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VCE Biology Implementation Frequently Asked Questions Question: Are students expected to know specific biomacromolecule structures? Answer: It is expected that students will recognise a limited number of biomacromolecular structures. Students are expected to recognise diagrammatic representations of glucose, identify glucose as a monomer of polysaccharides and other carbohydrates, and understand the mechanism of the condensation reaction (that is, a water molecule is lost when a monomer is added to another monomer or a polysaccharide structure). For lipids, students are expected to recognise diagrammatic representations of fats (triglycerides) and phospholipids, and identify the role of phospholipids in the cell membrane. Students should understand that the formation of triglycerides involves condensation reactions. Although the role of cholesterol in the plasma membrane should be understood, the specific chemical structure of cholesterol is not required. Students are expected to understand that polypeptides and proteins are polymers of amino acids, formed through condensation reactions. They are also expected to understand that the primary structure of a polypeptide or protein is the sequence of amino acids that form the polypeptide or protein, and that the way that polypeptides and proteins are folded, coiled or pleated can be described by secondary (within the chain) and tertiary (overall chain shape) structures, and that those proteins made up of two or more polypeptide chains may be described by a quaternary structure. Students are expected to identify α-helices and β-pleated sheets as being the most common secondary structures. They are expected to understand that the shape of a protein determines its properties and that protein denaturation through changes in temperature, changes in pH or reaction with various chemicals may lead to a loss of biological function. Classifications of, and differences between, different types of proteins such as globular and fibrous proteins are not required. The names for the specific types of bonds (for example, glycosidic, peptide) or bonding (for example hydrogen, covalent, disulfide) in carbohydrates, lipids, proteins and nucleic acids are not required. Students are expected to recognise the monomers of DNA and RNA and identify complementary base pairs. The structures of more complex molecules such as carotenoids and specific glycoproteins and glycolipids are not required. Question: Which processes should be considered in the movement of substances across membranes? Answer: Diffusion, osmosis, active transport, facilitated diffusion, endocytosis and exocytosis are required in Unit 3. Although simple diffusion, active transport and facilitated diffusion are introduced in Unit 1, they are also relevant in Unit 3, in particular with respect to protein transport, movement of neurotransmitters across a synapse and the movement of other substances important in cellular processes such as photosynthesis and cellular respiration. Exocytosis and endocytosis are also important in both Units 3 and 4 as they are relevant to events including the release of signalling molecules, secretion of antibodies from plasma cells and the phagocyticity of macrophages and neutrophils. VCE BIOLOGY Question: To what extent does homeostasis need to be covered in Unit 3? Answer: In Unit 3, coordination and regulation are considered at the cellular, rather than whole organism, level. Hence, references to homeostasis and feedback mechanisms have been deleted from Unit 3. The treatment of homeostasis at a systems level, including feedback mechanisms, involving hormonal control (for example, regulation of blood glucose), water balance and temperature control, is included in Unit 2 Biology. Question: How much detail is needed for signal transduction? Do different types of cascades need to be covered? What about secondary messenger molecules? Answer: Students are expected to understand the process of signal transduction involving lipid-based and protein-based signalling molecules in general terms. Differences between paracrine, autocrine and other specific types of signalling are not required. Details of specific chemicals, reaction mechanisms or cascade reactions are not required. Signal transduction can be considered in terms of a stimulus-response model and should be described, in simple terms, as a three-step process: reception (information is received by a cell’s receptor), transduction (information from the receptor is passed on to an effector) and induction/response (various cellular responses are initiated). Lipid-based (water insoluble, lipid soluble) signalling molecules are able to pass straight through the cell membrane to bind onto receptors within the cytosol to initiate transduction. Protein-based (water soluble, lipid insoluble) signalling molecules, which are unable to pass through the cell wall, bind to receptors on the surface of the cell membrane, thereby activating a second messenger within the cytosol to initiate transduction. Names of second messengers are not required and G protein pathways do not need to be defined. Transduction for both lipid-based and protein-based signalling molecules involves a cascade of reactions that amplify the initial message, and can lead to a range of cellular responses. Teachers are advised that they