Download 8th Grade Final Assessment Study Guide

8th Grade Final Assessment Study Guide 2015-16
Chapter 3 – Earth is a system consisting of 4 spheres that interact:
Biosphere – all living organisms/biotic factors
Geosphere – rocks and the interior of Earth, *sphere with the most mass
Hydrosphere – all of Earth’s fresh and salt water
Atmosphere – thin envelope of gases that surrounds our planet
Constructive (building up – ex. Mountains, volcanoes, earthquakes, deposition, deltas)
and destructive forces (weathering – breaking down of rock by wind, ice or water and
erosion – the movement of sediment) shape Earth’s surface
Scientists have discovered the composition of the interior of the Earth by
1. Direct methods – sampling rocks (limit to how deep we can drill though)
2. Indirect methods – analyzing the reflection and refraction of seismic waves that
bend when they go through different materials/layers of the Earth.
Order of layers of Earth:
1. Crust (tectonic plates here), made of less dense materials – oxygen & silicon
Types: continental (thicker, less dense – granite), oceanic (thinner, denser – basalt)
2. Mantle (convection currents occurs here) - made of magnesium and iron
3. Outer Core - made of LIQUID iron & nickel (very dense)
4. Inner Core made of SOLOD iron & nickel (hottest, densest layer & most pressure)
The crust and mantle can also be described as:
1. Lithosphere - crust and upper mantle – contains the tectonic plates
2. Asthenosphere - solid rock that flows
3. Mesosphere -lower mantle
Three types of heat transfer:
1. Conduction – direct contact, touching
2. Radiation – electromagnetic waves (visible light, infrared, ultraviolet, xray, etc.)
3. Convection – circulation of fluids (warm materials rise because they are less dense,
cooler materials sink because they are more dense).
Convection Currents –heat from the mantle and the core and the force of gravity cause
rock in the asthenosphere to rise and sink which causes tectonic plates (lithosphere) to
move. The formation of the Earth generated heat from gravitational energy and the decay
of radioactive elements that are still present today.
-------------------------------------------------------------------------------------------------------------------------------Chapter 4 Alfred Wegener came up with the Continental Drift Theory which states that
plates have moved slowly and were together in a large supercontinent, Pangaea. His
proof was that pieces fit together like a jigsaw puzzle, plant and animal fossils, minerals
and glacier marks were found on different continents that used to fit together, and
evidence of climate change. (Fossils of animals that live in warm areas found in areas that
have moved to a location that is colder).
Mid ocean ridges from long chains of mountains that rise up from the ocean floor. Seafloor spreading adds more crust to the ocean floor at mid ocean ridges. Proof of sea floor
spreading is pillow lava formed when ocean plates pull apart and magma comes up,
rock samples by the ridge are younger, farther from the ridge are older, and magnetic
minerals lining up north for awhile on each side of the divergent boundary and then
switching to point the other direction for many years due to magnetic reversals.
The Plate Tectonic Theory says that the plates are in still in slow constant motion due to
convection currents.
-------------------------------------------------------------------------------------------------------------------------Chapter 5 & 6 – Stress causes rock to change it’s volume and shape – 3 types:
1. Compression – plates collide at a convergent boundary, results in:
a. folded mountains (Continental crust & continental crust)
b. subduction at a deep ocean trench – less dense plate sinks back into the
mantle volcanoes can form (Continental & Ocean crust, Ocean & Ocean
crust)
2. Tension - pulling apart of rocks, divergent boundary – results in:
a. rift valley (Continental & continental) or
b. mid-ocean ridge with sea floor spreading (Ocean & Ocean)
3. Shearing - sliding sideways across each other – causes earthquakes, ex. San
Andreas fault in California (NA & Pacific plates)
Earthquakes mostly happen near plate boundaries,
P-waves – primary – fastest, first to arrive, compress & expand ground
S – waves – secondary – can’t move through liquids, vibrate at an angle of 90O
Surface waves – last, creates circular motion of ground, causes most damage
Epicenter – point directly ABOVE where the earthquake starts
Focus – point IN the earth where the earthquake starts
Earthquakes are measured by 3 scales:
Richter Scale – STRENGTH of earthquake
Moment Magnitude Scale – total amount of ENERGY released
Modified Mercalli Scale – total amount of DAMAGE, SHAKING, & INTENSITY
Ring of Fire - where earthquakes & volcanoes happen frequently, around the Pacific plate
Volcanoes – occur at plate boundaries, where plates diverge like the mid ocean ridges or
plates subducts (ex. Alaskan volcanoes) or hot spots (Hawaiian islands).
-------------------------------------------------------------------------------------------------------------------------------Chapter 7 Fossils - mostly in sedimentary rock, Intrusions - igneous rock (can be radiometric
dated)
Types of fossils – molds, casts, petrified, preserved remains carbon films and trace.
Index fossil – only found in one time period but can be found in many locations
Relative age – this rock layer is older than that one and younger than this one.
