Download Chapter 5 - Mrs. Wiley`s Environmental Science Site

7th Grade Science Midterm Exam Review
Show your completed study guide to Mrs. Wiley on the day of your exam for +5.
Nature of Science
What are the steps of the Scientific Method?
Identify a
PROBLEM
/QUESTION
ANALYZE the
data
Draw
CONCLUSIONS
Gather and
organize
INFORMATION
Collect DATA
COMMUNICATE
Form a
HYPOTHESIS
TEST your
hypothesis
What are some ways you might gather information?
Researching on the internet, reading articles, the library, interviews, etc.
How might you collect data in your experiment?
Measuring, counting, observing, etc.
What are ways to analyze your data?
Graphs, calculations, looking for trends and differences, etc.
What is important to remember when you draw conclusions?
To avoid bias and to make sure to back your conclusion with data.
How may a scientist communicate their results?
Writing articles, lectures, etc.
What are the types of variables in an experiment? Explain each one.
Control/Constant- Things you purposefully keep the same so they do not affect the outcome of your
experiment.
Independent- Manipulated variable. You purposefully change this to examine the effects in your experiment.
Dependent- Responding variable. You measure or observe this variable.
What is a hypothesis? A prediction?
Hypothesis- a possible explanation for an observation that can be tested by scientific investigations.
Prediction- A statement of what will happen next in a sequence of events.
What is the difference between a scientific law and a scientific theory?
Law- describes a pattern in nature (says something WILL happen)
Theory- an explanation of observations or events based on knowledge gained from many observations and
investigations.
How may you use critical thinking in science?
Sampling- make sure you select a random representation of the whole.
Bias- Avoid it in science.
Blind study- Keeps personal bias from affecting results.
Repetition- to make sure your results are accurate.
What is the difference between a description and an explanation?
A description is a spoken or written summary of observations. An explanation is an interpretation of
observations.
Describe accuracy and precision. Which is more important in an experiment?
Accuracy is a description of how close a measurement is to an accepted or true value. Precision is a
description of how similar or close measurements are to each other. Both are equally important.
Chapter 1: Earth’s Layers
How do you calculate density?
Density= mass/volume OR d=m/v
If layer A is more dense than layer B, which would be on the top?
Layer B would be on top because the most dense layer would sink (THINK: the core of Earth)
What happens as you go deeper into Earth?
Both pressure and temperature increase. Also, the material that makes up Earth becomes more dense.
What are the layers of Earth?
Crust, Mantle, Core
What are the 5 systems of Earth? (Think “-sphere”)
Geosphere (land), Atmosphere (air), Hydrosphere (water), Biosphere (life), Cryosphere (frozen)
What is the general composition of each layer of Earth?
Crust- Low mass elements like silicon and oxygen
Mantle- Magnesium and iron silicates
Core- Mostly iron
Are landforms permanent? Why or why not?
NO! Their characteristics change over time due to factors like uplift and erosion.
How do mass and distance affect gravity?
The force of gravity increases as mass increases. It decreases as distance between objects increase.
Compare and contrast plains, plateaus, and mountains.
Plains- Low relief, low elevation
Plateau- Low relief, high elevation
Mountain- High relief, high elevation
ALL ARE LANDFORMS
Distinguish between the lithosphere and asthenosphere.
The lithosphere is the layer of Earth that includes the crust and brittle uppermost mantle (it also makes up the
tectonic plates)
The asthenosphere is a layer of the upper mantle that is plastic and slowly flowing.
How is continental crust different from oceanic crust? How are they similar?
They are both the upper layer of Earth- Continental crust is on land and Oceanic crust is under the ocean. The
oceanic crust is denser and the continental crust is thicker.
Where does Earth’s magnetic field originate?
Outer and inner core.
How is Earth’s magnetic field produced?
The inner core spins more quickly than the outer core, which generates a magnetic field.
What are some benefits of Earth’s magnetic field?
It protects Earth from cosmic rays and charged particles coming from the sun.
Chapter 2: Minerals and Rocks
What are the characteristics of a mineral?
A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical
composition.
What physical characteristics deal with how a mineral breaks?
Fracture (uneven) and cleavage (straight lines)
What physical characteristic deals with if something can scratch a mineral? What scale is used to measure
this?
Hardness- Mohs hardness scale.
What is an ore? How might a mineral not be classified as an ore anymore?
An ore is a mineral that can be produced at a profit. If a mineral can no longer produce a profit, it is no longer
an ore.
What are the three types of rocks?
Igneous, sedimentary, metamorphic,
Describe igneous rocks and tell how they are formed.
Igneous rocks can be fine or coarse-grained. They are formed when magma or lava cools.
Describe metamorphic rocks and tell how they are formed.
Metamorphic rocks form when parent rocks are heated, squeezed, or exposed to hot liquids. They do not
melt, but may change texture and composition.
Describe sedimentary rocks and tell how they are formed.
Sediment undergoes lithification and turns into rock.
What are the two types of igneous rocks? How are they similar and different?
Extrusive igneous rock forms when lava cools on Earth’s surface. Intrusive igneous rock forms when magma
cools inside Earth.
Compare and contrast cementation and compaction.
Compaction is when sediments are pressed together. Cementation is when the liquid minerals between
sediments crystallize and cement grains together.
How does temperature affect rock grain size?
If molten rock cools quickly, grains are smaller. If molten rock cools slowly, grains are larger.
How are rocks classified?
By how they are formed.
Why is ice a mineral but not liquid water?
Because a mineral must be a solid.
What is lithification?
When sediments are turned into rocks.
Using your textbook, draw and label a diagram of the rock cycle.

