BIOLOGY a guide by Alon Douek
Abstract: Biology is an amazing subject, and one I personally recommend to anyone interested in the study of life itself. Biology has something for everyone, from the chemically-oriented (photosynthesis, aerobic/anaerobic respiration) to the physicists and mathematicians amongst us (Hardy-Weinberg Equilibrium Principle). Biology is both broad in its scope yet specific in its details, and it gives a wondrous insight into the world around us.
Are Units 1 and 2 needed for Biology 3/4?No. It is possible, and common, to complete VCE Biology 3/4 without having undertaken units 1/2. However, I
do endorse taking units 1/2 in year 11 if you are not proficient in the subject but still want to take it. Unit 1 gives a very important introduction to cellular and molecular biology which proves very useful throughout Unit 3 and the more chemical parts of Unit 4. I would personally argue that Unit 2 is nowhere near as key to the year 12 course as Unit 1, but it does give some insight into adaptations, plant and animal behaviour and ways of understanding species distribution, all of which is fairly useful at different times in the 3/4 course.
What you need to score well in VCE Biology:- Strong organisational skills
- Decent memory and critical thinking ability
- A passion for the subject
- A commitment to work hard and go above the minimum requirements set to you
- Proper use of scientific language and terminology
- Attention to detail
That's about it. Obviously, having a good teacher helps, but with VCE Biology often the onus to learn, and more importantly,
understand, is on
you.
Ways to approach work:As mentioned above, one of the keys to success in biology is organisation. Due to the broad nature of the subject, you could come across a concept that was either only mentioned briefly by your teacher or referred to in a single handout. Ostensibly, you should keep yourself organised, and keep EVERY piece of information you get throughout the year.
How to do this?
1. A comb-bound plastic-pocket book is very good for holding loose handouts and single-page notes. It keeps everything together, and when combined with tabs or sticky notes, becomes a veritable filing system.
2. A 2-ring Marbig lever arch folder to keep absolutely everything together; be it the theory notes you're provided (if applicable) to the summary notes you'll be writing (we'll get to this later on). VCE biology, quite ironically, uses a massive amount of paper per student; you need a place to keep everything together and an arch-lever folder is the best option, in my opinion.
SACsBiology SACs vary quite a lot in type. At my school, the SACs were of the following (though SAC methodology for varies from school to school):
- Designed experiment SAC - One has to perform a practical (with a partner), then individually use the results of said prac to construct a detailed, professional write-up consisting of a title, aim, hypothesis, list of apparatuses, method, results (including graph if required), risk and safety analysis, and conclusion
- Research-based SAC - Prior to the SAC, one must find a news/academic article that discusses a topic related to the current area of study. The article must be approved by the teacher. Then, under exam conditions, one must construct a ~2000 word essay that discusses and explores the subject matter in a way that satisfies a list of questions provided to you by the teacher
- Excursion-based SAC - Similar to the first type of SAC, just done away from campus; for example, my school went to UoM to perform an experimental SAC on the genetics of Drosophila Melanogaster, as well as an observation-based experimental SAC at Melbourne Zoo to investigate primate evolution
How to learn and understand concepts:Biology as a subject is extremely heavy in information. This can be managed in a number of ways, but I'll outline the way that worked for me. (All references to 'textbook' are Nature of Biology; I believe this is by far the superior textbook offered for the Biology course)
1.
Summarise by chapter: Assuming you are following the textbook as a sequence of learning the biology course, it is important that you summarise each section of each chapter. One can either do this before the chapter's material is taught in class, or after; I prefer before, because it
a) gives you breadth of understanding of the subject matter before your teacher starts discussing it in further detail in class and
b) forces you to read the textbook in detail.
2.
