NAME……………………………………………….
VCE BIOLOGY UNIT 3
CHAPTER 5&6 TEST
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.
QUESTION 1
The endocrine system contains ductless glands which secrete their hormones into the
bloodstream before they reach their target cells. A water-soluble hormone of the endocrine
system includes:
A The peptide hormone insulin.
B The thyroid amino acid derivative thyroxin.
C The steroid oestrogen.
D The neurotransmitter acetylcholine.
QUESTION 2
Certain hormones do not travel in the bloodstream to reach their target cells. In some cases,
the hormone travels in extracellular fluid to reach neighbouring target cells. This type of
signalling is known as:
A Autocrine signalling.
B Paracrine signalling.
C Proximal signalling.
D Synaptic signalling.
QUESTION 3
Tiny quantities of a hormone cause profound responses in target cells. In the case of a
signal transduction pathway within a liver cell, for instance, one molecule of adrenalin
causes the release of 100,000,000 molecules of glucose.
The change in the number of molecules involved at most subsequent steps in a signal
transduction pathway is known as:
A Magnification.
B Amplification.
C Translation.
D Reception.
QUESTION 4
Endorphins are neurotransmitters which reduce the chances of impulses travelling along
pain pathways to the brain. The ultimate effect of endorphins would be to:
A Hyperpolarise the membrane of the post-synaptic cell.
B Enhance the effect of excitatory transmitters at the synapse.
C Attach to excitatory neurotransmitters before they reach the post-synaptic membrane.
D Act as competitive inhibitors for the enzymes responsible for digesting
neurotransmitters at the synapse.
QUESTION 5
The bola spider of Australia has a unique technique for capturing its prey. It laces a sticky
globule (a bola) with the scent of a female moth, and dangles and twirls the bola from a silky
thread in order to attract unsuspecting male moths. If the technique has proven unsuccessful
for a period of time, the spider hauls in the bola, only to produce a new one that is laced with
the scent of a female of a different moth species.
The chemical scent used by the spider is:
A A pheromone.
B A hormone.
C Neurohormone.
D A cytokine.
QUESTION 6
Action potentials (nerve impulses) can pass along all neuron membranes. The following
events occur during an action potential:
A Electrons jump from one node of Ranvier to another along myelinated axons.
B Sodium ions rush into the cell via facilitated diffusion.
C Sodium ions actively rush into the cell via sodium-potassium pumps.
D Potassium ions rush into the cell via facilitated diffusion.
QUESTION 7
What type of cell is shown in the diagram?
A A sensory neuron with a receptor.
B An interneuron.
C A sensory neuron with an effector.
D A motor neuron with an effector.
QUESTION 8
A ground squirrel, with a usual body temperature of 38°C, has a hibernation
temperature of only 4°C. Body fat is very slowly consumed during hibernation.
When compared to their activity at 38°C, the enzymes responsible for the
breakdown of body fat cannot be very
active at 4°C as:
A They begin to denature.
B The motion of enzyme and substrate molecules is greatly reduced.
C Competitive inhibitors are activated to prevent excessive respiration.
D Peptide linkages within the enzymes are broken down to provide valuable sources
of energy.
A target cell for both a specific peptide hormone and a particular steroid hormone is
represented in Figure 2 below. A steroid and peptide hormone have both signalled the cell
in the diagram.
QUESTION 9
Structures A, B, C and D represent the following molecules:
A A = receptor, B = steroid hormone, C = hormone-receptor complex, D = peptide
hormone.
B A = G protein, B = receptor, C = hormone-receptor complex, D = cyclic AMP
C A = receptor, B = peptide hormone, C = G protein, D = steroid hormone.
D A = G protein, B = peptide hormone, C = receptor, D = steroid hormone.
QUESTION 10
Signal transduction pathways can involve the response of millions of molecules to a single
chemical messenger molecule. For instance, one molecule of adrenalin causes the
breakdown of 100,000,000 molecules of glucose from the glycogen store in a liver cell.
If the activation of a cytoplasmic receptor initiates a signal transduction pathway, the original
signal could have been provided by:
A A neurotransmitter such as acetylcholine (ACh).
B A steroid hormone such as cortisone.
C A peptide hormone such as insulin.
D A protein hormone such as thyroid stimulating hormone.
