2.3: flows of energy & matter

Question 1

ecological efficiency -

Answer 1

percentage of energy transferred from one trophic level to the next
(energy used for growth (new biomass)) / energy supplied multiplied by 100

Question 2

productivity -

Answer 2

conversion of energy into biomass for a given period of time is measured as productivity

Question 3

primary productivity & secondary productivity –

Answer 3

primary productivity – gain by autotrophs in energy or biomass per unit area per unit time

secondary productivity – biomass gained by heterotrophs thru feeding and absorption, measured in units of mass or energy per unit area per unit time

Question 4

gross productivity -

Answer 4

• total energy captured or “assimilated” by an organism.
• measured in joules (J)

plant (Gross Primary Productivity)
GPP = sunlight energy used during photosynthesis

animals (Gross Secondary Productivity)
GSP = food eaten - energy in faeces

Question 5

net productivity -

Answer 5

• energy left over after organisms have used what they need to survive. (plants & animals have to use some of the energy they capture they keep themselves growing)
• all organisms have waste energy and respiratory loss given off as heat, metabolism (R)

Net productivity = Gross productivity - Respiration Energy (NP = GPP - R) (NP = GSP - R)

Question 6

solar radiation composition

Answer 6

visible light + ultraviolet radiation

Question 7

solar radiation process

Answer 7

solar radiation absorbed
converted to heat energy
energy is reflected or absorbed

Question 8

fate of plant material

Answer 8

1. decays
2. eaten

Question 9

fate of glucose produced by photosynthesis

Answer 9

1. helps in respiration
2. produces biomass

Question 10

why amount of biomass varies;

Answer 10

1. spatially (tundra vs rainforest)
2. temporarily/ seasonal

Question 11

fate of energy in hebrivores/ carnivores

Answer 11

1. respiration (& during hunting)
2. urine/ feces
3. stored as dry mass

Question 12

what are biogeochemical cycles

Answer 12

nutrients are absorbed, circulated through the trophic levels and released when decomposed

(water cycle, carbon cycle, nitrogen cycle, sulphur & phosphorous )

Question 13

carbon cycle

Answer 13

stored in living things (plants), oceans, soil, atmosphere, fossil fuels/rocks

released via respiration, combustion of fossil fuels, decomposition, deforestation

plants absorb it and use it in photosynthesis

Question 14

nitrogen cycle

Answer 14

stored in organisms, fossil fuels, atmosphere, soil, water

released in decomposition

1. nitrogen fixation (atmospheric nitrogen -> ammonium ion)
   done by;
   - nitrogen-fixing bacteria living in soil/
   - nitrogen-fixing bacteria living in leguminous plants
   - lightning
2. nitrification
   ammonium ion ->nitrite -> nitrate
3. denitrification
   ammonium ion, nitrite, nitrate -> atmospheric nitrogen

Question 15

what is assimilation

Answer 15

nitrogen is built up via protein synthesis into amino acids & proteins for animals

Question 16

how do humans change nitrogen levels

Answer 16

• use fertilisers
• remove animals/plants for food
• planting leguminous plants

Question 17

efficiency of assimilation- how much of what is eaten is absorbed into the body

Answer 17

(gross productivity *100)/ food eaten

Question 18

efficiency of biomass productivity- how much of what is abrobed is turned into meat/productive

Answer 18

(net productivity *100)/ gross productivity

Question 19

reasons for low trophic efficiency (trophic inefficiency)

Answer 19

• lots of energy lost in respiration;
  eg. warm-blooded, high metabolic rate, large area to hunt
• everything not eaten
• used in other processes ( eg. reproduction)
• inefficient digestion