# 8th Grade Science Quick Review - Mr. Greenberg's Class

8th Grade Science Quick By: Mindy Mahar Review Table of Contents Matter and Change (Slides 3-21) Earth History (Slides 22-37) Structure and Function of Living Organisms (Slides 38-46) Ecology and Energy (Slides 47-63) Earths Systems, Structures and Processes (Hydrology-Slides

64-76) Matter and Change Standards 8.P.1.1 Classify matter as elements, compounds, or mixtures based on how the atoms are packed together in arrangements. 8.P.1.2 Explain how the physical properties of elements and their reactivity have been used to produce the current model of the Periodic Table of elements. 8.P.1.3 Compare physical changes such as size, shape and

state to chemical changes that are the result of a chemical reaction to include changes in temperature, color, formation of a gas or precipitate. 8.P.1.4 Explain how the idea of atoms and a balanced chemical equation support the law of conservation of mass. Scientific Method A researcher suggests that behavioral therapy will help people who have moderate depression. Of 100 individuals with moderate

depression, 50 receive 8-weeks of a behavioral therapy, while the other 50 are placed on a waiting list for 8-weeks. During that 8week period, all 100 people get the same amount of sleep each night and eat the same exact breakfast each morning. At the end of the 8-weeks, all 100 people are given psychological tests to assess their level of depression. 45 of the 50 who received therapy are no longer depressed, while 49 of the 50 who were on the waiting list are still depressed. Identify the following: Hypothesis, Independent Variable, Dependent Variable, Experimental Group, Control Group,

Constant(s) and Conclusion Answers Hypothesis: Answers will vary Independent Variable: Behavioral therapy Dependent Variable: Level of depression Experimental Group: 50 given the behavioral therapy Control Group: 50 placed on the waiting list Constants: Amount of sleep and type of breakfast

8.P.1.2: Atomic Structure Calculate each of the following for an atom of Aluminum: Protons=_______________________ Neutrons=_____________________

Electrons=_____________________ Atomic #=_____________________ Atomic Mass=__________________ Answers Protons= 13 Neutrons= 14

Electrons= 13 Atomic #= 13 Atomic Mass= 26.98154 (27) 8.P.1.2: Valence Electrons 1. Calculate the number of valence electrons for an atom of Br. 2. Draw a Lewis Dot Diagram for an atom of Br. 3. Draw a Bohr Model for an atom of Li.

4. Explain why it is likely for the atom of Lithium and the atom of Bromine to react. Answers 1. Br has 7 valence electrons (in group 17) 2. 3.

4. It is likely that Br and Li react because Li has one valence electron and Br has 7, which means that Li can help Br get 8 valence electrons which will make it nonreactive/stable (all atoms want 8 to be stable) 8.P.1.2: Periodic Table 1. How are groups and periods arranged on the periodic table? 2. Use the periodic table below to determine what group N, P and As are in.

3. Use a periodic table to determine how many valence electrons N, P and As have? 4. Kr, Xe and Rn (all considered Nobles Gases) are in Group 18. What does this tell you about how many valence electrons they have? 5. Why arent these elements reactive? Answers

1. Groups are vertical and periods are horizontal (the word group has up in it and groups go up and down, whereas, you put a period at the end of a sentence and sentences are written horizontally. 2. Group 15 3. They each have 5 valence electrons because they are in Group 15 and the number of valence electrons is determined by looking at the last digit of the group number. 4. They each have 8 valence electrons in their outer shell. 5. They are not reactive because they are stable/their outer shells

are full (maximum 8). 8.P.1.3: States of Matter Below is a diagram of the three phases of matter. Identify each as being either a solid, a liquid or a gas and then back your answer up with reasons for each (discuss particle arrangement, volume and shape). A

Gas Particle Arrangement Tightly packed in a crystalline arrangement

Close together with no arrangement Far apart with no arrangement

Definite Volume? Yes Yes No

Definite Shape ? Yes No No

8.P.1.3:Physical and Chemical Properties of Matter 1. How do an elements physical and chemical properties of matter help determine its position on the periodic table? 2. Why are phase changes considered physical properties of matter? Answers