Do the 'Quick-Check' and 'Biochallenge' questions: Quick check should be done before you start the topic in class; my teacher set it as homework along with the summaries before she began to teach it to us in class. Again, it gives one knowledge that is valuable to have when learning and understanding the conceptual material in class. 'Quick Check' questions are fairly simple, and they should be done in the numbered sequence that they are presented as in the textbook. When answering the Quick Check questions, practice both writing in full sentences, as well as practicing brevity and appropriate scientific language. The Biochallenge questions are slightly harder, more application-based and should be attempted after covering the chapter's material in class. These questions are similar to the application-type questions one may encounter in the Short-Answer section of the exam.
3.
Write detailed notes with labelled diagrams: Using your textbook and the notes provided to you in class, construct a book of detailed theory notes accompanied by appropriate labelled diagrams. This book, which you will update over the course of the year each time you cover a new topic, will become an extremely valuable resource come exam time. The notes you keep can vary by type; for example, you may want to write out in great detail the steps involved in protein synthesis, but only construct a series of detailed flowcharts for various types of homeostasis (i.e. gluco/thermo/osmoregulation).
Below are a couple of pages from my notes (>100 pages in total)

And here are a couple of (parts of) pages from some of the theory notes constructed by my teacher. She taught with a combination of these notes, the textbook (used more for homework) and her own knowledge:

With all the above, have them evaluated by your teacher. They are very experienced in picking up minor errors, which are the type you want to avoid because that's what loses you marks during the exam.
Prior to the exam:As of the 2013-2016 VCAA study design, there are no longer mid-year Unit 3 examinations, and only one exam at the end of the year. Personally, I think this is a terrible idea, but we won't get into that now

. What I will discuss is what to do prior to the exam period.
1.
Practice exams: Practice exams are easily the best way of preparing oneself for the actual exam. Although the past VCAA exams are segmented into Unit 3 and Unit 4, there is no reason not to complete these VCAA exams anyway; they are still a valuable resource with which you can ready yourself for the exam and practice and refine your biological knowledge.
The best biology practice exams are:
- VCAA past exams (obviously)
- ATARnotes practice exams
- NEAP
- STAV
- Lisachem
2.
Identify your weaknesses: This is one of the places where the (now massive) book of notes you've been updating throughout the year becomes even more useful. Read over it and identify the areas of the course that you are not entirely comfortable with. Then:
- Approach your teacher for some one-on-one sessions revisiting and revising the topic
- Revisit the textbook area for that topic, and reread until everything makes sense and sits comfortably
- Having done step 2, touch up your personal notes so that they reflect your level of understanding with the topic
3. Do the questions in the A+ 'Biol Notes' - this is a handy little publication that contains both summary notes, glossaries and practice exam questions. This is available for both Units 3 and 4.
4.
Don't Panic! If ever you feel that you're becoming overwhelmed, STOP. Take a deep breath and analyse your situation. Refer to point 2 of this section, and make a checklist of the topics you need help with. Then, ask your teacher and classmates for help, and post your questions of the ATARnotes forum so one of the many resident experts can get back to you quickly

Most importantly, NEVER GIVE UP.
During the examKeep a level head, and don't get panicky - most marks are lost by anxious students who rush and make careless errors. Make use of reading time by reading each question carefully, and consider what the question is
REALLY asking you. If you see something you don't understand during reading time, DON'T WORRY! It'll probably come to you during writing time when you're 'in gear'.
Also, stay hydrated (but don't drink water to the point that you need the bathroom) - your brain won't function optimally if you're dehydrated.
Concepts by Area of StudyNow that we've discussed tactics and strategy to effectively manage the workload of VCE biology, we can move on the actual meat of the subject. Here, I'll go through as many specific concepts of each respective Area of Study as possible.
Unit 3 - AoS1
The Chemical Nature of CellsHere, we discuss both organic biomacromolecules and inorganic molecules (mainly water) that have significant roles in cellular biology.
