Headstart Revision Program
VCE Biology Unit 3 Exam Revision
Session 1. Area of Study 1 – Molecules of Life
The chemical nature of the cell
Synthesis of biomacromolecules
Biomacromolecules are the big molecules involved in the biochemical processes of
organisms involved in communication within and between cells, transforming energy and
translating and transferring genetic information. These include complex carbohydrates
like starch, lipids, proteins and deoxyribonucleic acid.
Autotrophs (organisms that synthesise their own energy) are able to synthesise their
own macromolecules from inorganic molecules. For instance, when green plants make
glucose through the process of photosynthesis they combine two inorganic molecules –
carbon dioxide and water with light in the presence of a catalyst (chlorophyll) to make
glucose (an organic molecule) and oxygen. Some autotrophs use a chemosynthetic
process to achieve similar outcomes.
light energy
6CO2 + 12H2O  C6H1206 + 6H20 + 6O2
chlorophyll
Heterotrophs are organisms that must consume other organisms to synthesise
macromolecules. That is they consume organic matter which is digested in specialised
organs to reduce the molecules to glucose and other simple sugars, amino acids and
lipids so that they can then be used to build new macromolecules.
The structure and function of carbohydrates
Organisms use carbohydrates as an energy source and for structural components of
cells. Two examples are glucose which is a simple sugar used to provide energy to the
cell for various processes and cellulose which is found in the wall of cells, giving the cell
structure. Carbohydrates are grouped into three main types – monosaccharides
(simple sugars), disaccharides (such as sucrose which bonds two monosaccharides
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together) and polysaccharides (such as starch which are many monosaccharides
and/or disaccharides bonded together).
Starch
Glucose
The structure and function of lipids
Lipids are a diverse group of molecules
which include fats, oils and steroids. They
are used for energy storage, as the
structural component of membranes and
for biological functions (eg. transmission of
chemical signals between cells). Lipids are
classified based on their relationship with
water. Some are hydrophobic as they
posses no polar regions on the molecule
and won’t dissolve in water. Some do
posses polar regions, will therefore
dissolve in water and are known as
hydrophilic and others have a
hydrophobic and hydrophilic region and
are referred to as amphipathic.
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The structure and function of DNA and RNA
DNA is a large protein found in the nucleus of eukaryotic cells and in the cytoplasm of
prokaryotic cells. It is comprised of nucleotides, which in turn are comprised of a five
carbon sugar, a negatively charged phosphate group, and a Nitrogen containing base
(there are four types: Adenine, Thymine, Guanine and Cytosine). The molecule is
comprised of two long chains of nucleotides which join by hydrogen bonds between the
N-bases which twists the molecule into its distinctive double helix shape.
Deoxyribonucleic
Acid
DNA contains the codes for all the proteins made by a cell. These proteins are
responsible for movement, structure, biochemical reactions, transport, poisons,
immunoglobins, neurotransmitters, hormones and cell surface receptors.
RNA is used to transmit the information contained in the DNA and construct the proteins
coded for by DNA. RNA is different to DNA by containing one strand of nucleotides,
having one less oxygen atom in the ribose sugar and the base Uracil replaces Thymine.
Protein Synthesis
Transcription is the process by which the DNA strands are unzipped, either for the full
length of the strand, or just for the segment coding for a protein and copied into mRNA.
1.
RNA polymerase attaches to a region of DNA and unwinds the double
stranded DNA and exposes the bases of the template strand.
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VCE Biology Unit 3 Exam Revision
The base sequence of the DNA template guides the building of a
complementary copy of the mRNA sequence.
3.
The result is a single-stranded molecule called pre-mRNA.
4.
The introns are removed to produce mRNA
5.
The final mRNA molecule is chemically capped and a poly-A tail added to
produce the operational mRNA.
Before the pre mRNA leaves the nucleus it undergoes a number of modifications to
become mRNA. A methylated cap (a modified guanine nucleotide that has a methyl and
phosphate group bonded to it) is added to the 5’ end as soon as the mRNA leaves the
DNA template.
