Did you know HSC Biology students consistently rate Biology Module 5: Heredity as the toughest module in Year 12 Biology? 😮
So if you’re struggling to keep up or master the sharp twist into genetics, I’ve got your back.
I went from an average rank in Year 11 to coming 1st in the HSC Biology course — and YOU can do the same!
Drawing from our experience tutoring thousands of students at Art of Smart, I’ll share exactly what you need to know (with some advanced tips and tricks) to ace Module 5.
In this guide, you’ll get:
- The KEY concepts for each Inquiry Question that you need to memorise
- The critical MISTAKES to avoid across the syllabus dot points in Module 5
- Must-know acronyms I used to memorise content FAST
- My top 5 strategies for getting a Band 6 in the HSC Biology course
HSC Biology Module 5: Heredity General Overview
Topic 1: Reproduction
Topic 2: Cell Replication
Topic 3: DNA and Polypeptide Synthesis
Topic 4: Genetic Variation
Topic 5: Inheritance Patterns in a Population
How to Get a Band 6 in HSC Biology Module 5: Heredity
HSC Biology Module 5: Heredity General Overview
This module covers a lot of the essential aspects of genetics. You’ll be learning about the genetics of both plants and animals, and applying this understanding to processes in the real world.
The topics under this module include:
- Reproduction
- Cell Replication
- DNA and Polypeptide synthesis
- Genetic Variation
- Inheritance Patterns in a Population
If you’re looking for some learning resources for these topics, make sure you check out HSC Together which has FREE video resources on every single HSC Biology dot point so that you can grasp concepts and revise effectively!
Without further ado, let’s get into it!
Topic 1: Reproduction
Inquiry question: How does reproduction ensure the continuity of a species?
Depending on the organism, genetic information can be passed down either sexually or asexually.
You’re probably familiar with sexual reproduction, which involves combining a sperm and an egg in order to produce a new organism.
On the other hand, asexual reproduction involves one parent creating genetically identical offspring. There are 4 methods of asexual reproduction you need to be familiar with: binary fission, budding, spores and fragmentation.
To help me easily remember the 4 methods, I used the following table:
| Asexual Reproduction Method | Description | Example |
|---|---|---|
| Binary Fission | Imagine if people reproduced by splitting in half? It’d be a strange world, but bacteria do it all the time: | Bacteria |
| Budding | Or, instead, a small outgrowth may appear on the surface of a parent organism, eventually breaking off to form 2 individuals… see this classic example of hydra: | Hydra, Yeast |
| Spores | Meanwhile fungi produce reproductive cells (spores) that develop into a new organism without fusion to another cell. These spores are then released and dispersed by wind and water… | Fungi |
| Fragmentation | Finally, there’s fragmentation- where a part of the parent breaks off and grows into a new individual:  | Starfish, coral colonies, & sponges |
The other key areas you need to be familiar with are the processes of sexual reproduction, in particular, fertilisation, implantation and hormones throughout pregnancy.
To grasp these concepts, I created annotated diagrams like the one below, and I recommend you do the same:
Common Questions
A commonly tested question for this inquiry question is one that asks you to read and interpret graphs of fluctuating hormones throughout pregnancy.
Take this example from the 2023 HSC:
The question asks us to use the graph in order to name a hormone, describe its function and the trimester in which the peak occurs.
Here you will notice that Human Chorionic Gonadotropin (hCG) is steadily released throughout the first trimester of pregnancy (until Week 12). This maintains a structure called the corpus luteum, which strengthens the uterine lining and supports the implanted embryo. But, as you will see from the marked drop following week 12, hCG declines as the corpus luteum deteriorates and hormones are produced by the placenta instead!
When studying the hormones, it’s clearly crucial that you have an understanding of any notable rises and falls, and the reasons that caused them!
Topic 2: Cell Replication
Inquiry question: How important is it for genetic material to be replicated exactly?
This topic is arguably one of the more content heavy areas in Module 5 Biology and the entire syllabus more broadly. You will not only learn about the processes of mitosis and meiosis, but about how these systems maintain their integrity.
You’ll also dive deep into the complex mechanisms of DNA replication, with its sometimes imperfect process enabling us to both evolve but also get cancer (we’ll get to this topic in Module 8).
Mitosis and Meiosis
Cells divide in two ways, mitosis and meiosis.
A top tip that helped me nail down the processes of mitosis and meiosis is to compare them in a table, or draw them out side-by-side.
Pearson Education Biology Textbook also gives us a great resource:
A key acronym I used to memorise these phases- and for you to learn too – is ‘PMAT’. This stands for Prophase, Metaphase, Anaphase and then Telophase, with meiosis going through PMAT twice.
Although some students would just leave it at that, it’s important to add a level of nuance & detail to your response.
An important way of doing this is by incorporating relevant terminology — a serious game-changer that helped me achieve a Band 6 response (and which I’ve used to help countless others do the same!).
