7th Grade Science Midterm Review

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7th Grade ScienceMidterm Review
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What is science?

• Science is the study of the natural world.
• Science is divided up into three areas
• Biology/Life science
• Geology/Earth science
• Physics/Physical science

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What is empirical evidence?

• The observations, measurements, and other types
  of data that people gather and test to support
  and evaluate scientific explanations.

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What is a theory?

• The explanation for some phenomenon that is based
  on observation, experimentation, and reasoning
  that is supported by a large quantity of
  evidence and that does not conflict with any
  existing experimental results or observations.

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What is a law?

• A descriptive statement or equation that reliably
  predicts events under certain conditions.

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What is the difference between a theory and a law?

• Theory is an explanation for why something is the
  way it is and law describes what is happening in
  the natural world.

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Where do scientists get their evidence?

• In the field
• In the laboratory
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

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How do scientific ideas change?

• By new evidence
• By collaboration and debate

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What is an experiment?

• An organized procedure to study something under
  controlled conditions.

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What is an observation?

• The process of obtaining information by using the
  senses the information obtained by using the
  senses.

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What is a hypothesis?

• A testable idea or explanation that leads to
  scientific investigation

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What is an independent variable?

• The factor that is changed by the experimenter

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What is a dependent variable?

• The factor that changes as a result of
  manipulation of one or more independent variables.

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What is data?

• Information gathered by observation or
  experimentation that can be used in calculation
  or reasoning

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What are the steps of the scientific method?
(Please refer to your notes and foldable)
1. Make an observation 2. Ask a question 3.
Hypothesis 4. Experimentation / collect data 5.
Results (typically represented in data tables,
graphs, mean, median, etc in middle and high
school) 6. Analyze / conclude 7. Repeat
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What is repetition? What is replication? What is
the difference between them?

• Repetition is when a scientist repeats their own
  experiment
• Replication is when a scientist repeats different
  scientists experiment

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What characterizes a good scientific
investigation?
It needs to be able to be repeated
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How do you evaluate the quality of scientific
information?

• The most reliable scientific information is
  published in peer-reviewed scientific journals.
  (The information has to be peer-reviewed.)

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What is a model?

• A pattern, plan, representation, or description
  designed to show the structure or workings of an
  object, system, or concept

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How do scientists organize data?

• Scientists organize data in tables and then in
  charts, models, and graphs.

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What are the different types of graphs and why do
we use them?

• Circle Graph- shows how each group of data
  relates to all of the data
• Bar Graph- Used to display and compare data in a
  number of categories
• Line Graph- Used to show change in variables over
  time

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Unit 2 Study Guide
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What is a mineral? How are minerals formed?

• A mineral is a naturally occurring usually
  inorganic solid that has a definite crystalline
  structure and chemical composition.
• Minerals are formed
• As magma and lava cool
• By metamorphism
• From solutions

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What is an element?

• Elements are pure substances that cannot be
  broken down into simpler substances by ordinary
  chemical means

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What is a compound?

• A substance made up of atoms or ions of two or
  more different elements joined by chemical bonds.

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What is the difference between silicate and
nonsilicate minerals?

• Silicate minerals contain silicon and oxygen,
  normally in the form of silicate tetrahedrons.
• Nonsilicate minerals do not.

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What are the different properties that can be
used to identify minerals? Define each property.

• Color- color of the mineral
• Streak- color of the powdered form of the
  mineral. (Remember that if a scientist draws on
  a white tile with the mineral, this is how the
  streak is found.)
• Luster- way a surface reflects light
• Cleavage and Fracture- The way the mineral
  breaks/splits
• Density- measure of how much matter in a given
  amount of space.
• Hardness- minerals resistance to being
  scratched.
• Special Properties- any property specific to the
  mineral

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Know the three different rock types What are
they? How are they each created?

• Igneous rock forms when magma or lava cools and
  hardens
• Sedimentary rock forms from compressed or
  cemented layers of sediment.
• Metamorphic rock forms from other rocks as a
  result of intense heat, pressure, or chemical
  processes.

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What is weathering?

