Frequently Asked Questions
The following questions have been raised during the implementation of the Study Design:
What is included in synthesis of biomacromolecules in Unit 3 Area of Study 1 (first bullet point, p. 22)?
Synthesis of biomacromolecules includes the starting molecules (the monomer) and the finishing material (the polymer) for polysaccharides, nucleic acids and proteins.
Is transcription and translation included in Unit 3 Area of Study 1 as part of structure and function of DNA and RNA?
DNA and RNA are nucleic acids. Nucleic acids store information as base pairs. Students need to know which base pairs are complementary and which are the monomers of DNA and RNA. They also need to know the general concept of primary, secondary, tertiary and quaternary structure of proteins.
Details of Transcription and translation are included in Unit 4 Area of Study 1 Heredity, page 27.
What should I cover about DNA in Unit 3?
In Unit 3 Outcome 1 (p. 22 of the study design) students should understand the structure of DNA a polymer made from monomers and that its functions as a store of information to code for proteins.The nucleus holds the genetic code in its base sequence. The code is carried to ribosomes by mRNA which is complementary to the DNA codons. There the code specifies the order of amino acids to form polypeptides that are converted into proteins by folding and cross-chain bonding. The genetic code is based on the base pairs that form the code.
Students should understand that three bases in sequence (a triplet) code for a particular amino acid. A gene can be defined as a sequence of triplets.
The process by which the code assembles the amino acids is gene expression. The mechanism of gene expression involves transcription and translational. Knowledge of gene expression (transcription and translation) is required in Unit 4 Outcome 1 (p. 27 of the study design).
How can I assist my students to understand the chemical nature of the cell?
In Unit 3 Outcome 1 (p. 22 of the study design) the understanding of the chemical nature of the cell requires students to have an overview of the structure and function of the cell. Students are required to focus on the basic structure and function of four classes of biomacromolecules: proteins, polysaccharides, nucleic acids and lipids.
Students should understand that these large molecules are produced by the cell from smaller molecules. Proteins, nucleic acids and polysaccharides are polymers, formed by the chemical bonding of monomers in a condensation polymerisation reaction that involves the use of ATP. Lipids are important macromolecules but are not polymers.
The basic structure of the monomers-amino acids, nucleotides, and glucose and the functional groups that give them specific chemical characteristics should be understood but isomeric forms of glucose are not required.
In Unit 3 Area of Study 1: What is included in the role of plasma membrane in transport of biomolecules (part of second bullet point p. 22)?
The role of plasma membranes in transport includes its function in diffusion, osmosis, active transport, exocytosis and endocytosis.
What should my students understand about organelles?
In Unit 3 Outcome 1 (p. 22 of the study design) students should understand organelles are involved in packaging and transport of biomolecules. This includes nucleus, ribosomes, endoplasmic reticulum, golgi bodies and vesicles. They should also understand that chloroplasts are organelles and where the different stages of photosynthesis take place. Students should understand mitochondria and its role in aerobic cellular respiration.
Are NADP, Calvin and Krebs’s cycle included in Unit 3 Area of Study 1 Molecules of life (p. 22)?
The main stages and their names (Calvin, Kreb’s) are required for photosynthesis and cellular respiration. No details of the biochemical pathways are required; however, the inputs and outputs of each should be known in general terms.
The role of the ATP/ADP cycle in biochemical pathways is required.
What examples of the applications of molecular biology in medicine could I teach in Unit 3?
In Unit 3 Outcome 1 (p. 22 of the study design) students should understand how the principles of molecular biology are applied, for example cell mechanisms, transport of molecules and the techniques used. One example in the study of applications of molecular biology is Relenza. It arose from Australian (CSIRO) research. It operates at a molecular level by blocking the action of an enzyme found on the surface of the flu virus. The development of a variety of vaccines by Australian scientists could also be studied. For example, the work by Professor Ian Frazer in developing a vaccine against the papilloma virus that causes many cases of cervical cancer.
What do my students need to understand about signalling molecules?
