Stem reviewer

• Rock Cycle

  1. Igneous and sedimentary rock can turn into metamorphic rock with high pressure and heat

  2. Sedimentary and metamorphic rock can turn into igneous rock by melting back into magma

  3. Igneous and metamorphic rock can turn into sedimentary rock through erosion
• Minerals are substances formed naturally in the Earth with definite chemical composition and structure. There are over 3000 known minerals, some rare and precious like diamond, while others are more ordinary like quartz
• Mechanical weathering

  Produces clasts of rock/mineral smaller than the original, with the same general composition. Includes fracturing which produces angular clasts and abrasion which rounds off rough edges
• Biological weathering

  The actions of plants (and animals) can lead to both mechanical and chemical weathering
• Fault is a break or crack along which rocks move, with hanging wall (rock above fault plane)
• Chemical weathering


  Produces smaller pieces of different chemical composition, changing minerals to be more in balance with surface conditions. The most common product is clay
• Elements on the Earth’s Crust

  • Oxygen
  • Silicon
  • Aluminum
  • Iron
  • Calcium
  • Sodium
  • Potassium
  • Magnesium
  • All other elements
• Stress can change the shape and volume of the Earth's crust, leading to movement and deformation. Includes Compression, Tension, and Shearing
• Weathering is one of the destructive processes on earth, together with Erosion and Transportation, exposing most rocks to a different physio-chemical environment from where they formed
• Kepler’s Laws of Planetary Motion

  1. The orbit of a planet is an ellipse with the Sun at one of the two foci

  2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time

  3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit
• Continental Drift - theory that continents can drift from one another
• Types of Faults

  1. Normal fault - hanging wall goes down relative to foot wall (vertical)

  2. Reverse fault - compression causes hanging wall to move up relative to foot wall

  3. Thrust fault - compression causes hanging wall to slide over the foot wall

  4. Lateral Strike Slip fault - one moves to left/right in relation to another (horizontal)
• Types of Plate Boundaries

  1. Transform boundaries occur where two lithospheric plates slide or grind past each other along transform faults; plates are neither created nor destroyed

  2. Divergent boundaries occur where two plates slide apart from each other (rifting)

  3. Convergent boundaries occur where two plates slide toward each other to form either a subduction zone or a continental collision
• Steps of Scientific Method

  1. Observation and description of a phenomenon

  2. Formulation of an hypothesis to explain the phenomena

  3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations

  4. Performance of experimental tests by several independent experimenters and properly designed experiments
• Half-life is the amount of time required for a quantity to fall to half its value as measured at the beginning of the time period. The term "half-life" can be used to describe any quantity which follows an exponential decay
• Ocean-to-ocean subduction


  Older, cooler, denser crust slips beneath less dense crust, causing earthquakes and a deep trench to form in an arc shape. The upper mantle of the subducted plate then heats and magma rises to form curving chains of volcanic islands
• Alfred Wegener: 'From supercontinent named Pangea continents moved, the leading edge of the continent would encounter resistance and thus compress and fold upwards forming mountains near the leading edges of the drifting continents'
• Plate tectonics: The Earth's surface is made up of a series of large plates which are in constant motion, travelling at a few cms per year, spreading from the centre and sinking at the edges, termed as convection currents sourced from radioactive decay of Earth
• Geological Periods
• Sources of Experimental Error

  Random error - error intrinsic to instruments of measurement
• Continent-to-continent subduction


  The dense oceanic lithosphere plunges beneath the less dense continent, earthquakes trace the path of the downward-moving plate as it descends into asthenosphere, a trench forms, and as the subducted plate partially melts, magma rises to form continental volcanoes
• Plate boundary zones


  Occur where the effects of the interactions are unclear, and the boundaries, usually occurring along a broad belt, are not well defined and may show various types of movements in different episodes
• Confirmation of hypothesis

  Results of new observations
• Standard ways of estimating and reducing errors exist
• Sources of Experimental Error

  • Random error
  • Non-random or systematic error
• Hypothesis


  A limited statement regarding cause and effect in specific situations; also refers to our state of knowledge before experimental work has been performed
• Scientific theory or law


  Represents a hypothesis, or a group of related hypotheses, which has been confirmed through repeated experimental tests
• Creation of larger molecules = dehydration (removal of H2O)
• No experiment can be perfectly precise
• It is important to determine the accuracy of a particular measurement and to quote the measurement error when stating quantitative results
• Performance of experimental tests

  By several independent experimenters and properly designed experiments
• Ruling out of hypothesis

  Results of new observations
• Models


  For situations when it is known that the hypothesis has at least limited validity
• Breakdown of larger molecules = hydrolysis
• Variables in an Experiment

  • Independent variable
  • Dependent variable
  • Controlled variable
• Cellulose


  Long, straight, rigid molecule with glucose rings arranged in a flip-flop manner, no side chains, many -OH groups forming hydrogen bonds
• Amylose


  Linear chain of glucose units linked by 1-4 glycosidic bond
• Starch hydrolysis


  Done by amylases
• Triglyceride

  3 fatty acid chains + glycerol bound by ester linkage
• Cis fats

  Carbon chains on the same side, considered "good oils"