Ecosystems

Question 1

biosphere

Answer 1

only part of earth where living things inhabit a restricted zone

Question 2

ecosystem

Answer 2

a stable settled unit consisting of a community of organisms interrelated with the physical and chemical environment

Question 3

components of an ecosystem

Answer 3

habitat, population, community

Question 4

niche

Answer 4

role of each species in an ecosystem including: how/what feeds on, what it excretes, how it reproduces

Question 5

why are ecosystems dynamic

Answer 5

living elements grow/die, non-living elements change, populations fall/rise, interact with each other and environment

Question 6

types of dynamic changes affecting population size

Answer 6

cyclic, directional, unpredictable/erratic changes

Question 7

cyclic changes

Answer 7

changes repeat themselves in a rhythm e.g. tides

Question 8

directional changes

Answer 8

go in one direction and tend to last longer than lifetime of organisms, variables increase/decrease e.g. erosion

Question 9

unpredictable/erratic changes

Answer 9

no rhythm/constant direction e.g. lightning

Question 10

autotrophs

Answer 10

organisms that make their own food from the substances available in their surroundings using light/chemical energy e.g. producers

Question 11

heterotrophs

Answer 11

cannot synthesise their own food so rely on other organisms e.g. consumers

Question 12

trophic level

Answer 12

level a particular organism holds/feeds in, in a food chain

Question 13

pyramid of numbers

Answer 13

the width of each block is proportional to the number of organisms present at each trophic level

Question 14

pyramid of biomass

Answer 14

the mass of material for each trophic level

Question 15

how biomass is lost at each trophic level

Answer 15

life processes within living organisms, dead organisms/waste material only available to decomposers

Question 16

pyramid of energy

Answer 16

measured in productivity, rate at which energy passes through each trophic level

Question 17

how to get dry mass

Answer 17

ecologist collects organisms, puts in oven at 80’C until all water evaporated by checking periodically the mass until it stops reducing

Question 18

why is dry mass more difficult

Answer 18

the method is destructive so mostly just calculated from wet mass using previously published data

Question 19

gross primary productivity (GPP)

Answer 19

the rate at which plants convert light energy into chemical energy

Question 20

net primary productivity (NPP)

Answer 20

difference between GPP and plant respiration (R)

Question 21

concept of increasing primary productivity

Answer 21

manipulating environmental factors to make energy conversion more efficient

Question 22

concept of increasing secondary productivity

Answer 22

humans manipulating the energy transfer

Question 23

endotherms

Answer 23

organisms with a constant body temperature (birds/mammals)

Question 24

ectotherms

Answer 24

varying body temperature (worms, fish, reptiles)

Question 25

would endo/ectotherms be more efficient to farm

Answer 25

ectotherms because they have a varying body temperature so are able to change to keep it stable and not waste energy

Question 26

climax community

Answer 26

the final stable community that exists after the process of succession has occurred

Question 27

succession

Answer 27

progressive change in a community of organisms over time

Question 28

pioneer species

Answer 28

the species that begin the process of succession, often colonising an area as the first living things there

Question 29

deflected succession

Answer 29

when succession is stopped/interfered with e.g. golf course, garden, garden pond

Question 30

primary succession

Answer 30

the change in a species composition over time in a habitat that hasn’t been previously inhabited

Question 31

as the distance from the shore increases, the sand…

Answer 31

becomes more stable and succession towards a climax community begins

Question 32

secondary succession

Answer 32

changes in original community/habitat changing species composition over time in a habitat that has been previously inhabited

Question 33

a plagioclimax

Answer 33

sub-climax community that develops resulting from deflected succession

Question 34

sere

Answer 34

each stage of succession

Question 35

biotic potential

Answer 35

maximum rate at which a population could increase under ideal conditions, different species have different biotic potentials

Question 36

abiotic factors

Answer 36

non-living components of an ecosystem that affect other living organisms

Question 37

biotic factors

Answer 37

environmental factors associated with living organisms in an ecosystem that affect each other

Question 38

quadrant

Answer 38

an instrument used to measure angles

Question 39

saprotrophs

Answer 39

bacteria/fungi that feed on dead and decaying matter

Question 40

saprotrophic decomposition

Answer 40

saprotrophs secrete enzymes onto dead, waste material
digest material by extracellular digestion into small molecules which absorb into body
molecules are stored/respired to release energy

Question 41

when does saprotrophic decomposition most occur

Answer 41

warm, moist conditions and more active when plenty of oxygen

Question 42

most plants take up nitrogen in which 2 forms

Answer 42

ammonium and nitrate

Question 43

processes of bacteria in the nitrogen cycle

Answer 43

ammonification, nitrogen fixation, nitrification, denitrification

Question 44

deamination

Answer 44

saprophytic fungi/bacteria decompose proteins via amino acids to ammonia when organisms die