When outlining the process of meiosis, you almost certainly need to mention ‘Crossing Over’, ‘Independent Assortment’ and ‘Random Segregation’ as the 3 sources of variation, as well as the 2 phases — ‘reduction division’ and ‘separation division’ which result in the production of ‘four haploid gametes’.
The other aspect of this topic is DNA replication. Like mitosis, it’s an important process within the cell cycle. Its purpose is to ensure cells make a copy before dividing, so that each daughter cell has a complete copy of genetic information.
But first, what is DNA?
DNA (aka deoxyribose nucleic acid) is a molecule found in all living organisms, and many viruses. It stores genetic information in the form of genes, which can be used for the transmission of inherited traits.
DNA is a large molecule consisting of many repeated subunits, called nucleotides. Nucleotides are composed of 3 main parts: a (deoxyribose) sugar, phosphate, & a base. There are four nitrogenous bases: adenine, guanine, cytosine, and thymine.
DNA molecules are shaped in the form of a double-helix, each consisting of two DNA strands.
The DNA Replication Process
Replication is the process in which a double stranded DNA molecule is copied to produce two identical DNA molecules. During mitosis, one copy of DNA is passed to each daughter cell, which then acts as ‘templates’ for the creation of a new DNA strand.
This makes DNA replication a semi-conservative process, because it produces DNA molecules containing both one old and one new strand.
Common Questions
Many HSC trial questions either ask specifically about the enzymes involved in the replication process, or require you to mention them in order to achieve higher marks.
When trying to learn this process, organise the steps according to the relevant enzymes. add small sections of RNA primer to the template DNA. Having this memorised streamlines the process while ensuring sufficient detail in an exam!
For example, you would start off with the enzyme, Helicase, ‘unzipping’ the double stranded DNA. At a later step, RNA Primase would add small sections of RNA primer to the template DNA. Having this memorised streamlines the process while ensuring sufficient detail in an exam!
Topic 3: DNA and Polypeptide Synthesis
Inquiry question: Why is polypeptide synthesis important?
You are your proteins. Who does the grunt work of digesting your food? Proteins. Who carries oxygen around your body? Proteins. What keeps your brain up and running? You guessed it—proteins.
The central dogma of biology is that DNA replicates, is transcribed into RNA and translated into proteins!
Protein Synthesis can be broken down into 2 main steps: Transcription and Translation.
Transcription
Transcription is that first flow where genetic information is copied from DNA to mRNA. This process occurs in the nucleus, and you can think of it as making photocopies (mRNA) of the manual (DNA).
Translation
Once the mRNA strand is created, it enters the cytoplasm and attaches itself to the ribosome, where translation begins. Here, mRNA is converted into tRNA, allowing us to form a protein.
It’s important to know the structure of a tRNA molecule, which has an amino acid on one end and an anticodon (triplet of complementary bases) on the other end:
#1: Initiation
Translation begins when the start codon in the mRNA molecule is read by the ribosome (this is the base sequence, ‘AUG’).
This mRNA codon matches with a specific tRNA anticodon (here it would be ‘UAC’), which carries a specific amino acid (here, methionine)
Note, each original mRNA codon specifies the tRNA anticodon, which then determines the specific amino acid!
#2: Elongation
Now the ribosome continues to move the mRNA along. This brings more tRNA units, which each bring an amino acid.
Peptide bonds form between amino acids, lengthening the polypeptide chain.
(A ‘Polypeptide Chain’ just refers to the long chain of Amino Acids that are linked together by peptide bonds)
This process of elongating the polypeptide chain is shown below:
#3: Termination
But our polypeptide chain doesn’t continue forever! So, how does this process stop? As the mRNA is pushed along, eventually the ribosome will reach a STOP codon. This causes the polypeptide chain to be released from the tRNA molecule.
Finally, this polypeptide chain is either folded or combined with other polypeptide chains in order to form proteins!
It’s important to note that transcription and translation are moving processes that are constantly occurring in your body.
This can be a hard concept to grasp, and watching it happen is key to understanding it:
Topic 4: Genetic Variation
Inquiry question: How can the genetic similarities and differences within and between species be compared?
Genetic variation comes from both meiosis and outside the reproduction process.
In this topic under Biology Module 5, you’ll be modelling what happens to the genes of an organism when meiosis occurs. Variation comes from crossing over of homologous chromosomes, fertilisation and mutations.
Not all genes have the same ‘impact’ on an organism. They can be autosomal, sex-linked, co-dominant, incomplete dominant or have multiple alleles. To understand what happens in this process, we use Punnett squares and pedigrees.
Constructing Punnet Squares
A Punnett Square is a table you will use to predict the genotype and phenotype of offspring, when given the parents’ genotypes. Essentially, a Punnet Square represents all possible allele combinations that arise when two parents are bred.
A monohybrid (combination of alleles of one gene) Punnet Square generally looks like this:
This enables us to generate a ratio of genotypes, giving us the probability of getting a specific genotype when two individuals reproduce.
Remember, alleles of two parents must be alleles for the same gene- we can’t combine an allele for eye colour and an allele for hair colour!
