Biology is the study of the fascinating diversity of life as it has evolved and as it interacts and functions. Investigation of biological systems and their interactions, from cellular processes to ecosystem dynamics, has led to biological knowledge and understanding that enable us to explore and explain everyday observations, find solutions to biological issues, and understand the processes of biological continuity and change over time.


Structure of Biology

Biology is the study of the fascinating diversity of life as it has evolved and as it interacts and functions. Investigation of biological systems and their interactions, from cellular processes to ecosystem dynamics, has led to biological knowledge and understanding that enable us to explore and explain everyday observations, find solutions to biological issues, and understand the processes of biological continuity and change over time.


Links to Foundation to Year 10

The senior secondary Biology curriculum continues to develop student understanding and skills from across the three strands of the F-10 Australian Curriculum: Science. In the Science Understanding strand, the Biology curriculum draws on knowledge and understanding from across the four sub-strands of Biological, Physical, Chemical, and Earth and Space sciences.


Representation of Cross-curriculum Priorities

While the significance of the cross-curriculum priorities for Biology varies, there are opportunities for teachers to select contexts that incorporate the key concepts from each priority.


Achievement standards


Unit 4: Maintaining the internal environment

Unit 4: Maintaining the internal environment Description

In order to survive, organisms must be able to maintain system structure and function in the face of changes in their external and internal environments. Changes in temperature and water availability, and the incidence and spread of infectious disease, present significant challenges for organisms and require coordinated system responses. In this unit, students investigate how homeostatic response systems control organisms’ responses to environmental change – internal and external – in order to survive in a variety of environments, as long as the conditions are within their tolerance limits. Students study how the invasion of an organism’s internal environment by pathogens challenges the effective functioning of cells, tissues and body systems, and triggers a series of responses or events in the short- and long-term in order to maintain system function. They consider the factors that contribute to the spread of infectious disease and how outbreaks of infectious disease can be predicted, monitored and contained.

Through the investigation of appropriate contexts, students explore the ways in which models and theories of organisms’ and populations’ responses to environmental change have developed over time and through interactions with social, economic, cultural and ethical considerations. They investigate the ways in which science contributes to contemporary debate about local, regional and international issues, including evaluation of risk and action for sustainability, and recognise the limitations of science to provide definitive answers in different contexts.

Students use science inquiry skills to investigate a range of responses by plants and animals to changes in their environments and to invasion by pathogens; they construct and use appropriate representations to analyse the data gathered; and they continue to develop their skills in constructing plausible predictions and valid conclusions.

Unit 4: Maintaining the internal environment Learning Outcomes

By the end of this unit, students:

  • understand the mechanisms by which plants and animals use homeostasis to control their internal environment in a changing external environment
  • understand how plants and animals respond to the presence of pathogens, and the ways in which infection, transmission and spread of disease occur
  • understand how models and theories have developed over time, and the ways in which biological knowledge interacts with social, economic, cultural and ethical considerations in a range of contexts
  • use science inquiry skills to design, conduct, evaluate and communicate investigations into organisms’ responses to changing environmental conditions and infectious disease
  • evaluate, with reference to empirical evidence, claims about organisms’ responses to changing environmental conditions and infectious disease and justify evaluations
  • communicate biological understanding using qualitative and quantitative representations in appropriate modes and genres.

Unit 4: Maintaining the internal environment Content Descriptions

Science Inquiry Skills (Biology Unit 4)

Identify, research and construct questions for investigation; propose hypotheses; and predict possible outcomes (ACSBL096)

Design investigations, including the procedure/s to be followed, the materials required, and the type and amount of primary and/or secondary data to be collected; conduct risk assessments; and consider research ethics, including the rights of living organisms (ACSBL097)

Conduct investigations, including using models of homeostasis and disease transmission, safely, competently and methodically for valid and reliable collection of data (ACSBL098)

Represent data in meaningful and useful ways, including the use of mean, median, range and probability; organise and analyse data to identify trends, patterns and relationships; discuss the ways in which measurement error, instrumental accuracy, the nature of the procedure and sample size may influence uncertainty and limitations in data; and select, synthesise and use evidence to make and justify conclusions (ACSBL099)

Interpret a range of scientific and media texts, and evaluate models, processes, claims and conclusions by considering the quality of available evidence; and use reasoning to construct scientific arguments (ACSBL100)

