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Unit 4: Surviving in a Changing Environment

13 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

What causes infectious disease and how do pathogens spread?

Classify pathogens and explain how infectious diseases are transmitted

Pathogens and disease. Covers types of pathogens, modes of transmission, the difference between infectious and non-infectious disease and how pathogens cause harm.

7 min read →

How do plants regulate water loss and respond to a changing environment?

Explain how plants maintain water balance and respond to environmental stimuli

Homeostasis in plants. Covers stomatal control of transpiration, the role of guard cells and abscisic acid, tropisms and adaptations of xerophytes.

7 min read →

How does vaccination protect individuals and populations from disease?

Distinguish types of immunity and explain how vaccination and herd immunity protect populations

Immunity and vaccination. Covers active and passive immunity, natural and artificial immunity, how vaccines work through memory cells, and herd immunity with Australian examples.

7 min read →

How do infectious diseases spread from one host to another?

Describe the modes of transmission of infectious disease and the factors that affect their spread

Disease transmission. Covers direct and indirect transmission, vectors, droplet and waterborne spread, and the factors affecting transmission rate with Australian examples.

6 min read →

How do plants respond to environmental stimuli without a nervous system?

Explain how tropisms and plant hormones such as auxin allow plants to respond to their environment

Plant responses. Covers phototropism, gravitropism and other tropisms, the role of auxin and its uneven distribution, and how these responses help plants survive.

6 min read →

How do animals maintain a stable internal environment as conditions change?

Explain how animals maintain homeostasis using negative feedback, with reference to thermoregulation and osmoregulation

Homeostasis in animals. Covers negative feedback, the stimulus-response model, thermoregulation, osmoregulation and blood glucose control.

8 min read →

How does the body keep blood glucose within a narrow range?

Explain how insulin and glucagon regulate blood glucose concentration by negative feedback

Blood glucose regulation. Covers insulin and glucagon, the role of the pancreas and liver, negative feedback, and the link to diabetes as a failure of control.

6 min read →

How do plants defend themselves against pathogens without an immune system like ours?

Describe the physical, chemical and active defences plants use against pathogens

Plant defences. Covers physical barriers, chemical defences, and active responses such as sealing off infected tissue, with Australian agricultural examples.

6 min read →

How does the body defend itself against pathogens?

Describe the lines of defence and explain the specific immune response and immunity

Immune response. Covers the three lines of defence, the humoral and cell-mediated responses, memory cells and types of immunity including vaccination.

9 min read →

How do health authorities predict, control and respond to disease outbreaks?

Explain the strategies used to predict and manage the spread of epidemics and pandemics

Managing epidemics. Covers surveillance and modelling, quarantine and isolation, contact tracing, vaccination programs and biosecurity, with Australian examples.

7 min read →

How do we track infectious disease and control its spread in populations?

Explain epidemiological terms and evaluate strategies used to control the spread of disease

Epidemiology and disease control. Covers epidemics and pandemics, transmission rate, herd immunity, quarantine, vaccination programs and antibiotic resistance.

8 min read →

How do animals maintain water and salt balance in their bodies?

Explain how the kidney regulates water and solute balance and removes nitrogenous waste

Osmoregulation. Covers water and salt balance, the role of the kidney and ADH, nitrogenous waste, negative feedback, and adaptations of Australian desert animals.

7 min read →

How do animals keep their body temperature within tolerable limits?

Explain how endotherms and ectotherms regulate body temperature using behavioural and physiological mechanisms

Thermoregulation. Covers endotherms and ectotherms, behavioural and physiological cooling and warming mechanisms, negative feedback control, and Australian animal examples.

7 min read →