CH3 Test_answers_2011

SECTION A – Multiple-choice questions
Instructions for Section A
 Answer all questions by circling the response that is correct for the question.
 A correct answer scores 1, an incorrect answer scores 0.
 No marks will be given if more than one answer is completed for any question.
The following information is required for Questions 1 and 2.
The enzyme lactase digests lactose.
Two test tubes where set up using 5 mL of lactose syrup and 0.5 mL of lactase. Test tube one was
incubated at 37°C, while test tube two was incubated at 15°C. Both tubes were incubated for 10 minutes.
Question 1
At the end of 10 minutes, the amount of glucose produced in test tube two when compared to test tube one
would be
lower as the enzyme’s active site would have denatured at this temperature.
equal as lowering the temperature does not affect digestion of lactose.
lower as there would be fewer collisions between the substrate and the enzyme.
equal as the two test tubes contained the same amount of lactose and lactase enzyme.
Question 2
In another experiment, test tube three was compared with test tube four. Each tube contained 5 mL of
lactose syrup. Tube three contained 0.5 mL of lactase and tube four contained 0.25 mL of lactase. The two
tubes were incubated at 15°C and monitored for 10 minutes.
The result for test tube three is shown below.
The graph of results for tube four would resemble (C)
Question 3
Examples of an exergonic (catabolic) reaction include the formation of
maltose from glucose.
fatty acids and glycerol from lipids.
ATP and water from ADP and inorganic phosphate.
glucose and oxygen from carbon dioxide and water.
Question 4
Fermentation in yeast
produces ethanol.
requires lactic acid.
involves the Kreb’s cycle.
requires the presence of oxygen.
Question 5
In aerobic respiration the final product of the electron transport chain combines with
A. oxygen.
B. glucose.
C. pyruvate.
D. carbon dioxide.
Question 6
In this plant cell, the light-dependent reactions of photosynthesis occur in
A. N.
B. M.
C. Q.
D. P.
Question 7
The enzyme maltase catalyses the breakdown of maltose into glucose. Maltase was added to a tube
containing a solution of maltose in water and incubated at 37°C. The amount of glucose produced was
monitored over a period of time. No maltose remained at the end. The graph showing the change in glucose
concentration in the tube is (D)
Question 8
The following graph shows the relationship between light intensity and net oxygen uptake or output by a
particular green plant.
At a light intensity of 10 units
the rate of photosynthesis is zero.
the rate of aerobic respiration is zero.
oxygen produced by photosynthesis is equal to the oxygen used by aerobic respiration.
oxygen produced by photosynthesis is equal to twice the oxygen used by aerobic respiration.
Question 9
Sucrose (cane sugar) is a disaccharide used by plants as a transport molecule. Sucrose is formed in the
following reaction
With reference to this process it can be stated that
glucose and fructose are polysaccharides.
the production of sucrose is an endergonic reaction.
sucrose is a reactant and glucose is a product of the reaction.
a molecule of fructose contains more stored energy than a molecule of sucrose.
Question 10
Activation energy in a biological reaction
increases in the presence of an enzyme.
increases with an increase in temperature.
is the energy required to start the reaction.
is involved in the formation of complex molecules only.
Question 11
A student was asked to identify differences between the overall processes of photosynthesis and aerobic
respiration in eukaryotic cells. The student prepared the table below to outline the differences.
The only correct comparison listed by the student is (D)
Question 12
During periods of strenuous exercise or prolonged fasting, glycogen stored in liver and muscle cells is
depleted. All glucose in the blood and cells may be completely depleted as well.
If this occurs, the compound that is next most accessible for use in glycolysis is
A. lipid.
C. starch.
D. protein.
Question 13
Anabolic reactions, also called endergonic reactions, include
A. glycolysis.
B. Kreb’s cycle.
C. photosynthesis.
D. protein digestion.
Question 14
The chloroplast is the organelle responsible for photosynthesis in eukaryotic cells. In chloroplasts
the light independent reactions require water as the initial reactant.
the light independent reactions occur in the inner membrane area.
the final product of the light reaction is glucose.
the light reactions occur in the grana.
Question 15
Consider the following diagram that is a summary of an important biochemical process.
The product, X, in this biochemical process is
a polymer.
an amino acid.
a monosaccharide.
Question 16
The following image shows a portion of an electron photomicrograph of a chloroplast.
Light-dependent reactions occur in region P and the Calvin cycle reactions occur in region Q. Considering
events that occur in a chloroplast during photosynthesis it is reasonable to claim that
oxygen is an input to reactions at P.
carbon dioxide is an input to reactions at Q.
chlorophyll is essential for reactions that occur at Q.
ADP produced during the events at P is used by events at Q.
Question 17
Bacteria such as Thermus aquaticus live in hot springs where temperatures are around 90°C. The most
likely reason that the bacteria are able to carry out their metabolic functions in this environment is that the
have enzymes with a high optimal temperature.
can lower the temperature of the cellular environment.
use compounds other than enzymes to catalyse reactions.
have enzymes other than proteins that do not respond to changes in temperature.
Question 18
In the production of isoleucine from threonine in bacteria (Biochemical Pathway 1 [BP 1]), the end product
acts as an inhibitor of the first enzyme in the pathway. In the production of arginine (Biochemical Pathway
2 [BP 2]), the end product has no influence on other enzymes in the pathway.
It is reasonable to conclude that in
BP 1, if the production of enzyme 3 stops there would be continuous production of isoleucine.
BP 2, if the production of enzyme 3 stops there would be continuous production of arginine.
BP 1, providing all enzymes are present, the production of isoleucine would be continuous if there
was a continuous supply of threonine.
