Biology Unit 3: How do Cells Maintain Life?
Students are advised to complete Biology Units 1 and 2 before undertaking Biology Unit 3.
In this unit, students investigate the workings of the cell from several perspectives. They explore the importance of the insolubility of the plasma membrane in water and its differential permeability to specific solutes in defining the cell, its internal spaces, and the control of the movement of molecules and ions in and out of such spaces. Students consider base pairing specificity, the binding of enzymes and substrates, the response of receptors to signalling molecules and reactions between antigens and antibodies to highlight the importance of molecular interactions based on the complementary nature of specific molecules.
Students study the synthesis, structure and function of nucleic acids and proteins as key molecules in cellular processes. They explore the chemistry of cells by examining the nature of biochemical pathways, their components and energy transformations. Cells communicate with each other using a variety of signalling molecules. Students consider the types of signals, the transduction of information within the cell and cellular responses. At this molecular level students study the human immune system and the interactions between its components to provide immunity to a specific antigen.
Areas of Study
How do cellular processes work?
In this area of study, students focus on the cell as a complex chemical system. They examine the chemical nature of the plasma membrane to compare how hydrophilic and hydrophobic substances move across it. They model the formation of DNA and proteins from their respective subunits. The expression of the information encoded in a sequence of DNA to form a protein is explored and the nature of the genetic code outlined. Students use the lac operon to explain prokaryotic gene regulation in terms of the switching on and switching off of genes.
Students learn why the chemistry of the cell usually takes place at relatively low, and within a narrow range of, temperatures. They examine how reactions, including photosynthesis and cellular respiration, are made up of many steps that are controlled by enzymes and assisted by coenzymes. Students explain the mode of action of enzymes and the role of coenzymes in the reactions of the cell and investigate the factors that affect the rate of cellular reactions.
How do cells communicate?
In this area of study students focus on how cells receive specific signals that elicit a particular response. Students apply the stimulus-response model to the cell in terms of the types of signals, the position of receptors, and the transduction of the information across the cell to an effector that then initiates a response. Students examine unique molecules called antigens and how they elicit an immune response, the nature of immunity and the role of vaccinations in providing immunity. They explain how malfunctions in signalling pathways cause various disorders in the human population and how new technologies assist in managing such disorders.
|Explain the dynamic nature of the cell in terms of key cellular processes including regulation, photosynthesis and cellular respiration, and analyse factors that affect the rate of biochemical reactions.
A report related to at least two practical activities from a practical logbook.
- An investigation of cellular respiration or photosynthesis.
- An investigation of enzyme action.
- An investigation of the movement of substances across membranes.
|Apply a stimulus-response model to explain how cells communicate with each other, outline human responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.
At least one task selected from:
- a report of a practical activity.
- annotations of activities or investigations from a practical logbook.
- a graphic organiser.
- a bioinformatics exercise.
- an evaluation of research.
- media response.
- data analysis.
- a response to a set of structured questions.
- problem-solving involving biological concepts, skills and/or issues.
- a reflective learning journal/blog related to selected activities or in response to an issue.
Overall Final Assessment
||Contribution to Study Score (%)
||Unit 3 Coursework
||Unit 4 Coursework
Reproduced by permission of the Victorian Curriculum and Assessment Authority, Victoria, Australia: www.vcaa.vic.edu.au