring that are all roan. Roan colour occurs when there are both red
hairs and white hairs present. Identify this type of inheritance and draw a
Punnett grid to show the F1 inheritance.
This type of inheritance is called:
Question 30 (12 marks)
As part of your Biology work, you were required to perform a first-hand
investigation to demonstrate the effect of environment on phenotype.
(a) Distinguish between genotype and phenotype. (2 mark)
(b) Identify factors that were kept constant in this experiment. (2 mark)
(c) Identify the independent and dependent variables in the experiment. (2
mark)
(d) What determines phenotype? (2 mark)
(e) Discuss how your results show the effect of environment on
phenotype. (2 mark)
(f) How could you increase the reliability of this experiment? (2 mark)
Question 31 (6 marks)
As part of your study of the Blueprint of Life, you had to perform a first-hand
investigation or process information from secondary sources to develop a simple
model for polypeptide synthesis.
(a) Explain how you developed a simple model for polypeptide synthesis. (2
marks)
(b) Outline the role of mRNA in the synthesis of a polypeptide. (2 marks)
(c) Outline the role of tRNA in the synthesis of a polypeptide. (2 marks)