CH 37 Communities & Ecosystems

Question 1

Define Commuinty

Answer 1

assemblage of all pops of organisms living close enough together for potential interaction

Question 2

Define Interspecific interactions

Answer 2

relationships w/ individuals of other species in community (-/-)

Question 3

Interspecific competition occurs when…

Answer 3

pops of two different species compete for same limited resource (-/-)

Question 4

Define Mutualism

Answer 4

symbiotic relationship where both
pops benefit (+/+)

Question 5

Define Predation & Herbivory

Answer 5

A species kills & eats another / eating plant parts or algae by an animal

Question 6

Define Parasites & pathogens

Answer 6

A species uses a host species at its detriment.

Question 7

Interactions where one organism
involved is neither harmed nor benefited but the other is harmed is…

Answer 7

Amensalism.

Question 8

Interactions where one organism
involved is neither harmed nor benefited but the other benefits is…

Answer 8

Commensalism

Question 9

Species that need the other to survive are known as… / Species dat don’t need other species to survive (but still benefit) are known as…

Answer 9

Obligates / Facultative

Question 10

Define Ecological Niche

Answer 10

Sum of comm. use of biotic & abiotic resources in its environment

Question 11

Define Coevolution

Answer 11

series of reciprocal evolutionary
adaptations in 2 species

Question 12

What are Endoparasites? (inside)

Answer 12

flukes, tapeworms, etc.

Question 13

What are Ectoparasites? (outside)

Answer 13

ticks, lice, mites, mosquitoes, etc

Question 14

What are Plant parasites?

Answer 14

aphids and nematodes

Question 15

Define Trophic Structure

Answer 15

Pattern of feeding relationships consisting of several diff levels

Question 16

Define Tertiary & Quaternary consumers

Answer 16

T - carnivores that eat 2nd con & lower / Q - carnivores that eat Tert con & lower

Question 17

Define Food Chain

Answer 17

sequence of food transfer up the trophic levels

Question 18

Define Producers

Answer 18

autotrophic (self-feeding) organisms / Usually photosynthetic

Question 19

Define Primary & Secondary consumers

Answer 19

P - Herbivores that eat producers / S -carnivores (including
insectivores), usually smaller organisms

Question 20

Define Detritus

Answer 20

dead material produced at all the trophic levels.

Question 21

Define Scavengers,

Answer 21

large animals like crows & vultures / feast on carcasses

Question 22

Define Food Web

Answer 22

Network of interconnecting food chains.

Question 23

Species diversity is defined by two components:

Answer 23

Species richness (# of diff species in community) / Relative abundance (representation of each species in C)

Question 24

Define Decomposers

Answer 24

mainly prokaryotes & fungi / secrete
enzymes that digest molecules in organic material & convert to inorganic forms

Question 25

Define Decomposition

Answer 25

Breakdown of organic materials to inorganic materials

Question 26

Define Keystone species

Answer 26

Species whose impact on its Comm is much larger than its abundance/total biological mass would indicate

Question 27

Define Disturbances

Answer 27

Storms, fires, floods, droughts, or human activities that change biological comm by removing organisms from it/altering availability of resources

Question 28

Define Ecological succession

Answer 28

Disturbed area colonized by a variety of species, which gradually replaced by a succession of other species

Question 29

Define Primary & Secondary succession.

Answer 29

P - When Eco Succc begins in virtually lifeless area with no soil (rubble from glacier or fresh volcanic lava flows) / S - Disturbance has cleared away existing community but left soil intact (fires/floods)

Question 30

Define Invasive species

Answer 30

New species cause environmental & economic damage by colonizing/dominating wherever they find a suitable habitat.

Question 31

Define Ecosystem

Answer 31

All Organisms in a comm + abiotic environment

Question 32

Define Energy flow

Answer 32

passage of energy thru components of the ecosystem,

Question 33

Define Chemical Cycling

Answer 33

Transfer of matter within the ecosystem.

Question 34

Define Primary Production

Answer 34

Conversion of solar energy to chemical energy (as organic compounds) by photosynthesis..

Question 35

Define Gross Primary Production

Answer 35

Total amt of primary production during a given time period

Question 36

Define Net Primary Production

Answer 36

amt of new organic material added to a ecosystem in given period (The remainder)

Question 37

Define Biogeochemical cycles

Answer 37

Chemical cycles in an ecosystem include both biotic and abiotic

Question 38

Define Abiotic reservoirs

Answer 38

Chemicals accumulate/are stockpiled outside of living organisms

Question 39

Explain Carbon Cycle

Answer 39

Photosynthesis removes CO₂, / incorporates into organic matter. Consumers transfer it / respiration returns it & decomposers release CO₂ / Burning fossil fuels, increase CO₂ levels faster than photosynthesis can offset.

Question 40

Explain Phosphorus Cycle

Answer 40

Rock weathering adds phosphate to soil / Plants absorb & consumers ingest / Decomposers return phosphates to soil from waste/dead organisms / Some phos reach ocean - new rocks / Geo uplift exposes them to weathering - restarts cycle

Question 41

Explain Nitrogen Cycle (part 1)

Answer 41

Nit-fixing bacteria convert atmospheric nitrogen (N₂) into ammonium (NH₄⁺) - plants absorb to synthesize proteins. / Some ammonium converted into nitrate (NO₃⁻), more accessible for plants / Herbivores eat plants, break down proteins to amino acids / higher consumers obtain nitrogen from prey.

Question 42

Explain Nitrogen Cycle (part 2)

Answer 42

Excretion & decomposition return NH₄⁺ to soil. / Denitrifying bacteria, in low-oxygen conditions, convert NO₃⁻ back to N₂, release in atmosphere & deplete soil nitrogen. / Cycle maintains nitrogen balance in ecosystems.

Question 43

Define Eutrophication

Answer 43

Standing-water ecosystems gain nutrients from decomposition & land influx, boosts primary production over time