1. The properties of an atom relate directly to the number of electrons in various orbitals, and the periodic table is much like a road map among those orbitals and chemical properties can be figured out based on the position of an element on the Periodic Table. The electrons in the valence shell are especially important because they are the ones that can share and exchange and

are responsible for chemical reactions. 2. Phase changes are physical properties of matter because they can be observed without changing the identity of the substance. 8.P.1.3: Physical and Chemical Changes of Matter Ms. Mindy mixes yeast and sodium acetate in a graduated cylinder. She passes the test tube

around for her students to feel. The students notice that the test tube is hot and has produced bubbles and has changed colors. Ms. Mindy asks the students to decide if the mixing of the two chemicals involved a physical change, a chemical change or both. Justify your answer. Explain why cooking an egg is a chemical change, but the melting of an ice cube is a physical change.

8.P.1.1: Elements, Compounds and Mixtures 1. Why is Letter C in the diagram to the right considered a mixture of elements and a compound? 2. What type of mixture is Letter C considered? 3. Which letter represents a Pure Substance of elements and why? 4. Why is Letter A considered a compound

while Letter D is considered a molecule (with elements as well)? Answers 1. The white circles represent one type of element and when connected to a shaded circle, represent that element chemically combined to another element. 2. The mixture is heterogeneous.

3. Letter B represents a pure substance of elements (Letter A is also a pure substance, but with compounds-C and D are both mixtures-C is heterogeneous and D homogeneous) 4. Letter A is a compound because there are two different elements combined chemically. Letter D is a molecule (and a compound!) because there are two of the SAME elements

combined chemically. 8.P.1.4 : Law of Conservation of Mass Explain whether the diagram below is consistent with the law of conservation of mass and why or why not. Answers

The diagram IS consistent with the Law of Conservation of Mass because there are the same number of red on each side and the same number of blue on each side. Atoms were not created or destroyed, but were involved in a chemical reaction, which changed the arrangement. Earth History 8.E.2.1 Infer the age of Earth and relative age of rocks and

fossils from index fossils and ordering of rock layers (relative dating and radioactive dating). 8.E.2.2 Explain the use of fossils, ice cores, composition of sedimentary rocks, faults, and igneous rock formations found in rock layers as evidence of the history of the Earth and its changing life forms. 8.L.4.1 Summarize the use of evidence drawn from geology, fossils, and comparative anatomy to form the basis for biological classification systems and the theory of evolution.

8.L.4.2 Explain the relationship between genetic variation and an organisms ability to adapt to its environment. Rock Cycle 1. Create a recipe for each of the following rock types: igneous, sedimentary and metamorphic (include as many details as possible). 2. Explain why not all rocks go through each part of the rock cycle.

Answers 1. -Igneous: Igneous rocks form when existing rocks melt because they were exposed to heat within the Earth and then cooled (either above or below Earths surface) -Sedimentary: Sedimentary rocks form when existing rocks get weathered, eroded, deposited, compacted and cemented. This type of rock depends on heat from the sun NOT heat within Earth.

-Metamorphic: Metamorphic rocks form when existing rocks get buried and are exposed to intense heat and pressure. 2. A rock may get buried and exposed to heat and pressure before having a chance to erode and turn into a sedimentary rock. It may also melt before metamorphosis, thus turn into an igneous rock. Relative Dating Sequence the letters from youngest to oldest in the diagram below.

Answers Youngest: A, D, C, B, E Absolute Dating 1. How can scientists use ice cores to learn about air composition from the

past? 2. How are tree rings used in absolute dating? Answers 1. They can test the tiny air bubbles trapped in the ice to learn about the composition of the air from the past. 2. In general, each tree ring indicates a different year.

The rings are thin during dry years and thick during wet years. Absolute Dating 1. Use the graph to determine how many half-lives have occurred if of the original parent material remains. 2. If the half-life time in #1 above was 5,000 years, how old is the

fossil? 3. Use the graph to determine what fraction of parent material remains if 4 half-lives have passed. Answers 1. 2 half-lives have occurred 2. 10,000 years old 3. 1/16

Plate Tectonics 1. Describe three pieces of evidence for Wegners Continental Drift hypothesis. 2. Describe how new crust gets created at divergent boundaries. 3. How do convergent boundaries destroy crust (2 ways). 4. Explain the process of subduction. 5. How are transform boundaries different from divergent and convergent?

