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EBC Reading Guide
Ecosystems and Environment
Chapter 21 Sections 1 & 2
Terms:

Ecology

Biotic

Abiotic

Population

Community

Ecosystem

Trophic levels

Produces

Consumers

Niche

Symbiosis
21.1 Organisms and Their Environment
Directions: Read pages 475 through 476 to help you answer the questions that follow.
1.
List the 4 different levels at which ecology can be studied.
individual, population, community and ecosystem
2.
Studies that focus on individuals often ask how an organism’s anatomy, physiology, and behavior help it to
function in its environment. In the space below give an example of each of these.
answers may vary
3.
A Population is a group of individuals of a single species that occupies a given area.
4. What do ecological studies at the population level frequently focus on?
Size of a population
How a population size changes over time
5. What do ecosystem-level studies frequently focus on?
Links between the biotic and abiotic worlds
6. An ecologist is interested in studying how hyenas and cheetahs compete for food. What type of ecological
study is this?
This study relates to an interaction between two different species that occupy the same habitat, so it
is a community-level study.
7. An ecologist is interested in studying how the number of mountain lions in a certain park has changed over
the past decade. What type of ecological study is this?
This study relates to a group of individuals belonging to a single species that occupies the given
area, so it is a population-level study.
8. Matching: Match the study to their correct level of study.
__C__ How do fireflies use light signals to attract mates? a. ecosystem-level
__D__ How many giant pandas are there in the bamboo b. community-level
forests of central china? Are their numbers
decreasing?
__B__ Who eats whom in a Pennsylvania woodland?
c. individual-level
d. population-level
__A__ How do important resources like water and
carbon move between the biotic and abiotic
components of an ecosystem?
9. Does an organism’s environment include only nonliving components?
10. What is the difference between a community and an ecosystem?
21.2 Species Interactions
Directions: Read pages 477 through 480 to help you answer the questions that follow.
11.
A diagram of who eats what within a community is called a
___Food Chain or Food Web_____.
12. What organisms are at the base of a food chain or food web?
A food chain begins with producers, species that live by making organic molecules out of inorganic
materials and energy.
13. What role do decomposers play?
Decomposers such as bacteria and fungi consume dead organic matter.
14. To be sure that you have a solid understanding of what a food chain consists of, label the following on the
food chain below: top predator, producer, primary consumer, secondary consumer.
Top Predator
Secondary Consumer
Primary Consumer
Producer
15. What position do humans occupy in your food chain?

Most humans are omnivores that eat at many levels of the food chain

Because humans are not preyed upon by other species, we are considered to be top predators
16. Can an organism be both a producer and a consumer? Why or why not?
Yes. Certain parasitic plants both photosynthesize and obtain nutrients from their hosts – other
plant species. These parasitic plants are both producers and primary consumers. There are even a
number of predatory plants that eat higher up the food chain by trapping insects. The Venus
flytrap, which snaps specialized leaves together to catch unsuspecting insects, is probably the most
famous.
17. Can two species have the same niche in a community? Why or why not?
No two species in a community have exactly the same niche. Otherwise, the species that is better at
exploiting the resources eventually outcompetes the other and drives it to extinction – this is called
the competitive exclusion principle.
18. How does symbiosis differ from a niche? Explain.
Answer may vary
19. List the three forms of symbiosis.

Parasitism

Commensalism

Mutualism
20. An organism, such as a tape worm, that lives in a host and obtains nutrients from them is an example of
__parasitism________.
21. A cleaner shrimp removes parasites from the mouth of a moray eel. The shrimp obtains food, and the eel is
freed from harmful parasites. The previous would be an example of _____mutualism_____.
22.
A remora hitches a ride on a shark. The remora obtains protection from its host and feeds on leftover
scraps from the shark’s meals. This would be an example of ___commensalism______.
23. In some places, dwarf mongooses and hornbills forage for food in close proximity to one another. Boot look
out for potential predators, but hornbills are better at detecting predatory birds overhead, and mongooses,
with their exceptional sense of smell, are better at detecting terrestrial predators. What type of symbiosis
does this represent?
Mutualism – both species benefit