Select, construct and use appropriate representations, including diagrams and flow charts, to communicate conceptual understanding, solve problems and make predictions (ACSBL101)

Communicate to specific audiences and for specific purposes using appropriate language, nomenclature, genres and modes, including scientific reports (ACSBL102)

Science as a Human Endeavour (Units 3 & 4)

ICT and other technologies have dramatically increased the size, accuracy and geographic and temporal scope of data sets with which scientists work (ACSBL103)

Models and theories are contested and refined or replaced when new evidence challenges them, or when a new model or theory has greater explanatory power (ACSBL104)

The acceptance of scientific knowledge can be influenced by the social, economic and cultural context in which it is considered (ACSBL105)

People can use scientific knowledge to inform the monitoring, assessment and evaluation of risk (ACSBL106)

Science can be limited in its ability to provide definitive answers to public debate; there may be insufficient reliable data available, or interpretation of the data may be open to question (ACSBL107)

International collaboration is often required when investing in large-scale science projects or addressing issues for the Asia-Pacific region (ACSBL108)

Scientific knowledge can be used to develop and evaluate projected economic, social and environmental impacts and to design action for sustainability (ACSBL109)

Science Understanding


Examples in context

Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.

Modeling human thermoregulation

Computer models of human thermoregulation responses, including heat transfer, perspiration, respiration and blood flows, have been developed for use in the design of clothing and environments that aim to protect humans from hyper- and hypothermia (ACSBL103). Models of human thermoregulation can aid in the design of military chemical suits, industrial protective clothing, space suits, and environments such as space stations, aircraft, vehicles and buildings. Simulating and modeling the human thermoregulatory system also enable scientists to study and predict the effects of extreme environments on the human body, and to design safety regulations for people working in these environments, such as firefighters, pilots, foundry workers and soldiers (ACSBL106).

Use of hormones in the dairy industry

Use of growth hormones and other hormones is controversial in the livestock industry, with proponents arguing that they increase productivity, reduce the cost of production and improve food affordability. Recombinant bovine somatotropin (rBST) is a synthetically produced hormone that has been shown to increase milk yield. While proponents of rBST point to studies that show that milk products produced using rBST cannot be distinguished from other milk products, the Codex Alimentarius Commission, a United Nations body that sets international food standards, has to date refused to approve rBST as safe (ACSBL107). While the United States and other countries currently allow the use of rBST, countries such as Australia and New Zealand have banned it based on evidence that it increases the risk of health issues in cows and because of concerns regarding milk contamination (ACSBL106). This issue is significant in international trade of dairy products, prompting debate about appropriate labeling of milk products, international standards and reasonable import bans.

Snake antivenom production

Globally, hundreds of thousands of people die of snake bite each year, most of them in developing countries. The venom of many species of snake contains neurotoxins that cause paralysis. Antivenom is conventionally manufactured by ‘milking’ venomous animals, immunising large animals with small quantities of the collected venom and then extracting the antibodies produced in the animals’ blood. The process is risky and labour-intensive and the products are highly expensive, often provoke allergic reactions, and are difficult to transport and store, making availability of antivenoms a significant challenge in developing countries. Some organisations have called for global cooperation and investment by science, business and government bodies to increase the availability of antivenoms in the developing world (ACSBL108). Part of this challenge may be met by new research that has demonstrated it is possible to generate an antibody response using synthetic DNA which is injected into cells to produce a protein that closely resembles the most toxic parts of the actual venom (ACSBL109).

Homeostasis involves a stimulus-response model in which change in external or internal environmental conditions is detected and appropriate responses occur via negative feedback; in vertebrates, receptors and effectors are linked via a control centre by nervous and/or hormonal pathways (ACSBL110)

Changes in an organism’s metabolic activity, in addition to structural features and changes in physiological processes and behaviour, enable the organism to maintain its internal environment within tolerance limits (ACSBL111)

Neural pathways consist of cells that transport nerve impulses from sensory receptors to neurons and on to effectors; the passage of nerve impulses involves transmission of an action potential along a nerve axon and synaptic transmission by neurotransmitters and signal transduction (ACSBL112)

Hormones alter the metabolism of target cells, tissues or organs by increasing or decreasing their activity; in animals, most hormones are produced in endocrine glands as a result of nervous or chemical stimulation, and travel via the circulatory or lymph system to the target cells, tissues or organs (ACSBL113)

Endothermic animals have varying thermoregulatory mechanisms that involve structural features, behavioural responses and physiological and homeostatic mechanisms to control heat exchange and metabolic activity (ACSBL114)

Animals, whether osmoregulators or osmoconformers, and plants, have various mechanisms to maintain water balance that involve structural features, and behavioural, physiological and homeostatic responses (ACSBL115)

Infectious disease

Examples in context

Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.

