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.

Human Evolution

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One of the earliest defining human traits, bipedalism — the ability to walk on two legs — evolved over 4 million years ago. Other important human characteristics — such as a large and complex brain, the ability to make and use tools, and the capacity for language — developed more recently. Many advanced traits — including complex symbolic expression, art, and elaborate cultural diversity — emerged mainly during the past 100,000 years.

Since Darwin first proposed that humans and apes had a common ancestor, our understanding of human evolution has improved due to fossil finds, analysis of our closest living and extinct relatives, studies of geographic distribution and DNA analysis. Although the image above is often used to represent human evolution, the process is not the simple linear procession that is shown. Your task is to write an essay of at least eight paragraphs that explains why this image is suitable, but also why it is an inaccurate representation of human evolution.

  • Introduction – what will the following paragraphs explain?
  • Outline primate family tree, including lemurs, monkeys, apes, hominins and Homo sapiens.
  • Where do Australopithecus sp., Homo erectus, Homo habilis, Homo neanderthalensis and Homo heidelbergensis fit in?
  • Discuss bipedalism – location of foramen magnum, shape of spine  and ratio of arm to body length.
  • Discuss skull shape, brow ridges, sagittal and nuchal crests, prognathous jaw and facial sloping.
  • Discuss cranial capacity and relationship to body mass and intelligence.
  • What is the evidence that human evolution is not a linear progression, but a many-branched family tree?
  • Conclusion – what are the main characteristics that can be identified in the image and why is the image an inaccurate representation of human evolution.

Introduction to Human Evolution from the Smithsonian 

7 Strange and Surprising ways that humans have evolved recently

Human intervention in evolution

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This fruit is from a genetically modified papaya plant, bred to reduce the risk of disease. How are genetically modified organisms created? (YouTube video, 5.31min)

Quizlet – Flashcards for Chapter 16

While genetic techniques have certainly provided health benefits to our society (disease diagnosis and therapies, production of insulin and increased production of more nutritious and disease resistant foods), there are also community concerns about the ways that these technologies are being used and the future consequences. ABC Splash have some short videos that outline some of the issues of genetic technologies:

The Science of Human Evolution

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Video Source (YouTube, 54.42 min)

  1. What vestigial organ, a remnant from our primate ancestors, is apparent in humans?
  2. Which species does the video refer to as our “distant cousins”?
  3. Name three characteristics that we share with these monkeys.
  4. Notharctus tenebrosus is a fossil that scientists believe to be a common ancestor of humans – how old is this fossil?
  5. What feature of this fossil’s hand is important for climbing and gripping objects?
  6. How was colour vision an important evolutionary advantage in early primates?
  7. What genetic mutation occurred to allow primates to see in colour like humans?
  8. What sense diminished as humans evolved high-colour vision? What evidence is there for this?
  9. ‘Lucy’ is a 3.2 million year old fossil from Ethiopia – why is this fossil significant?
  10. What advantages does this particular characteristic give the species?
  11. What disadvantages does bipedalism have for modern humans?
  12. What characteristic of stone-age man is an indication that human ancestors had the ability for complex thought, together with highly developed hand-eye co-ordination?
  13. In what test do 3 month old monkeys out-perform human babies?
  14. What fundamental brain architecture do all vertebrates, including sharks and humans, share?

The Hardy-Weinberg Principle of Allele Frequencies

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The Hardy-Weinberg Principle is a mathematical law that predicts allelic frequencies, making several assumptions:

  • Large population
  • Random mating
  • No immigration
  • No emigration
  • No natural selection

In nature, these assumptions are extremely unlikely to occur, but it is the deviation from the expected distribution of alleles (according to the HW Principle) that informs us about the action of these natural conditions.

Please complete Activity 13.2 (page 141) Looking at Allele Frequencies – Parts A and B.

Unit 4: Area of Study 2: Change over time

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“The theory of evolution by natural selection, first formulated in Charles Darwin’s book “On the Origin of Species” in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.”

“Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as be the main process that brings about evolution.”