BP 2, providing all enzymes are present, the production of arginine would be continuous if
there was a continuous supply of substrate.
Section A total marks
SECTION B – Short-answer questions
Instructions for Section B
 Answer all questions in the spaces provided.
Question 1
The leaves of a particular species, species X, of a tree in Victoria were investigated at monthly intervals and
the following pigments were observed to be present in the months shown. The size of each band is
proportional to the amount of pigment present.
Some trees have leaves throughout winter while others shed their leaves.
Explain to which of these two groups species X belongs.
2 marks
Scientists exposed two groups of identical plants to a range of temperatures. One group was kept in a low
light intensity and the other in a high light intensity environment. The following graph summarises the
results obtained by the scientists.
b. Account for the difference in the rate of photosynthesis for the two groups of plants over the range of
temperatures shown.
2 marks
/7 marks
Question 2 (modified)
The following diagram shows a simplified representation of the first stage of photosynthesis.
i. Name one input item that X could represent.
1 mark
Name one output item that Y could represent.
1 mark
The breakdown of glucose in aerobic respiration can be represented by the simplified equation
b. What is the energy yield per molecule of glucose as a result of aerobic respiration?
1 mark
i. Within a cell, where does the electron transport stage of aerobic respiration occur?
1 mark
Describe what happens during the electron transport stage. In your answer include the name of
product Z.
2 marks
/6 marks
Question 3
Living organisms cannot survive without the presence of enzymes.
Explain why enzymes are necessary in living organisms.
1 mark
Describe the ‘active site’ of an enzyme and explain its role.
2 marks
/3 marks
Question 4
Many living cells produce hydrogen peroxide as a by-product of some metabolic reactions. Hydrogen
peroxide is a poisonous substance for these cells and is immediately decomposed into water and oxygen by
an enzyme called catalase. The reaction is represented by the equation
Which is the substrate in this chemical reaction?
1 mark
The activity of catalase in humans was tested across a number of different temperatures and the results
graphed. The results are shown below.
Catalase is found in many plants, including carrots.
A student predicted that if a temperature graph was prepared for carrot
catalase activity, the optimal temperature would be expected to be much
lower than that shown by catalase from humans.
b. Do you agree or disagree with the student’s prediction? Explain the
reason for your choice.
1 mark
c. Describe (or outline) an experiment you would carry out with pieces of
carrot to test the accuracy of the student’s prediction. Hydrogen peroxide
is available as a 3% in water solution. Explain fully what results would
support or negate the student’s prediction.
3 marks
/5 marks
Question 5
The birds-nest fern, Alocasia marcrorhizza, usually grows in deeply shaded rainforests and has dark green
fronds. Sometimes it is found in open, sunny locations by roadsides where it tends to have lighter coloured
fronds. Two birds-nest ferns, one from each of the two habitats described above, were examined. A sample
of cells from a frond of each of the ferns was collected. These cells were examined under an electron
microscope and a typical chloroplast from each habitat (deeply shaded rainforest and sunny location) was
drawn. These drawings are shown below.
Which of the labelled parts, X, Y or Z, absorb light energy? Name the part.
1 mark
Which drawing, A or B, shows a chloroplast from the rainforest habitat? Explain the reason for your
choice in terms of the relationship between structure and function.
2 marks
Name the process by which the chemical reactants for the light-dependent reactions of
photosynthesis enter a chloroplast.
Chloroplasts contain large numbers of ribosomes.
Explain the importance of the presence of these ribosomes.
1 mark
1 mark
It is now widely accepted by biologists that chloroplasts and mitochondria were once independent
prokaryotic organisms which came to live symbiotically inside larger eukaryotic cells. This idea is known
as the endosymbiotic theory.
Name one structural feature of chloroplasts or mitochondria and outline how it supports the
endosymbiotic theory for the origin of these organelles.
1 mark
The simplified diagram below summarises the light-independent reactions (Calvin cycle) of photosynthesis.
f. Name reactant Q
1 mark
You will note that during the light-independent reactions many energy-carrier molecules of NADPH and
ATP are used.
g. What is the source of these energy carriers?
1 mark
h. What is compound P?
1 mark
/9 marks
Question 6
2,4-dinitrophenol is a chemical that is toxic to mitochondria. When added to mitochondria this chemical
allows electron transport to occur but prevents the phosphorylation of ADP to ATP. The chemical achieves
this by breaking the essential link between electron transport and ATP synthesis. This toxin causes
mitochondria to produce heat instead of ATP. The greater the amount of toxin added, the quicker is its
If mitochondria are poisoned with 2,4-dinitrophenol by what process could a plant cell produce more
1 mark
Where in the mitochondria does electron transport and ATP production occur?
1 mark
A researcher wanted to study cellular respiration in insect cells. She cultured some muscle cells from the
common field cricket, Teleogryllus oceanicus, then studied the effects of adding 2,4-dinitrophenol to these
cells. An agricultural company may want to fund this research.
Give one reason why an agricultural company might want to fund research on the effects of this toxin
on field crickets.
1 mark
The experiment is summarised in the table below. Temperature observations in each trial were made at
equal time intervals.
In terms of energy production, why did the temperature go up in trial 1 and not in the control? 1 mark
e. Explain why the temperature went down after the fifth observation in trial 1.
1 mark
f. Trial 2 had twice the concentration of 2,4-dinitrophenol added. Complete the table above by writing in
temperatures in the spaces provided to predict the trend.
2 marks
Another researcher suggested adding pyruvate to the cells to cancel out the effects of this toxin.
Explain what effect adding pyruvate would have on cancelling out the effect of this toxin. 1 mark
/8 marks
Section B total marks
/38 marks
Section A & B total marks
/57 marks
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