In Unit 3 Outcome 2 (p. 23 of the study design) students should understand the role of signalling molecules including neurotransmitters, hormones, pheromones and plant growth regulators. They should also understand that cells produce a response to the signal. There are two types of hormone signalling molecules. They are steroid hormones and amino acid and polypeptide-based hormones.
How do I teach the principles of homeostasis?
In Unit 3 Outcome 2 (p. 23 of the study design) students should understand the principles of homeostasis including the stimulus-response model and negative feedback model and the roles of the nervous and endocrine systems.
What level of detail is required on receptors?
In Unit 3 Outcome 2 (p. 23 study design) students need to understand that there are protein receptors and receptors of steroid based chemical signals and how these are related to plasma membranes. They need to understand how hormones determine how the signalling system operates when the hormone reaches its target cells. Overall, the signal is received, either at the membrane or inside the cell followed by signal transduction and the response by the cell. Students should be able to apply the principles of homeostasis to different contexts.
What do my students need to know about apoptosis?
Apoptosis is included as part of Unit 4 Area of Study 1 (fourth bullet point). Apoptosis can be defined as ‘genetically programmed cell death’ in which the death of a cell is controlled by influences either inside or outside the cell. Cells that are damaged and no longer functioning normally may be destroyed by apoptosis. Healthy cells may also undergo apoptosis if they are no longer required by the organism.
Cells undergoing apoptosis exhibit changes very different from those of cells dying from necrosis, reflecting the controlled nature of apoptosis. Apoptosis eliminates cells without releasing dangerous molecules like proteases and glutamate that might harm neighbouring cells. In contrast, necrosis is the death of a cell by damage in which chemicals released by the dying cell may be lethal to surrounding cells.
During apoptosis, mitochondria receive the death signals and produce enzymes that break down cell components. In most cells, enzymes cut DNA into unequal pieces. This DNA degradation may have evolved as a defence against viruses that attempt to establish residence within cells. Cells dying through apoptosis release chemicals that induce surrounding cells to collect and re-use their parts to construct new cells.
Apoptosis is an essential process in the construction of several organs and tissues. For example, a fetal human hand (or foot), that initially looks like a mitten is converted into a hand (or foot) by the death of cells between the developing digits. Apoptosis is also involved in body maintenance during adult life, for example the removal of immunological cells, no longer needed after recovery from an infection.
(Teachers may also choose to use apoptosis as an example of signalling molecules and signal transduction in Unit 3 Area of Study 2.)
Are linked genes, crossing over, recombinations and gene mapping included in Unit 4 Area of Study 1 Heredity (sixth bullet point, p. 27)?
Sex linked inheritance relates to a single character (i.e. a gene) only on a sex chromosome.
Dihybrid crosses concerns two genes carried on different pairs of chromosomes (the principle of independent assortment only).
Crossing over occurs in meiosis and that crossing over is one of the causes of variation.
Crossing over results in recombinations. Students will be expected to understand recombination of two linked genes only. Students will NOT be expected to calculate the percentage of recombinants nor determine a gene map.
The Hardy-Weinberg law is not required.
Do my students need to know and use the term hominin as well as hominid?
When studying hominid evolution (eighth bullet point page 28 study design) students will encounter the term hominin and when answering relevant questions on Examination 2 will be expected to be familiar with and use both terms correctly as outlined below.
The taxonomic family Hominidae refers to the great apes (chimpanzees, gorillas and orangutans) and includes humans. Hominin refers to modern and extinct humans and their erect-walking ancestors including, for example, Australopithecus , Kenyanthropusand Homo genera. Under some older taxonomic classifications, hominin is used instead of hominid to refer to humans and humanlike ancestors and to describe the early humans now called Hominins. When the classification system changed to include apes in the human lineage (Hominidae), the term Hominid came to include apes and humans.
The term Hominin is used today, when talking about the human lineage and its ancestors. These changes in taxonomy have arisen from fossil, biochemical and genetic data. For further information: www.amonline.net.au/human_evolution/about.htm
Is Paranthropus a separate genus of hominids?
Yes, Paranthropus is now considered a separate genus of the family Hominade. It encompasses what used to be robust Australopithecines but now deemed to be different enough to have their own genus. For example, what used to be calledAustralopithecus boisei is now Paranthropus boisei.