1. Superposition - if horizontal rock layers are undisturbed, oldest rocks on bottom,
youngest on top
2. Law of cross cutting – intrusions(magma that rises) are younger than what they
cut across (can't cut PB & Jelly until have PB & J)
3. Unconformity - gap in geologic record where erosion or non-deposition
occurred.
Absolute age – finding the actual age of the rock
1. Radiometric dating used to measure radioactive decay using Half-life – time it
takes for half of the radioactive parent isotope to decay into the stable
daughter isotope.
A. Rocks – Uranium/Lead & Potassium/Argon- long half life - good for rocks
B. Fossils (bones, teeth, wood) - Carbon 14 decays to Nitrogen 14
Geologic Column – record of all the layers of Earth in an area since time began
Early Earth – Earth began as a ball of dust, rock and ice in space. Gravity pulled masses
together, comets brought water.
Eras of Earth’s History:
1. Pre-Cambrian Time – Earth forms 4.6 billion years ago, oceans, rocks, single cell
organisms only, algae makes oxygen & ozone layer
2. Paleozoic Era
Cambrian – first marine invertebrates, brachiopods, trilobites
Ordovician – first jawless fish, first insects
Silurian – first land plants
Devonian – Age of Fishes, amphibians
Carboniferous (Pennsylvanian & Mississippi)- swamps, ferns, reptiles
Permian – larger reptiles, Pangaea forms, LARGEST mass extinction
3. Mesozoic Era – Age of Reptiles
Triassic – first dinosaurs
Jurassic – large land dinosaurs
Cretaceous – T-Rex, birds, first flowering plants
4. Cenozoic Era – Age of Mammals
Paleogene – mammals, grasses
Neogene – large mammals and birds
Quaternary – Ice Age, Humans appear
-----------------------------------------------------------------------------------------------------------------------------Chapter 12: Speed – time it took to go a certain distance, speed = distance / time
Velocity – speed + direction
Acceleration – change in speed or direction A = (Vf – Vi)/t
Vf= Vi + (a x t )
Be able to interpret a distance-time graph and a speed-time graph
Force is a push or pull that moves objects and is measured in Newtons.
Net force – add force if in same direction, subtract forces if in
opposite directions. Change in motion occurs with unbalanced
forces. An object in motion stays in motion with a constant
velocity if there is a balanced force.
Friction occurs when 2 objects rub against each other – depends on how hard surfaces
are pushed together and the type of surface. Know the four kinds of friction: rolling,
sliding, static and fluid.
Mass – amount of matter (does not change) vs. weight – amount of gravitational force of
an object (changes with different gravity).
Law of Universal Gravitation – all objects with mass have an attractive force that depends
on distance (closer = > gravity) and mass (> mass = > gravity).
Newton’s first law – an object at rest stays at rest, an object in motion stays in motion at a
constant velocity unless acted upon by a non-zero net force. INERTIA (the
greater the mass of an object, the greater the inertia)
Newton’s second law – force = mass x acceleration F=MxA
Newton’s third law – for every action, there is an equal and opposite reaction
Momentum = mass x velocity
Law of Conservation of Momentum –if no outside forces, the total momentum doesn’t
change
Free fall – only the force of gravity causes the object to accelerate
Acceleration due to gravity = 9.8 m/s2 – ex. Object falling for 4 seconds = about 40 m/s
Orbiting is caused by two forces: Inertia & Gravity. Satellites continuously fall toward Earth
because of the force of gravity, but because Earth is curved, they travel around it.
Centripetal force– a force that causes an object to move in a circular path around a
larger object.
----------------------------------------------------------------------------------------------------------------------------Chapter 9 - Heredity – passing of traits from parent to offspring. Genetics – the study of
heredity
Genes – carry specific allele for a trait (ex. Brown hair color), found on chromosomes.
Dominant – if one dominant allele, is present that trait will appear
Recessive – trait that is hidden by the dominant allele, trait will appear can appear in
second generation if there are two recessive alleles.
Phenotype – appearance of trait (brown hair)
Genotype – genetic make-up (alleles – Gg)
Homozygous – two of the same alleles, GG or gg,
Heterozygous – two different alleles Gg
Purebred – all generations have had the same alleles (homozygous dominant or
homozygous recessive) Hybrid – mixed heterozygous alleles
Types of dominance:
1. Dominance – dominant trait over recessive trait (need 2 recessive traits to have
characteristic) ex, B= black fur, b – brown fur
2. Incomplete dominance – blending of two traits (red & white snapdragons cross to
make pink) ex. RR = Red, WW = white, RW = pink
3. Codominance – both traits appear (white feathers and black feathers cross to make
black and white feathers) FBFB = black feathers, FWFW = white feathers, FBFW =
speckled black & white feathers
Sex-linked – some traits are found only on the X or Y chromosome
(ex. Colorblindness, hemophilia), Women = XX, Men = XY
Know how to use a punnett square and pedigree chart and to find
the probability of the offspring.
