Download Seventh grade Study guide with Answers

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7th Grade End of Year Test Study Guide
METRIC SYSTEM
1. Which number is the metric system based on?
10
2. What are you really measuring if you measure the mass of an object? (Chemical Building Blocks p. 17)
Mass is the amount of matter (atoms) an object is made up of.
3. Which units and instrument are used for measuring mass?
Mass is measured in GRAMS and can be measured using a scale or a triple beam balance.
4. What are you really measuring when you measure the volume of an object?
Volume is the amount of space an object takes up.
5. What units are used to measure volume? Which instruments (more than one) could you use?
Volume is measured in LITERS, MILLILITERS, or CM3. Volume can be measured by multiplying
length, width, and height (length x width x height) or by using a graduated cylinder and water
displacement.
6. What units and tools are used to measure length?
Length is measured in METERS, MILLIMETERS, KILOMETERS, etc. Length can be measured with a
ruler or meter stick.
7. How could you measure the mass of a liquid? A gas?
To measure the mass of a liquid, first measure the mass of a container. Then pour the liquid into the
container and measure the mass of the two. If you subtract the mass of the container from the mass of
the container and liquid, you are left with the mass of the liquid. The same can be done for a gas with a
very sensitive scale.
8. How would you measure the volume of an oddly shaped object?
Irregular volume is measured using water displacement. A graduated cylinder is filled to a known
volume of water. The object to be measured is placed in the water. However far the water moves up is
the volume of the object (in other words, the measurement of water you started with subtracted from the
measurement of water you finished with.)
CELLS AND LIVING THINGS
1. What are the 6 characteristics of all living things? (Bacteria to Plants p.7)
They are made of cells, cells contain DNA, they grow and develop, they use energy, they respond to
their environment, and they reproduce.
2. What are 4 needs of all living things? (p. 12)
Food, Water, Living Space, Stable Internal Conditions
3. What is the difference between non-living and dead things?
Non-living things have never had all 6 of the characteristics of living things. Dead things once had all 6
of the characteristics, but they no longer have all 6.
4. What makes plant cells and animal cells different? Name at least 3 things. (Cells and Heredity p. 20)
Plant cells have cell walls and chloroplasts, bigger vacuoles, and typically no lysosomes. Plant cells are
also usually straight sided (square, rectangle, octagon, etc.) where animal cells are usually round.
5. Identify the function of each of the following parts of a cell:
Cell membrane— Protects the cell and controls what substances enter and leave the cell
Cell wall— Protects the cell and gives it structure
Mitochondria— Takes food, water, and oxygen and converts them into energy the cell can use
Chloroplast— Capture energy from sunlight and use it to produce food for the plant cell
Nucleus— Directs all of the cell’s activities
Vacuole— Stores water, food, waste products, and other materials
6. How are cell walls and cell membranes different?
Cell walls are mostly for protection and support and found in plant cells (and fungi cells!) Cell
membranes control what goes in and out of the cell and are found in all cells.
7. What is diffusion? (p. 33)
Diffusion is the movement of molecules from areas of high concentration to areas of low concentration.
Diffusion happens naturally and does not take energy.
8. What is osmosis?
Osmosis is the diffusion of water molecules. Osmosis happens naturally and does not take energy.
9. What is active transport?
Active transport is the movement of molecules from areas of low concentration to areas of high
concentration. This goes against the natural movement of particles and thus requires energy. An
example is your cells moving Sodium and Potassium across the cell membrane.
10. Predict how water would move for each cell if they were all in an environment of 85% water:
22 %
Water
IN
84%
Water
IN
96%
Water
OUT
11. Predict which way particles would move for each cell if they were all in an environment of 12% salt:
17 %
Salt
OUT
25%
Salt
OUT
8%
Salt
IN
12. What is a selectively permeable membrane?
A membrane that allows only certain substances to go through.
