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Study for Final

8th Grade Science Questions to Prepare for the Final

What are four parts of natural selection? Overproduction, Variation,Competition, & Selection
How might a change in the environment of a species contribute to its extinction? If an organism’s habitat is destroyed/disturbed, that may lead to the species not being able to adapt or reproduce. Without reproduction the species will go extinct.
What are the 3 types of heat transfers? Conduction, Convection, & Radiation
Which group of elements on the periodic table is the least reactive? Group 18, Noble Gases
What is a phenotype? The physical appearance of an organism; like brown fur
What is a genotype? The genetic make-up or alleles of an organism;example: BB
What is meant by the terms costs and benefits when discussing the environment? Making decisions about issues by balancing needs of environment & needs of people
Explain why the world has experienced population growth in the past years. *Birth rates outnumber death rates *Medical care & improved technology allow result in fewer deaths
How is lake-effect snow caused? Cold dry air moves across a warmer lake and then on the other side the land is cool so the water vapor condenses & falls as snow.
Describe ways humans can reduce the emissions that contribute to smog and the greenhouse effect. Take public transportation or walk
How are clouds formed? Water vapor in the air condenses on dust particles in the air
Why is the ozone layer important to the Earth? Protects from harmful UV rays
Describe some major causes of permanent habitat destruction. Clearing areas for buildings & farms
What is photochemical smog? Haze formed as a mixture of ozone & other chemicals when pollutants react with sunlight.
How are winds caused?  Differences in air pressure (Unequal heating of Earth’s surface creates convection currents that change density of air)
What is a renewable resource? Either always replaceable or can easily be renewed—examples: trees, wind, sunlight
What is a nonrenewable resource? Not replaced in a useful time—examples: metals, fossil fuels
How do scientists classify the 4 main layers of the atmosphere? By changes in temperature
Where is the ozone layer found? Stratosphere
What drives the motion of Earth’s atmosphere system? Energy from the sun
What causes air pressure? Weight of a column of air pushing down on an area
What causes deep ocean currents to curve? Coriolis effect—the effect of Earth’s rotation on the direction of winds & currents
What is eutrophication? Nutrients build up in lakes & ponds leading to the growth of algae
How do humans contribute to eutrophication? One way humans affect it is by using fertilizers that run off into the lakes/ponds
If the Earth is ¾ water, how can there be water shortages in parts of the world? Most water on Earth is salt water
Explain how conduction transfers heat. Touching
What is convection? Heat transfer by the movement of a fluid
What is a convection current? Warm fluids rise and cold fluids sink
How does air pressure change with increasing altitude? Decreases
What effect do ocean currents have on the climates of coastal areas? Ocean currents warm or cool the air above & influences the climate.
How does the water on Earth behave as it travels through the water cycle? Evaporation--Condensation--Precipitation
Does the total amount of water in the water cycle change? total amount of water in the system stays the same
What factors affect the density of ocean water? Temperature, Salinity, Depth
What does the law of conservation of mass state? In a chemical reaction, the reactants equal the products; matter is neither created nor destroyed.
What is a group on the periodic table? Group is a vertical column—similar properties due to valence e-
What is a period on the periodic table? Period is horizontal—properties differ in a periodic manner
Describe the properties of molecular compounds (covalently bonded molecules). Low boiling and melting points; poor conductivity
How can you tell that a chemical reaction has occurred? Bonds break & new bonds form creating a new product 1. precipitate 2. temp. change 3. Color change (sometimes) 4. gas produced
Describe the electrical attraction that holds atoms together. Opposite charges attract (think positive and negative ions)
What is an atom? basic particle from which all elements are made
What is an element? A substance made entirely from one type of atom
What is a molecule? neutral group of two or more atoms held together by covalent bonds
What are some properties of metalloids? Metalloids have properties of both metals & nonmetals. They are especially useful as semiconductors because they have varying abilities to conduct electricity.
Who formatted the first periodic table and how was it organized? Mendeleev—used increasing atomic mass
How is the periodic table now organized? Increasing atomic number
What are some properties of metalloids? Metalloids have properties of both metals & nonmetals. They are especially useful as semiconductors because they have varying abilities to conduct electricity.
What are some properties of metals? Malleable, ductile, shiny, good conductors
Where are the most reactive metals located on the periodic table? Group 1; Alkali Metals; Far left side
Describe a proton. positively charged, in nucleus
Describe a neutron. no charge (neutral), in nucleus
Describe an electron. negative charge, in electron clouds
What variable is changed by the experimenter? manipulated variable
What are the variables that are left the same in an experiment named? controlled variables
What variable may be affected by the manipulated variable? Responding variable
Created by: MrsMonagle