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ASK 8 Science
6th Grade Review
aka: Everything You Learned in 6th Grade and a Few Things You Forgot…
ECOLOGY: the Study of the Interrelationships and Interactions Among
Organisms and their Environment
Key Concept: Everything is connected!!
Key Terms: Ecosystem, Producer, Consumer, Decomposer, Food Chain, Food Web, Niche, Habitat, Species,
Population, Community, Photosynthesis, Respiration, Water Cycle aka Hydrologic Cycle, Condensation,
Precipitation, Evaporation, Transpiration, Carbon-Oxygen Cycle, Glucose, Nitrogen Cycle, Energy, Abiotic
(nonliving), Biotic (living), biome, biodiversity
1. Put the levels of organization in the proper order:
a. population  organism –> species  community  ecosystem
b. organism  species  community population ecosystem
c. organism speciespopulationcommunity ecosystem
2. An ecosystem includes all the ____________ and ____________ factors in an environment.
3. How do each of these organisms get their energy?
a. Producer
b. Consumer
c. Decomposer
4. A food chain shows the flow of energy in an ecosystem. A food web is a group of interconnected food webs.
A food chain consists of only one straight line. Here is an example of a food chain:
sun corn  mouse  barn owl
5. Make a food chain using the following organisms: hawk, leaves, robin, caterpillar
sun
A food web is made up of interconnected food chains. Here is an example of a food web:
corn
mouse
sun
owl
insect
berries
shrew
bird
6. Answer the following questions about this food web:
a. List the producers:
b. List the consumers and tell whether each one is an herbivore, carnivore, or omnivore. Also tell
whether the consumer is 1st level (primary), second level (secondary), 3rd level (tertiary), etc. Can a consumer
occupy more than one level in a food web?
7. Create a food web using these organisms. Make sure that the arrows are pointing in the direction of the flow
of energy! Don’t forget to start with the sun.
Orca, leopard seal, small fish, zooplankton, phytoplankton, medium-sized fish, krill, penguin, baleen whale
8. Explain what would happen to the organisms in this food web if ozone depletion caused a decrease in marine
phytoplankton.
9. Define:
a. carnivore: _________________________________________________________________________
b. herbivore: _________________________________________________________________________
c. omnivore: _________________________________________________________________________
d. scavenger: _________________________________________________________________________
e. predator: _________________________________________________________________________
f. prey: _________________________________________________________________________
10. What does the root “vore” mean?
11. Which of the following statements describes the energy changes involved in an ecosystem?
(a) The largest animals usually provide the energy for smaller animals and for plants in a given ecosystem?
(b) The sun’s energy is made available to an ecosystem by the producers in that ecosystem.
(c) The energy for living plants in an ecosystem comes mainly from dead animals, which are broken down by
decomposers.
(d) In an ecosystem, the smaller organisms require more energy than larger organisms.
12. What do the arrows in a food chain or food web indicate?
13. When a predator species is eliminated from the ecosystem, which of the following is likely to happen?
(a) The number of prey will increase and the amount of vegetation will decrease.
(b) The number of prey will decrease and the amount of vegetation will increase.
(c) The number of prey will decrease and the amount of vegetation will decrease.
(d) The number of prey will stay almost the same and the amount of vegetation will increase.
14. Fill in the blanks: Energy _______________________ through an ecosystem once, while matter
____________________ through ecosystems over and over.
15. Photosynthesis is the process by which producers capture the sun’s energy and manufacture food (glucose)
from it. Write the word equation for photosynthesis:
Write the chemical equation for photosynthesis:
16. Respiration is the process by which organisms release the energy stored in food (glucose) in order to use it to
carry out their life processes. Write the word equation for respiration.
Write the chemical equation for respiration.
17. Make a simple diagram of the hyrdrologic (water) cycle. Use the following terms to label it:
evaporation, condensation, precipitation, infiltration, groundwater, surface water, run-off, transpiration
Important: Earth is not getting any new supplies of water. The same water is recycled over and over and over.
18. 78% of the earth’s atmosphere is composed of nitrogen, which is a requirement of living things, yet most
organisms are unable to utilize gaseous nitrogen. How do organisms procure nitrogen?
19. Draw a diagram of the Carbon-Oxygen Cycle in this space. How is human activity causing this cycle to
become unbalanced?
Important: CO2 is considered a “greenhouse gas” because its presence in the atmosphere helps trap heat energy.
Which environmental problem is being exacerbated by excess emissions of CO2 from human activity, such as
the burning of fossil fuels?
