“Body at War” at Federation University, Ballarat

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On Friday 17th April, four VCE Biology students attended the “Your Body at War” program, facilitated by the Gene Technology Access Centre at Federation University. Kiri, Leah, Che and Stephanie travelled to Ballarat to participate in the program, which celebrates the “Day of Immunology”.

Together with about 100 students from three other schools, they had the opportunity to hear from Associate Professor Robyn Slattery (Monash University) about the history of vaccination, current research in immunology and exciting new discoveries about immunotherapy in cancer treatment.

They then donned lab-coats and entered the science laboratories at Federation University, where they learned how to use specialist equipment and techniques, such as the Enzyme-linked Immunosorbent Assay (ELISA). They also had the opportunity to discuss career perspectives in science with staff and Dr Misty Jenkins from the Peter MacCallum Cancer Centre.

One of the sponsors of this event is the Walter and Eliza Hall Institute of Medical Research. Later this year we have three Year 11 students who have been very fortunate to obtain a work experience placement at WEHI in Melbourne. This is an exciting opportunity for them to find about authentic medical research, working with expert scientists in a world-leading facility.

Also in science news, students in Year 10 have the opportunity to attend the Science Experience Ballarat, at Federation University from 29th June to 1st July. This three day, hands-on program is a great introduction to the diverse world of science and it’s connection to a range of interesting careers. Please apply online prior to 8th June. Speak to Mrs Gow for further information.

Distribution of Materials

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In this unit of work we are looking at the ways plants and animals distribute nutrients, hormones, gases, water and waste products to and from different cells throughout the organism. In animals, this involves the circulatory, respiratory and excretory systems. In vascular plants, we consider gaseous exchange, transpiration and substances moving through the xylem and phloem.

Circulatory System: Once food has been digested, these nutrients needs to be distributed to every cell within the body to enable cellular respiration to occur. These nutrients, as well as hormones, waste products (CO2 and urea), salts and heat are transported in the circulatory system. The circulatory system of mammals includes  a four-chambered heart, arteries, veins and capillaries that allow the movement of blood to every cell within the body.

Respiratory System: The mammalian respiratory system includes the lungs, trachea, bronchi and alveoli that allow the transfer of oxygen and carbon dioxide between the internal blood supply and the external environment. Insects have an open respiratory system in which the air and the internal cells are in close contact, oxygen entering through spiracles and passing in to branching tubes within the organism. Don’t get confused between cellular respiration and breathing! Cellular respiration is the process that converts glucose and oxygen to energy within the cells. Oxygen is supplied to those cells by the red blood cells, which carry oxyhaemoglobin to cells and remove carbon dioxide from cells.

Excretory System: Our kidneys are part of our excretory system, to remove nitrogenous wastes from our body. The nephron is the functioning unit that removes urea from the blood and allows water, nutrientsand salts to be re-absorbed to the body. Ureters are the tubes that carry urea from the kidneys to the bladder and urine leaves the body via the urethra.

Gaseous Exchange in Plants: Plant cells need to exchange oxygen and carbon dioxide with the environment and they do so through stomata (pores) in their leaves.

Transpiration: How do the tallest trees draw water from the soil to hydrate leaves many metres in the air?

Xylem and Phloem in Vascular Plants: What are vascular plants and how do they transport water with dissolved minerals and nutrients to cells in the roots, stems and leaves?

Please let me know in the comments below if any of these links are no longer working!

Co-ordination and Regulation – Endocrine Systems

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In this chapter you need to become familiar with the following concepts:

  • homeostasis (maintaining a stable internal environment in terms of temperature, hydration, pH, blood pressure and volume, oxygen and carbon dioxide concentration in the blood and the concentration of various ions, including sodium and glucose).
  • stimulus-response and sensors-effectors
  • positive and negative feedback mechanisms
  • glands and hormones, including phermones
  • signal transduction and signaling molecules

it is important to understand that lipid soluble hormones (lipophilic or hydrophobic) can pass through the cell membrane directly, but water-soluble hormones (hydrophilic or lipophobic) bind to a receptor molecule embedded in the cell membrane, which results in the activation of a secondary protein or messenger. This secondary messenger causes the cell to initiate a response. Signal transduction is a series of events (sometimes called a ‘cascade’) that changes the signal received by the cell.

 

Mammalian Digestive System

Digestive-system

Image Source – Attribution: By Leysi24 (Own work) [CC BY-SA 3.0  via Wikimedia Commons

Firstly, dismantle the human torso model in the science laboratory and describe what you know about each part of the alimentary canal and associated glands and organs. Draw and label  a detailed diagram, showing each of the organs above. Then complete the “Cut-and-Paste your Guts” activity, identifying each organ from it’s description and pasting each description into your book, in the order that food would pass through, on it’s 12 hour journey through the 7 metres of the digestive system.