13. What are the 5 levels of organization from simplest to most complex? (Not in book)
Atoms→Molecules→Macromolecules→Organelles)→Cells→Tissues→Organs→Organ System→Organism
From Organelles left is considered non-living, from Cells right is considered living.
14. What is a tissue? Give 2 examples.
A tissue is a group of the same type of cells working together to accomplish something. Blood and
muscle are examples of tissues.
15. What is an organ? Give 2 examples.
There are 4 main tissue types in the human body. An organ is two or more of them working together to
accomplish something. Heart and lungs are examples of organs.
16. What is an organ system? Give 2 examples and state what they do.
An organ system is two or more organs working together to accomplish something. The circulatory
systems main task is to pump blood (and thus oxygen, food, water, and waste) throughout the body. The
nervous systems main task is to relay information back and forth between the brain (the control center)
and the rest of the body.
17. Label the cell parts:
A. Cell Wall
B. Cell Membrane
C. Nucleus
D. Cytoplasm
GENETICS AND ADAPTATIONS
1. What contributions did Gregor Mendel make to genetics? Try to be specific. (Cells and Heredity p. 76)
Gregor Mendel explained that we get half of our genetic information from one parent and half from the
other parent. That genetic information does not combine, it stays separate. You can hand down either
set of information to your offspring.
2. What are inherited traits? Give two examples.
Inherited traits are traits you get genetically from your parents. Hair and eye color are inherited traits.
3. What are acquired traits? Give two examples.
Acquired traits are traits that you work for and develop on your own, such as playing the piano and
being good at sports.
4. What is the difference between a dominant and a recessive trait? Give an example of each.
A dominant trait is one that if you have the genetic information for it, it is going to show up. A
recessive trait is one that if you have the genetic information for it, it will only show up if a dominant
trait is not there. If the dominant trait is there with a recessive trait, the recessive trait will be hidden.
5. What is the difference between a pure-bred and a hybrid?
Pure-bred is another word for homozygous. Homozygous genotype is HH or hh. Hybrid is another way
of say heterozygous. Heterozygous genotype is Hh.
6. What is a genotype? Give an example. (p. 88)
A genotype is a 2 letter combination that represents the alleles an individual has for a particular
characteristic. For example, if we use a “B” to represent Brown hair and a “b” to represent Blond hair,
and an individual has the allele for brown hair and the allele for blond hair, the genotype would be “Bb.”
7. What is a phenotype? Give an example.
A phenotype is the actual physical appearance. If you use the example from above and we assume that
brown hair is dominant (because it is a capital letter) then the person’s phenotype would be brown hair.
8. How is randomness part of the genetic process of reproduction?
Because genetic information is handed down from parent to offspring randomly, individuals can be
different. That difference is called Genetic Variation and helps a group of organisms survive an
environmental change. If something kills some of them, it will most likely not kill all of them because
they are different.
9. Where is DNA located in your cells?
DNA is located in the nucleus of your cells.
10. What is the difference between sexual and asexual reproduction? (Bacteria to Plants p. 52)
Asexual reproduction requires only one parent and all of the offspring are exact genetic copies of that
parent. Sexual reproduction requires two parents and the offspring have a unique combination of
genetic information because half of it comes from one parent and half of it comes from the other parent.
11. Give three examples of organisms that reproduce asexually and explain how they reproduce.
Starfish: Fragmentation and Regeneration
Aphids: Parthenogenesis
Bacteria: Fission
12. Give examples of organisms that reproduce sexually.
Mammals, Fish, Birds, Reptiles, Amphibians
13. Name two advantages to reproducing sexually.
The population will have genetic variation and will be able to adapt to environmental changes.
14. Name two disadvantages to reproducing sexually.
It requires a mate, it requires more energy, and there is typically lots of investment put into offspring.
15. Name two advantages to reproducing asexually.
No mate is required, it takes less energy, and in a stable environment lots of offspring can be produced
fairly quickly.
16. Name two disadvantages to reproducing asexually.
There is no genetic variety (no differences) and an environmental change can be fatal to a whole
population.