may use specific examples of signal transduction mechanisms, such as those described in the expert paper on signal transduction, in the VCE Biology section of the VCAA website, or those published in textbooks and online web resources, to illustrate the general principles of signal transduction. Signalling molecules, specifically neurotransmitters, animal hormones, pheromones and plant growth hormones, should be distinguished at a functional (rather than a structural) level, but teachers may also elect to use one or more of these to illustrate the process of signal transduction. Apoptosis may also be explained in terms of signal transduction, and intrinsic and extrinsic causes of this process are expected to be identified by students. The distinction between different types of growth regulators (auxins, cytokinins, gibberellins, abscisic acid and ethylene) are not required, although teachers may use one or more of them to illustrate a particular signal transduction pathway. Question: Do I need to teach about action potentials in nerve pathways? What about the interference of nerve messages by drugs and toxins? Answer: Details related to the mechanism of the transmission of an action potential through an axon in terms of specific ionic changes are not required. Students are expected to understand the roles of the nerve pathway, neurotransmitters and chemical signals in the transmission of information. Mechanisms of action such as the mechanism of polarisation, depolarisation, repolarisation, hyperpolarisation and resting potential in terms of ion movement are not required, nor are details related to the mechanism of interference of nerve messages by drugs and toxins. However, students are expected to understand in general terms that there are some membrane proteins that allow the passage of ions that would ordinarily be stopped by the lipid bilayer of the membrane, and that electrical transmission through an axon is © VCAA, July 2013 2 VCE BIOLOGY facilitated by Na+/K+ pumps on the membrane. They are also expected to know that Ca 2+ ions are involved in neurotransmitter release into a synapse, with further details not required. Students are expected to recognise that nerve transmission is an ‘all-or-nothing’ response, that electrical transmission occurs through the axon, that there is a ‘refractory’ or ‘resting’ period during which the neuron does not respond to incoming stimuli, and that the impulse is transmitted across a synapse to another neuron via neurotransmitters. Students are expected to understand that different proteins serve as receptors for different neurotransmitters; specific names of neurotransmitters are not required. Question: Do I need to teach about interleukins, or multicellular parasites and their life cycle? Answer: No, although teachers may choose to use parasites as contexts for illustrating biological concepts. Question: Are we still expected to teach active and passive immunity? What about immunisation and booster shots? Answer: Yes, all are required. Question: The study design refers to the ‘… nature and production of vaccines and antibody serums …’. Does this refer to the commercial production of these materials? Answer: No. As in the previous study design, students are expected to understand the role of artificial materials, specifically vaccines and antibody serums, in an acquired immune response. Question: Have the factors affecting the rate of photosynthesis been deleted from Unit 3, Outcome 1? Answer: Yes. It should be noted that the dot point in the previous study design ‘factors affecting rate of energy transformations’ has been deleted from the current study design. Further, there is a specified focus on ‘requirements for photosynthesis’ with specific direction as to what is to be studied in the ‘dot point’ (refer to page 22 of the study design). Question: Is incomplete/partial dominance included in Unit 4? Answer: No. Monohybrid crosses are restricted to dominant/recessive and co-dominant patterns of inheritance. Question: Are students expected to deal with dihybrid cross ratios? Answer: Yes. Determination of ratios, including dihybrid test crosses, enables decisions to be made regarding whether genes assort independently according to Mendel’s second law or whether they are linked. Question: Are map units and gene mapping included in Unit 4? Answer: No. Question: With the discontinuation of mid-year examinations, are we now able to rearrange the content of Units 3 and 4 so that some content in Unit 4 is taught in Semester 1 and some content in Unit 3 is taught in Semester 2? Answer: Results for School-assessed Coursework and satisfactory completion of Unit 3 Outcomes must be reported early in Semester 2, as per the Important Administrative Dates for each year, which are published on the VCAA website: www.vcaa.vic.edu.au/pages/schooladmin/admindates/index.aspx. © VCAA, July 2013 3 VCE BIOLOGY However, teachers may wish to draw on relevant conceptual links from Unit 4 in the delivery of Unit 3 outcomes. Similarly, drawing on Unit 3 concepts when delivering Unit 4 outcomes serves to strengthen conceptual understanding and make links between different concepts. Question: Are students able to use diagrams, rather than or in addition to, text when answering examination questions? Answer: Yes, if appropriate. All diagrams used should be clearly and fully labelled. © VCAA, July 2013 4