2.3

Question 1

gross primary productivity

Answer 1

total gain in energy or biomass per unit area per unit time by green plants, it is the total energy converted from light to chemical energy

Question 2

gross productivity

Answer 2

is the total gain in energy or biomass per unit area per unit time

Question 3

net productivity

Answer 3

is the gain in energy or biomass per unit area per unit time that remains after deductions due to respiration

Question 4

net primary productivity

Answer 4

is the gain in energy or biomass per unit area per unit time bu green plants after allowing for losses to respiration
NPP = GPP_R

Question 5

gross secondary productivity (GSP)

Answer 5

is the total energy/biomass assimilated (taken up) by consumers
GSP = food eaten - fecal loss

Question 6

net secondary productivity

Answer 6

total gain in energy or biomass per unit area per unit time by consumers after allowing for losses to respiration
NSP = GSP - R

Question 7

carnivores vs herbivores assimilation + that

Answer 7

carnivores;
assimilate 80% of the energy in their diets
egest about 20%
have to chase moving animals, higher energy intake is offset by increased respiration during hunting

Herbivores;
assimilate about 40% of the energy in their diet
they egest 60%
they graze static plants

Question 8

carbon cycle steps

+ see image

Answer 8

photosynthesis
respiration
decomposition
combustion
\+ see image of cycle

Question 9

nitrogen cycle context; about the gas and its stores

Answer 9

• mist abundant gas in the atmosphere but unavailable to plants and animals
  stored in organisms, soil, fossil fuels, atmosphere

Question 10

nitrogen fixation

Answer 10

when atmospheric nitrogen is made available to plants through the fixation of it. Can be carried out in 5 ways;
by nitrogen fixing bacteria, cyanobacteria, lightning (causing oxidation of nitrogen gas), Haber process (used to make fertilizers)

Question 11

nitrification

Answer 11

nitrifying bacteria can convert ammonium to nitrites and convert nitrites to nitrates which are then available to be absorbed by plant roots

Question 12

denitrification

Answer 12

denitrifying bacteria in waterlogged and anaerobic conditions reverse the process of nitrification by converting ammonium, nitrate and nitrite ions to nitrogen gas which escapes to the atmosphere

Question 13

assimilation

Answer 13

once nitrogen is taken in by living organisms, they assimilate it or build it into more complex molecules

Question 14

decomposition

Answer 14

supplies soil with more nitrogen than nitrogen fixation

Question 15

nitrogen cycle (see image)

Answer 15

see image

Question 16

calculating efficiency of assimilation

Answer 16

efficiency of assimilation = (gross productivity x 100)/ food eaten

Question 17

calculating efficiency of biomass productivity

Answer 17

net productivity x 100)/gross productivity

Question 18

trophic inefficiencies occur because;

Answer 18

not everything is eaten
digestion is inefficient - feces
heat is lost in respiration
some energy assimilated is used in reproduction and other life processes

Question 19

maximum sustainable yield

Answer 19

is the largest crop or catch that can be taken from the stock of a species without depleting the stock.