I find the best way to familiarise yourself with Punnet Squares is practice constructing your own. Let’s work through an example:
Worked Example
In pea plants, green peas (G) are dominant to yellow peas (g). You cross a Green pea plant with genotype (Gg) and a Yellow pea plant with genotype (gg).
What are the possible genotypes and phenotypes of the offspring? What can we say about the probability of these genotypes using the resulting ratio?
As you’ll notice above, the only possible genotypes for the offspring are Gg and gg.
Since G is completely dominant over g, genotype ‘Gg’ produces green pea plants. Meanwhile, ‘gg’ has the recessive trait, and will produce yellow plants.
The ratio of Gg: gg is 1:1. This means that each offspring has a 50% chance of having the Gg genotype (and the green phenotype), and a 50% chance of having the gg genotype (hence being yellow).
Single Nucleotide Polymorphisms
Meanwhile, this topic also introduces methods for determining the frequency of characteristics in a population, such as through analysing Single Nucleotide Polymorphisms (SNPs, pronounced ‘SNIPs’).
SNPs are a single base pair variation found in >1% of the population (enough people have the variation for the gene to be a mutation), and can be identified by looking at trends in data.
Image from Nutrigenetics Specialists: What is a SNP?
These terms may not be familiar to you now, so it’s a good idea to make a word back for this topic!
Want to make sure you’ve mastered Module 5? Bookmark our Master List of HSC Biology Past Papers to test yourself!
Topic 5: Inheritance Patterns in a Population
Inquiry question: Can population genetic patterns be predicted with any accuracy?
This aspect of Module 5 Biology focuses on DNA sequencing and profiling. Never has it been so easy or cheap to sequence a genome.
DNA Sequencing determines the precise order of nucleotide bases (A,C, T or G) in a sequence of DNA. Scientists can use this to determine similarities and differences between two DNA samples, and identify which sequence changes may cause disease.
Meanwhile DNA profiling can be cheaper and less time consuming than DNA sequencing, although it provides us with less detailed information as a whole.
As opposed to giving us the order of DNA sequences for us to compare, DNA profiling compares the sizes of DNA sequences between different samples.
The Process of DNA Profiling
You’ll also be investigating data analysis. Numbers or quantification of experiments are critical to turning data from an experiment into something useful.
You’ll be looking at genetics by looking at large-scale collaborative projects, or simply just data from a wide range of people.
What can you find from these studies? You can find out what mutations a lot of people seem to have, how disease is inherited and patterns in DNA.
How to Get a Band 6 in HSC Biology Module 5: Heredity
Tip #1: Visualise Processes
For processes, a couple videos or a diagram should tell you more than words could. For comparisons, for example, between prokaryotic and eukaryotic DNA replication, you can use a table.
Don’t underestimate the power of a good video!
A site we recommend is from the National Human Genome Research Institute. It covers Transcription and Translation, genetic variation, cloning, heredity and much, much more!
Tip #2: Complete Past Papers
Practising answering questions is a great way to test your understanding of a topic in Module 5 Biology. It’s one thing to understand a concept, or memorise a video, and it’s another to explain it using the relevant criteria and scientific terminology.
If you need some practice papers and questions, check out the NESA Past Biology Papers Master List and module-specific practice questions!
Tip #3: Incorporate relevant terminology into your responses
Speaking from experience, the biggest difference in elevating responses into that Band 6 range is to incorporate as many relevant terms into your vocabulary.
Doing so shows the marker you know what you’re talking about, and often schools will include this as part of the marking criteria!
See above for examples of what this looks like.
Tip #4: Take an Interest in Your Depth Study
In Biology Module 5, you’re going to have to complete a depth study! This is an awesome chance for you to dig your teeth into a topic that interests you, and to get a sense of what university level Science is like!
If you’re starting to think about what topic you’re going to look into for your Depth Study, The Garvan Institute of Medical Research, a prestigious institution that tackles issues such as cancer, diabetes, obesity and other major diseases gives us a great guide to some topics of depth studies.
Key Areas for Revision…
Some key processes for HSC Biology Module 5: Heredity that you should definitely get down pat are:
- DNA replication
- Cell replication (meiosis/mitosis)
- Recessive/dominance
- Reproduction
- Transcription and Translation
- Mutations
Keep in mind that even just 5 minutes of study is better than none. You have plenty of time to learn concepts, so take it one step at a time.
Good luck for your studies with HSC Biology Module 5: Heredity!
Wondering where you can find guides to other HSC Biology Modules?
Check out other modules we’ve created guides for below:
- HSC Biology Module 6: Genetic Change
- HSC Biology Module 7: Infectious Disease
- HSC Biology Module 8: Non-Infectious Disease and Disorders
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Mia Manji is a Digital Editor and an experienced Biology Class Teacher at Art of Smart Education. She graduated as a HSC all-rounder in 2022, ranking 1st internally in three of her subjects. With an avid interest in Biology, Mia is passionate about fostering a love for learning while sharing her top tips and skills to help her students succeed. She is currently in her second year at the University of Sydney, undertaking a Bachelor of Science and Bachelor of Laws.