(Molecule in cell) | (Biomacromolecule?) | (Use in the body) | (Elements involved in their composition) |
Water | No | Medium for/reactant in metabolic reactions | H, O |
Proteins | Yes | Growth, strength, support | C, H, O, N, (P), (S) |
Lipids | Yes | Energy storage, insulation | C, H, O, (N), (P) |
Nucleic Acids | Yes | DNA/RNA/ATP/Protein synthesis | C, H, O, N, P |
Carbohydrates | Yes | Energy storage | C, H, O |
BiomacromoleculesLet's look at biomacromolecules in more depth:
Info | Carbohydrates | Lipids | Proteins | Nucleic Acids |
Monomer Unit | Monosaccharide | Glycerol and fatty acids | Amino acids | Nucleotides |
Examples of sub-units | Glucose, fructose, ribose | Triglycerides, phospholipids, steroids | 20 amino acids (i.e. alanine, leucine) | Monomers consist of a nitrogenous base (Adenine, thymine, guanine, cytosine, uracil), a five-carbon sugar (deoxyribose in DNA, ribose in RNA) and a phosphate group (PO43-) |
Polymer bonding type | Strong covalent glycosidic bond (C-OH) | Rarely ever bonds; instead forms aggregates | Primary - Strong covalent peptide bond (C-N); Secondary - weak hydrogen bonds; Tertiary - may have sulfide bonds | Strong covalent bonds between sugar and phosphate (C-P); weak hydrogen bonds between bases |
Examples of polymer | Starch, glycogen, cellulose, inulin | N/A | Enzymes, some hormones, antibodies, collagen | DNA, RNA, NADPH, ATP |
Found in | Cell wall | Cell membrane | Blood, cell cytosol | Nucleus, cytosol |
Functions | Energy storage, some structural function | Energy storage, insulation, vesicular transport | Catalysis of metabolic reactions, immune defense, structure, chemical messengers, diffusive functions (as carrier and channel proteins) | Genetic information |
The Water MoleculeWater, H
2O, is a vital part of cell metabolism, as it provides both a medium for metabolic reactions to take place, as well as being a reactant in some metabolic reactions. Water has several key properties that allows it to fulfil such an important role in the body:
- Covalent bonding - Strong bonding between the oxygen atom and the hydrogen atoms that compose the water molecule
- Hydrogen bonding - A weaker form of bonding between the a hydrogen of one water molecule and an oxygen of another

- Cohesiveness - the tendency of water molecules to stick together and to other surfaces due to inter-molecular bonding
- Solvent - Water is the 'universal solvent'; it is able to pull apart and dissolve other compounds and molecules due to the polar nature of the water molecule
- Polarity - due to unequal charges at each 'pole' of the molecule: the red represents a negative charge (from the oxygen atom), while the blue represents a positive charge from the hydrogen atoms

- Neutrality - A solution of pure water has a pH of 7 at 25°C (though this varies with temperature). As such, water is amphiprotic (can both donate and receive protons). This gives it a wide range of uses in metabolic reactions
Chemical BondingThere are three major types of chemical bonding that you may come across in VCE biology:
Type of bonding | Description | Examples |
Covalent bond | Strong chemical bonding characterised by the sharing of pairs of electrons between atoms | - A peptide bond is formed between two amino acid molecules when the carboxyl group of one amino acid react with the amine group of the other
- Disulfide bond in the tertiary folding of some proteins
- In DNA between the phosphate group and the deoxyribose 'backbone'
- In H2O
|
Hydrogen bond | Bond between the water atom of one molecule to the hydrogen of another; weaker than covalent or ionic bonds | Hydrogen bonding occurs in both inorganic molecules such as water and organic molecules such as DNA between the nitrogenous base pairs |
Ionic bond | Strong bonding, where one or more electrons from one atom are remove and subsequently attached to another atom. This results in positive and negative ions, which are attracted to one another | Na+ and Cl- bond to form NaCl (table salt) |
PolymerisationKey reactions are required to take place in the synthesis or breaking down of a biomacromolecule.
