1. 8th
Grade Science EOG Review
 Scientific Method
 PHEOC: Problem, Hypothesis, Experiment (Materials & Procedure), Observations & Conclusion
 Hypothesis: an educated guess
 Observation: a fact determined by senses (sight, touch, etc)
 Inference: conclusion based on observation
 Ex: Observation: the rose plant is wet, Inference: the rose bush has been recently watered
 Trial: each repeat of an experiment
 Variable: what changes in an experiment
 Independent Variable: variable that is changed, change only 1 at a time! Ex: Changing the amount of
plant food for roses to test its affects
 Dependent Variable: changes as a result of the independent variable, measured variables! Ex: How much
the roses grew due to the type of plant food
 Constants: variables that do not change. Ex: the type of rose, the type of soil, how much water
 Control: part of the experiment that does not receive the independent variable. Ex: the rose plant that
does not receive any plant food
 Chemistry
 Atom = basic unit of matter, everything is made of matter, elements combine to form chemicals (natural &
synthetic)
 Element: composed of one kind of atom, ex: gold
 Compounds: pure substances that are composed of two or more types of elements that are chemically
combined, ex: water, salt
 Periodic Table classifies elements based on their properties
 Group # = # at the top of the column
 Period # = row #, tells how many energy shells there are in the atom
 Group Name = (From left to right) Alkali Metals, Alkaline Metals, Transition Metals, Boron, Carbon,
Nitrogen, Oxygen, Halogens and Noble Gas
 Atomic number = # of protons
 Atomic mass = # of protons & neutrons
 # of Electrons = # of protons in uncharged atom
 Valence Electrons are the electrons in the outermost energy level
 Valence # = # of electrons atom needs to gain or lose to have 8 electrons in the outer shell
 Metals are on the left side of the table, metalloids are along the stair-step and nonmetals are to the
right of the table
 Most elements are metals, metals are good conductors of heat and electricity, shiny, malleable
(hammered into sheets) and ductile (pulled into wire)
 Nonmetals: poor conductors of heat & electricity, dull in color and brittle (breakable)
 Metalloids: have properties of both metals & nonmetals, semiconductors can be made to carry energy
under certain conditions and are useful in electronics, Ex: Silicon & Germanium
 Highly reactive metals: Group 1
 Highly reactive nonmetals: Chlorine, Fluorine, Oxygen
 Chemical Reactions: a process that produces a chemical change
 Chemical Change: creates a new product that cannot be reversed, Ex: burning a match
 Physical Change: changes shape or state, Ex: tearing paper
 Formulas: show the number of atoms of each element in the substance
 Subscript tells how many atoms are present, Ex: H2 = 2 hydrogen atoms
 Coefficient tells how many molecules are present, Ex: 2H20 = 2 molecules of water
 Equation: tells you what and how substances combine to form new substances
 The left side is the reactant side
 The arrow is the yield sign

2.  The right side is the product side
 Equations must be balanced!!! They should have the same types and numbers of atoms on each side
of the yield.
 Must follow the Law of Conservation of Matter (Mass): matter (mass) can’t be created or
destroyed
 The mass of the reactants must equal the mass of the products, Ex:
50 grams of reactants = 50 grams of product
 To balance an equation you can change only the coefficients not the subscripts!
 Evidences of a chemical reaction are bubbles, change in color, change in state (solid, liquid, and gas),
increase or decrease in temperature; odor or a precipitate forms (solid particles that form when liquids
are mixed).