The Introns are removed by RNA splicing. The introns are regions of base sequences
not translated into amino acid sequences (non-coding regions of DNA). Exons are the
coding regions that contain the information for protein formation.
Translation
The mRNA passes through the nuclear membrane into the cytoplasm and attaches to
sub-microscopic organelles known as ribosomes.
Amino acids are brought to the
ribosome by tRNA which corresponds to the triplet code on the mRNA.
The Amino Acids are joined together at the ribosome to make a protein.
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Comparison of DNA and RNA
Sugar unit
Nitrogen bases
Double/single stranded
Location
DNA
Deoxyribose
A, T, G, C
Double
Nucleus
RNA
Oxyribose
A, U, G, C
Single
Mostly Cytoplasm
The outcome of transcription and translation is a functional protein.
DNA complimentary strand
DNA template strand
mRNA
tRNA
amino acid sequence
ATG GTC GCC GGC AGA TGA (not copied)
TAC CAG CGG CCG TCT ACT (copied)
AUG GUC GCC GGC AGA UGA
UAC CAG CGG CCG UCU ACU
Start, Val, Ala, Gly, Arg, Stop (a very short protein)
Genetic Code
The main features of the genetic code are:

Pieces of information in the genetic code consist of triplets or three-base
sequences.

The code is non-overlapping (bases are read three at a time).

The code is universal (same in all organisms, except a few protozoa and
bacteria).

The code is said to be redundant or degenerate since, more than one triplet of
bases codes for one particular amino acid.
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The information encoded in DNA are instructions to assemble amino acid subunits into proteins

The information is unambiguous (one codon codes for only one amino acid)

The information also includes a START instruction and a STOP instruction
The proteome
The proteome is a term used to describe the complete set of proteins produced by a
particular cell.
Protein
Almost everything that occurs in the cell relies on proteins. Proteins consist of large
complex molecules made by combining the 20 different amino acids in different
sequences. This occurs at the ribosomes under instruction from information held in the
DNA of the nucleus. Proteins are used for movement of cells and organisms, to provide
structure, strength and protection, act as enzymes to catalyse reactions, carry molecules
from one location to another and across membranes, as hormones to stimulate or inhibit
cell processes, label cells as self, neurotransmitters, immunoglobins, and poisons or
toxins to defend the organism against predators or pathogens.
Plants are able to make their own amino acids, but animals must consume amino acids
from other organisms.
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Cell organelles
Plasma membrane
The plasma membrane or cellular membrane is made up of two layers of
phospholipids. Each molecule has a hydrophilic head facing outward and a
hydrophobic tail facing into the centre of the membrane. It can be described as partially,
selectively or differentially permeable as it allows some molecules to cross by diffusion
and bars the passage of other molecules.
Small hydrophobic molecules such as oxygen, carbon dioxide and nitrogen pass through
as do small uncharged polar molecules such as water, ethanol and glycerol. Various
ions and larger uncharged polar molecules such as amino acids, nucleotides and
glucose are able to cross the membrane via channels in the membrane with the
assistance of transport proteins.
Osmosis/Diffusion
Diffusion is the movement of molecules of a substance from an area of high
concentration of that substance to an area of low concentration. This is easily achieved
by gases not contained within a vessel and for solids such as salts and sugars dissolved
in water. In organisms this takes place across partially permeable membranes.
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Osmosis refers to the movement of water molecules. They will move from an area of
low concentration of a dissolved substance such as sugar to an area of high
concentration of that dissolved substance. This is important to organisms for the
movement of water and other substances into and out of cells. There are three
conditions to consider.
Isotonic. The surrounding
fluid and the cellular fluid
are of equal concentration.
Molecules will move in both
directions, but there will be
no change in concentration
either side of the cellular
membrane.
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Hypotonic. When cells are
surrounded by a solution of lower
concentration to the cellular fluid
then water will diffuse into the cell.
This can be a problem as the cell
will swell and possible burst.
Plant cells have a cell wall that
partially protects the cell from this
and plant cells have mechanisms
which regulate and control the
concentration of cell fluids.
Hypertonic. If the cell is
surrounded by a solution with a
higher concentration than the
cellular fluid, then water will leave
the cell by diffusion. This can lead
to cells drying out. We say they
have become desiccated.