Next, match the skulls (noting the teeth structure and position of eye sockets) with the corresponding herbivore, omnivore and carnivore digestive systems. Describe the diet of each organism, explaining your reasoning in terms of teeth structure, size of stomach and length of intestines, any enlarged organs and corresponding diet.

Term 1 Study Break

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Unit 1 – Year 11 Biology 

  • Read Chapter 5 – Obtaining Energy and nutrients for life.
  • Make sure you understand the key terms and definitions (pg 125).
  • Complete Chapter 5 Review Questions.
  • Create a set of study notes for Unit 1: Area of Study 1: Cells in Action
  • Download Mr Barlow’s Unit 1 and Unit 2 Biology apps from the iTunes or Google store.

 Unit 3 – Year 12 Biology

Photosynthesis by video conference from GTAC

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GTAC – Introduction to Photosynthesis on YouTube

GTAC – Photosynthesis – Light Dependent Cycle and an Animation showing six cycles of the Light Independent Cycle on YouTube

Tony, from GTAC, demonstrated a photosynthesis experiment in which equal quantities of spinach leaves were placed in four clear, closed containers. Each container was subjected to light of the same intensity, but one had no filter (control) and the other three were wrapped in coloured cellophane (red, blue and green, as shown above). The coloured cellophane filters out different wavelengths of light, so the red cellophane reflects red wavelengths and allows other wavelengths to pass through. Each container had two probes, measuring oxygen and carbon dioxide concentrations in parts per million (ppm). What would you expect to happen in the cellophane-covered containers compared to the control?

Tony was also able to answer two questions that students have about DNA transcription.

(1) Where does the mRNA molecule go after transcription? “A single mRNA can be translated many times by ribosomes into polypeptides (it’s one way a cellular response dependent on gene expression can be amplified).  After that mRNA is degraded, releasing individual nucleotides which can then be recycled into new mRNA.  In eukaryotic cells, the mRNA is protected by the 5’ methylguanosine cap and the 3’ poly-A tail.  When these are removed from the ends, presumably in response to an intracellular signal that says the mRNA is no longer required, the mRNA becomes susceptible to degradation.”

 (2) When and where does transcription occur? “I would say transcription (the process by which the mRNA is first made from DNA template) occurs in the nucleus of eukaryotic cells almost continuously but the genes being expressed change throughout the cell cycle and in response to stimuli.  For example, genes relevant to growth may be transcribed during G phases.  A special set of genes relevant to DNA synthesis are transcribed during S phase.  If a (stem) cell received a differentiation signal, a relevant set of genes would be switched on for differentiation into a particular cell type.  I would say the only time transcription ceases is when the chromosomes condense for mitosis and cytokinesis.  Essential proteins are still around to ensure cell division proceeds as intended.  After cell division and the chromosomes de-condense, it’s back to business as usual.”

Thanks Tony for these valuable extensions to our Year 12 Biology program at Hawkesdale P12 College.

Cupcake mitosis

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Students in Year 11 Biology are learning the phases of mitosis, so we baked and decorated these cupcakes. Students now have a good understanding of what happens inside the nucleus during:

  • Interphase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase and
  • Cytokinesis.

Watch the Cells Alive Interactive and describe where in each cycle are the three checkpoints that allow DNA replication and mitosis to continue. Why is it incorrect to suggest that the cell is “resting” during interphase, between mitotic cycles?

Mutants can be beautiful!

 

Both these roses come from the same bush in my garden at home. The one on the left is how the rose normally looks, year after year. This year, on a single branch sprouting to the side, there are about six flowers that look striped, like the one on the right. This article, from the American Rose Society, describes how a genetic mutation can cause this change in pigments.

Stripes may also result from spontaneous or induced mutations. Mutations are sudden changes that occur at a very low frequency in a gene. Spontaneous mutations (popularly known as ‘sports’) alter the existing genes and their expression, resulting in stripes. Induced mutations by irradiation or chemical mutagens also lead to genetically-altered  pigmentation, and the result is stripes. Stripes may develop as a result of the transmission of genes responsible for stripes through hybridization. Viral infection that causes variegation in tulips may also cause stripes in roses. These infections could interfere with physiological functions of pigmentation, giving them a striped appearance.

It is possible that a mutation has occurred during mitosis somewhere at the base of the new branch and all the cells in the new branch carry the mutated gene, which is expressed as a striped phenotype. If this is the case, a cutting from this branch will also produce striped flowers. So, I will take a cutting and propagate this rose, to see if we can produce more of these beautiful mutants!