Topic 20 - Community Ecology

Question 1

Amensalism

Answer 1

Association between organisms of two different species in which one is inhibited or destroyed and the other is unaffected. (-/0)

Question 2

Biomass

Answer 2

The total mass of all organisms in a given population or geographical area; usually expressed as total dry weight.

Question 3

Biomass pyramid

Answer 3

A diagram showing biomass at different trophic levels in an ecosystem, usually plotted as dry matter or calorific value per unit area or volume. Typically, this gives a gradually sloping pyramid.

Question 4

Co-evolutionary arms race

Answer 4

A series of adaptation and counter-adaptations observed in species that interact closely over time and affect each other’s fitness.

Question 5

Commensalism

Answer 5

A species relationship in which one organism (the commensal) benefits and the other (the host) is unaffected. (+/0)

Question 6

Competition

Answer 6

In Ecology, the interaction of two species or two individuals trying to use the same limited resource (e.g., water, food, living space). May occur between individuals of the same species (intraspecific competition) or different species (interspecific competition)

Question 7

Competitive exclusion

Answer 7

The principle that two species cannot coexist in the same ecological niche in the same area because one species will outcompete the other.

Question 8

Detritivore

Answer 8

An organism whose diet consists mainly of dead organic matter (detritus). Various bacteria, fungi, protists, and animals belong to this group of organisms. Also called decomposers.

Question 9

Ecological efficiency

Answer 9

The efficiency with which energy is transferred from one trophic level to the next.

Question 10

Exploitation/Consumption

Answer 10

Occurs when one organism eats another (+/-). Examples are herbivory, predation, parasitism and parasitoidism.

Question 11

Gross primary productivity

Answer 11

In an ecosystem, the total amount of carbon fixed by photosynthesis (or more rarely, chemosynthesis), including that used for cellular respiration, over a given time period.

Question 12

Keystone species

Answer 12

A species that has an exceptionally great impact on the other species in its ecosystem relative to its abundance.

Question 13

Mutualism

Answer 13

Interactions that involve a wide variety of organisms and rewards, in which all participants benefit from the association (+/+).

Question 14

Net primary productivity

Answer 14

In an ecosystem, the total amount of biomass generated by the fixation of carbon through photosynthesis per year minus the amount oxidized during cellular respiration.

Question 15

Niche

Answer 15

The range of resources that a species can use and the range of conditions that it can tolerate. More broadly, the role that a species plays in its ecosystem.

Question 16

Omnivore

Answer 16

An animal whose diet includes a variety of organisms, including plants, animals, fungi, protists, archaea, and/or bacteria.

Question 17

Primary consumer

Answer 17

An herbivore; an organism that eats plants, algae, or other primary producers.

Question 18

Primary producer

Answer 18

An organism that creates its own food by photosynthesis or from reduced inorganic compounds and that is a food source for other species in its ecosystem. Also called autotroph.

Question 19

Secondary consumer

Answer 19

A carnivore; an organism that eats herbivores.

Question 20

Tertiary consumer

Answer 20

A carnivore; in a food chain or food web, organisms that feed on secondary consumers.

Question 21

Trophic cascade

Answer 21

A series of changes in the abundance of species in a food web, usually caused by the addition or removal of a key predator.

Question 22

Trophic level

Answer 22

A feeding level in an ecosystem.