Interactions within Ecosystems

Which of the following statements best defines an ecosystem?

• A group of organisms of the same species that live in an area

• Many groups of organisms of different species that live in an area

• Many groups of organisms of different species interacting with each other and the environment in which they all live in

• The study of the interactions between many groups of organisms of different species and the environment in which they all live in

Which of the following examples does not illustrate that physical factors are important in determining the kind of organisms that live in a certain location?

• Camels are able to live in desert environments but cows are not.

• Mangrove trees grow well in waters with high salt content.

• Earthworms need a damp and dark environment to survive.

• Polar bears depend on animals like fish and seals to survive.

Which pair of organisms does not have a predator–prey relationship?

• A

• B

• C

• D

Parasitism is the relationship between two organisms in which _______________.

• the two organisms help each other to find food in the environment

• the two organisms compete for food in the environment

• one organism helps the other organism to find food in the environment

• one organism benefits at the expense of the other organism

Energy is lost in a food web as it is transferred from one organism to another. Which of the following is not a means by which energy is lost?

• Photosynthesis

• Respiration

• Excretion

• Defecation

The ultimate source of energy in an ecosystem is/are _______________.

• primary consumers

• producers

• green plants

• the sun

Refer to the pyramid of energy shown below and answer the question.

An organism in trophic level P is a _______________.

• producer

• primary consumer

• secondary consumer

• tertiary consumer

Refer to the pyramid of energy shown below and answer the question.

Which of the following organisms can belong in trophic levels R and S?

• Snake and Eagle respectively

• Fish and Worm respectively

• Cow and Grass respectively

• Corn and Human respectively

Refer to the pyramid of energy shown below and answer the question.

Energy is lost as it is transferred from one organism to another. In the pyramid of energy above, where does the greatest loss of energy occur?

• From S to R

• From R to Q

• From Q to P

• From P to S

Refer to the pyramid of energy shown below and answer the question.

Approximately ____ percent of energy is lost when food is transferred from one trophic level to the next.

• 10

• 50

• 90

• 99