Chapter 3: Earth’s History
Hypothesize why an asteroid impact may lead to a mass extinction event.
Crushed rock and dust would enter the atmosphere, which would block out the sun. This would lead to global
cooling and changing climates.
How might an asteroid impact cause climate change?
See above.
What happened in the fossil record as organisms developed hard parts?
Harder parts fossilize more easily, so we would see more of them in the fossil record.
What can major changes in the environment cause?
Adaptation or extinction.
What was the MAJOR environmental change in the Proterozoic eon? What was an alternate name for it?
Great Oxygenation Event. Oxygen Catastrophe.
Where did Earth’s oceans come from?
During the Archean eon, the temperature in Earth’s atmosphere dropped. This caused water vapor in the air
to condense and fall as acid rain, which eventually formed the firs oceans.
How are the divisions in the geologic time scale determined?
They are based on changes in rocks and fossils.
If Earth’s history took place in one year, when did humans appear?
The afternoon of December 31. CRAZY!
List the units of the geologic time scale in order from largest to smallest.
Eon, Era, Period, Epoch
How did protocontinents compare to present-day continents?
They were much smaller.
What is the Snowball Earth hypothesis?
600-800 million years ago the Earth may have been completely frozen over, looking like a giant snowball.
Do all changes to Earth’s surface happen slowly? Why or why not?
NO! Earthquakes, man, weather events, asteroids, etc.
Why do sea levels increase as global temperatures increase?
Because ice on Earth melts and adds liquid water to the oceans.
Chapter 4: Plate Tectonics
Where are the youngest rocks on Earth located?
At a mid-ocean ridge
What do tectonic plates float on?
The asthenosphere
What are the three pieces of evidence Wegener used to support his theory of continental drift?
Fossil- Glossopteris Climate- glacial grooves, glacial sediments Rock- volcanic rock in S. America and Africa
AND the Appalachian/Caledonian mountains.
What do the alternating magnetic bands of basalt on the seafloor show?
That seafloor spreading is actually happening.
What drives plate motion?
Convection currents in the mantle.
What are the three types of plate boundaries? Explain each of them.
Convergent- Plates coming together
Divergent- Plates moving apart
Transform- Plates sliding past each other
How were the Himalayan Mountains formed?
When the Indian plate and the Eurasian plate collided- in fact, they are STILL colliding.
What is an example of a transform boundary?
The San Andreas fault in California
Study the diagram of plate boundaries in your textbook. Be able to interpret the symbols on the map.

How are the Caledonian Mountains and the Appalachian Mountains related?
They are made of the same kinds of rock, formed the same way, and the same age.
What might happen if Africa were to eventually collide with Europe?
A brand new mountain range? A new continent?
How does a mid-ocean ridge form?
When two plates move apart underwater, and magma is pushed to the surface by convection
Why did Wegener have a hard time convincing others that continental drift was occurring?
Because he could not prove it was happening or describe why.
Chapter 5: Earth Dynamics
What are the two kinds of vertical motion?
Uplift and subsidence
How does uplift contribute to the rock cycle?
In brings material that is inside Earth to the surface.
What are the three types of stress? Provide a real-world example of each.
Tension- Pulling taffy apart
Compression- Stepping on a snowball
Shear- Falling down and scraping your knee
What landforms form when two plates converge?
Mountain ranges, ocean trenches, and volcanic arcs
What stress is present at a convergent boundary?
Compression
What landforms form when two plates diverge?
Mid-ocean ridges, continental rifts
What stress is present at a divergent boundary?
Tension
What landforms form when two plates slide past each other?
Transform fault, fault zones
What stress is present at a transform boundary?
Shear
How does subduction contribute to the rock cycle?
It pulls material back into the mantle to be melted and made into igneous rocks all over again.
What is isostasy?
The balance between the mantle and crust.
What is the rate at which tectonic plates move?
1-9 cm a year
What is the difference between plastic and elastic strain?
Plastic is permanent and elastic is temporary.
Good luck studying! I love you bunches. See ya
Monday!