• Weathering is the natural process by which
  atmospheric and environmental agents, such as
  wind, rain, and temperature changes, disintegrate
  and decompose rocks.

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What is erosion?

• Erosion is the process by which wind, water, ice,
  or gravity moves soil and sediment from one
  location to another.

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What is deposition?

• Deposition is the process in which material is
  laid down.

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What is the rock cycle?

• The rock cycle is the series of processes in
  which rock forms, changes from one type to
  another, is destroyed, and forms again by
  geologic processes.
• Look in your book on page 78 for a diagram of the
  rock cycle.

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What is uplift?

• Uplift is the rising of regions of Earths crust
  to higher elevations.

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What is subsidence?

• Subsidence is the sinking of regions of the
  Earths crust to lower elevations.

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What is a rift zone?

• A rift zone is an area of deep cracks that forms
  between two tectonic plates that are pulling away
  from each other.

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What are Earths compositional layers?(Make sure
you can label them)
Crust
Mantle
Core
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What is convection? Where does convection take
place in Earth and why is it important?

• Convection is the movement of matter due to
  differences in density that are caused by
  temperature variations can result in a transfer
  of energy as heat.
• Convection takes place in the Earths mantle.
• Convection helps rocks move slowing in the
  mantle. (Cooler rocks sink and warmer rocks rise)

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What are the Earths physical layers?(Make sure
you can label them)
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core
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What is Pangaea? Why is the idea of Pangaea
important in understanding Earths history?

• Scientists think that about 245 million years ago
  the continents were joined in a single large
  landmass that they call Pangaea.
• Its important to understand that at one time
  scientists think that all the continents were
  connected and during millions of years the
  continents moved into their current locations.

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What is sea-floor spreading?

• Sea-floor spreading is the process by which new
  oceanic lithosphere sea floor forms when magma
  rises to Earths surface at mid-ocean ridges and
  solidifies, as older existing sea floor moves
  away from the ridge.
• Older rock- far from ridge
• Newer rock- formed near ridge

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Theory of plate tectonics

• This theory explains how large pieces of the
  lithosphere, called plates, move and change shape.

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What is a tectonic plate?

• A tectonic plate is a block of lithosphere that
  consists of the crust and the rigid, outermost
  part of the mantle.

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Different plate boundaries(Know the arrow
diagrams!)

• Convergent- Two plates collide.
• Divergent- Two plates move away from each other
• Transform- Two plates move past each other
  horizontally

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What are the three different mechanisms that
cause tectonic plates to move?

• Mantle Convection
• Ridge Push
• Slab Pull

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What is an anticline?(Look on Page 107 for a
diagram)

• Anticlines- oldest layers of rock are in the
  middle of the fold. The youngest rocks are
  towards the outside.
• Anticlines are shaped like a n

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What is a syncline?(Look on Page 107 for a
diagram)

• In syncline folds the youngest rocks are in the
  middle and the older rocks are on the outside
  edges.
• Synclines are shaped like a u

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Faults

• Strike-Slip Faults
• Formed when rocks are under shear stress and at
  transform boundaries
• Normal Faults
• Formed when rocks undergo tension and at
  divergent boundaries
• Reverse Faults
• Formed when rocks undergo compression and at
  convergent boundaries

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Faults

• Be able to label a diagram of each fault, with
  where the hanging wall, footwall and fault plane
  are! (Look on page 109)

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Three types of mountains

• Folded Mountains- Form when rock layers are
  squeezed together and pushed upward.
• Usually at convergent boundaries
• Volcanic Mountains- Form when melted rock erupts
  onto Earths surface
• Fault-Block Mountains- Form when tension makes
  the lithosphere break into many normal faults.
  Along the faults, pieces of the lithosphere drop
  down compared with other pieces. The pieces left
  standing form fault-block mountains.

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What is an earthquake?

• Earthquakes are ground movements that occur when
  blocks of rock in Earth move suddenly and release
  energy.
• Label 6 page 116 in your book.
• Know that the Focus is the point underneath the
  Earth
• The Fault Line is the line between both of the
  plates
• The Epicenter is on the Earths surface.

