Topic 10

Question 1

ecosystem

Answer 1

an environment including the community of living organisms interacting within it, interacting with the nutrient cycle and the physical and chemical environment in which the organisms are living (range in size)

Question 2

GPP

Answer 2

(gross primary productivity) amount/rate of energy fixed by producers and stored as chemical energy in glucose/ organic material depending on photosynthesis

Question 3

NPP

Answer 3

(net primary productivity) amount of energy assimilated into biomass and available to be passed on from a producer to a consumer
NPP (kJm-2year-1) = GPP - Respiration

Question 4

sustainable

Answer 4

renewable, does not run out so can be available for future generations

Question 5

productivity

Answer 5

amount of biomass produced by an ecosystem in a year (mass or energy/area/time)

Question 6

decomposers in carbon cycle

Answer 6

final trophic level release hydrolytic enzymes and decompose organic material to form monomers
monomers are soluble so organisms take them up
respiration of organisms releases CO2 and water

also decomposers anaerobically respire to produce CH4 used as fuel

Question 7

CO2 from atmosphere and ocean

Answer 7

dissolved in water
for carbon fixation in LIR
by photosynthesis of algae

Question 8

nitrogen fixing bacteria

Answer 8

N2 -> NH3 -> NO3^-

in legumes’ root nodules

Question 9

nitrifying bacteria

Answer 9

NH3 -> NO2^- -> NO3^-

Question 10

denitrifying bacteria

Answer 10

NO3^- -> N2

Question 11

decay bacteria

Answer 11

nitrogen containing compounds in dead organisms waste products -> NH3

Question 12

succession

Answer 12

a process by which communities of plants and animals colonise an area after a disturbance and are replaced over a period of time

Question 13

primary succession

Answer 13

an empty area is colonised by new organisms

Question 14

secondary succession

Answer 14

soil is established in an area which is colonised by new organisms (faster) containing different pioneer species to primary succession

Question 15

pioneer species

Answer 15

first to colonise a previously damaged ecosystem as they are able to grow in little soil, beginning a change in succession
e.g. lichens and moss decay forming soil which retains water and minerals producing humus layer for other species with short roots to grow

Question 16

climax community

Answer 16

end of succession, self sustaining community with a dominant species and constant high biodiversity and species range, stable if no change to environment

Question 17

plagioclimax

Answer 17

climax community as a result of human intervention

Question 18

conserving rare species (5)

Answer 18

conserving genetic diversity/ variation
no extinction
aesthetic reasons
plants are useful e.g. medicines
other animals depend on plants as a source of food/ part of food chain