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dagaz

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Everything posted by dagaz

  1. Give me some examples of mathematics in biology.
  2. No, gravity is a scientific law (Law of Universal Gravitation), whereas evolution is still just a scientific theory.
  3. Some good evidence for the evolution of humans is the different species of hominids in the fossil record: Home erectus, Australopithecus, etc. This is beautiful in its simplicity.
  4. The work of Urey & Miller at the University of Chicago showed that when an electrical discharge (representing lightning) was passed through a gas chamber containing methane, ammonia and hydrogen (representing the early atmosphere) in a controlled experiment complex amino acids were produced after only one week. Follow up experiments using UV radiation instead of electricity produced nucleic acids - the precursors of RNA and DNA. Also the microspheres is still just a theory, but they are only made from lipids (C,H & O) and they have also been found to form under controlled experimental conditions. The part that's still causes the most confusion is how the two processes actually came together, but you have to remember all this is happening over evolutionary time frames, i.e. millions of years.
  5. The easy one first, there is no equation for time per se, but it can be broken up into arbitrary units such as seconds, minutes etc. The correct equation for gravity (as defined by Sir Isaac Newton) is: where: F is the gravitational force, M and m are the masses of two bodies, r is the distance between them and G is the universal gravitational constant (= 6.67 x 10-11).
  6. dagaz

    Languages

    I don't think it should be a "requirement" - I think it should be up to the individual concerned, although I do think it should be strongly encouraged. For example, here in Australia we have many instances of some people emigrating here and learning to live and work here (including learning English) and then they have other family members wanting to emigrate here after they have retired from work back in their home country - I don't have a problem with that. The more international travel I have done - the poorer I consider myself for only knowing the one langauge - although I do know a few phrases in Pitjantjara (an Australian Aboriginal language), Hindi and Spanish. I also know a fair whack of botanical Latin - it can be a bit hard to strike up a converstion in it however!
  7. Only plants cells can be affected by plasmolysis as only plant cells have a cell membrane which is surrounded by a semi-rigid (to rigid in some cases) cell wall. Plasmolysis occurs when a plant cell loses water due to osmosis at such a rate that the cell membrane shrinks faster than the cell wall - leaving a gap between the two.
  8. I was being slightly sarcastic when I said that. Even though teaching definitely has its days, generally I'm really enjoying it (this is only my 2nd year of teaching) but most of my friends were blown away when I left the rainforest work because they thought I just had the best job - being paid quite good money to go and work in World Heritage Rainforests.
  9. Even objects with no net overall charge (i.e. neutral) can gain localised charges, e.g. the positive glass stick will 'pull' (attract) electrons from the paper towards the surface until the surface has a localised negative charge which then attracts the glass stick, the ebonite rod will 'push' (repel) electrons away from the surface of the paper so that there becomes a localised positive charge at the surface which then attracts the rod. A simple experiment is to get a balloon and rub it vigorously against a woolen jumper (or your own hair will do) and then 'stick' it against the wall.
  10. Another way to test radiation would be to use a microwave oven, e.g. put groups of seeds in for different periods of time (obviously a control group with no radiation) and see if this has any effect on germination/growth. Some students of mine actually did this once and came up with some interesting results.
  11. I had a really cool job for several years where I was involved in rainforest restoration in the Big Scrub rainforests of NE NSW. I worked for National Parks, community groups, private jobs, etc, but now I'm a boring old high school biology teacher.
  12. Both plants and animals require oxygen for cellular respiration which involves the breakdown of sugars into ATP which can then be broken down to release energy. Plants also require CO2 for photosynthesis in which they produce the sugars, but they still need oxygen for respiration so they can get energy from the food they make.
  13. Our closest living relatives, chimpanzees and bonobos, are both omnivorous as are many other primates.
  14. dagaz

    are atoms real

    Protons, neutrons and electrons are convenient sub-atomic particles which help us to visualise an atom. Electrons are not particles but a 'cloud of probable negative charge' which encircles the nucleus in certain 'orbitals', the nucleus is made of protons and neutrons which are made of even smaller subatomic particles such as bosons and quarks which aren't really particles at all but 'wavelets of vibration and energy'. An atom is 99.999% empty space (between the nucleus and the electron clouds). So at the subatomic level we are mostly empty space with some vibration, energy and charge but with no solidity - its only electrostatic forces between atoms which give the appearance of solidity at the macro scale.
  15. Sure the world is currently in the middle of the sixth mass extinction and this will be really devastating for many of the larger life forms (probably not going to have too great an effect on bacteria) in human time scales BUT in geological time scales biodiversity will recover and come up with some amazing new forms and adaptations, e.g. it was only after the extinction of the dinosaurs that mammals really came to be such a dominant animal of so many ecosystems.
  16. A couple of quick answers to help get you started. Provide oxygen to cells for respiration obviously, plus in autotrophs carbon dioxide is required for photosynthesising cells. Angio: stomates, lenticels- Insect: spiracles, trachea - Amphibians: skin, nostrils, lungs - mammal: nostrils, lungs
  17. speed by definition is equal to distance divided by time, how can time equal distance divided by time?
  18. Another good web resource is Scirus - the science search engine.
  19. They hunt and kill everything from Antechinus' (often called 'marsupial mice') right up to bandicoots, the Long-eared Bandicoot (the Bilby) is precariously close to extinction and its two main threatening processes are listed as feral foxes and feral cats. The Eastern Quoll (also called the 'native cat' or 'marsupial cat') is now extinct on the mainland and only survives on the island of Tasmania because feral cats and foxes have absolutely decimated its food source. The Tiger Quoll is heading that way and is listed as Vulnerable to extinction.
  20. I'd actually prefer the cats to be sleeping than out reeking havoc on the native wildlife - here in Australia feral cats are one of the major causes for declining populations of small marsupials.
  21. Which is part of the reason that viruses are still under debate as to whether they qualify as being a living organism - the other being that they can only reproduce in other cells.
  22. dagaz

    books to read

    Three excellent introductions to the field of science are: 1) Almost Everyone's Guide To Science by John Gribbin 2) A Short History Of Nearly Everything by Bill Bryson - for a travel writer/humourist he does a remarkable job of covering the basics between "the Big Bang and the rise of civilisation" 3) Science: a history 1543-2001 also by John Gribbin
  23. Kind of, as RNA is synthesised from DNA, however it is responsible for protein synthesis rather than genetic traits. The reason RNA is not specifically mentioned is because it is not present in viruses or certain primitive procaryotic cells.
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