What is the evidence for evolution? from Stated Clearly (YouTube, 11.21min)

  • Fossil evidence – organisms have changed over time and some have become extinct
  • Comparative morphology (anatomy) – there are similarities between some organisms that suggest a common ancestor
  • DNA evidence – Similar species have more genes in common than dissimilar species, suggesting a common ancestor; Chimpanzees and humans have 99% of their DNA in common
  • Distribution of species (biogeography) shows that islands have unique species, due to an original inhabitant becoming adapted to its’ environment over many generations, by natural selection
  • Similarities of embryos suggest that all vertebrates have a common ancestry

Tree of Life video HD with David Attenborough (YouTube, 6.29 min) – Complete the student worksheet – Highlighting important stages in evolution. 

VCE Genetics

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In Chapter 9, you learned about genes, chromosomes and patterns of inheritance, including genotypes and phenotypes, multiple alleles, dominant and recessive genes and co-dominance.

In Chapter 10, you learned about the nature, structure and organisation of the genetic material (DNA), including Mendels’ discoveries with pea plants and the genetic code.

In Chapter 11, you learned about genes in action – replication, transcription and translation to produce the proteins that make up all living organisms.

Chapter 12 is all about the tools and techniques we use to investigate and alter the DNA of organisms – DNA profiling and paternity testing, gene transfer and genetically modified organisms. These processes are newly discovered and there is still community debate about their use. It is important to consider the ethical issues surrounding genetic technologies, as our legal system lags behind scientific knowledge and practice. For example, the recent birth of an IVF baby to a 63 year old woman has made headlines in Australia – she was treated overseas, because the procedure is against the law for women over 53 in this country.

 

Homeostasis – Regulation of Blood Glucose Levels

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The pancreas is an important exocrine and endocrine gland located between the stomach and small intestine. It has two important roles (1) as an exocrine gland it releases digestive enzymes into the duodenum that aid in the break down of food (2) as an endocrine gland it releases insulin and glucagon into the bloodstream.

Insulin is produced in the beta cells of the islets of Langerhans in response to the stimulus of rising blood glucose levels. Insulin travels in the bloodstream and binds with receptor sites on the cell membranes, resulting in a cascade of events dependent on the cell type. In liver cells, for example, glucose in converted to glycogen, fat and carbon dioxide.

Glucagon is produced by alpha cells in the islets of Langerhans in response to the stimulus of falling blood glucose levels. Glucagon travels in the bloodstream and binds to receptor sites on liver cell membranes, resulting in the breakdown of stored glycogen into glucose. This results in an increase in blood glucose levels.

These two hormones act to regulate the body’s blood glucose levels, maintaining an average concentration of 5.0 mmol/Litre (between 3.5 mmol/Litre after several hours without food and 7.0 mmol/Litre soon after a meal). This is a negative feedback loop, as the response results in a change in the stimulus in the opposite direction. A person with diabetes is unable to regulate their own blood glucose levels without external intervention – it may be that their body does not produce enough insulin, as in Type 1 Diabetes mellitus.

Week 4: Molecular Biology in Medical Diagnosis

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This week we will study how molecular biology can be used for a range of applications in medicine, including diagnosis of deficiency conditions before and after birth, rational drug design and the production of hormones and plant vaccines. We will also consider some of the ethical concerns that may be associated with the application of molecular biology. First, we will review the process of DNA transcription and translation, as the first stage in the genetic process that results inherited diseases being expressed in an individual.

Week 3: Biochemical Processes

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The biological cell is not the static, neat drawing you find in text books, but a dynamic, differentiated, three-dimensional, living unit with many specialised processes occurring simultaneously. You should already know the basic structure and function of the cell, including the main organelles. This animated video shows some of the inner life of a cell – can you identify the cell membrane, embedded proteins and ribosomes? Over the next fortnight you will need to better understand the following biochemical cellular processes:

Biology Q&A’s

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This site is a great resource for VCE Biology students, allowing you to learn and review key concepts. The Biochemistry section has seven areas of study including:

If you are a Twitter user, you can follow BiologyQuestions for regular questions and links about Biology topics. This site has over 17 thousand followers from across the world, so you will be part of a global community!