Life Science Chapter Two: What are the Interactions in
Ecosystems?
Multiple Choice
Lesson One: Ecosystems
1. What are some examples of nonliving parts of an ecosystem?
Water, air, soil, and rocks are examples of nonliving parts of an
ecosystem.
2. One year, an ecosystem receives only a small amount of its
usual rainfall. What will most likely happen because of the lack
of rain?
Both the animal and plant populations will reduce in numbers.
3. What is an example of two species interacting in an ecosystem?
An arctic fox preying on a lemming is an example of two species
interacting in an ecosystem.
4. What are some examples of living parts of an ecosystem?
Animals, plants, and bacteria, are all examples of living parts of an
ecosystem.
Lesson Two: Predation and Competition
1. What is an organism’s niche?
An organism’s niche is the role it plays in the ecosystem.
2. Which of these is a way that competition helps ecosystems?
Competition helps a community because the strongest and
healthiest organisms are the ones most likely to survive.
3. Look at the picture of a watering hole. How does this picture
show competition?
The animals need the same water.
Lesson Three: Living Together
1. What is an example of symbiosis?
A birds eating tics off of a wart hog is an example of symbiosis.
2. What are the benefits of the symbiotic relationship between the
bullhorn acacia tree and acacia ants?
The tree produces nectar for the ants to eat, the thorns on the
tree provide a place for the ants to nest, and the ants sting
animals that eat acacia leaves.
3. In the symbiotic relationship between the mistletoe plant and
its host tree, how does mistletoe damage its host?
The mistletoe plant takes water and nutrients from the host tree.
4. What is the symbiotic relationship between a shark and a
remora?
Remoras ride with sharks and eat their scraps.
Lesson Four: Changing Communities
1. Over time a pond becomes a marsh. The land gradually dries,
and the marsh becomes a meadow. What is this transition
from one ecosystem to another called?
When an ecosystem transitions to another type is called
succession.
2. What is the first change to occur as an ecosystem recovers
from fire?
Grass, weeds, and flowers begin to grow.
3. When a beaver builds a dam and cuts off a stream, a pond is
formed. The pond begins to change almost as soon as it is
formed. What is the first change to take place?
Mud and sand wash in to make the pond shallower.
4. How do invasive species, like zebra muscles affect an
ecosystem?
The invasive species use up the resources that the native species
need.
Lesson Four: Changing Communities
1. What human actions pollute the air in an ecosystem the most?
Burning oil and coal to create electricity pollutes the air.
2. What are some ways humans can help the environment?
Humans can drink tap water, recycle paper, carpool, and use
reusable bags for groceries.
Short Answer
Hyenas and lions are part of the community of animals in the African
savanna. Because food can be scarce in the savanna, hyenas and
lions often compete for food. What will most likely happen to the
hyena and lion population if they are competing for the same
resources?
Both the hyena and lion populations will decrease in number and the
stronger, more adapted species will thrive.
How might the need to compete for resources be good for the hyena
and lion?
The competition will make both species stronger because only the
strongest and healthiest will survive.