Learing Targets 6 - 10 Study Guide ANSWER KEY

Targets 6-10 Study Guide
Target 6: fossils
6.1 Identify a mold and cast fossil. Define and explain how they are formed:
 A mold forms when hard parts of an organism are buried in sediment, such as sand, silt, or clay.
 The hard parts completely dissolve over time, leaving behind a hollow area with the organism’s shape.
 A cast forms as the result of a mold.
 Water with dissolved minerals and sediment fills the mold’s empty spaces.
 Minerals and sediment that are left in the mold make a cast.
 A cast is the opposite of its mold.
6.2 Identify a trace fossil. Define and explain how they are formed:
 Trace fossils show the activities of organisms.
 An animal makes a footprint when it steps in sand or mud.
 Over time the footprint is buried in layers of sediment. Then, the sediment becomes solid rock.
6.3 Identify petrified fossil. Define and explain how they are formed:
 Petrified fossils form when minerals replace all or part of an organism.
 Water is full of dissolved minerals. It seeps through the layers of sediment to reach the dead organism.
 When the water evaporates, only the hardened minerals are left behind.
6.4 Identify preserved remains. Define and explain how they are formed:
Some organisms get preserved in or close to their original states. Here are some ways that can happen.
 An organism, such as an insect, is trapped in a tree’s sticky resin and dies. More resin covers it,
sealing the insect inside. It hardens into amber.
 An organism, such as a mammoth, is trapped in a tar pit and dies. The tar soaks into its bones and
stops the bones from decaying.
 An organism, such as a woolly mammoth, dies in a very cold region. Its body is frozen in ice, which
preserves the organism—even its hair!
6.5 Identify carbon fossils. Define and explain how they are formed:
• All living things contain an element called carbon.
• When an organism dies and is buried in sediment, the materials that make up the organism break
• Eventually, only carbon remains.
• The thin layer of carbon left behind can show an organism’s delicate parts, like leaves on a plant.
Target 7: Determine the age of fossils
7.1 Explain Relative dating using index fossils.
 Index Fossils - are fossils that must be widely distributed and represent a type of organism that existed
only briefly.
 Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
7.2 Identify sequence of rock layers using Superpositioning (explain)
 According to the Law of Superposition, in horizontal sedimentary rock layers the oldest layer is at the
 Each higher layer is younger than the layers below it.
7.3 Determine the Absolute age using Radioactive decay (define radioactive decay)
 As a radioactive isotope within the rock decays, it changes into another stable element. Therefore, the
composition of the rock changes slowly over time.
 The amount of the radioactive element goes down, but the amount of the new element goes up.
 The more radioactive isotopes (undecayed material) available, the younger the rock.
 The more stable element (decayed material) available, the older the rock.
 So, scientist can tell how old a rock is by comparing the radioactive elements to the stable elements.
Targets 6 and 7 – Name three methods for dating rocks. Make sure that you know the difference in how they
are dated (absolute and relative dating)
Explain how each method dates the rocks.
Target 8: Types of Heat Transfer
8.1 Explain Conduction (define and give example)
 The transfer of heat between substances that are in direct contact with each other. The better the
conductor, the more rapidly the heat will transfer. Good conductors are copper, iron, and silver.
8.2 Describe Earth's interior/motion of plates due to Convection. (define and give example)
 Convection is the up and down movement of gases and liquids caused by heat transfer.
 As a gas or liquid is heated, it expands and rises because it is less dense. When a gas or liquid
becomes cool, it becomes denser and sinks.
 Heat from Earth’s mantle and core causes convection currents to form in the asthenosphere, which in
turn causes the plates floating on top to move in the same direction as the convection current.
8.3 Define and analyze radiation. (define and give example)
 The transfer of heat energy through space by way of electromagnetic waves. An example of radiation
would be a microwave, incandescent light bulbs, and the sun heating the Earth.
Target 9: Energy
9.1 Describe Solar energy (how does it form & give Advantages/Disadvantages)
The sun is a ball of hot gases which is the primary source of all energy on Earth. In the high temperature of the
sun, small atoms of hydrogen are fused, that is, the centers of the two atoms are combined. Fusion releases far
greater energy than splitting the atom (fission, see below).
Pros –
• It is renewable
• Gives off no pollution
• Allows us to become less dependent on fossil fuels
Cons  The photovoltaic cells are expensive
• Weather can impact the efficiency of solar cells
• Pollution can impact the efficiency of solar cells
9.2 Describe Wind energy(how does it form & give Advantages/Disadvantages)
The unequal heating of the earth's surface by the sun produces wind energy, which can be converted into
mechanical and electrical energy. Today windmills can be connected to electric generators to turn the wind's
motion energy into electrical energy, and wind over 8 miles per hour can be used to generate electricity .It is a
renewable, but unpredictable, energy source.
Pros –
• It is renewable
• Wind is free
• Wind turbines do not produce pollutants or greenhouse gases
Cons • Turbines can be damaged during storms
• Can be harmful to wildlife
• Low wind speed can impact efficiency
9.3 Describe Hydroelectric energy(how does it form & give Advantages/Disadvantages)
When water is collected behind dams on large rivers, it provides a source of energy for the production of
electricity. The enormous power of falling water is capable of turning giant turbines. These turbines drive the
generators, which produce electricity. The degree of power is determined by the amount of water and the
distance it falls
Pros –
• No waste or pollution
• More reliable than wind, solar, or wave power
• Water can be stored above the dam ready to cope with peaks in demand
Cons –
• It is very expensive to build a dam
• Very few places to build them
• They destroy habitats by flooding.
9.4 Describe Nuclear energy(how does it form & give Advantages/Disadvantages)
This is splitting of the uranium atom. Splitting the nucleus of an uranium atom releases a tremendous amount of
heat energy. Power companies use the heat produced by nuclear fission to produce electricity.
Pros  Cost efficient
 Highly effective
Cons –
 radioactive waste products
 meltdowns
 radiation exposure of workers.
Target 9 and 10 - Name and describe three types of alternative energy.
Give the positive points for each type of energy described above.
Give the negative issues for each of the energy types described.
Target 10: Variables that impact the Environment
10.1 Explain Greenhouse effect (Describe and Draw diagram)
In the atmosphere, water vapor, carbon dioxide, and certain other gases act like windows. These gases allow
sunlight to reach the Earth’s surface, but they prevent the most of the heat from escaping back into space.
Some of the heat that is reflected off of Earth’s surface is in the form of infrared rays. The heat is then trapped
near the Earth’s surface.
10.2 Explain Carbon footprint (what actions can you take to reduce your carbon footprint?
The amount of carbon dioxide emitted due to the the consumption of fossil fuels by a particular person
Recycle, car pool, walk…etc.
10.3 Explain Climate change (associated with the Greenhouse gases and greenhouse effect)
 Climate change is a shift in temperature, precipitation, wind and other long-term weather patterns due
to the combustion of fossil fuels and the greenhouse effect