Facilitated Diffusion
Some molecules required by a cell are either to large to move by diffusion across the
membrane or the cell already has a high concentration of the substance but requires
more and must move it against the concentration gradient.
Carrier proteins – some proteins have a specific site to which certain other molecules
can bind. These then cross the membrane taking the molecule with them.
Channel proteins – there are pores in the membrane which are water filled and allow
certain hydrophilic substances to pass through.
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This is referred to as Active Transport. It is thought that energy is provided to carrier
proteins to bring substances through the protein channels. Cells in which active transport
regularly takes place generally have many mitochondria.
Nucleus
Is the one of the most easily viewed
structures in eukaryotic cells. It contains
the information that controls the production
of proteins by the cell – DNA.
Ribosomes
Ribosomes are extremely small molecules that
can be found attached to the Endoplasmic
Reticulum or free floating in the cytosol. There
are lots of them as they have a very important
role to play translating the code from the DNA
into proteins.
Endoplasmic Reticulum (ER)
The rough ER (ER associated with ribosomes) is responsible for the production of
membrane proteins and proteins to be secreted from the cell. Smooth ER are
responsible for the production of phospholipids and cholesterol.
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Golgi Apparatus
Once the cell has produced protein and
lipid molecules they have to be
packaged and delivered elsewhere.
The Golgi Apparatus (also described as
a Golgi body or Golgi complex) is
responsible for packaging these
molecules and transporting them
around the cell or to the membrane.
Vesicles
Vesicles are membrane bound organelles that are associated with transport of
biomolecules within the cell. Lysosomes are a special class of vesicles that contain
digestive enzymes which break down all the major classes of biomacromolecules. They
help the cell by recycling materials and removing potentially hazardous wastes.
The nature of biochemical processes
Enzymes as organic catalysts
Enzymes are a protein based molecule, created by the organism, that act as catalysts in
chemical processes within cells and the organism generally. Enzymes have an active
site which binds with one specific substrate or family of molecules. Enzymes work within
given ranges of temperature and pH. Below that temperature the enzyme can’t work or
works slowly, but if the enzyme is held at a temperature above that normal range then
the active site can be damaged and the enzyme can no longer do its work – it is said to
be denatured. Enzymes are also denatured when the enzyme is exposed to pH values
either side of the enzymes normal range.
In animals, enzymes have a specific task to perform. They are generally produced in
endocrine glands and secreted into the blood or lymph systems where they make there
way to the target cell. In this way they are specific, slow to act but usually have a
prolonged effect. In plants, cells are responsible for production of enzymes. These
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enzymes move slowly through the phloem or are excreted as gases. They are less
specific in their function and also have long lasting effects.
Energy requirements of cells
The term metabolism is used to describe the complete set of biochemical reactions that
take place in the organism.
Catabolic Reactions
These are reactions that break down complex molecules into simpler molecules. The
most important of these in a biochemical sense is cellular respiration.
C6H12O6 + 6O2  6CO2 + 6H20 + energy as 36 - 38 molecules of ATP
In Cellular Respiration glucose is used by almost all organisms as the primary source of
energy for cellular metabolism. To release the energy in glucose requires the cell to
break down the glucose into ATP and other by-products which include water and carbon
dioxide. This takes place in the cytosol and the mitochondria of cells.
The first step is called Glycolysis. This part takes place in the cytosol. The glucose is
broken done into 2 molecules of ATP, 2 molecules of NADH and 2 molecules of
pyruvate. If the process stopped here we would describe this as anaerobic respiration (in
the absence of oxygen) and poisonous by-products could build up and damage the cell.
However, if oxygen is present then a biochemical process known as Krebs cycle takes
place within the cristae (inner folded membrane) of the mitochondria. In Krebs cycle the
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2 pyruvate molecules are broken down to release 6 molecules of carbon dioxide, 2 units
of ATP, 6 molecules of NADH and 2 of FADH2. These enter the electron transport
system and are broken down to release a further 32 – 34 molecules of ATP.