Multiple Alleles – some traits have several different alleles (ex. Blood type: A, B or O blood)
Polygenic Inheritance – some traits are determined from many genes (ex. Height)
Asexual reproduction – one organism required (budding, cloning, mitosis)
a. Advantage - Don’t need to have a mate, less time,
b. Disadvantage – less variety, less chance for survival if environment changes.
Sexual reproduction – two organisms required, makes sex cells – egg, sperm, 23
chromosomes in each to make total of 46 chromosomes for human
a. Advantage - better genetic variety in case of disease or environmental changes
b. Disadvantage - harder to find mate, takes longer, adv –
Mitosis – asexual reproduction – DNA is copied one, cell divides once to make 2 IDENTICAL
copies of the cell.
Meiosis – sexual reproduction – DNA is copied once, cell divides twice to make 4 new sex
cells (sperm or egg)
---------------------------------------------------------------------------------------------------------------------------Chapter 13 Electricity & Magnetism
Magnets have a North and a South pole and a magnetic field around them that flows
from the north pole to the south pole. Opposite poles attract, like poles repel. Earth has a
magnetic field.
Magnetism can be created by current (a compass will point north in an electric field) and
current can be created by magnetism (by placing a magnet in a coil of wire).
An electromagnet (a temporary magnet) can be made with a piece of iron wrapped in
coils of wire and connected to a battery. To increase the strength of the electromagnet:
1. Increase the number of coils
2. Increase the closeness of the coils to each other
3. Use a stronger material than iron
4. Use a stronger voltage (battery).
Electricity – protons have positive charges, electrons have negative charges. Charges
have an electric field that go away from the positive and towards the negative particle.
Charges that are alike repel, charges that are opposite attract.
Four methods by which charges can build up (static electricity): Friction (rubbing),
conduction (direct contact), induction, and polarization.
Current electricity – electrons flow through a closed circuit. Conductors have loosely
bound electrons that can move freely while insulators have tightly bound electrons.
Current (amp) is affected by voltage (volts = electric potential energy) and resistance
(ohms).
An electric motor transforms electrical energy into mechanical energy.
A generator transforms mechanical energy into electrical energy using motion in a
magnetic field.
A transformer is a device that increases or decreases voltage as it goes from the power
plant to the street wires to your house to your game system.
------------------------------------------------------------------------------------------------------------------------------Review of potential and kinetic energy
Potential energy – energy that is stored because of its position or motion:
1. Gravitational potential energy –related to the mass of an
object and its height above a reference point.
2. Elastic potential energy is associated with how much an elastic
object has been stretched or compressed and how difficult such a compression
or stretch is.
3. Chemical potential energy is associated with the position and arrangement of
the atoms within substances. (ex. Food, coal, oil, chemical reactions, candle)
4. Magnetic potential energy – distance affects the amount of PE
5. Electrical potential energy -distance & the size of the charge affects PE
Kinetic energy – energy of motion, increases as an object falls from a higher height
Conservation of Energy = the total amount of energy (PE + KE) before the action must
EQUAL the total amount of energy after (PE + KE)
------------------------------------------------------------------------------------------------------------------------------Chapter 11 Evolution – process of change over time
Adaptation –having traits that increase an organism’s ability to survive and reproduce.
Charles Darwin’s Theory – Species change
over many generations and become
better adapted to new conditions. Over
time natural selection can lead to change.
Helpful variations may accumulate in a
species, while unfavorable ones may
disappear.
Natural Selection – process by which individual that are better adapted to their
environment are more likely to survive and reproduce more than other members of the
same species. Includes:
Overproduction- more offspring are produced than can survive (lack of resources)
Variation- differences in individuals
Competition- direct or indirect struggle for resources to survive
Evidence that supports evolution: Fossils, similarities in early development, similarities in
body structure, similarities in DNA and Protein structure.
Homologous structure – structurally similar body parts in
related species that have been inherited by a common
ancestor.
How do new species form? Isolation – group of individuals
remain removed from the rest of its species long enough to
evolve different traits that prevent reproduction (ex.
Natural barrier)
Theories about the RATE of evolution :
1. Gradualism – small changes that add up to major changes over long periods of
time
2. Punctuated equilibrium – species evolve during short periods of rapid change and
then don’t change much.
Biodiversity – number of different species in an area. Important for: source of beauty and
recreation, economic value, ecological value
Keystone species – species that influences the survival of many other species in an
ecosystem.
Factors that affect biodiversity: Climate, area, niche diversity, genetic diversity, and
extinction of species.
Endangered species – in danger of becoming extinct.
Threatened species – may be endangered soon.
Humans affect biodiversity by habitat
destruction, poaching, pollution, and exotic
species
Humans can protect biodiversity by captive
breeding, laws and treaties, and habitat
preservation.