 Mixtures: two or more different substances that are physically combined; retain their own properties
 Heterogeneous: not uniform throughout, ex: pizza, salads
 Homogeneous: same throughout, ex: ink
 Factors that affect how quickly a reaction occurs: increased temperature will speed up a reaction, the
amount of substance present (concentration) and surface area (how much of the substance is exposed)
 Chemicals and Your Health:
 Some chemicals can lead to various diseases
 Radioactive elements are known to cause cancer
 Asbestos causes cancer
 Alcohol can affect your liver as well as an unborn child
 Smoking can cause cancer (ex: lung or mouth cancers)
 DDT (a pesticide) can cause cancer
 Mercury can impact brain development
 Several factors can determine how unhealthy a substance is
 Concentration = amount of a substance in a certain volume
 Potency = how “strong” the substance is
 Dose = amount of a chemical given
 Exposure (time) = how long you are in contact with the substance
 Individual susceptible = how a person responds to the substance (“your tolerance”)
 Chemicals and their benefits:
 Medicines
 Food preservatives
 Increase crop production: fertilizers, pesticides (kill insects), herbicides (kill weeds)
 Sanitation (ex: chlorine used to kill bacteria in water)
 The Hydrosphere
 Freshwater
 Is polar (has a slight charge creating a positive and negative end)
 Is the universal solvent because it will dissolve so many substances
 Soluble: ability to dissolve in water
 Solvent: what does the dissolving
 Solute: what is being dissolved
 Supersaturated: no more will dissolve into the water
 States (Phases) of matter: solid ( Latent heat of fusion) liquid (Heat of Vaporization) gas
 Cohesion: water molecules stick to other water molecules
 Surface tension: water molecules attracted to other water molecules from all sides and below
 Adhesion: water molecules stick to other surfaces
 Meniscus: slightly curved water line in the graduated cylinder
 Density: amount of mass in a given volume
 Formula: Mass/Volume
 Water’s density = 1 g/mL or cm3

3.  Anything less than 1 will float
 Buoyancy: how well something floats (density and shape will affect this)
 Anything greater than 1 will sink
 Specific Heat: amount of energy needed to change the temperature of water (1kg, 10
C)
 Water has a high specific heat meaning it takes a lot of energy to change its temperature
 Allows water in lakes, rivers, oceans to keep a constant temperature
 Water Distribution
 Most freshwater located in ice (polar regions)
 Most NC drinking water in NC comes from aquifers (porous rock that holds water) and reservoirs
(man-made lakes)
 Watershed: areas of land that water drains in to when the ground is saturated or impermeable
 Cape Fear is NC’s largest river basin
 Stream or rivers carry a load (sediment carried by the water)
 Deltas: sediment dropped at the mouth of the river
 Stream Discharge: the volume of water flowing through a stream in a given amount of time
 Oceans
 About 70-75% of Earth is covered with water, there is one ocean with many basins
 Salinity: measure of salts in the water; comes from land erosion, volcanic eruptions, seafloor reactions
& atmospheric gasses
 Desalination removes salt from ocean water
 Currents: movements of large volumes of water
 Surface: upper layers of water, Ex: Gulf Stream
 Density: more dense water sinks beneath the less dense seawater
 Upwelling: cold nutrient rich waters forced to the surface when winds blow warmer surface water
away from the shore
 Currents play a large role in our climates
 Tides: rise and fall of sea level due to the gravitational attraction of the Earth, moon, sun
 Neap tides: Earth, Moon & Sun form a right angle, high tides lower & low tides higher
 Spring tides: Earth, Moon & Sun form a line, high tides higher & low tides lower
 Waves: energy moves through ocean, caused by wind (parts: crest, trough, wave height & wavelength)
 Estuary: area where freshwater meets salt water
 Serves as nature’s nursery, buffers for pollution, and habitat for species, filtration of pollutants
 Ocean Topography: what the bottom looks like, studied by SONAR (problems with studying deep ocean
(too much pressure, darkness, cold and vast space)
 Continental shelf: between shoreline and continental slope
 Intertidal: area between high and low tides
 Continental slope: steep drop from the continental shelf to the ocean floor
 Abyssal plain: flat seafloor areas
 Mid-Ocean ridge: underwater mountain chain, divergent boundary, created by sea-floor spreading
 Trench: long, narrow steep-sided depression
 Hydrothermal Vents: rely on chemical energy (chemosynthesis)
 Ocean life
 Productivity greater at surface due to sunlight penetration (photosynthesis)
 Plankton: tiny marine organisms that float with the currents
 Phytoplankton: plant plankton
 Zooplankton: animal plankton
 Nekton: swimming organisms
 Benthos: bottom dwellers
 Water Pollution
 Dissolved Oxygen: necessary for organisms to survive, DO is about 6 ppm for most fish to survive,
needs to stay constant to avoid stressing fish, warmer water has less D.O.

