Nature of Science 2016

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…