Unit 1 and Unit 3 Biology Exam Revision

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There are several strategies you can use to revise for mid-year exams – here are just a few:

  • Use the Hawkesdale Biology Quizlet Class to revise terms and definitions for each chapter
  • Copy and revise the Slideshows I have saved in the Year 11 and Year 12 Biology class folders (Student Public Drive)
  • Create a set of study notes with the Chapter headings, diagrams and key concepts. These will be very useful at the end of the year for revision too.
  • Create mind maps that link each of the main concepts – use colour to help you remember.
  • Use the posts in this blog to review YouTube videos and other resources for each chapter.
  • Past exams are a good indication of the standard of questions you will be asked – do as many as you can reasonably cope with! Use questions you find difficult as a guide to what you need to study more of.
  • Create flow charts and posters for the wall at home of concepts that can be represented diagrammatically.

Chapter 8 – Immunology

Immunity

Biological Classification

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Classification of living organisms has been a human pastime throughout history – it is important that we can name and identify organisms, especially if they are harmful (venomous snakes and spiders for example) or beneficial (organisms that provide food, fibre, medicine or services). It also helps us to group and organize the huge variety of living organisms on our planet. The science of identifying and naming organisms is referred to as ‘taxonomy’. Carl Linnaeus, a Swedish scientist, is often referred to as the ‘father of taxonomy’ because he developed the naming system that we still use today, called binomial nomenclature, which literally means “two-name naming-system”. Every organism belongs to a particular species and is identified by two latin words – the Genus and species. So, Homo sapiens (modern humans) belong to the genus Homo and species sapiens. Note that the genus name is capitalized, but the species name is not.

Two organisms that belong to the same genus (Eg. Eucalyptus citriodora and Eucalyptus camaldulensis) are more closely related than two organisms with the same species name (Eg. Eucalyptus citiodora and Backhousia citriodora). This is because the species name (citriodora) is a descriptive name that can refer to a characteristic of different groups, in this case, Lemon-scented Gum and Lemon-scented Myrtle.

Within the Five Kingdoms of Living organisms (Protists, Prokaryotes, Fungi, Animals and Plants) are the Phyla, Classes, Orders, Genera and species. It helps to remember this sequence of groups:

  • Kingdom
  • Phylum (and sub-phyla)
  • Class (and sub-class)
  • Order (and sub-order)
  • Genus
  • Species

Some more resources to learn about classification:

Fern Reproduction – Alternation of Generations

fern_sporangiumfern

1. Watch the Secret Life of Ferns; the Fern Life Cycle and the Fern sporangium catapult on YouTube.

2. Go to The Fern Life Cycle – Student Tutorial and label the Fern Life Cycle diagram as you work through the tutorial.

3. Use this worksheet to create a new task for next year’s Biology class to learn about the Alternation of Generations in ferns.

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This image is a screenshot from the YouTube video “The fern sporangium catapult” showing spores being released from a sporangium and the annulus colored blue, representing the water that is critical to the process of ejecting the spores. Due to the cohesive properties of water molecules and the structure of the annulus, as water evaporates, the sporangium ruptures as the annulus curls back. At a critical point, when water continues to evaporate, there are not enough water molecules to hold the annulus open and the ‘head’ of the sporangium springs back, ejecting the spores.

Chapter 7: Infection and Disease

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Image from WorldMapper: The world as you’ve never seen it before

This map shows the size of the country in proportion to the absolute number of people that died from infectious and parasitic diseases in one year. Australia, Europe and America are barely visible due to good sanitation practices, education and high quality health care, including vaccination programs. Africa and India are disproportionately large due to HIV/AIDS (27% of total deaths); diarrhoeal diseases (17%);  tuberculosis (14%); malaria (8%); measles (6%) and whooping cough (3%).