QUESTION 11
The following statement is true of plant hormones:
A Auxins cause increased levels of mitosis resulting in phototropic responses.
B Ethylene is a gaseous hormone that is used to prevent stored fruit from ripening.
C With rising temperatures in spring, abscisic acid overrides the inhibitory influence of
gibberellins within seeds, thereby stimulating germination.
D Cytokinins delay leaf death (senescence).
QUESTION 12
The term “hormone” is applied to chemical messenger molecules in both plants and animals.
One difference in the action of plant and animal hormones is that:
A Some plant hormones exert opposite effects on target cells in different parts of the
same organism.
B Plant hormones do not travel in the vascular system.
C Plant hormones are inorganic.
D Animal hormones are exclusively endocrine.
QUESTION 13
Neurotransmitter molecules have a very short lifespan once they have attached to a receptor
on a postsynaptic membrane. Enzymes will rapidly degrade the neurotransmitter molecules,
and the breakdown products may be returned to the presynaptic cell.
Some insecticides act as competitive inhibitors on the enzymes responsible for the
breakdown of excitatory neurotransmitters. The insecticide kills the insect by:
A Preventing impulses from being generated in the postsynaptic cells.
B Preventing the release of more neurotransmitter across the synapses.
C Overstimulating the postsynaptic cells.
D Interfering with the release of inhibitory neurotransmitters of pain control pathways.
QUESTION 14
Interneurons occur within the grey matter of animal nerve tissues. An interneuron:
A Is the most common type of neuron in the human body.
B Only produces myelin when part of a reflex arc.
C Contains many dendrites and axons.
D Uses nodes of Ranvier to speed up impulse transmission.
QUESTION 15
The most accurate description of the difference between hormones and pheromones is
A. pheromones are small, volatile molecules whereas hormones are not.
B. pheromones are signals that function between organisms, whereas hormones communicate within
an organism.
C. pheromones use neurons as their means of transmission, whereas hormones use chemicals as their means
of transmission.
D. pheromones are involved in reproduction, whereas hormones are not.
Explanatory notes
• A is incorrect. Both pheromones and hormones are small molecules.
• B is correct. Pheromones are signals that function intraspecifically, whereas hormones communicate
within an organism.
• C is incorrect. Pheromones are released into the external environment and interact chemically; they do not
use neurons as their means of transmission.
• D is incorrect. Both pheromones and hormones are involved in reproduction.
QUESTION 16
Epinephrine is a hormone produced in humans. When it binds to the muscle cells of the small intestine,
contraction of the muscles is inhibited. In contrast, when it binds to heart muscle, it speeds up the
contraction. Epinephrine can have different effects on muscle cells because
A. small intestine muscle is not as strong as heart muscle and has a weaker response to epinephrine.
B. the cells in small intestine muscle and heart muscle have different signal transduction pathways
for epinephrine, producing different cellular responses.
C. there are more receptors for epinephrine in heart muscle cells than there are in small intestine muscle
cells.
D. epinephrine circulates to the heart first and the higher concentration around heart muscle cells results in
a stronger response.
Explanatory notes
• A is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the
signal transduction pathway of epinephrine, it is not related to the strength or weakness of the muscle.
• B is correct. Cellular responses to hormones can be different depending on the nature of the signal
transduction pathway in the cell.
• C is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the
signal transduction pathway of epinephrine. It is not related to the number of receptors in the plasma
membrane of the cells.
• D is incorrect. The contraction of muscle cells in the small intestine and the heart is a response to the
signal transduction pathway of epinephrine. It is not related to the order of circulation of epinephrine
around the body.
QUESTION 17
A signal molecule that binds to a plasma membrane protein functions as a
A. protein kinase.
B. receptor protein.
C. second messenger.
D. ligand.
Explanatory notes
• A is incorrect. A protein kinase is an enzyme that transfers phosphate groups from ATP to a protein. It
does not bind to a plasma membrane protein.
• B is incorrect. A receptor protein is found embedded in the plasma membrane. Signal molecules are not
incorporated in the plasma membrane; they are produced in endocrine cells and travel in the bloodstream.
• C is incorrect. A second messenger is a small, non-protein, water-soluble molecule or ion that relays a
signal within a cell in response to a signalling molecule; it does not bind to a plasma membrane protein.