Modeling disease outbreak and spread

The first mathematical models of the spread of disease were developed in the eighteenth century by Daniel Bernoulli, who created a model to predict increased life expectancy if populations were inoculated against smallpox. As these models preceded an understanding of germ theory, it was not until the early twentieth century that more reliable models were developed (ACSBL104). Contemporary models project how the disease will progress and simulate the effects of possible interventions. Such models are used to inform public health interventions such as mass vaccination programs. Supercomputing increased processing capacity and data storage has enabled models to increase in their complexity, with new variables examined and new relationships found, such as the relationships between epidemic frequency and location and factors such as population size, environmental change and antibiotic resistance (ACSBL103).

Managing pandemics in the Asia region

Epidemics and pandemics that are global or regional are becoming more prevalent, with outbreaks of diseases such as HIV/AIDS, diphtheria, malaria, measles and swine flu at a global level, and Severe Acute Respiratory Syndrome (SARS) and avian flu at regional levels. Asia has been described as particularly susceptible to epidemics and pandemics of infectious disease due to increasing migration and global travel, high population density in urban areas and underdeveloped healthcare systems in some countries. The high cost of drugs and vaccines presents a particular challenge for developing countries in Asia, as does community mistrust of vaccination (ACSBL105). International business has recognised the costs associated with global and regional epidemics and has advised that businesses, governments and international organisations should collaborate to help prevent infectious diseases among poor populations by strengthening regional and national pandemic preparedness planning and expanding public-private partnerships to increase drug and vaccine availability (ACSBL108).

Quarantine and biosecurity

As an island nation, Australia has had an advantage over many other countries because its borders are easier to protect against the influx of disease-carrying materials and organisms. However, as global trade and air travel become more prevalent, it is increasingly important for Australia to protect its agriculture industry and environment through quarantine measures. These include surveillance, monitoring, examination and clearance activities and conform to policies and protocols that are based on scientific data and risk analysis (ACSBL109). Quarantine policy is determined through bilateral and multinational negotiations and involves consideration of protection of Australia’s animal and plant health status, Australia’s international obligations, the trade impact of quarantine policies, and environmental protection (ACSBL108).

Infectious disease differs from other disease (for example, genetic and lifestyle diseases) in that it is caused by invasion by a pathogen and can be transmitted from one host to another (ACSBL116)

Pathogens include prions, viruses, bacteria, fungi, protists and parasites (ACSBL117)

Pathogens have adaptations that facilitate their entry into cells and tissues and their transmission between hosts; transmission occurs by various mechanisms including through direct contact, contact with body fluids, and via contaminated food, water or disease-specific vectors (ACSBL118)

When a pathogen enters a host, it causes physical or chemical changes (for example, the introduction of foreign chemicals via the surface of the pathogen, or the production of toxins) in the cells or tissues; these changes stimulate the host immune responses (ACSBL119)

All plants and animals have innate (general) immune responses to the presence of pathogens; vertebrates also have adaptive immune responses (ACSBL120)

Innate responses in animals target pathogens, including through the inflammation response, which involves the actions of phagocytes, defensins and the complement system (ACSBL121)

In vertebrates, adaptive responses to specific antigens include the production of humoral immunity through the production of antibodies by B lymphocytes, and the provision of cell-mediated immunity by T lymphocytes; in both cases memory cells are produced that confirm long-term immunity to the specific antigen (ACSBL122)

In vertebrates, immunity may be passive (for example, antibodies gained via the placenta or via antibody serum injection) or active (for example, acquired through actions of the immune system as a result of natural exposure to a pathogen or through the use of vaccines) (ACSBL123)

Transmission and spread of disease is facilitated by regional and global movement of organisms (ACSBL124)

The spread of a specific disease involves a wide range of interrelated factors (for example, persistence of the pathogen within hosts, the transmission mechanism, the proportion of the population that are immune or have been immunised, and the mobility of individuals of the affected population); analysis of these factors can enable prediction of the potential for an outbreak, as well as evaluation of strategies to control the spread of disease (ACSBL125)