20. Some environmental problems that are facing humankind in the 21st century are listed here:
a. global warming (more accurately called global climate change)
b. ozone depletion
c. habitat destruction
d loss of species diversity
e. air and water pollution
f. solid waste disposal
ENVIRONMENTAL ISSUES: Many people confuse global warming with ozone depletion. These are two
different issues:
Global Warming (aka Global Climate Change) is caused by increased levels of greenhouse gases. The
“greenhouse effect” in and of itself is not bad – it is what keeps Earth’s temperatures warm enough for living
organisms to survive here. However, increasing the concentrations of CO2 and other heat-trapping gases is
causing the average global temperatures to rise. This in turn is causing the melting of glaciers, a rise of sea level,
and changes in ocean and wind currents, which will likely result in flooded coastal areas, more severe storms,
more severe droughts and increased desertification (with resulting food and water shortages), and loss of species
diversity.
Ozone Depletion Ozone (O3) is a molecule made up of 3 atoms of oxygen instead of two, which is Oxygen gas
(O2). It is found in the upper atmosphere of Earth and protects living organisms from harmful ultraviolet
radiation. Certain molecules produced by human activity, such as CFCs, react with ozone to break it up. As a
result, holes in the ozone layer have formed, particularly over polar regions. Since the ban of CFCs, the holes in
the ozone layer have been getting smaller. This is an example of how people really can make changes that have
a positive effect on the environment
.Biodiversity Crisis: Biodiversity generally refers to the number of different species in an area, but on a different
scale, it also refers to the genetic diversity within a specific population. Biodiversity is important because it has
both economic and ecological value. Not only that, healthy, functioning ecosystems provide us with crucial
ecosystem services, such as drinkable water and breathable air. Without these services, living organisms,
including human beings, cannot survive. Biodiversity is currently being threatened by poaching, pollution, the
introduction of exotic species, but most especially by habitat destruction. In addition, the remaining habitats are
being broken into smaller, isolated fragments, which also makes the organisms living there very vulnerable. In
addition, global climate change, discussed above, is having a negative impact on biodiversity. The extinction
rate has increased to an alarming rate, with still more organisms threatened or endangered. Some ways we can
help protect biodiversity are captive breeding, enacting laws and treaties, and preserving and restoring habitat.
Standardized Test Practice: Ecology
1. The major cause of extinction today is
A.
B.
C.
D.
poaching
pollution
habitat destruction
introduction of exotic species
2. In some areas, foresters plant one tree for every tree they cut. This activity is an example of a
A. nonsustainable approach to a nonrenewable resource.
B. a sustainable approach to a nonrenewable natural resource.
C. a nonsustainable approach to a renewable resource.
D. a sustainable approach to a renewable resource.
3. A freshwater lake has a muddy bottom, which is home to different types of algae and other organisms. Many
species of fish feed on the algae. Which of the following is an abiotic feature in this ecosystem?
A. the temperature of the water
B. the color of the algae
C. the number of species of fish
D. the amount of food available to the fish
4. In general, which of the following is a true statement about population size?
A. If birth rate < death rate, population size increases.
B. If death rate < birth rate, population size decreases.
C. If birth rate > death rate, population size increases.
D. If death rate > birth rate, population size increases.
5. Geothermal energy is not a widely used source of energy because
A. dams can have a negative effect on the environment.
B. methane gas is produced as a waste product.
C. it is difficult to store.
D. magma only comes close to Earth’s surface in a few locations.
Geology: The Study of Earth and its Processes
Key Concept: Earth is a dynamic planet that is always changing.
Key Terms: constructive forces, destructive forces, lithosphere, asthenosphere, continental drift, pangaea,
convection, plate tectonics, convergent boundary, subduction, divergent boundary, transform boundary, hot spot,
sea-floor spreading, ring of fire, magma, lava, earthquake, fault, focus, epicenter, moment magnitude
1. Diagram the layers of the earth. Check your diagram by looking at fig. 8-11 on p. 195 of your review book.
2. What layers of the earth make up the plates?
3. What mechanism causes the plates to move? Draw a diagram and describe.
4. Draw arrows to indicate the movement of plates at each of the three types of plate boundaries:
a. transform
b. convergent
c. divergent
5. Explain what is most likely to happen at each of the following types of plate boundaries?
a. transform
b. convergent
continental crust vs. oceanic crust –
continental crust vs. continental crust –
oceanic crust vs. oceanic crust –
c. divergent
continental crust –
oceanic crust –
6. There are three ways that mountains can be formed. Explain how each one occurs:
a. fault-block mountains
b. folded mountains
c. volcanic mountains
7. Even though volcanoes seem very destructive to us, they are actually a constructive force, geologically
speaking. How can this be so?