17. Which form of reproduction is better for an environment that changes a great deal?
Sexual reproduction because it ensures differences in the population
18. What is an adaptation?
An adaptation is a characteristic or trait that helps an organism to survive in its environment.
19. What is the difference between a structural and a behavioral adaptation? Give examples of each.
Structural Adaptation: physical trait that improves an organism’s survival.
Examples: fur, special coloring, long neck
Behavioral Adaptation: something an organism does that improves its survival.
Examples: burrowing, panting, storing food
20. Give an example of an adaptation that would be useful to an organism in one environment, but harmful in
another environment.
Thick fur is good for a polar bear in the Arctic but would be very harmful if the bear was in the Sahara
Desert.
21. Do individuals creatures adapt or do adaptations form over an entire population?
Individual creatures do not adapt! If you take a grizzly bear and put it in the Arctic, it will not turn
white! Instead, if you have a thousand grizzly bears move north to the Arctic, the ones that have the lightest fur
have the greatest chance for survival. Those who survive pass on their genetic information and their offspring
have lighter fur like their parents. Mutations might happen that give them lighter fur and those bears would also
have a greater chance of survival and thus pass on those genes to their offspring. This happens over long
periods of time to entire populations.
22. Shape can be important to adapting. Give three examples of how the shape of a body part can be an
adaptation.
The aerodynamic shape of a penguin helps it swim fast.
The large circular paws of a snow leopard help it walk and not sink into snow.
The shape of a bird beak helps it eat specific food.
CLASSIFICATION
1. What does it mean to classify things? (Bacteria to Plants p. 17)
To classify is to put into groups based on similarities.
2. Who was the first person to try to classify organisms?
Aristotle was the first scientist to classify living organisms.
3. How many kingdoms did Aristotle break all life into?
Aristotle separated living things into plants and animals. From there he separated the animals into
“having blood” and “being bloodless”, and then each of those was broken into groups of walk, swim, or
fly.
4. Name two problems with Aristotle’s system of classification.
First, most of the animals he thought were bloodless actually had blood. Second, there are many
animals that can fit into more than one group, in other words they swim and walk or walk and fly.
Third, Aristotle’s system only gives 7 final groups for organisms to be classified in. It would be very
hard to fit the 1.2 million organisms we know of today into just 7 groups.
5. How did Linnaeus break organisms into groups—the groups were based on what? (p. 18)
Linnaeus separated organisms based on their physical structures. He also separated living things into
plants and animals because there were no microscopes at that time and he was not aware of microscopic
organisms.
6. Why did Linnaeus give every organism a scientific name?
The scientific name is helpful for identifying the organism anywhere in the world. It is the name that an
organism is known by everywhere despite being known by several common names.
7. What are the two parts of every scientific name? (p. 18)
The first part is the genus and the second part is the species. An example is Salmo trutta, the scientific
name for a brown trout. Salmo is the genus, trutta is the species.
8. Which is more important in classifying an organism–its behavior or its structure?
Structure!
9. Why did Linnaeus only have 2 kingdoms if we use 5 today?
They did not have microscopes in his day and thus were not aware of the members of monera and
protista. They also were not aware of some basic differences between plants and fungi. We have better
technology and information now so we separate into more kingdoms.
10. Fill in the following table concerning the 5 kingdoms. (p. 27-29)
Kingdom Name
Monera
Number of
Cells
One
Does it have a
nucleus?
No
What surrounds
its cell?
How does it get
energy?
Examples
No Cell Wall
Some make
their own food,
some don’t
Bacteria
Paramecium
Euglena
Protista
One
Yes
No Cell Wall
Some make
their own food,
some don’t
Fungi
Many
Yes
Cell Wall made
of chitin
Does not make
its own food
Mushrooms,
mold, yeast
Make their own
food through
photosynthesis
Plants
Does not make
its own food
Animals
Plantae
Many
Yes
Cell Wall made
of cellulose
Animalia
Many
Yes
No Cell Wall
11. What makes monerans and protists different?
Monerans do not have a nucleus and protistans do.
