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Study for Final
8th Grade Science Questions to Prepare for the Final
| Question | Answer |
|---|---|
| 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
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