Ch.20 Communities and Ecosystems

Question 1

community

Answer 1

An assemblage of species living close together for potential interaction.

Question 2

interspecific competition

Answer 2

The population growth of species may be limited by the population densities of competing species and by the density of its own population.

Question 3

ecological niche

Answer 3

total use of the biotic and abiotic resources in its environment.

Question 4

competitive exclusion principle

Answer 4

If 2 species have an ecological niche that is too similar, they cannot coexist the same place.

Question 5

mutualism

Answer 5

Both species benefits from an interaction. Some mutualisms occur between symbiotic species-those in which the organisms have a close physical association with each other.

Question 6

predation

Answer 6

An interaction in which one species (the predator) ills and eats another (the prey). Numerous adaptations for predator avoidance have evolved in prey populations through natural selection.

Question 7

cryptic coloration (camouflage)

Answer 7

Makes potential prey difficult to spot against its background.

Question 8

warning coloration

Answer 8

Bright patterns of yellow, red, or orange in combination with black, often marks animals with effective chemical defences.

Question 9

copycat adaptation

Answer 9

One species looks like another.

Question 10

herbivory

Answer 10

Consumption of plant parts or algae by an animal.

Question 11

parasites

Answer 11

Organisms that live on or in a host from which it obtains nutrients, such as ticks or aphids, or pathogens

Question 12

pathogens

Answer 12

Disease-causing bacteria, viruses, fungi, and protists.

Question 13

commensalism

Answer 13

An interaction in which the individual of one species benefits and the individuals of the other species is neither helped nor harmed.

Question 14

trophic structure

Answer 14

The feeding relationships among the various species in a community.

It determines the pathways that transform energy and matter as they move up in the food chains in a community.

Question 15

food chain

Answer 15

The sequence of food transfer between trophic levels.

Question 16

producers

Answer 16

The trophic level that supports all other trophic levels consisting of autotrophs.

Question 17

herbivores

Answer 17

Eat plants, algae, or phytoplankton = primary consumers.

Question 18

carnivores

Answer 18

Eat the consumers from the level below.

• secondary consumers: eat primary consumers
• tertiary consumers: eat secondary consumers
• quaternary consumers: eat tertiary consumers

Question 19

detritus

Answer 19

Dead material left by all trophic levels.

Question 20

decomposers

Answer 20

Digest molecules in organic material and convert organic materials into inorganic forms.

Question 21

food webs

Answer 21

Feeding relationships in a community.

Question 22

omnivores

Answer 22

Animals that eats producers and consumers of different levels.

Question 23

species diversity

Answer 23

The variety of species that make up the community:

1) species richness - the number of different species in the community
2) relative abundance - the proportional representation of each species in the community

Question 24

keystone species

Answer 24

Species whose impact on its community is much larger than its total mass or abundance indicates.

Question 25

disturbances

Answer 25

Episodes that damage biological communities by destroying organisms and altering the availability of resources such as mineral nutrients and water.

• storms, fire, floods, droughts
• often have positive impact promoting new habitats

Question 26

ecological succession

Answer 26

After a disturbance strips away vegetation, the are may be colonised by a variety f species, which are gradually replaced by other species.

Question 27

primary succession

Answer 27

Ecological succession that begins in a virtually lifeless area with no soil.
-cooled lava flows

Question 28

secondary succession

Answer 28

Ecological succession that begins in a destroyed community with an intact soil.
-forest fires

Question 29

ecosystems

Answer 29

The community of species in a given area and all the abiotic factors, such as energy, soil characteristics, and water.

Question 30

energy flow

Answer 30

Passage of energy through the components of the ecosystem.

Question 31

chemical cycling

Answer 31

Use and reuse of chemical elements such as carbon and nitrogen within the ecosystem.

Question 32

biomass

Answer 32

Amount. or mass, of living organic material in an ecosystem.

Question 33

primary production

Answer 33

The rate at which an ecosystem’s producers convert solar energy o the chemical energy stored in organic compound.

Question 34

energy pyramid

Answer 34

Cumulative loss of energy with each transfer in a food chain.

The amount of energy available to top-level consumers is small compared with that available to lower-level consumers.

Question 35

biogeochemical cycles

Answer 35

Chemical cycles in an ecosystem which involves biotic components (organisms and nonliving organic material) and abiotic (geologic and atmospheric) components.

Most important cycles are: carbon, phosphorus, nitrogen.

Question 36

abiotic reservoir

Answer 36

Where chemical accumulates or is stockpiled outside of living organisms.

Question 37

nitrogen fixation

Answer 37

• Converts gaseous N2 to ammonia (NH3).

- Ammonia then picks up another H+ to become ammonium (NH4+), which plants can assimilate.

Question 38

conservation biology

Answer 38

Goal-oriented science that seeks to understand and counter the loss of biodiversity.

Question 39

restoration ecology

Answer 39

Uses ecological principles to develop methods of returning degraded areas to their natural state.