12. What makes plants and fungi different?
Plants have a cell wall of cellulose and make their own food through photosynthesis, fungi have a cell
wall of chitin and do not make their own food, they eat decaying organisms.
13. What makes animals different from fungi?
Animal cells do not have a cell wall.
14. List the groups that a kingdom is broken into from biggest to smallest. (p. 20)
Kingdom, Phylum, Class, Order, Family, Genus, Species
15. If I was going to create a key for shoes, tell me three good characteristics I could use in my key
Laces or no laces, open or closed toe, high or low tops
16. How is a classification tree different from a classification (dichotomous) key? (p. 22)
A classification chart shows the connections with lines, it is more of a picture. A classification key is a
written version that is more compact and does not show the connections.
17. Name two uses for a dichotomous key.
Keys can be used to classify organisms, to see their connections, to identify what an organism is, etc.
18. How many choices do you have on each step of a key?
Usually 2 if the key is dichotomous (“di” means two.) Some keys may have more than two choices at
each step like the jelly belly key we used.
19. When making a classification tree, what is the final goal or result at the end of each “branch.”
The goal is to have the organism by itself, a single species.
20. Why would using a field guide be better than using a dichotomous key?
A field guide is less scientific and not as accurate but is better for casual or recreational identification of
organisms.
21. When would it be better to use a key, than a field guide?
It is better to use a key when accurate identification is important, for example for scientific purposes.
ATOMS AND MATTER
1. What two characteristics does something have to have in order to be matter? (Chemical Interactions p. 6)
All matter has mass and takes up space.
2. What is not considered matter?
Energy is not considered to be matter.
3. What is all matter made of?
Atoms
4. What makes mixtures and compounds different?
A mixture is two or more substances that are mixed together but are not chemically combined. A
compound is a pure substance made of two or more elements that are chemically combined.
5. What is a molecule?
A molecule is a particle made of two or more atoms bonded together.
6. What important contribution did Democritus make to science?
Democritus was the first person to suggest that all “stuff” is made of tiny particles, atoms.
7. What did J.J. Thomson discover? He make a famous model of an atom called the “plum pudding model.”
What did his model of an atom actually look like?
J.J. Thomson discovered that atoms have negatively charged parts called electrons. His idea of what an
atom looked like could be compared to a blueberry muffin where the blueberries are the electrons.
8. What did Rutherford discover about the atom? Name two things.
Rutherford discovered that the atom was made mostly of empty space and that it had a very small, hard
center called the nucleus. He also said that the nucleus was positively charged.
9. How did Niels Bohr change the atomic model?
Bohr said that the electrons were not randomly placed (like the blueberries in a blueberry muffin) but
rather they move about the nucleus in specific layers or orbits (think of the layers of an onion or the
layers of color in a gobbstopper.)
10. Name two reasons why it is impossible to build an accurate, scale model of an atom.
First, the electrons in an atom are always moving very fast. It would be next to impossible to
incorporate this motion into a model. Second, the size of the parts compared to the amount of empty
space would make it very difficult to create an accurate scale model of the atom (a scale model is where
the size and distance proportions are correct.)
11. What type of charge does an electron have? Proton? Neutron?
An electron is negatively charged, and proton is positively charged, and a neutron is neutral, it has no
charge.
12. Which 2 particles are found in the nucleus? (p. 10)
Proton and Neutron
13. What is the definition of a solid? (Chemical Building Blocks p. 42)
A solid is a state of matter that has a definite shape and volume. Atoms are close together and move
very slowly, sort of like a vibration.
14. What is the definition of a liquid?
A liquid is a state of matter that has a definite volume but not a definite shape. It takes the shape of the
container it is in. Atoms are further apart that in a solid and move slightly faster.
15. What is the definition of a gas?
A gas is a state of matter that has no definite volume or shape. It takes up as much space as it is allowed
and takes the shape of the container it is in. Atoms are very far apart and move very fast.
