energy flow in ecosystems

Question 1

what does an ecosystem include?

Answer 1

all the biotic and abiotic facotrs

Question 2

what are primary producers?

Answer 2

organisms that make their own glucosew

Question 3

where do terrestrial plants get their CO2 from?

Answer 3

the atmosphere

Question 4

where do aquatic plants get their CO2 from?

Answer 4

CO2 dissolved in the water

Question 5

how does the food chain go?

Answer 5

producer –> primary consumer –> secondary consumer –> tertiary consumer
–> quaternary consumer

Question 6

what do the arrows show in a food chain?

Answer 6

the flow of energy or the transfer of biomass

Question 7

what is biomass?

Answer 7

the mass of living matter of the organism or tissue
the chemical energy stored in an organismi

Question 8

in what terms can biomass be measured?

Answer 8

the dry mass of an organism or tissue
the mass of carbon in an organism

Question 9

what is gross primary productivity (GPP)?

Answer 9

the storing of chemical energy as plant biomass in a given area

Question 10

how can GPP be expressed?

Answer 10

g m^-2
kg m^-2
J m^-2
kJ m^-2

Question 11

why are not all the products from photosynthesis used to form new plant biomass?

Answer 11

• used up in respiration to release energy and some of the energy is lost as heat
• this is known as respiratory loss (R)

Question 12

what is the net primary productivity (NPP)?

Answer 12

the chemical energy left over after respiratory loss

Question 13

how can NPP be calculated?

Answer 13

NPP = GPP - R

Question 14

what does productivity mean?

Answer 14

the rate of production

Question 15

how can primary and secondary productivity be expressed?

Answer 15

mass/energy per unit area of unit time
e.g. g m^-2 day^-1
J m^-2 day ^-1

Question 16

what is secondary production?

Answer 16

when consumers ingest other organisms, the chemical energy in the biomass if these organisms is transferred to the consumer

Question 17

why is not all of the chemical energy in the consumers food transferred to them?

Answer 17

• not all of the biomass is eaten
• consumers aren’t able to digest 100% of the good they ingest so some is always egested as faces
• lots of chemical energy is lost to the environment when the consumer respires (mainly lost as heat) and during excretion of waste products

Question 18

what is the net production of consumers?

Answer 18

energy left after all the losses are accounted for

Question 19

how can the net production of consumers be calculated?

Answer 19

N = I - ( F + R )

I = chemical energy store in ingested food
F = chemical energy lost in feces and urine
R = respiratory losses