4.  Turbidity: how clear the water is, usually affected by sediment (silt) runoff
 pH: measures the strength of acids and bases
 pH is measured on a scale of 0-14
 pH of 7 = neutral, pH of 1-6.9 = acid, pH of 7.1-14 = base
 Nitrates: chemical formed by decaying material and animal wastes, both contain lots of nitrogen
 Bioindicators: using living organisms to rate the water quality of a stream
 Point Source: when you can trace the pollution back to its source, Ex: sewage spill
 Nonpoint Source: can’t easily identify its source, Ex: runoff from parking lots
 Eutrophication: an increase in nutrients and organisms in a body of water leading to algal blooms which
will eventually deplete the oxygen supply
 Conservation: careful use of resources
 Stewardship: looking after a resource and keeping it clean
 EPA: Environmental Protection Agency
 Clean Water Act & Safe Drinking Act
 Cells
 Requirements of living organisms: composed of cells, perform life functions like growth and digestion,
reproduce, either make nutrients or ingest them, respond to stimuli (light, touch)
 Cell Theory: All things are made of cells; Cells are the basic unit of organization in all organisms, all cells
come from cells
 Eukaryotic cells have organelles
 Prokaryotic cells do not have organelles
 Cell Organelles: mini structures that have specific jobs in the cell
 Nucleus: controls cell, contains DNA
 Cytoplasm: gel-like material that organelles sit in
 Nucleolus: makes ribosomes
 Mitochondria: energy producer
 Lysosome: digestion and process waste products
 Ribosomes: make proteins
 Endoplasmic Reticulum: Moves material around (smooth= no ribosomes, rough = ribosomes)
 Golgi Body/Apparatus: packages and moves material
 Vacuole: stores food/water/waste
 Cell membrane: allows material to enter and exit the cell, selectively permeable (will allow some
things through)
 Cell wall: only found in PLANT cells, provides protection and structure
 Chloroplasts: site of photosynthesis, provides energy for PLANT cell
 Cell Process
 Sugars are used to produce energy for the cell
 Passive Transport: no energy required
 Diffusion: material crosses cell membrane from areas of high concentration to low
concentration
 Osmosis: is diffusion but when the substance is water, water moves from area of high
concentration to low concentration
 Diffusion/Osmosis will continue until equilibrium is reached
 Active Transport: requires energy to move materials
 Endocytosis: material is taken into the cell
 Exocytosis: material is released from the cell
 Mitosis: cell growth & division
 1 cell goes through mitosis creating 2 cells that have the SAME number of chromosomes as the
original cell
 Known as a diploid cell
 Meiosis: creates sex cells

5.  Sex cells called gametes, fertilized sex cell called zygote
 1 cell goes through meiosis to create 4 cells that have HALF the number of chromosomes as the
original cell
 Known as a haploid cell
 Respiration: reaction that takes place in cells where glucose and oxygen are broken down to release
energy, carbon dioxide and water
 Photosynthesis: chemical reaction by plants that break down carbon dioxide and water to produce
sugar and oxygen; carried out by chloroplasts which contain chlorophyll (green pigment)
 Metabolism: the total chemical reactions in an organism
 Microbes: too small to be seen without a microscope
 Viruses: strand of hereditary material surrounded by a protein coating, they have no cell membrane, nucleus
or organelles
 Not considered a living organism, can’t reproduce itself, doesn’t grow, doesn’t respond to stimuli, etc.