• D is correct. A ligand is a molecule that specifically binds to another molecule. Ligand binding causes a
receptor protein to undergo a change in shape, and is what occurs when a signal molecule binds to a plasma
membrane protein.
Section A total marks
/17
SECTION B – Short-answer questions
Instructions for Section B
 Answer all questions in the spaces provided.
QUESTION 1
In animals, homeostasis is a term used to describe a relatively stable internal environment.
(a) What is the internal environment of the body?
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I mark
Type 1 diabetes mellitus is characterised by loss of the insulin-producing beta cells of the
islets of Langerhans in the pancreas, leading to insulin deficiency. A common treatment has
been NPH insulin but recently the activity of a new type of insulin, called LANTUS insulin,
has been tested and compared with NPH insulin.
Participants in the test were divided into two groups. One group received NPH insulin. The
second group received LANTUS insulin. All participants received the same amount and
concentration of the appropriate insulin.
The following graph shows the average results for participants in each of the two groups:
Insulin is regarded as being effective when the glucose uptake by cells is above 0.4
mg/kg/min.
(b) After the injections, for how long was each kind of insulin effective?
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2 marks
(c) Suggest why using LANTUS insulin may be an advantage for a person who has insulindependent
diabetes.
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1 mark
(d) Explain what events may occur to regulate the uptake of glucose in a non diabetic.
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2 marks
Total 6 marks
answers
(a) The internal environment of the body is the extracellular fluid that surrounds the cells.
(b) NPH was effective for 12.5 hours. AND Lantus was effective for 24 hours.
(c) Lantus lasts almost twice as long as NPH which means it only needs to be
administered once over a 24 hour period. The glucose uptake is also maintained within
a more narrow limit, creating less stress on the homeostatic mechanisms of the
patient.
(d) Blood glucose regulation relies on negative feedback systems. If the glucose levels of
blood slightly overshoots the optimal as a result of effector action, the counter negative
feedback system will respond to correct the overshoot (1). These actions occur
continuously in the body of a normal person so that optimal levels of blood glucose are
continually fine-tuned (1).
QUESTION 2
The concentration of an unknown protein (X) increased dramatically after depriving a
particular plant of water.
(a) Assuming this protein belongs to a class of signalling molecules, identify protein X.
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1 mark
(b) Describe the process that would have initiated the production of Protein X under these
conditions.
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2 marks
In order to accurately identify this protein was isolated from the plant and subjected to
proteomic analysis. This involved trypsin digestion followed by mass-spectrometry of the
resulting peptides. The results are presented in Table 1 below. Each amino acid has a
unique molecular mass and isoelectric point which is affected by pH. The Molecular Weight
(daltons) and the isoelectric point (pI) shown in Table 2 is calculated from the primary
structure.
(c) (i) From the data in Tables 1 and 2 identify the most likely 8 amino acids in sequence
for the protein X peptide.
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(ii) Briefly justify your answer.
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1+1=2 marks
(d) What is the rationale for the identification of unknown proteins using MolWt and pI of
amino acids in a peptide?
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1 mark
Total 6 marks
answers
(a) Phtyohormone-most likely Abscisic Acid.
(b) The plant cells responded to environmental stimulus of water stress (1). This involves a
series of molecular steps called a signal transduction pathway where the information is
relayed through secondary messenger molecules. Finally, a specific effector moleculeProtein X brings about the cellular response (1).
(c) (i) Arginine-Proline-Leucine-Serine-Valine-Threonine-Alanine-Valine.
(ii) The first 7 amino acids have molecular masses corresponding to the known masses from Table 2. The
last amino acid, Valine, was determined using simple arithmetic (842-743) following the pattern used on
the grap and matching the calculated mass of 99 daltons to Table 2.
(d) The primary structure of a protein consists of a sequence of amino acids. Each amino
acid has individual properties based on the chamical composition of the R group. These properties include
molecular mass and the charge (pI). A peptide can be taken
from the protein and the amino acid sequence analysed and matched to a data base to
determine its identity.
QUESTION 3
Using an example of a hormone you have studied, describe what a signal transduction
pathway involves (Include a labelled diagram).