Geologic Time Scale 1. Describe the 5 major events of the Precambrian. 2. How did life differ between the Paleozoic, Mesozoic and Cenozoic Eras? 3. Explain the extinctions that took place in each of the above eras. Fossils

1. Give a brief description of each type of the 6 main types of fossils. 2. Why is Letter A the best choice for an index fossil in the diagram to the right? 3. Why would a bat have a better chance of turning into a fossil compared to a caterpillar? 4. Explain why an animal at the bottom of a dry riverbed would have less of a

chance becoming a fossil compared to one that was buried in a landslide. Evolution 1. How did Darwin use finches to begin the study of evolution? 2. Why do organisms overproduce? 3. How do variation and

adaptation affect an organisms chance of survival? Evolution/Natural Selection 1. There are two pieces of evidence for evolution; similar structure and functions and vestigial organs. Explain why these are important pieces of evidence and give examples of each.

2. How are living things classified and what is another name for classification? 3. Why do alleles change in response to a species change in environment? Structure and Function of Living Organisms 8.L.1.1 Summarize the basic characteristics of viruses, bacteria, fungi and parasites relating to the spread, treatment and prevention of disease.

8.L.1.2 Explain the difference between epidemic and pandemic as it relates to the spread, treatment and prevention of disease. 8.L.2.1 Summarize aspects of biotechnology including:

Specific genetic information available Careers Economic benefits to North Carolina Ethical issues Implications for agriculture 8.L.5.1 Summarize how food provides the energy and the molecules required for building materials, growth and survival of all organisms (to include plants). 8.L.5.2 Explain the relationship among a healthy diet, exercise, and the general

health of the body (emphasis on the relationship between respiration and digestion). Microbes 1. Explain the difference between viruses, bacteria, fungi and parasites. 2. Explain how viral infections are treated as opposed to bacterial infections. 3. Why are viruses considered to be non-living?

4. Why are some bacterial infections becoming harder to treat? Microbes 5. Fungi can reproduce both sexually and asexually. How does this give them an advantage over other species? 6. How do humans compete with fungi? 7. How are tapeworms and parasites similar?

Diseases (Pandemic vs. Epidemic) 1. Explain the main difference between epidemics and pandemics. 2. Explain how the vector for malaria spreads disease. 3. Explain 3 ways that you can reduce the risk of spreading disease.

Biotechnology 1. How does the study of biotechnology use DNA? 2. Why is biotechnology important in todays society? 3. Explain why there is such a big debate with GMOs (genetically modified organisms). Cellular Respiration 1. Explain the difference between cellular respiration

and photosynthesis. 2. Write out the formula for cellular respiration and then circle the reactants and put a square around the product. Exercise and Nutrition 1. Why does your rate of respiration increase when you exercise?

2. Why do adolescents require a different diet? 3. How does a lack of exercise affect a cells ability to perform cellular respiration? Ecosystems 8.L.3.1 Explain how factors such as food, water, shelter, and space affect populations in an ecosystem. 8.L.3.2 Summarize the relationships among producers,

consumers, and decomposers including the positive and negative consequences of such interactions including: coexistence and cooperation competition (predator/prey) parasitism mutualism 8.L.3.3 Explain how the flow of energy within food webs is interconnected with the cycling of matter (including water, nitrogen, carbon dioxide, and oxygen).

Population Factors 1. Explain the difference between density-dependent and density independent limiting factors. Give two examples of each. 2. Explain the difference between abiotic and biotic factors. Give two examples of each. 3. Explain the hierarchical organization using the following terms: ecosystems, communities, populations, biosphere, organisms and species.