 Copies using the Lytic cycle: invade host cell, tells cell to make copies, new viruses form, host cell
bursts releasing viruses
 Active: host cell is making new viruses
 Latent (inactive): become part of cells hereditary material but does not immediately make new
viruses
 Bacteria: can reproduce (divide), have a cell wall, cell membrane, ribosomes, cytoplasm and hereditary
material
 Have three basic shapes: spirilla (spiral), bacillus (rod-shaped) and coccus (sphere-shaped)
 Benefits: some produce antibiotics, others break down sewage, others fix nitrogen (take nitrogen from
air and change it into a form plants can use), others are used for bioremediation (clean up or remove
environmental pollutants, others used in food production (cheese, yogurts, olives)
 Biotechnology: many advances in careers, medicine, agriculture, genetics and food science
 Uses: make medicines in large quantities and human insulin, solve crimes using DNA and forensic testing,
removing pollutants from the soil (bioremediation)
 Must consider ethical issues such as genetic modification and cloning
 Diseases
 Immunity: body’s natural defense against pathogens (disease-causing organisms)
 Antibody: protein made in response to a specific antigen making the antigen useless
 Active Immunity: body makes its own antibodies, Ex: after vaccination
 Passive Immunity: antibodies produces by another animal are introduced into the body, Ex: immunity
passed from mother to fetus, does not last as long as active immunity
 Infectious Disease: can be passed from one organism to another
 Spread by biological vectors (disease carrying organisms), Ex: rats, dogs, mosquitoes, flies, fleas
 Disease Examples:
 Bacterial: Strep Throat, Diphtheria, Pneumonia, Pertusis, Scarlet Fever, STDs (Gonorrhea,
Chlamydia, Syphilis)
 Viral: Chicken Pox, Small Pox, Rubeola (Red Measles), Rubella (German Measles), Mumps, Influenza,
Polio, Rabies, STDs (Herpes, AIDS)
 Prevention of Infectious Diseases
 Vaccinations, Washing Hands, Pasteurization, Sterilization of Equipment, antiseptics
 Vectors: spread diseases without getting sick; ex: rats, ticks, mosquitoes
 Epidemic (regional outbreak, ex: typhoid) vs. Pandemic (spreads throughout human population,
possibly globally, ex: flu, smallpox)
 Chemicals and Your Health:
 Some chemicals can lead to various diseases
 Radioactive elements are known to cause cancer
 Asbestos causes cancer
 Alcohol can affect your liver as well as an unborn child; addiction

6.  Tobacco (Smoking) can cause cancer (ex: lung or mouth cancers); addiction
 DDT (a pesticide) can cause cancer
 Mercury can impact brain development
 Several factors can determine how unhealthy a substance is
 Concentration = amount of a substance in a certain volume
 Potency = how “strong” the substance is
 Dose = amount of a chemical given
 Exposure (time) = how long you are in contact with the substance
 Individual susceptible = how a person responds to the substance (“your tolerance”)
 Chemicals and their benefits:
 Medicines
 Food preservatives
 Increase crop production: fertilizers, pesticides (kill insects), herbicides (kill weeds)
 Sanitation (ex: chlorine used to kill bacteria in water)
 Energy:
 Energy is the ability to work
 Work: the transfer of energy
 Laws of Thermodynamics
 1st
: states that the total amount of energy in the universe is constant. This means that all of the
energy has to end up somewhere, either in the original form or in a different from.
 Energy Conversions Examples: Plants (radiant chemical), Batteries (chemical  electrical), Food
(Chemical  Thermal, Mechanical)
 2nd
: states that the disorder in the universe always increases. After cleaning your room, it always has a
tendency to become messy again. This is a result of the second law. As the disorder in the universe
increases, the energy is transformed into less usable forms.
 3rd
: all molecular movement stops at a temperature we call absolute zero, or 0 Kelvin (-273o
C).
 Two types of energy:
 Potential: stored
 Kinetic: working
 Six different forms of energy: Thermal (heat), Radiant (light), Mechanical, Chemical, Nuclear, Electrical
 Characterized in two ways:
 Renewable: can be replenished
 Solar
 Photovoltaic Cells: transform solar energy into electric energy
 Solar Reflectors: concentrate solar rays for industrial use & generation of electric current
 One way to confine solar energy is heating water by passing it through collectors and keeping it
in isolated containers.
 Wind
 Geothermal: Earth’s heat
 Biomass: derived from plants (wood from trees, ethanol from corn, and biodiesel from vegetable oil)
 Hydropower: Water
 Nonrenewable: can’t be easily replenished
 Fossil Fuels: oil, natural gas, and coal, formed over millions of years by the action of heat and
pressure on the remains dead plants and animals.