Condensation, or "condensation polymerisation" is a chemical process in which two molecules join together to form a larger, more complex molecule. With each new bond formed, one unit of H
2O is eliminated. Here is a generic condensation polymerisation reaction, note the elimination of
two water molecule is this case:

The bracketed product simply represents that it is a repeated monomer in a polymer chain.
Condensation polymerisation is the basis for the synthesis of all important biomacromolecules from their polymer subunits. It can also be referred to as 'dehydration synthesis'.
Hydrolysis can be considered the 'opposite' of condensation polymerisation; it involves the addition of water to a polymer, which in turn dissociates into a simpler form, along with the water molecule splitting into H
+ cations and OH
- anions. Here is a generic hydrolysis reaction. Note the effect water has on the reactant molecule:

To completely hydrolyse a carbohydrate polymer that is 100 monomer units long, 99 molecule of water would be required.
CarbohydratesCarbohydrates can be classed as 'simple' or 'complex'. Simple carbohydrates are monosaccharides (one sugar unit) and disaccharides (two sugar units), while complex carbohydrates are polysaccharides (3 or more sugar units). The table below lists some common carbohydrates:
Carbohydrate | Purpose in cell | Image of structure |
Glucose | Immediate source of energy storage |  |
Sucrose | Carbohydrate transport in plants |  |
Cellulose | Structural basis of plant cells |  |
Starch | Main energy-storage carbohydrate in plants |  |
Glycogen | Storage carbohydrate in liver and muscle tissue |  |
Inulin | Storage polysaccharide in plants |  |
Below is a structural carbohydrate known as chitin; it forms the cell wall of all fungi, as well as the exoskeleton of certain animals such as the lobster.
Chitin is described as a 'derivative' of cellulose - it is formed from the same subunits as cellulose. The only difference is in the bonding; but this is a major difference - as it leads to the synthesis of an entirely different type of carbohydrate. The case is the same for pectin and cellulose; same monomer units, different bonding - therefore different carbohydrate.
ProteinsProteins are natural polymers, formed from amino acid monomers joined together by peptide bonds (also known as peptide or amide linkages).
Each amino acid has three major components:
- An 'amine group' (left side of diagram - NH2)
- An 'R-variant group' (middle of diagram, excluding the hydrogen - R)
- A 'carboxyl group' (right side of diagram - COOH)
A dipeptide is two amino acids joined by a single peptide bond.
A polypeptide is made up of many amino acids joined together by peptide bonds.
A peptide bond is a form of covalent bond formed between the carbon of the
carboxyl group and the nitrogen of an
amine group of another amino acid. This 'joining' eliminates a molecule of water; hence we can say that a peptide bond arises through the process of condensation polymerisation.
There are four types of protein structure:
1.
Primary structure: The linear sequence of amino acids (or, the 'amino acid chain').
2.
Secondary structure: The shape of the protein molecule caused by hydrogen-bonding between -C=O and -N-H groups within the amino acid chain.
Secondary structures have three main classifications:
Classification | Example | Diagram |
Alpha-helix (α-helix) | Wool |  |
Beta-pleated sheet (β-pleated sheet) | Silk |  |
Random coil | Myoglobin |  |
3.
Tertiary structure: The result of interactions between R-variant groups that cause folding and bending of the protein molecule. These interactions may be as a result of hydrogen-bonding, covalent bonding or ionic bonding (via salt bridges). For example, when two cysteine amino acids in an amino acid chain attract each other, a disulfide bond forms between them, and this results in the bending of the amino acid chain:
Many proteins simply exist in tertiary form, and do not undergo further development into a quaternary structure.
4.