Anabolic Reactions
These are reactions that build up complex molecules from more simple molecules. The
most important of these in a biochemical sense is photosynthesis.
light energy
6CO2 + 12H2O  C6H1206 + 6H20 + 6O2
chlorophyll
Photosynthesis (phs) takes place in specialised organelles known as chloroplasts,
which contain chlorophyll. The chloroplast consists of two main structures – the stroma
and thylakoid membranes consisting of flat, sac-like structures called grana where the
first stage of phs takes place - the light dependent stage.
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The light energy is absorbed by different pigments. The electrons within the molecule
become energised. This energy is used to split water into H+, electrons and oxygen gas
which is released as a by product. The electrons pass along a chain of molecules giving
off energy which is used to pump protons into the thylakoid space and results in the
production of ATP (adenosine triphosphate). ATP is used to make sugar molecules.
NADP is used to transport spent electrons and excess protons to the stroma for the
second stage of phs.
The light independent stage uses the ATP produced in the grana and the excess protons
and electrons carried by the NADP to combine with carbon dioxide to form a sugar
molecule. This process is described by the Calvin-Benson cycle. Carbon fixation
requires carbon dioxide to be attached to ribulose biphosphate, forming an unstable 6
Carbon compound. This splits to two 3 Carbon compounds. NADP donates H+ ions to
form 3 Carbon sugar phosphate molecules – some exit the cycle to be used by the plant
to form more complex carbohydrates and some remains in the cycle to make new
ribulose biphosphate.
Applications of molecular biology in medicine
In the past 20 or 30 years there have been major advances in the design of drugs and
the diagnosis of disease based on our developing understanding of the cell, its
processes and in particular the structure and function of proteins.
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Kidney dialysis was an early development based on this knowledge. Having learnt how
the kidney uses diffusion to remove wastes from the blood a machine was constructed to
mimic this function. The blood was removed from the patient, filtered through partially
permeable membranes to remove water, glucose, lipids, amino acids, oxygen, carbon
dioxide, and urea using diffusion and then the blood was returned to the patient with the
useful materials such as water, glucose, lipids, amino acids and oxygen added.
Since then we have been able to use our knowledge of the biochemistry of the body to
many wonderful procedures and develop drugs. Such as the development of Relenza.
Relenza is an Australian made drug which binds to a protein on the surface of the
influenza virus and prevents the virus from causing any harm. Similar research is being
conducted across the globe to try to find treatments for many diseases including Bird Flu
and HIV.
There are many examples of the use of our knowledge of the cell and its processes
which the examiners could use in your exam. It is important to not become distracted by
the example, but to look carefully at the information presented and use your knowledge
of these concepts to answer the questions asked.
Homework
1. List 5 concepts from this section of the course and display these in your home
(bedroom, fridge door, toilet wall etc).
2. Create a poem about one of the important concepts that you are having
difficulty understanding.
3. Create flash cards for all the glossary words for this section of the course.
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VCAA 2008
Question 1
A process occurring at structure W in this plant cell would be
A. packaging of molecules.
B. aerobic respiration.
C. protein synthesis.
D. DNA replication.
Question 2
In this plant cell, the light-dependent reactions of photosynthesis occur in structure
A. N.
B. M.
C. Q.
D. P.
Question 4
The four main types of biomacromolecules in a cell are
A. monomers, polymers, DNA and RNA.
B. proteins, carbohydrates, DNA and RNA.
C. nucleic acids, proteins, carbohydrates and lipids.
D. monosaccharides, disaccharides, polysaccharides and proteins.
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Question 5
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
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Question 6
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
A. the rate of photosynthesis is zero.
B. the rate of aerobic respiration is zero.
C. oxygen produced by photosynthesis is equal to the oxygen used by aerobic respiration.
D. oxygen produced by photosynthesis is equal to twice the oxygen used by aerobic respiration.
Question 7
Glycogen is
A. a polysaccharide found in animal cells.
B. an energy-storing lipid molecule.
C. a molecule in which plants store sugars.
D. a polysaccharide found in plant cell walls.
Question 8
Lipids characteristically
A. are hydrophobic.
B. catalyse reactions.
C. have a low energy content.
D. are information-storage molecules.
Question 12
Insulin is a complex protein that is said to have a quaternary structure.