 Uranium: splitting atoms (nuclear fission)
 Limits on energy include: cost, location and ability to collect the energy source
 Environment:
 Ecology: study of interactions among organisms
 Abiotic (nonliving): water, temperature, light, air, soil
 Biotic (living); food, reproduction
 Habitat: where organism lives

7.  Water Cycle
 Carbon Cycle: starts with autotrophs
 Nitrogen Cycle: Lightening and certain bacteria convert the nitrogen in the air into useable forms,
bacteria in the soil transform nitrogen so that it can be stored & used in plants
 Niche: role and position species has in its environment (how it meets food, shelter and survival needs)
 Population: all the members of a species that live together
 Population Density: number of species in an area
 Coexist: Symbiosis (relationships which benefit one or both species)
 Commensalism: one benefits other is neither benefited or harmed
 Parasitism: one benefits at the expense of the other
 Mutualism: both species benefits
 Limiting Factors: abiotic or biotic factor which limits a population
 Carrying Capacity: largest number of individuals that an environment can support
 Ecosystems: Terrestrial (land), Aquatic (water)
 Food Webs: interactions between predators and prey, energy flows through food web (original
energy source is sunlight)
 Producers (Autotrophs): make their own food
 Consumers (Heterotrophs): eat producers or other consumers; herbivores (plant eaters),
carnivores (meat eaters) and omnivores (both)
 Decomposers: consumers which use waste materials and dead organisms for food, ex: bacteria,
fungi
 Terrestrial (land) vs. Aquatic (water): energy flows between the two, Ex: bear eats salmon
 Biological Classification: organize all life on Earth
 Taxonomy: Kingdom, Phylum, Class, Order, Family, Genus, Species
 Shows relationships among organisms
 Geologic Time
 Organizes Earth’s history into a timeline based on changes in fossils and organisms
 Divided into eons, eras, periods, epochs
 Fossils are most likely to form if the organism has hard parts and is protected from scavengers (i.e. buried
quickly)
 Types of Fossils: Molds, casts, carbonaceous film, permineralization, trace and original remains
 Index Fossils: spread over the world, abundant and around for a short period of time, they help to
determine the relative age of a rock layer, Ex: trilobites
 Earth’s History
 Absolute age = age in numbers found through radiometric dating; ex: Carbon 14
 Relative age = compares layers (older or younger)
 Based on the Law of Superposition: in undisturbed rock layers the oldest are on bottom
 Intrusions (magma in rock layers), folds (bends) & faults (cracks in rocks) are younger than the
layers they pass through
 Unconformities: gaps in time due to erosion
 Ice Cores can be used to determine the types of gases & temperatures from a specific time in Earth’s
past, use ice cores to see climate changes
 Geologic Time divided into segments:
 Eons are the largest group; currently we live in the Phanerozoic
 Eras are the next largest; mass extinctions mark the boundaries between eras
 Periods are the next largest; characterized by life existing world-wide at the time.
 Epochs are the smallest; characterized by differences in life forms but may vary between
continents.
 Eras & Periods in Earth’s history
 Precambrian: longest time, soft bodied organisms
 Paleozoic: organisms with hard parts, Devonian = Age of Fish

8.  Cambrian Period: explosion of variety of life forms
 Mesozoic: Age of Reptiles, Jurassic = Age of Dinosaurs
 Cenozoic: Current Era, Age of Mammals, humans, Ice Ages
 Extinction can occur naturally, most follow a sudden drastic change in the environment to which the
organisms can’t adapt
 99% of all species having lived on Earth are now extinct
 End of the Permian Period saw the largest mass extinction (90% of marine species died) followed by the
extinction of the dinosaurs at the end of the Cenozoic Period
 Humans can influence extinction: Overharvesting, Pollution, Introducing non-native species, habitat
destruction
 Evolution: Change over time
 Biological: Theory of Evolution proposed by Charles Darwin
 Living things evolve in response to their environment
 Adaptation: changes in structure, behaviors or physiology to enhance survival and reproductive
success
 Based on Natural Selection: species have traits that help them adapt to changes in the environment,
those traits passed on to offspring, species unable to adapt become extinct; species must be able
to reproduce
 Genetic Variation: variation in the alleles of genes; mutation is the ultimate source of variation
 Analogous Structures: similar in function but do not come from a common ancestor (example
dragonfly & bird)
 Homologous Structures: similar in function and come from a common ancestor (example: dolphin’s
flipper and human arm)
 Vestigial Structures: structures that appear to have lost all or most of their original function.
Examples: legs on snakes, the appendix in humans, legs on whales
 Geological: Earth’s landforms change over time, continents have moved, Pangaea was the
supercontinent, evidence for change in fossils, rocks, climate, seafloor spreading