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Label a volcano

• Label 5 on page 126 in your book.
• Know this!
• Know magma is underneath the Earth lava is when
  it has reached the Earths surface

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Three types of volcanoes

• Shield Volcanoes- Broad base, gently sloping
  sides, and form from mild eruptions.
• Cinder Cones- Steep volcano formed from violent
  eruptions
• Composite Volcanoes- Alternates between mild and
  violent eruptions.

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Where do volcanoes occur?

• Divergent boundaries
• Convergent boundaries
• Hot Spots

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Unit 3 Review

• Please see pages 145-194 in your book for more
  information
• This study guide is just to get you started
  studying please look at your notes and book too.

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What is uniformitarianism?

• A principle that geological processes that
  occurred in the past can be explained by current
  geologic processes.

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What is climate?

• The weather conditions in an area over a long
  period of time.

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What is a fossil?

• The trace or remains of an organism that lived
  long ago, most commonly preserved in sedimentary
  rock.

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What is a trace fossil?

• A fossilized structure, such as a footprint or
  coprolite, that formed in sedimentary rock by
  animal activity on or within soft sediment.

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What is an ice core?

• A long cylinder of ice obtained from drilling
  through ice caps or ice sheets used to study
  past climates.

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How do organisms become preserved as fossils?

• Fossils can be trapped in amber or asphalt
• Buried in rock
• Become frozen
• Become petrified

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What can fossils tell us?

• Fossils tell scientists about changes to the
  environment
• Fossils tell scientist how life forms have
  changed over time

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How does sedimentary rock show Earths history?

• The composition of sedimentary rock show the
  source of the sediment that makes up the rock
• The texture of the sedimentary rock shows the
  environment in which the sediment was carried and
  deposited
• Features in the rock show what was happening to
  the sedimentary rock

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What do Earths surface features tell us?

• How continents move
• How landforms change over time

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What other materials tell us about Earths
climate history?

• Trees
• Sea-Floor sediments
• Ice cores

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What is relative dating?

• Any method of determining whether an event or
  object is older or younger than other events or
  objects.

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What is superposition?

• A principle that states that younger rocks lie
  above older rocks if the layers have not been
  disturbed.

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What is unconformity?

• A break in the geologic record created when rock
  layers are eroded or when sediment is not
  deposited for a long period of time.

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What is a geologic column?

• An ordered arrangement of rock layers that is
  based on the relative ages of the rocks and in
  which the oldest rocks are at the bottom.

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How are undisturbed rock layers dated?

• Older layers are on the bottom
• Younger layers are on the top

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How are sedimentary rock layers disturbed?

• Tilting
• Folding
• Faults and Intrusions
• Unconformities

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How are rock layers ordered?

• Law of crosscutting relationships states that
• A fault or a body of rock, such as an intrusion,
  must be younger than any feature or layer of rock
  that the fault or rock body cuts through.

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How are fossils used to determine relative ages
of rocks?

• Fossils can help us determine the relative age of
  rocks by giving us a reference point for the
  rocks.
• Younger fossils younger rocks
• Older fossils older rocks

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What is absolute dating?

• Any method of measuring the age of an event or
  object in years.

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What is radioactive decay?

• The process in which a radioactive isotope tends
  to break down into a stable isotope of the same
  element or another element.

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What is half-life?

• The time required for half of a sample of a
  radioactive isotope to break down by radioactive
  decay to form a daughter isotope.
• If you have 6 milligrams of the original isotope
  in one half-life 3 milligrams of the isotope
  would be left and 3 milligrams would be the
  daughter isotope

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What is radiometric dating?

• A method of determining the absolute age of an
  object by comparing the relative percentages of a
  radioactive parent isotope and a stable daughter
  isotope.

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How can the absolute age of rock be determined?

• Thru absolute dating methods

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What is the best rock for radiometric dating?

• Igneous rock

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What are some radiometric dating methods?

• Radiocarbon dating
• Potassium-Argon dating
• Uranium-Lead dating

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How is radiometric dating used to determine the
age of Earth?

• Radiometric dating can be done on meteorites to
  determine the age of the Earth.

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How are index fossils used?

• Index fossils are markers for the time that
  organisms lived on Earth
• Index fossils can date different layers of Earth