Infectious diseases have had significant impacts on population numbers, politics and society throughout history, from the Athens epidemic (430-427BC) that killed up to half the population of ancient Athens, waves of plague (‘Black death’) that killed up to 90% of Europeans in the 12th century and smallpox that ravaged populations as the Spanish and Portuguese conquistadors invaded the Americas. (“Early History of Infectious Disease” by Nelson and Williams)

More recently, vaccination programs have been very successful in eradicating smallpox and dramatically reducing the numbers of cases of polio, measles/rubella and tetanus. However, diseases such as HIV/AIDS, various influenza strains and Ebola are still causing many deaths throughout the world. The pathogens that cause these diseases are very good at evading the immune system, making it difficult for the immune system to recognise or remember them.

Term 2 – Week 5: Reproduction (Year 11)

asexual_sexual_reproduction

This week in Year 11 Biology we are starting to discuss another body system – the reproductive system. First we will study the concepts of asexual and sexual reproduction and then learn how reproduction occurs in unicellular and multicellular organisms.

Asexual Reproduction – Plants, bacteria and fungi

Draw a diagram to show each of the following types of asexual reproduction:

  • binary fission (eg. bacteria, some algae)
  • budding (eg. yeast, hydra)
  • bulbs (eg. daffodils)
  • runners and rhizomes (eg. strawberries)
  • fragmentation (eg. sea stars, flatworms)
  • spore formation (eg. fungi)
  • parthenogenisis (eg. stick insects, some reptiles)

This YouTube video, Asexual Reproduction, shows budding in Hydra and Anenomes and binary fission in Paramecium, as well as asexual reproduction in Volvox, a green algae.

Sexual Reproduction Handout

Polycom session with GTAC – Hendra virus

ELISA

ELISA technique with materials supplied by Zoetis Australia.

This week we had another opportunity to connect with the Gene Technology Access Centre via Polycom. The topic of this session was the Hendra virus and a method to detect antibodies with a colour change (called ELISA – Enzyme-Linked Immuno-Sorbent Assay). We are very grateful to Zoetis for supplying the materials for this practical work and Fran at GTAC for stepping us through the process.

In a suburb of Brisbane in 1994, a horse-trainer and fourteen horses died of a mysterious illness within days of falling ill.  CSIRO’s Australian Animal Health Laboratory, in Geelong, swung into action and worked intensively on blood and tissue samples for two weeks before identifying the virus responsible as Equine morbillivirus.  However, further genetic analysis showed that the most appropriate classification of the virus was to place it in a new genus within the family Paramyxoviridae. It was later renamed Hendra virus, after the name of the Brisbane suburb in which the original outbreak occurred.

Zoetis Australia is a global animal health company who research and create animal medicines and vaccines, complemented by diagnostics products and genetics tests. As well as a Hendra virus vaccine, they have developed a technique for determining if an animal has virus antibodies present, which indicates that the individual has been exposed to the disease or has been vaccinated previously. We will use this technique to determine if three horses have had prior exposure to the disease or if they need to be vaccinated or receive booster shots.

Rat Dissection

 

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Today we planned to do a rat dissection, but due to the frosty state of our subjects, we have postponed this investigation until Tuesday. In the meantime, we will answer the questions we can, using digital resources:

Plant adaptations for dry environments.

stomata_marram

Terrestrial plants need to maintain their water balance, while still allowing the exchange of gases between the plant cells and the external environment. Gas exchange occurs through stomata, which also allows the escape of water vapour. The image above shows a cross section of a leaf from Marram grass, common on sand dunes, where it is very salty and often dry. You can see how the leaf is rolled, creating an internal micro-climate that is much more humid than the external environment. This reduces water loss and allows stomata to remain open, even in the driest of climates. PIne needles (Pinus) and Casaurina also have cylindrical leaves, an adaptation for dry environments.

stomata_sunken

The sunken stomata in this image (cross section of a leaf) allows a moist layer of air above the stomata, protecting the leaf from excessive evaporation.

stomata_hairs&sunken

This image shows a cross section of a leaf from a plant adapted to a very arid environment. The stomata are sunken into pits with lots of epidermal hairs, which provide a humid micro-climate, allowing the stomata to remain open, despite very dry external conditions.

 

“Body at War” at Federation University, Ballarat

Stephanie_2015

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.