Ecology: Chapter 4

Question 1

Biotic Factors

Answer 1

• the biological influences on organisms within an ecosystem
• includes all of the living things that an organism may interact with: the ecological community
• example: food; parasites; competitors for food/space/mates

Question 2

Abiotic Factors

Answer 2

• the physical or nonliving factors that shape an ecosystem

- example: pH, soil, terrain, H2O, oxygen, CO2, temperature/weather/climate, minerals (N,P,K), salinity

Question 3

The Niche

Answer 3

• the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
• the role the organism plays in the environment

Question 4

Fundamental Niche

Answer 4

the total niche that an organism could potentially use within an ecosystem

Question 5

Realized Niche

Answer 5

the part of a fundamental niche that an organism actually occupies as a result of competition

Question 6

The Competitive Exclusion Principle

Answer 6

no two species can share/occupy the same niche in the same habitat at the same time; however, different species can occupy niches that are very similar

Question 7

Resource Sharing

Answer 7

• phenomenon characterized by different species of a community dividing similar resources instead of competing for them
• different niches will be occupied; feeding may occur at different times or in different areas

Question 8

Keystone Species

Answer 8

single species that are not actually abundant in a community, yet exerts strong control

Question 9

Competition

Answer 9

• occurs when organisms of the same or different species attempt to use an ecological resource at the same place at the same time
• example: food, water, shelter, mates

Question 10

Predation

Answer 10

• interaction in which on organism captures and feeds on another organism
• example: amoeba –> paramecium –> jumping spider –> captured moth

Question 11

Symbiosis

Answer 11

• an intimate relationship in which 2 species live closely together
• an excellent example of coevolution

Question 12

Mutualism

Answer 12

• both species benefit from the relationship; in many cases neither one could survive without the other
• example: a) lichens: fungal component absorbs minerals and algal component produces food

Question 13

Commensalism

Answer 13

• one member benefits and the other is neither helped nor harmed
• example: a) epiphytes: (orchid) plants that grow on some trees

Question 14

Parasitism

Answer 14

-one organism lives in or on another organism and harms it

Question 15

Ecological Succession

Answer 15

• the regular progression of species replacement in a developing ecosystem
• the gradual change in the structure of a community over time

Question 16

Primary Succession

Answer 16

takes place on land where no soil and no vegetation exists

-example: on the surface formed as volcanic eruptions build new islands; on the dunes of a beach

Question 17

Pioneer Organisms

Answer 17

• early settlers specialized for life in harsh conditions, such as bare rock
• example: lichens and mosses

Question 18

Secondary Succession

Answer 18

• the return of an area to its original condition after it has been disturbed; takes place on land where soil is already in place
• example: abandoned fields or forest clearings after major fires

Question 19

Climax Community

Answer 19

• a community of organisms that will remain stable in an area as long as the area is undisturbed
• a community that has reached the end of succession

Question 20

Biome

Answer 20

a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals

Question 21

Tropical Rainforest

Answer 21

most biodiverse; nutrient poor; thin topsoil; fragile

Question 22

Epiphytes

Answer 22

• plant that non parasitically grows upon another plant or object
• since the soil is thin and nutrient poor, if destroyed rainforest plants will not grow well

Question 23

Savannas

Answer 23

tropical grasslands; seasonal rainfall; scattered trees (low density); warm; found in East Africa; South Brazil; India; North Australia

Question 24

Deserts

Answer 24

all with <25 cm annual rainfall and variable temperatures; plants and animals can tolerate arid conditions
-example: insects, lizards and other reptiles, birds, cacti

Question 25

Xerophytes

Answer 25

plants that have adapted to and tolerate dey and arid conditions

Question 26

Temperate Grasslands

Answer 26

much of Midwestern US; seasonal changes in temperature; fertile soil; Pampas of South America; Steppes of Russia

Question 27

Temperate Woodland

Answer 27

example: Chaparral where we live; life forms similar to desert

Question 28

Temperate Deciduous Forest

Answer 28

most trees are deciduous | deciduous = looses their leaves in the fall

Question 29

Taiga (Boreal Forest)

Answer 29

dominated by evergreen conifers; none in the Southern Hemisphere

Question 30

Tundra

Answer 30

not much precipitation; permafrost; low growing plants and lichens

Question 31

First Two Links in Aquatic Food Webs

Answer 31

phyoplankton and zooplankton

Question 32

Aphotic Zone

Answer 32

permanently dark region below the photic zone; the onnly producers are chemosynthetic autotrophs

Question 33

Photic Zone

Answer 33

well lit upper layer (up to about 200m/600ft); photosynthetic producers cannot grow below this zone

Question 34

Benthos

Answer 34

bottom dweller

Question 35

Nekton

Answer 35

actively swimming aquatic organism in a lake or ocean

Question 36

Interdial or Littoral Zone

Answer 36

underwater during high tide; exposed to air/sunlight/temperature changes during low tide (the organisms that live here have adapted tothe changes)

Question 37

Freshwater Ecosystems

Answer 37

- lakes and ponds - rivers - wetlands (swamps = trees present; marshes = no trees present)

Question 38

Coastal Ocean or Neritic Zone

Answer 38

- extends from low tide mark to the outer edge of the continental shelf (the relatively shallow border, up to 200 m, that surrounds the continents) - mainly in the photic zone, thus rich in plankton and many other organisms

Question 39

Open Ocean (Oceanic/Pelagic Zone)

Answer 39

- begins at the edge of the continental shelf and extends outward - largest marine zone: depth from 500m-11,000m

Question 40

Benthic Zone

Answer 40

- the ocean floor from coastal ocean through open ocean - organisms living here are collectively referred to as benthos - example: sea stars, anemones, marine worms, crabs, flounder, etc.