This means that insulin
A. cannot be denatured.
B. lacks disulphide bridges.
C. contains all the known amino acids.
D. has more than one polypeptide chain.
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Question 15
Facilitated diffusion is a form of cell transport that
A. moves oxygen and carbon dioxide across membranes.
B. occurs against a concentration gradient.
C. requires specific protein channels.
D. uses energy supplied by ATP.
Question 18
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
A. glucose and fructose are polysaccharides.
B. the production of sucrose is an endergonic reaction.
C. sucrose is a reactant and glucose is a product of the reaction.
D. a molecule of fructose contains more stored energy than a molecule of sucrose.
Question 19
Activation energy in a biological reaction
A. increases in the presence of an enzyme.
B. increases with an increase in temperature.
C. is the energy required to start the reaction.
D. is involved in the formation of complex molecules only.
Question 20
Materials are constantly exchanged between a cell and its surroundings. The ease with which a
molecule passes through a plasma membrane can be represented by a permeability coefficient.
The graph below shows the permeability coefficients for a range of molecules plotted against
their solubility in oil (lipid).
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From the graph you can conclude that
A. water is more lipid-soluble than alcohol.
B. a cell gets rid of urea more slowly than excess water.
C. drugs like alcohol and codeine enter cells more slowly than ethylene glycol.
D. ethylene glycol passes through the plasma membrane more easily than diethylurea.
Question 1
The diagram below shows a cross section of part of the plasma membrane of a typical
mammalian cell. The substances labelled X and Y are about to be transported across the
membrane in the directions shown by the arrows ( ).
i. Structure A
Chemical composition
Explain how the chemical composition of structure A facilitates its role.
ii. Structure B
Chemical composition
Explain how the chemical composition of structure B facilitates its role.
1 + 1 = 2 marks
Question 2
There are structural differences between molecules of DNA and RNA.
a. Outline two of these differences by completing the following table.
b. Name one kind of RNA and state its function.
Type of RNA
Function
1 mark
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Proteins may be classified as fibrous or globular depending on their 3-dimensional shape.
In fibrous proteins, the polypeptide chains are arranged in parallel to form long fibres or sheets. In
globular proteins, the polypeptide chains are folded into compact spherical or globular shapes.
c. Name the subunit of a polypeptide.
1 mark
Keratin, found in fingernails and claws, is an example of a fibrous protein.
d. Name another example of a fibrous protein and briefly outline its function.
1 mark
e. Describe a distinctive property of a fibrous protein and explain how this property is due to the
arrangementof its polypeptides.
1 mark
Total 6 marks
Question 3
The following diagrams show
Graph one The rate of photosynthesis in a green plant at different wavelengths of light
Graph two The estimated absorption of the different wavelengths of light by the different plant
pigments
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a. Explain why the graph showing the rate of photosynthesis has approximately the same shape as
the absorption graphs of the plant pigments.
1 mark
The following diagram shows a simplified representation of the first stage of photosynthesis.
b. i. Name one input item that X could represent.
ii. Name one output item that Y could represent.
1 + 1 = 2 marks
The breakdown of glucose in aerobic respiration can be represented by the simplified equation
c. What is the energy yield per molecule of glucose as a result of aerobic respiration?
1 mark
The breakdown of glucose in aerobic respiration can also be represented as occurring in three
particular stages as indicated below.
d. i. Within a cell, where does the electron transport stage of aerobic respiration occur?
ii. Describe what happens during the electron transport stage. In your answer include the name of
product Z.
1 + 2 = 3 marks
Total 7 marks
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VCAA 2007
Question 1
A polysaccharide that can be made in some animal cells is
A. starch.
B. pectin.
C. glycogen.
D. cellulose.
Question 2
Liposomes are found in the cytosol and are formed from a double layer of phospholipid
molecules identical to those found in plasma membranes. Liposomes can also be
manufactured and used to carry medicinal drugs into cells.
Examine the following diagram.
