Author Archives: brittgow

About brittgow

Science and maths teacher at a small, rural school in Victoria, Australia. One husband, two children and three dogs on a sheep and cattle farm. Interests are: Education for Sustainability, web 2.0, beautiful gardens and good food.

Changes in the genetic make-up of a population

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Good introduction from BBC Earth: How do we know evolution is real?

Evidence for evolution:

Tree of Life Resources:

YouTube Videos:

 

Unit 4: How does life change and respond to challenges over time?

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Area of Study 1: How are species related? 

Outcome 1: “On completion of this unit the student should be able to (1) analyse evidence for evolutionary change, (2) explain how relatedness between species is determined, and (3) elaborate on the consequences of biological change in human evolution.”

Evidence for evolutionary change is abundant in the fossil record, biogeography (distribution of species across the earth), developmental biology and structural morphology. This area of study will allow us to investigate these four types of evidence.

Paleontologists have unearthed a wide range of evidence that provides a record of the change in the number of different species and the particular characteristics of those species over time. The fossil record demonstrates that living organisms first evolved in aquatic environments and gradually moved onto land. After plants had successfully colonized terrestrial habitats and converted a percentage of carbon dioxide into oxygen, animals were able to survive out of the oceans and freshwater environments. Evidence for these changes lies in the relative ages and absolute dating of fossils in different parts of the world.

Other evidence is provided by the similarities between living species – homologous structures in vertebrates, for example – and the similarities in developmental biology among different species. These similarities suggest that living organisms descended from a common ancestor and that species that are more closely related in the family tree have a more recent common ancestor. This evidence is supported by genetic research which confirms evolutionary relationships between species.

 

The Immune System – Like fighting invaders on the Great Wall

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First line of defence (innate immunity): This is like a moat and castle walls, preventing invasion by foreigners. There are physical and chemical barriers to infection.

Second line of defence (innate immunity): If the foreign materials breach the first line of defence, an infection forms. This is the inflammation (heated battle) where invaders are being killed indiscriminately.

Third line of defence (active immunmity) : The last line of defence is the active, specific response by trained killer cells (ninjas!) that recognise their targets and actively seek them out and destroy them. They may be proteins or pathogens that have taken over the reproductive capacity of the cell (prions and viruses, for example), so the infected cell must be destroyed.

Gene Technology Access Centre’s Online courses – Active immunity

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At the Gene Technology Access Centre for the “Body at War – Day of Immunology” seminar and workshops, you learned about pathogens, the human body’s response to antigens and how vaccines have been developed to reduce the spread of disease.  You conducted ELISA tests to identify infected individuals and observed diseased tissues through microscopy. A valuable activity was the Immunology Game, which demonstrated the response to antigens at a cellular level and gave you the experience of controlling the movement of white blood cells (dendrites, plasma cells, macrophages and B and T cells) around the body.

GTAC also have several online courses that I would like you to complete this week.

Action potential

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“Vaccines – a scientific success story” is a well written article that explains how scientists have developed vaccines that have allowed small pox to be eradicated and measles to be restricted to small areas of the world.

The Action potential explained by Bozeman Science.  The distribution of sodium (Na), potassium (K) and chloride (Cl) ions is what changes when a nervous impulse is transmitted along the axon of a neuron.

Signalling molecules, antigens and the immune system

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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.

Outcome 2 On completion of this unit the student should be able to apply a stimulus-response model to explain how cells communicate with each other, outline immune responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.

In Area of Study 2: How do cells communicate? we study cellular signals (signalling molecules, signal transduction and apoptosis); responding to antigens (including antigens, innate and adaptive immunity and the lymphatic system) and the immune system (including diseases of the immune system and cancer immunotherapy). The following links are some resources for study in these topics.

Chapter 6: Cellular Signals

Chapter 7: Responding to antigens

Chapter 8: Immunity, immune malfunctions and immunotherapy

Signal Transduction and Apoptosis

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Last lesson we learned about the different types of signalling molecules (plant and animal hormones, neurotransmitters, cytokines and phermones). Today we will learn what happens when these signalling molecules reach their target cells, causing a response in the cell. Lipophobic (hydrophilic) signalling molecules cannot pass through the cell membrane, so they rely on complementary protein receptors that are embedded in the cell membrane. Once the signalling molecule – or ligand – binds to the receptor protein, secondary messenger molecules are released inside the target cell. Learn more about the specifics of signal transduction here:

Signal transduction from the Penguin Prof Channel

Signal transduction from Mr Bozeman (simple animated diagrams with commentary)

In the video above, observe one of the consequences of signal transduction – apoptosis or programmed cell death.

Cellular Respiration – aerobic and anaerobic

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Cellular respiration is necessary to provide energy for cellular processes – repair and maintenance of cells, growth and cell division, active transport of substances across cell membranes and preventing disease.

Designing a scientific investigation poster

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Pretty great poster for Grade 4 students!

Student Investigations in Biology

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Unit 4: Area of Study 3 in the VCE Biology Study Design provides details of the practical investigation that students are required to complete, worth one third of the school assessed coursework for Semester 2.

On the completion of this unit the student should be able to design and undertake a practical investigation related to cellular processes and/or biological change and continuity over time, and present methodologies, findings and conclusions in a scientific poster.

There are a great number of practical investigations suitable for students, however, careful consideration of the materials and equipment available and the time taken to achieve useful results is prudent. The following resources provide lists of practical investigations that may be of interest:

When you have decided which investigation you are interested in and after discussion with your teacher, submit a proposal that includes the following information:

  • Your name
  • Title (up to ten words about the experiment)
  • Hypothesis (what exactly are you testing?)
  • Materials required (consumables)
  • Equipment required (experimental tools, glassware etc)
  • Estimated time for conducting the experiment and collecting results
  • References (Where did you get the idea from and what other information do you need?)