8. What is sea-floor spreading and how does it provide evidence to support the Theory of Plate Tectonics?
9. What causes Earth to have a magnetic field?
10. How do geologists know what the inside of the earth is like if we cannot go there? (see fig. 8 – 10 p. 194)
HUMAN BODY
Key Concept: The human body is organized in a hierarchical fashion. All the components work together.
levels of organization:
CELLS  TISSUES  ORGANS  ORGAN SYSTEMS  ORGANISM
CELLS: Shape, size, and structure contribute to function
e.g. neurons have long thin projections to carry messages
cardiac muscle contracts (heartbeat)
TISSUE = a group of similar cells that perform the same function
ORGAN = a group of tissues working together to perform a particular function
e.g. heart, kidney, lungs, stomach, brain
ORGAN SYSTEM= group of organs working together to perform a specific
life process
ORGANISM = the entire human body relies on all its organ systems to work
together to sustain good health and proper functioning
Organ Systems:
organ system
skeletal
muscular
nervous
endocrine
digestive
circulatory
function
provides support; protects internal organs
moves organs & body parts
e.g. of organs or parts
skull, ribs
bicep, quadriceps
controls body activities; carries and
interprets messages
regulates body activities via hormones
breaks down food into usable form
brain, spinal cord
adrenal glands, pituitary gland
stomach, intestines
respiratory
carries needed materials to body cells
and waste material away
exchanges gases with environment
lungs, bronchi, alveoli
excretory
removes waste from body
kidneys
reproductive
produces offspring
ovaries, testes
skin
(integumentary)
Protects body; keeps water inside the
body; helps regulate body temperature
skin, sweat glands, oil glands
HOMEOSTASIS= the maintenance of a constant internal environment
heart, arteries, veins
 Organisms respond to changes in their internal and external environment in order to regulate their body
processes and thus maintain homeostasis.
examples of regulation:
o when you’re hot, you sweat
o when your body gets low on water, you feel thirsty
Some processes:
RESPIRATION – release of energy stored in food; necessary for all bodily functions, (requires oxygen and
glucose; gives off carbon dioxide and water)
EXCRETION – process of removing waste
REGULATION – process by which organisms respond to changes in their internal or external environments
REPRODUCTION – process by which an organism produces new individuals (offspring)
GROWTH - an increase in size (new cells are made)
DEVELOPMENT – changes in the organism as it gets older
NUTRITION – includes INGESTION = taking in food
DIGESTION = the physical breakdown of nutrients*
ELIMINATION = the removal of undigested food from the body
*Nutrients and their uses:
Proteins – supply materials needed for growth and repair
Carbohydrates (Sugar & starches) – provide quick energy
Fats & Oils – provide stored energy; required for some life processes
Vitamins – assist life processes; prevent disease
Minerals – supply materials for growth and repair; help carry out life processes.
There are over 100 trillion cells in your body and at least 100 different types of cell. Find pictures of different
kinds of cells and draw them in this space. IMPORTANT: Specialized cells perform specialized functions.
Standardized Test Practice: Read the passage, then answer the questions:
Your nervous system and endocrine system work together to help keep your body healthy. Your brain, which is
part of your nervous system, constantly monitors different conditions inside your body. If your blood is low on
water, your brain sends a signal to an organ of the endocrine system, which then releases a chemical that brings
the water level in your blood back up top normal. If you get cold, your brain sends a signal to another organ in
the endocrine system, which releases a chemical that tells your cells to become more active. The activity of your
cells heats up the inside of your body.
1. Which general process does this paragraph best describe?
A. Maintaining homeostasis
B. Sensing a strong stressor
C. Preparing for the “flight-or-flight” response
D. Dealing with long-term stress
Astronomy: The Study of SPACE
Key Concepts: The universe is a very, very, very, very, very, very, very, very, very, very, very, very big place.
Most of space is empty space.
KEY TERMS: rotation, revolution, orbit, axis, ellipse, planet, dwarf planet, asteroid, comet, meteoroid, Oort
Cloud, Kuiper Belt, high-mass star, supernova, red giant, black hole, average-mass star, constellation,
circumpolar, seasonal constellation, astronomical unit, light-year, neutron star, equinox, solstice, radio
telescope, optical telescope, galaxy, Big Bang Theory, electromagnetic radiation, speed of light, geocentric,
heliocentric, terrestrial planet, gas planet, satellite, eclipse (solar vs. lunar), gravitational attraction, tide (neap
and spring), moon phases.
1. What causes the seasons on Earth? Diagram and explain.
2. What causes tides on Earth? Diagram and explain. (see page 246 of Review Book to check)
3. Why do we see phases of the moon?
ANSWER: The relative position of the sun, earth and moon.
Draw and label the phases of the moon in this space:
4. What would happen to tides if the earth-sun-moon always stayed in the same alignment?
(a) We would not experience tides on Earth.
(b) Tides would continue following their current pattern.
(c) The high and low tides would occur at the same time every day.
(d) There would be no low tides – only high tides.
