In Train With The Stuff Of Life
The Age
Monday May 7, 2007
Biology is a study relevant to the rest of your life, writes Marjory Martin.
A SWEDISH friend, Ausma, was visiting Australia and while in Melbourne wished to ride on Puffing Billy, an old steam train that runs in the scenic Dandenong Ranges east of Melbourne. As the train puffed along its track we passed through a biologist's paradise and I was in the middle of events mirroring what you are expected to know and understand from your study in Unit 3 VCE.The plants dominate in this environment; layer upon layer, each species with the characteristics that best suit its place in the layering system. There were also animals and birds. Living organisms. All having the same basic structure - cells. Of course differences exist but each has a basic similarity. The outer boundary of the living tissue is the cell membrane. What is its structure? What are the "doors" that allow entry and exit from a cell? Do different kinds of molecules have different ways of entering and leaving? If so what are these differences? Is energy required for such movement? Plant cells also have a layer external to the cell membrane. It is non-living, called the cell wall, and is made of cellulose. What are the macromolecules that are common in all cells? What is the defining feature of each? What monomers make up these protein, lipid, carbohydrate and nucleic acid macromolecules?So, what is inside a cell? A watery fluid called cytosol in which is suspended a number of organelles. The most obvious of these is the nucleus, the control centre of any cell. Chromosomes inside the nucleus contain DNA, the molecule that contains the blueprint of organisation and functioning, of not only the individual cell but also how the millions of cells in an organism work together. What are the other organelles and what is the function of each? What special roles do mitochondria, the Golgi apparatus, the endoplasmic reticulum and ribosomes play? By what processes do cells obtain energy? What are the significant differences in the different kinds of respiration? What is the outcome of each? What role do enzymes play? What environmental factors influence the rate of enzyme action?Many plant cells contain chloroplasts, organelles that contain chlorophyll. These organelles trap light energy and through a series of interrelated metabolic reactions create energy-rich molecules. What are these molecules? What is the relationship between the two distinct stages of photosynthesis? The energy in the molecules produced fuels all other reactions in plants. They also provide the energy for animal survival. How does increasing knowledge about macromolecules support the development of new medical technologies such as the design of drugs and vaccines?I received many signals from bush; my eyes and ears are significant receptors. The smell of eucalyptus was predominant. These senses activate nerve cells that transmit messages to appropriate parts of my body. What is the form of these messages? How are they transmitted through a neuron? How is the message transmitted from cell to cell? What molecules are involved? Does a neuron use different molecules to send a message to different receptors such as a neuron, a muscle cell or an organ? How do neuron networks operate to produce the fine control that we have over our movements?Nerves combine with the endocrine system to maintain a homeostatic state in an animal. What is homeostasis? What is a negative feedback model? In such a model what is the role of the receptor? How are messages relayed from organ to organ and from cell to cell? What responses occur in the different conditions that may exist in a particular system? What kinds of molecules act as messengers in plants and animals? What are the features that ensure a particular message is received by an appropriate cell or organ? What is signal transduction? Does the outcome of signal transduction vary from cell to cell?A man nearby us in the train coughed. It was deep-seated and prolonged and indicated a possible infection. My mind now travels a different path. What is the cause of the cough? What non-specific defence barriers has the invader already overcome? How does the immune system identify foreign material? What is the overall structure of the lymphatic system? What cells are involved? How do these cells communicate with each other? What particular roles does each type of cell in the immune system have? What compounds in the blood are also involved?Australia has a comprehensive program for vaccination. It begins in the first year of life with vaccinations against childhood diseases and continues into old age when vaccination against influenza is important. Is the immunity developed as a result of these injections active or passive? Is it artificially or naturally acquired? What are the characteristics of each of the situations? It is lunchtime. A woman at the next table alerted the waitress to her garlic allergy and the need to have a garlic-free meal. What is an allergy and what is an allergic response? What is an auto-immune disease and what key event is responsible for its development?The questions I have asked are central to your study of biology this year in which you have been taken to the forefront of current developments. Biology is a study of relevance, today and for the rest of your life, and I trust you can take your interest of it into the future.The examination paper has two sections. The first contains 25 multiple-choice questions. Select the correct alternative from a list of four given for each question. Answer with pencil and leave no blanks. Section two requires a pen and comprises extended-response questions. The spaces provided for answers and the marks indicated should guide you as to the extent of writing required. A few days before the examination your teacher will show you a copy of the front page of the examination booklet. Familiarise yourself with the instructions. My best wishes to you all.Marjory Martin is an experienced assessor of biology and a member of the science and technology faculty at Deakin University.
© 2007 The Age