Symbiotic Relationships 1. Compare and contrast mutualism, commensalism and parasitism. 2. Give an example of each of the above symbiotic relationships. Food Chains/Webs 1. Explain why predator-prey relationships help to

stabilize populations. 2. Explain the process in which organisms in each trophic level use energy. 3. Explain the difference between food chains and food webs. Ecological Pyramids 1. Draw an ecological pyramid and label the following: producers, primary consumers, secondary consumers and

tertiary consumers. Also label autotrophs, heterotrophs, omnivores, herbivores and carnivores. 2. Draw a pyramid of numbers for an ecosystem where a single tree supports many primary consumers, but not as many secondary or tertiary consumers. 3. Explain why energy levels are greater from level to level and why the amount of energy available decreases. Biogeochemical Cycles

1. Explain the water cycle using the following terms: evaporation, condensation, transpiration, runoff and groundwater. 2. Explain how the sun, animals, plants and humans play a role in the carbon cycle. 3. Why is the nitrogen cycle one of the most important nutrient cycles found in terrestrial ecosystems. 4. Explain why living things need phosphorous and how it cycles into foodchains.

Energy Conservation and Transfer 8.P.2.1 Explain the environmental consequences of the various methods of obtaining, transforming, and distributing energy. 8.P.2.2 Explain the implications of the depletion of renewable and nonrenewable energy resources and the importance of conservation.

Alternative Energy 1. Give 3 examples of renewable and nonrenewable resources. 2. Which type of resource is most used in the US? What percentage? 3. Give a detailed description of each type of alternate energy and the pros and cons to using each (nuclear, solar, etc) 4. How are population and resources related?

Earths Systems, Structures and Processes (Hydrology) 8.E.1.1 Explain the structure of the hydrosphere including: Water distribution on earth Local river basin and water availability 8.E.1.2 Summarize evidence that Earths oceans are a reservoir of nutrients, minerals, dissolved gases, and life forms:

Estuaries Marine ecosystems

Upwelling Behavior of gases in the marine environment Value and sustainability of marine resources Deep ocean technology and understandings gained Earths Systems, Structures and Processes (Hydrology) 8.E.1.3 Predict the safety and potability of water supplies in North Carolina based on physical and biological factors, including:

Temperature Dissolved oxygen

pH Nitrates and phosphates Turbidity Bio-indicators 8.E.1.4 Conclude that the good health of humans requires:

Monitoring of the hydrosphere Water quality standards Methods of water treatment Maintaining safe water quality Stewardship

Properties of Water 1. Explain the difference between cohesion and adhesion. 2. Explain how the surface tension of water can allow small insects to walk on it without falling through. 3. Explain why the water coming out of a faucet will move towards a balloon that has been rubbed on hair? 4. Explain how water and oil will act when mixed (use the term density).

5. Using the term specific heat, explain why water takes more time to heat up and cool off than land does. Distribution of Water 1. Describe the distribution of water on Earth (ocean, lakes, rivers, glaciers, etc). 2. Explain what an estuary is and why they have high levels of biodiversity. 3. Discuss the interactions that take place between the

ocean and the atmosphere that effect weather. 4. Describe what upwelling is and why fishermen like to fish in areas where upwelling happens. Ocean Zones 1. Explain the difference between the photic and the aphotic zone of the ocean. 2. Most of the oceans autotrophs live in the photic zone. Explain why.

3. Explain the living conditions that extremophiles live in. 4. Why is it important for scientists to study hydrothermal vent systems? Ocean Zones 5. Explain the difference in hydrothermal vents and cold seeps. 6. Explain why organisms

depend on chemosynthesis and not photosynthesis in the benthic layer of the ocean. 7. Which type of organisms are producers at vent communities? Water Quality 1. Explain the difference between physical, chemical and biological

variables when determining the health of a body of water. 2. A sample is taken from a body of water. It has high turbidity, low DO, a pH of 3 and a temperature of 20 degrees F. State whether this body of water has high or low diversity and why. 3. Explain the difference between point and non-point source pollution and give an example of each. 4. Explain the difference between potable and non-potable water. Water Quality

5. Summarize the 5 steps taken to clean drinking water. 6. How do levels of Nitrogen (N) and Phosphorous (P) affect levels of DO in water and how do they lead to eutrophication? 7. Explain how bioindicators can be used to determine the health of a body of water. Give an example. Water Resources 1. Explain how why the ocean is important for the

following: Fishing Shipping

Tourism Mining Drilling for Oil 2. Explain how each of the following above activities are harmful to the ocean

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