It is reasonable to expect that
A. drug 1 is lipophilic.
B. drug 2 is water soluble.
C. the interior of the liposome is aqueous.
D. liposome-based membranes have a rigid structure.
Question 4
A protein-based Þ bre could be constructed from repeated monomers of
A. C5H13N4COOH
B. CH3(CH2)nCOOH
C. Cx(H2O)y
D. C6H5COCl
Question 7
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
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Question 8
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.
B. DNA.
C. starch.
D. protein.
Question 9
The following diagram represents a nucleotide with subunits X, Y and Z.
This nucleotide could be identified as a monomer of DNA but not RNA if
A. X is ribose.
B. Z is thymine.
C. Y is phosphate.
D. Z paired with cytosine.
Question 11
A haemoglobin molecule is composed of four protein (globin) chains each attached to an
iron-containing haem group. Two are identical alpha chains and two are identical beta
chains. The following diagram is a stylised representation of a haemoglobin molecule.
A haemoglobin molecule would be classified as having a
A. primary protein structure.
B. secondary protein structure.
C. tertiary protein structure.
D. quaternary protein structure.
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Question 14
Nitrosomonas europa is a species of bacteria that obtains its energy by oxidising
ammonium ions to nitrite ions.
It is reasonable to argue that
A. the reaction is anaerobic.
B. the reaction is endergonic.
C. no heat is produced in this reaction.
D. ATP is produced as a result of this reaction.
Question 19
Myosin is a protein consisting of six chains and is the main component of some muscle
Þ laments.
It would be reasonable to classify myosin as a
A. contractile protein.
B. hormonal protein.
C. globular protein.
D. storage protein.
Question 20
Cell organelles and membranes that are involved in the transport of biomolecules from
inside a cell to outside a cell include
A. ribosomes.
B. microtubules.
C. membranes that form vesicles during endocytosis.
D. secretory vesicles that bud off from the Golgi complex.
Question 3
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
a. 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.
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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
Total 5 marks
Question 4
The bird’s-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 bird’s-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.
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a. Which of the labelled parts, X, Y or Z, absorb light energy? Name the part.
1 mark
b. 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
c. Name the process by which the chemical reactants for the light-dependent reactions
of photosynthesis enter a chloroplast.
1 mark
Chloroplasts contain large numbers of ribosomes.
d. Explain the importance of the presence of these ribosomes.
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.
e. 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.
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g. What is the source of these energy carriers?
1 mark
h. What is compound P?
1 mark
Total 9 marks
Question 6
During digestion, large molecules are broken down into their constituent monomers
(subunits).
a. Complete the table below.
b. Explain how a monosaccharide enters an epithelial cell.
1 mark
c. For what purpose would a cell use a lipid monomer?
1 mark
d. Part of the sequence of a DNA strand responsible for the production of an amino-acid
chain is shown.
Below it, write the complementary DNA base sequence.
e. What does G in AGC stand for?
1 mark
Total 6 marks
Question 7
Chromosomes are DNA structures in the nucleus of a cell. The ends of chromosomes
are called telomeres
Some changes in the DNA of these telomeres can trigger the development of cancer.
Scientists are working to detect these changes in telomeres at an early stage of their
development.
a. Outline one advantage of being able to detect early changes in telomere DNA.
1 mark
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VCE Biology Unit 3 Exam Revision
One normal sequence of DNA in a particular telomere was AATCGTCCAGGG. On
examination of the telomeres of one patient this sequence was found to have changed to
AACCGTCCTGGG. The doctor examined the relationship between a DNA sequence
and amino acids that could be expected. He used the following table to obtain
information.
b. Is the doctor likely to be concerned or not concerned about the change in the
telomere DNA of this patient? Explain your answer.
1 mark
c. Name one application of molecular biology in medicine that you have studied this year
and outline the significance of its use.
Name of application
Significance
2 marks
Total 4 marks
VCAA 2006
Question 1
Starch is a polysaccharide. Other polysaccharides synthesised by organisms include
A. lactose.
B. sucrose.
C. glucose.
D. glycogen.
Question 2
Anabolic reactions, also called endergonic reactions, include
A. glycolysis.
B. Kreb’s cycle.
C. photosynthesis.
D. protein digestion.
Question 3
The protein chymotrypsin is derived from a parent molecule, chymotrypsinogen.
