Nature of Science 2016
- Created by: IBonfire
- Created on: 17-04-16 09:42
Nature of Science
(With reference to the Pearson baccalaureate for the page numbers ISBN:9781447959007)
Topic 1:
1.1(page 5)
- Recent findings that have raised questions about cell theory include observations of striated muscle, giant algae and aseptate fungal hyphae
1.3(page 27)
- Membrane structure: TOK element – theories of membrane structure supersede each other
- Evidence falsified the Dason-Danielli model of the membrane structure
1.6 (page 41)
- Accidental discovery
- Tim Hunt and Joan Ruderman were studying gene expression in early embryos
- They found proteins that varied in concentrations at different times of the cell cycle (called cyclins)
- So this showed that scientists MUST be observant and this is an example of accidental discovery
2.1 (page 51)
- Falsification of theories
- The artificial synthesis of urea helped to falsify vitalism
2.1 (page 58)
- Vitalism = the belief that living organsims and inanimate things differed fundamentally because living things contained a non-physical or vitalistic element and were subject to different areas of nature than non-licing things
- Due to vitalism, it was believed that the only way ura was produced was through the liver, and filtered by the kidney and left as urine
- However, in 1828, Friedrich Wöhler mixed two inorganic substances (cyanic acid and ammonium in a beaker
- This formed urea
- So an organic molecule (urea) was synthesised from inorganic molecules contradicting vitalism
- This shows that:
· Scientific theories undergo modifications over time some are proved false
· Discoveries are often made accidentally
· Discoveries often aren’t appreciated immediately for their importance – why they need to be published – allows other scientists discover things from their findings
2.2 (page 65)
- Water = polar due to the polar covalent bonds
- Methane = non-polar due to the non-polar bonds
- When methane undergoes a phase change (freezing to boiling point), due to is lack of polarity, there are no hydrogen bonds that influence the change of phase
- When methane changed from a liquid to a gas there are no hydrogen bonds attracting the molecules, so they escape without much motion – why methane has a low freezing and boiling point
- NOT the case for water – due to its polarity – many hydrogen bonds are breaking and forming, so high motion is needed to enable the molecules to ‘escape’ = high freezing (O degrees) and boiling (100 degrees) points
- When methane changes from a liquid to a solid, it’s because it doesn’t have the molecular motion to stay as a liquid anymore
- Water changes at a much higher temperature because when the molecular motion becomes low enough, hydrogen bonding locks the H20 molecules into stable geometric forms (ice crystals)
- This shows:
· In science, a theory helps…
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