8th grade science study guide
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A food chain is a diagram that shows part of the energy flow in a community
A predator is a type of consumer that hunts other organisms for food
A close relationship between two species that usually involves an exchange of food or energy is
called symbiosis
A detrivore is an organism that gets energy by eating dead organisms
A consumer is an organism that gets energy by eating other organisms
An organism that is hunted for food by other organisms is called prey
A niche is what a species does in its habitat to survive
In a forest community, a bird species lives in holes in the trunks of trees, deer live on the forest
floor, and squirrels live in the trunks of trees. Identify the species that are in
competition and the resource for which they are competing.
The bird and the squirrel are competing for shelter because both live in the trunks of tree
State how the extinction of one population in a community could affect the rest of
the community.
should include the concept that populations in a community are interdependent. The loss of one
could have an effect on many others that depend on or interact with it
Explain the symbiotic relationship between a dog and its fleas. Identify the type of
symbiosis that this relationship represents.
The relationship is parasitism. The fleas are parasites that live on the dog. The fleas have a warm
home and get food from the dog. The dog is the host to the fleas and is harmed by losing its
blood.
Describe evaporation and condensation.
During evaporation, liquid water changes into a gas called water vapor. During condensation,
water vapor changes into liquid water.
Define abiotic factor and biotic factor. Tell which abiotic factor and which biotic factor
is found in soil—water, worm, leaf, or rock.
Abiotic factors are the nonliving things in an ecosystem. Biotic factors are the living things in an
ecosystem. Water and rock are abiotic factors. A worm and a leaf are biotic factors.
Arrange the following elements into a food chain: plants, snake, Sun, hawk, mouse.
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Sun→plants→mouse→snake→hawk
A population is all the members of one species living in one place at one time
The living parts of an ecosystem are called biotic factors
A consumer is an organism that eats other organisms
Herbivores eat only plants
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Directions: Use the diagram to respond to each statement.
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Tell what this diagram is called.
energy pyramid
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Explain why a pyramid shape is used for this diagram.
Possible answer: The pyramid shape shows that the amount of energy available in an ecosystem
decreases as the trophic level increases. At the bottom, where the pyramid is wide, there is more
energy available for consumers. At the top, where it is narrow, there is less energy available.
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Burning fossil fuels for heating and transportation releases carbon dioxide into the
atmosphere. Explain how adding carbon to the atmosphere can affect the carbon
cycle and ecosystems. Use the term greenhouse gas or greenhouse effect in your answer.
Carbon dioxide is one of the greenhouse gases in the atmosphere that absorbs thermal energy
from the Sun and keeps the Earth warm. This process is called the greenhouse effect. Burning
fossil fuels releases carbon dioxide into the atmosphere, which traps more of the Sun’s energy
and increases temperatures on Earth. This process can change the climate in Earth’s
ecosystems, and it can be hard for plants and animals to adapt quickly to these changing
conditions.
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A food chain is a model that shows how energy flows in an ecosystem through feeding
relationships.
An endospore is a thick wall around a bacterium’s chromosome and some of its cytoplasm
A living cell in ected with a virus is called a Host
When a virus is inactive inside a cell it is latent
Yogurt is produced with the help of bacteria
AIDS is a disease caused by viruses
Bacteria that can live without oxygen is anaerobic
Conversion of nitrogen into a form that plants can use is called fixation
Toxins cause illness when released by bacteria
Pasteurization is a process in which food is heated to a temperature that kills most harmful
bacteria
When an antibiotic is no longer effective against a type of bacteria, it is called bacterial resistance
Food poisoning is caused by eating food contaminated by certain bacteria
Replication is a process that viruses use to copy themselves
The process below is showing conjugation
Directions: Use the diagram to respond to each statement.
Capsule
d.
a.
e.
b.
Cell membrane
Ribosome
c.
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Label this diagram by writing the correct term from the word bank on each line.
cell wall
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cytoplasm
DNA
flagellum
pili
Describe the shape of the bacterium in the diagram.
The bacterium in the diagram is rod-shaped. Bacteria can also be sphere-shaped or spiralshaped
Describe the difference between fission and conjugation.
Fission is the division of a bacterium into two new and genetically identical cells. Conjugation
occurs when two bacteria attach to one another and exchange genetic material but do not produce
new cells
Identify what antibiotics are and how they are used.
Antibiotics are medicines that are used to stop the growth and reproduction of bacteria in the
body
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Explain what a virus is.
A virus is a piece of DNA or RNA surrounded by a layer of protein. It is not a living organism.
Describe one way that bacteria cause illness in humans.
Some bacteria cause illness by damaging the body’s tissues. Other bacteria release toxins that
cause illness.
An animal-like characteristic of some protists is the ability to move independently
Chloroplasts are plantlike structures in some protists
Hyphae is a structure found in fungi
A Paramecium is an animal like protest
A slime mold is a fungus-like protest
Algae is a type of plant-like protest
A mushroom is a type of club fungi
Yeast is a type of sac fungi
Bread mold is a type of zygote fungi
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Describe one group of protists.
should include a description of one group of protists: Plant-like protists, such as algae, produce
their own food. Animal-like protists, such as paramecia, ingest other organisms for nutrients.
Fungus-like protists, such as slime molds, break down organic matter for food.
Describe the reproductive structures of one group of fungi.
should include a description of the reproductive structures of one group of fungi. Club fungi,
such as mushrooms, are named for the clublike shape of their reproductive structures. Sac fungi,
such as yeast, have reproductive structures that look like tiny sacs. Zygote fungi, such as bread
mold, reproduce using tiny stalks called zygosporangia.
Describe the organisms that make up a lichen.
Lichens are usually made of two types of organisms—a fungus and an organism such as algae or
photosynthetic bacteria.
Describe two different ways protists move.
should include any two of the following: Amoebas use a footlike structure called a pseudopod
for movement. Paramecia use hairlike structures called cilia for movement. Euglenoids and
dinoflagellates use whiplike structures called flagella for movement