Cell organelles that are essential for the production of chymotrypsinogen include
A. ribosomes.
B. microtubules.
C. cell membrane.
D. Golgi apparatus.
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Headstart Revision Program
VCE Biology Unit 3 Exam Revision
Question 4
Molecules found in an animal cell membrane include
A. chitin.
B. cellulose.
C. cholesterol.
D. nucleotides.
Question 5
The formula that represents a protein is compound
A. C18H32O2
B. C58H114PNO8
C. C600H1000O500
D. C708H1130N180O224S4
Question 6
The chloroplast is the organelle responsible for photosynthesis in eukaryotic cells.
In chloroplasts
A. the light independent reactions require water as the initial reactant.
B. the light independent reactions occur in the inner membrane area.
C. the final product of the light reaction is glucose.
D. the light reactions occur in the grana.
Question 11
There are 4 polypeptide chains in a human haemoglobin molecule. The monomers in a small
section of each of the 4 chains is shown.
chain 1 … leu-ser-pro-ala-asp-lys-thr-asn-val-lys ...
chain 2 … leu-thr-pro-glu-glu-lys-ser-ala-val-thr …
chain 3 … leu-ser-pro-ala-asp-lys-thr-asn-val-lys ...
chain 4 … leu-thr-pro-glu-glu-lys-ser-ala-val-thr …
Consider the sections of the chains shown.
The information given suggests that
A. each of the chains is the result of the same DNA sequence.
B. each total chain contains the same number of monomers.
C. adjacent monomers are linked by a peptide bond.
D. each monomer is specified by a nucleotide.
Question 13
The following data represents a small section of a sequence of bases of a nucleic acid taken from
an animal cell. … G C U C G U U …
From this data it is reasonable to assume that the seven bases
A. would lead to the production of a chain of seven amino acids.
B. would be complementary to the sequence C G T G C T T.
C. must contain the sugar ribose.
D. would be from DNA.
Gary Simpson
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Headstart Revision Program
VCE Biology Unit 3 Exam Revision
Question 15
Consider the following diagram that is a summary of an important biochemical process.
The product, X, in this biochemical process is
A. ADP.
B. a polymer.
C. an amino acid.
D. a monosaccharide.
Question 17
The packaging and transport of biomolecules within a cell involves their
A. distribution through a series of microfilaments.
B. transport by Golgi apparatus to the endoplasmic reticulum.
C. movement from the ribosomes into the endoplasmic reticulum.
D. transport from the plasma membrane into the cytosol by secretory vesicles.
Question 19
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 bacteria
A. have enzymes with a high optimal temperature.
B. can lower the temperature of the cellular environment.
C. use compounds other than enzymes to catalyse reactions.
D. have enzymes other than proteins that do not respond to changes in temperature.
Question 18
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
A. oxygen is an input to reactions at P.
B. carbon dioxide is an input to reactions at Q.
C. chlorophyll is essential for reactions that occur at Q.
D. ADP produced during the events at P is used by events at Q.
Gary Simpson
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Headstart Revision Program
VCE Biology Unit 3 Exam Revision
Question 20
Phospholipids are built from lipids and phosphate. They are found in plasma membranes.
The diagram that most closely resembles the arrangement of phospholipids in a plasma
membrane is
Gary Simpson
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Headstart Revision Program
Gary Simpson
VCE Biology Unit 3 Exam Revision
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Headstart Revision Program
Gary Simpson
VCE Biology Unit 3 Exam Revision
34
Headstart Revision Program
VCE Biology Unit 3 Exam Revision
Question 4
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 action.
a. If mitochondria are poisoned with 2,4-dinitrophenol by what process could a plant cell produce
more ATP? 1 mark
______________________________________________________________________________
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Headstart Revision Program
VCE Biology Unit 3 Exam Revision
b. 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 2,4dinitrophenol to these cells. An agricultural company may want to fund this research.
c. 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.
d. 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 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.
g. Explain what effect adding pyruvate would have on cancelling out the effect of this toxin.
1 mark
______________________________________________________________________________
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