16. Draw the atoms of a solid, liquid, and a gas.
17. What does Brownian Motion prove about atoms?
Atoms are always moving, even in a solid.
18. Compare the movement of atoms in a solid, a liquid, and a gas.
In a solid the atoms move slowly, like a vibration. In a liquid the atoms move faster and can easily
move past one another. This is the reason you can pour a liquid. In a gas the atoms move very fast.
19. What is diffusion in general terms (not the cell definition)?
Diffusion is the movement of particles from high concentration (where there are a lot of them) to a low
concentration (where there are not very many of them.)
20. Give two examples of diffusion from everyday life.
Two examples of diffusion are air freshener moving throughout a room, the smell of cookies moving
throughout a house.
21. What really causes things to diffuse or spread out?
When the atoms are concentrated, they are close to each other. Because they are always moving, they
are bumping into each other. Each time they bounce off of each other, they move further apart.
Essentially, they spread out to get away from each other.
22. What two things does heat do to atoms?
Heat make atoms move faster and spread further apart from one another. This is the reason that object
expand (get bigger) when they are hot.
23. How does adding heat change the volume of objects?
See question 22. It makes the volume get bigger. Remember, volume is the amount of space that an
object takes up. If the object gets bigger, it takes up more space so the volume gets bigger.
24. What substance is an exception to the fact that things contract when they get cold?
Water is the exception. Most things get smaller as they get colder because their atoms slow down and
get closer together. The atoms of water get closer together as water cools until right before it freezes.
Then they move further apart from each other and thus ice floats.
25. What do you need to change in order for matter to change its phase? (Chemical Building Blocks p. 48)
You need to add or remove heat for matter to change its phase.
26. What are the names of the following changes?
Solid to liquid _Melting_________________
Liquid to gas _Vaporization ____________
Gas to liquid _Condensation____________
Liquid to solid _Freezing________________
DENSITY
1. What is the definition of (not the formula!) density?
Density is the measurement of how much mass or number of atoms of a substance that is contained in a
given volume.
2. What is the formula for calculating density?
Density = Mass / Volume
3. What is an easy way to remember this formula?
I
Density!
4. How does temperature affect the density of objects?
Because the temperature affects the volume, it affects the density. If you have the same amount of mass
but a bigger volume, it means the atoms have more room to spread out and your density is less. This is
what happens when you heat a substance. If you have the same amount of mass but a smaller volume, it
means the atoms have less room and are squished together, thus your density is greater. This is what
happens when you cool a substance (except water!)
5. Why do objects sink or float? (p. 20)
An object will sink if it is more dense than the “stuff” it is in. An object will float if it is less dense than
the “stuff” it is in.
6. If you change the size of an object, does that change its density?
See question 4.
7. Which two things affect how substances in streambeds, lakes, beaches etc. naturally sort themselves?
Their size and their density affect sorting of natural substances. More dense substances sort out first. If
two particles are the same density, then size is important. Large particles will sort out first.
8. What are the 5 layers of the Earth’s interior?
Moving from the outside in, you have the atmosphere, the crust, the mantle, the outer core, and the inner
core.
9. Which layers of the Earth are solid?
The crust, mantle, and inner core are all solid. The upper part of the mantle is considered a “plastic”
which is a solid that can move or flow.
10. Which layer of the Earth is liquid?
The outer core is a liquid.
11. Which layer of the Earth is considered a plastic?
The upper part of the mantle is considered like plastic because it flows like hot tar. The mantle is not
made of plastic
12. How is density related to the layers of the Earth?
The density increases as you move from the outside to the center of the earth.
13. What happens to liquids of different density when they are carefully combined in a jar?
They form layers according to their density.
14. How could you predict where an object would “land” in a jar full of various liquids of different densities?
If you know the density of the object and the density of the liquids, you would predict the object would
stop in between the liquids with densities above and below the density of the object.