Energy Transfers

Question 1

ecosystem

Answer 1

made up of a community of living organisms and all non living factors of its environment

Question 2

interdependence

Answer 2

different species in a community depend on each other for survival

Question 3

energy transfers

Answer 3

co2 is fixed into organic material (glucose) during photosynthesis
most of the sugars synthesised by plants in ps are used in resp
rest are used to make biological molecules incl starch and protein which make up biomass

Question 4

biomass

Answer 4

dry mass of tissue per given area (mass of carbon)
-chemical energy store in dry biomass can be measured using calirometry
measuring biomass
-collect plant sample eg wheat from area of 1m^2
-dry at 100c to remove water and weigh
-repeat until there is no change in mass

Question 5

gross primary production

Answer 5

total quantity of chemical energy stored in plant biomass in a given area
for growth to occur - rate of ps > rate of resp

Question 6

net primary production

Answer 6

chemical energy/biomass left after energy released in respiration has been removed
energy used for plant growth, reproduction and used by consumers
NPP=GPP-R

Question 7

consumers

Answer 7

net production- N= I- (F+R)
I= chemical energy stored in ingested food
F= energy lost in faeces and urine
R= energy lost in respiration

Question 8

primary productivity

Answer 8

rate of production of biomass/ chemical energy in a plant in a given time (kJ/m^2/year)

Question 9

secondary productivity

Answer 9

rate of production of biomass/chemical energy store in an animal in a given time (kJ/m^2/year)

Question 10

inefficient energy transfer

Answer 10

from light to plants- only 2% of solar energy that falls on plants is incorporated into their biomass/ chemical energy which is then available for animals in food chain

rest is: reflected, misses chloroplasts, wrong wavelength, converted to heat

between trophic levels
-10% from primary to secondary
-20% from secondary to tertiary
explains why there is a limit of 4-5 feeding levels as it can’t support any more + explains why total amount of energy is less at each level

Question 11

% efficiency

Answer 11

energy available after transfer/energy available before transfer x100

energy transferred to biomass/ energy intake x100

Question 12

farming methods

Answer 12

reduce respiratory losses so more biomass is passed onto feeding level
max growth
-animals kept in confined spaces so less energy is used for movement
-environment kept warm so less energy is used to maintain body temp and lost as heat
-predators kept out
-feeding is controlled s animals receive optimum food for max growth