Quaternary structure: The result of further interaction between protein subunits that lead to a larger, 'aggregate-like' conglomerate of proteins. Quaternary structures have three main classifications:
Classification | Examples |
Fibrous (or structural; insoluble) | Collagen, elastin, keratin, myosin |
Globular (soluble) | Neurotransmitters, ATP synthase, some hormones, immunoglobulin |
Conjugated (combined with other substances | nucleoproteins (when combined with nucleic acids), glycoproteins (combined with less than 4% carbohydrates - e.g. antibodies) |
The Diversity and Specificity of ProteinsWith proteins, the possibilities are endless. For example, given that there are 20 amino acids; if I had 300 free amino acids with which to construct a protein, and no restriction on order, I could create ~2.04x10
390 different proteins. Obviously, there are some caveats in protein synthesis such as RNA STOP codons (we'll get to those later), but the number is still significant.
Because of this diversity, specificity (probably the most important word in VCE biology) is exhibited through protein interactions with substrates and other biomolecules. Three specialised types of proteins that function in accordance with specificity are:
- Enzymes - biological protein catalysts that speed up reactions by lowering the activation energy needed to initiate said reaction. Enzymes can either separate or put together a substrate(s) via chemical reactions that occur at the active site of the enzyme. Here's where specificity comes into play; each and every enzyme has a uniquely-shaped active site, which interacts with a single, unique type of substrate. We'll discuss enzymes a little later on.
- Immunoglobulins - glycoproteins that are also known as 'antibodies'. There are unique antibody receptors on the surface of white blood cells, which exhibit specificity by binding to a specific antigen and assist in the detection and removal of said antigen. There are also specific antibodies that are synthesised and secreted by particular white blood cells, which bind to specific antigens to impede their movement. We'll look at the immune system and immunoglobulin later on.
- Hormones - part of the endocrine system, hormones are chemical messengers produced in endocrine glands. They transmit their messages by binding to specific receptors , which in turn commences an 'endocrine pathway' that leads to a response. We'll discuss the effects of hormones further when we explore homeostasis.
Sensitivities of ProteinsProteins function properly only in proper conditions. There are a wide range of factors that can cause inactivation and even denaturation of the protein's structure. For example, if an enzyme is denatured, its active site is altered and it can no longer carry out its specific function.
Factor that can cause the denaturation of a protein include pH, temperature, and the medium in which a protein exists (for example, alcohol can cause protein denaturation).
The (rudimentary) graph below demonstrates the relation between temperature and protein denaturation:
Nucleic AcidsThere are many forms of nucleic acid; these include DNA, mRNA, tRNA, rRNA, ATP, ADP, NADH, NADPH etc. etc. Below is a diagram of DNA:
Tiny side note in spoiler: Spoiler
The sugar molecule of DNA, deoxyribose, has five carbons and is arranged in a pentagonal form (refer to the diagram below). Those who are not doing chemistry may not know that when drawing molecules, two lines meeting at a point indicates a carbon. In DNA, we call the 5 carbons present "prime", counting rightwards from the oxygen molecule at the top:
For example, if I were to refer to the carbon directly to the right of the oxygen, I would call it the 1' carbon (said "one-prime carbon")
A strand of DNA or RNA consists of nucleotides linked together by
phosphodiester bonds.
A phosphodiester bond exists between the phosphate of one nucleotide and the 3' carbon of the next nucleotide. This forms a 'backbone' of alternating deoxyribose and phosphate molecules, which provides overall structure to the DNA molecule. This is also the case in RNA, but the sugar sub-unit is ribose rather than deoxyribose.
Antiparallel StrandsThe two strands of DNA in a double-helix run in antiparallel directions. A strand of DNA can have either the direction 3'-5' or 5'-3', but irrespective of whatever orientation one strand has, the other stand in the helix
MUST be the other. For example, in a DNA double-helix, Strand 1 runs 5'-3'; ergo Strand 2 runs 3'-5'.
The end of the strand with a free phosphate (refer to diagram above) is the
5' end because that phosphate molecule is bonded to the 5' carbon of the deoxyribose unit.
Conversely, the end with a free -OH (hydroxide) group is the
3' end, as the hydroxide group is bonded to the 3' carbon of the deoxyribose molecule.