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2 marks
Various answers possible:
Signal transduction refers to the series of events that occur after the receipt of a specific
extracellular signal and which result in a cellular response. (1)
The answer needs to highlight, at the molecular level, the transfer of information from one
form into another, which is then understood by the cell to produce a response. (1)
A sample answer could be:
In the fight-or flight response, the signal is the hormone adrenalin (epinephrine). Soon after a
stressful event is encountered, the adrenal glands release adrenalin into the bloodstream.
In the signal transduction pathway in a liver cell - the first phase (signal reception), adrenalin
acts as a ligand by binding to a receptor on the cells surface. In the second phase (signal
transduction), the activated receptor triggers a cascade of biochemical reaction within the
cell. This cascade involves a G protein, the second messenger cyclic AMP (cAMP), and a
number of enzymes. In the third phase (cellular response), the liver breaks down glycogen
into glucose and releases glucose into the bloodstream.
Question 4
4a. Select a homeostatic system you have studied in Unit 3 Biology and use all the components in the box
below to present a labelled diagram explaining how the specific system operates. You can also include your
own components to explain the model.
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2 marks
4b. Explain whether this is an example of a positive or negative feedback mechanism.
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1 mark
Huntington disease (HD) is an inherited disorder that results in progressive neurological deterioration and
in humans is controlled by a gene on the number 4 chromosome. Normally the gene produces a protein
called huntingtin, however, a mutation leads to the production of an abnormal protein. By aggregating or
clumping together inside neurons, the abnormal protein initiates a process that kills the neurons in a region
of the brain known as the corpus striatum. This causes tremors, loss of motor function and eventually
death. Mice also show the gene mutation for HD. A scientist hypothesised that a drug, cystamine, may
alleviate the symptoms and prolong life expectancy for mice with HD.
4c. Design an experiment to test the scientist’s hypothesis. You may use diagrams.
Your experimental design should
• clearly outline the experimental design that will be followed.
• identify the results that would support the hypothesis.
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4 marks
Total 2+1+4=7 marks
Solution
Response could be any suitable example but it must be explained with a diagram such as
Mark allocation
• 1 mark – using all the terms in the box.
• 1 mark – clear identification of the specific receptor, specific effector and specific response in the correct
order.
4b. • This is a negative feedback mechanism because the components in the box only allow for an example
in which a change in a physiological variable triggers a response that counteracts the initial fluctuation.
4c. Response could be any suitable experimental design but it must contain all components listed above,
i.e. experimental procedure and results that would support the hypothesis.
Experimental design:
Have one group of genetically identical mice with HD (large number – around 50 to 100 is reasonable).
Randomly divide the mice into two equal groups. Give cystamine in a regular regime to all the mice in one
group and give a placebo drug (also in a regular regime) to all the mice in the other group. Ensure that mice
are kept in controlled conditions (same temperature, surrounding, food, etc.). Make observations of mice
and record results. Repeat the experiment if necessary.
Results that support hypothesis:
Mice with HD that are treated with cystamine will show a reduction in tremors, improved (or a halt to loss
of) motor function and extended life expectancy. Mice with HD receiving placebo will not show relief from
symptoms and will show continued deterioration.
Mark allocation
• 1 mark – one large group of genetically identical mice (large number – around 50 to 100) OR smaller
groups of mice (around 5 to 10) AND repeat the experiment MANY times (e.g. 5 repetitions).
• 1 mark – random division of mice into two groups; give one group cystamine, the other group should
receive a placebo.
• 1 mark – controlled conditions (same temperature, surrounding, food, etc.); record observations.
• 1 mark – description of results that support hypothesis.
Question 6
The diagram below has two parts.
Part X – shows a high-speed golf ball approaching an eye and part of the pathway of an automatic blinking
response.
Part Y – comprises six boxes, each containing the name of a general component of an automatic regulatory
system that operates in the human body.
a. Select the two most appropriate words from the list given in part Y and complete the labels 1 and 2 in the
spaces provided on the diagram.
Answer: Part 1: effector Part 2: afferent (sensory) neuron
2 marks
The following diagram shows a synapse between the end of one neurone and the dendrite of another.
b. What is the general name for molecule X?
Answer: Neurotransmitter
c. Describe what occurs at stage P.
Answer: The neurotransmitter is being broken down by an enzyme.
1 mark
Total 4 marks
Section B total marks
Section A & B total marks
/33 marks
/50 marks
%