5. Compare the life cycle of an average-mass star, such as our sun, to a high-mass star. Diagram and explain.
6. Why would you weigh less on the moon than you do on Earth?
7. Describe how our solar system formed. About how long ago did this happen? (see page 229 of review book)
8. Compare the length of planetary day (rotational period) and length of planetary year (revolutionary period) on
the different planets of our solar system.
WHAT CAUSES THE SEASONS? ANSWER: THE EARTH’S TILT
The hemisphere that is tilted away from the sun experiences winter.
The hemisphere that is tilted toward the sun experiences summer.
COMMON MISCONCEPTION: The earth experiences the seasons because it is farther away from the sun
in the winter and nearer to the sun in the summer.
WHY THIS MUST BE WRONG: The Northern hemisphere has winter while the Southern hemisphere has
summer and vice-versa. The distance form the earth to the sun does vary somewhat, but this is not the reason
for the seasons. In fact, the earth is actually closer to the sun during winter in the Northern Hemisphere.
When the sun shines on the part of the earth that is tilted away from it, its rays are more diffuse and less
concentrated than when it shines on the part that is tilted toward it. (See fig. 1)
RELATED CONCEPTS:
Equatorial regions do not have seasons because they never tilt toward or away from the sun. Days and nights
are always equal. Temperatures are similar all year ‘round.
During the spring and fall, the earth is tilted sideways in relation to the sun. Days and nights are equal at the
spring (vernal) and fall (Autumnal) equinoxes.
Label the following on this diagram: June Solstice, December Solstice, Autumnal Equinox, Vernal Equinox.
Summer Solstice:





considered the “first day of summer”
around June 21st in the Northern Hemisphere
longest day of the year
shortest night of the year
after this day, the days get gradually shorter and the nights longer…
Fall (Autumnal) Equinox:
 considered the “first day of fall”
 around Sept. 21st in the Northern Hemisphere
 day and night are equal
 sun rises almost exactly in the East and sets almost exactly in the West
 the days continue to get shorter and the nights get longer until…
Winter Solstice:
 considered the “first day of winter”




around Dec. 21st in the Northern Hemisphere
shortest day of the year
longest night of the year
after this day, the days start to get gradually longer and the nights shorter
Spring (Vernal) Equinox:
 considered the “first day of spring”
 around March 21st in the Northern Hemisphere
 day and night are equal
 sun rises almost exactly in the East and sets almost exactly in the West
 the days continue to get shorter and the nights get longer until the summer solstice.
WHAT CAUSES THE TIDES?
ANSWER: THE GRAVITATIONAL ATTRACTION BETWEEN THE EARTH, MOON AND SUN.
Draw a diagram here.
spring tides – greatest difference between high and low tides
- occur when sun, earth, and moon aligned
neap tides – smallest difference between high and low tides
-- occur when sun, earth, and moon are at right angles to each other
WHAT CAUSES AN ECLIPSE?
ANSWER: SUN, EARTH, AND MOON ARE DIRECTLY LINED UP. TWO KINDS:
A. SOLAR ECLIPSE – The moon blocks the light from the sun – only along the pathway of the
moon’s shadow!!! (Draw a diagram here.)
B. LUNAR ECLIPSE – The earth casts its shadow upon the full moon – only can be viewed from
certain locations on Earth! (Draw a diagram here.)
Why doesn’t an eclipse occur during every full and new moon and why can’t eclipses be seen everywhere on
earth?
Eclipse trivia:
1. Lunar eclipses occur more frequently than solar eclipses.
2. If you look directly at a solar eclipse, you can permanently damage your eyes!
3. During a lunar eclipse, you can still see the moon, but it is dimmer. Often it appears reddish.
4. During a solar eclipse, scientists are able to study the sun’s corona, since this is the only time it can be
observed.
NOTE: The moon completes one rotation in the same time it takes it to complete one revolution around the
earth. As a result, the same side of the moon always faces toward the earth.
COMMON MISCONCEPTION (Sorry, Pink Floyd!): There is no “dark side of the moon” any more than
there is a “dark side of the earth.” Just like Earth, half of the moon is always lit by the sun and half of the
moon is always in the dark. There is a “far side of the moon.” Only a few NASA astronauts have ever seen
it in person, but they did bring back photographs for the rest of us.
Standardized Test Practice for Astronomy:
1. You observe a thin crescent moon in the western sky during the early evening. About two weeks later, a
full moon is visible in the eastern sky during the early evening. Which conclusion is best supported by
these observations?
A.
B.
C.
D.
The moon revolves around the earth.
The moon rotates on its axis.
Earth revolves around the sun.
Earth’s axis is tilted relative to the moon.
2. Only one side of the moon is visible from Earth because
A.
B.
C.
D.
The moons does not rotate on its axis.
The moon does not revolve around the earth.
The moon rotates faster than it revolves.
The moon revolves once and rotates once in the same period of time.