In DNA replication, the new strand is constructed in a 5' to 3' direction.Protein Synthesis - Transcription and TranslationNOTE: Protein synthesis is covered in much greater detail in Unit 4.Protein synthesis is a two-step process;
transcription, where the coded information for the construction of the protein is copied from a DNA template strand into mRNA (messenger RNA):
and
translation, where the mRNA codons are decoded into a polypeptide chain consisting of a specific sequence of amino acids using complementary tRNA (transfer RNA) anticodons. Translation is facilitated by the ribosome (rRNA):
RNARNA is 'ribonucleic acid'. A massive number of different types of RNA exist, but for the purpose of learning about protein synthesis in Unit 3 VCE biology, we only focus heavily on the following three types:
Abbreviation | Name | Function | Diagram |
mRNA | Messenger RNA | Acts as an RNA copy of the DNA template strand; its codons are complementary to the DNA triplet sequences of the template strand |  |
tRNA | Transfer RNA | Carries amino acids specific to the tRNA molecule's anticodon sequence (this can be referred to as a tRNA-amino acid complex). Transports the amino acid to the ribosome for translation |  |
rRNA | Ribosomal RNA | Component of the ribosome, which facilitates the process of translation |  |
Structurally, an RNA nucleotide consists of:
- A ribose sugar unit
- A phosphate unit
- A nitrogenous base (A, U, C, G in RNA)
Usually, RNA is single-stranded. We will briefly look at dsRNA (double-stranded RNA) when we study RNAi (RNA interference) in Unit 4.
In an exam, you may be asked to convert a DNA triplet sequence into an RNA codon sequence, and potentially identify the nature of the polypeptide chain produced. You will do so using this table:
As is apparent from the table, some RNA codons code for the same amino acid. This is important later on when we discuss silent genetic mutations.
It is important to recognise two aspects of an amino acid chain:
- Every polypeptide sequence begins with the amino acid methionine (Met). From the table, you can see that the mRNA codon that codes for Met is 'AUG'. From this information, what was the triplet that coded for methionine? What is the tRNA anticodon that codes for methionine?
Spoiler
DNA triplet = TAC
tRNA anticodon = UAC
- There are certain mRNA codons that code for "Stop". This means that the construction of the polypeptide sequence is terminated here; there is no "Stop" amino acid.
LipidsThere are three main types of lipids relevant to the VCE course:
- Triglycerides
- Phospholipids
- Fatty acids
Triglycerides are known as 'neutral fats'. They are composed of
glycerol (a type of alcohol with a hydroxyl group on each of its three carbons) and
three fatty acids.
In the image below, one can see the glycerol molecule (at left) bonded to three fatty acid 'tails'.
The main distinction between fats and oils is whether they're solid or liquid at room temperature. This is determined by the differences of the structures of the fatty acids they contain.
Fats = saturated lipids
Oils = unsaturated lipids
Our cell membranes are mostly
phospholipids arranged in a 'bilayer' with the hydrophobic (water-hating) fatty acid 'tails' facing inwards and the hydrophilic (water-loving) 'head' facing outwards, as shown below:
Cholesterol is a type of lipid known as a steroid. Other steroids are testosterone and oestrogen. In the 'fluid-mosaic model' of the phospholipid bilayer, cholesterol molecules provide structural support as well as making the area near that molecule less permeable to H
2O molecules.
The plasma membrane of the cells of a polar bear have a large number of embedded cholesterol. This is required because of the frigid environment in which the polar bear lives. The cholesterol molecules prevent crystallisation of hydrocarbons in the membrane as well as presenting phase transition (in this case, the freezing of the membrane).
Liposomes are artificial vesicles composed of a phospholipid bilayer. They are used as a means of artificially delivering nutrients and pharmaceutical drugs:
This concludes theory for biomacromolecules. Next up, 'Membranes and Cell Organelles'!
Part 2 - Membranes and Cell OrganellesBest of luck for the year ahead!