topic 5 (energy transfer in ecosystems)

Question 1

what is a producer?

Answer 1

organism that makes its own food

Question 2

what is a consumer?

Answer 2

organism that consumes on another organism to obtain its energy, rather than directly using energy from sunlight

Question 3

what is a primary consumer?

Answer 3

organism that directly eats a producer

Question 4

what is a secondary consumer?

Answer 4

organism that eats a primary consumer

Question 5

what is a tertiary consumer?

Answer 5

organism that eats a secondary consumer

Question 6

what is a saprobiont?

Answer 6

decomposer that breaks down complex material in dead organisms into simple matter

Question 7

what is biomass?

Answer 7

the mass of living material

Question 8

what does a food chain do?

Answer 8

describes a feeding relationship where producers are eaten by consumers

Question 9

what is a stage in a food chain called?

Answer 9

trophic level

Question 10

what does an arrow on a food chain represent?

Answer 10

the direction of energy flow

Question 11

what does a food web represent?

Answer 11

how food chains in a habitat link together

Question 12

how can you estimate the chemical energy stored in biomass?

Answer 12

by burning biomass in a calorimeter

Question 13

what can biomass be measured in terms of?

Answer 13

the mass of carbon an organism contains, or the dry mass of its tissue per unit area

Question 14

what is dry mass?

Answer 14

mass of an organism with all the water removed

Question 15

how can you find the dry mass of an organism?

Answer 15

sample of an organism dried in a low temperature oven
weighed at regular intervals
when mass ecomes constant all water has been removed
scale up to total population/area being investigated

Question 16

how much carbon is present in dry mass?

Answer 16

50%

Question 17

how does a calorimeter find the chemical energy given off?

Answer 17

sample of dry biomass burnt

energy used to heat a known volume of water

change in temperature of water used to calculate the chemical energy of the dry biomass

Question 18

what is gross primary production?

Answer 18

total amount of chemical energy converted from light energy by plants, in a given area

Question 19

how much of the GPP is lost as heat to the environment when plants respire?

Answer 19

50%

Question 20

what is respiratory loss?

Answer 20

GPP lost to the environment when plants respire

Question 21

what is the net primary production equation?

Answer 21

gross primary production - respiratory loss

Question 22

what is net primary production?

Answer 22

energy available to the plant for growth and reproduction

energy stored in a plant’s biomass

energy available to organisms at the next stage of the food chain

Question 23

what is primary productivity?

Answer 23

total amount of biomass in a given area at a given time

Question 24

where do consumers store chemical energy?

Answer 24

in their biomass

Question 25

how do consumers get energy?

Answer 25

ingesting plant material, or animals that have eaten plant material

Question 26

how much energy is lost between trophic levels?

Answer 26

90%

Question 27

why is energy lost between trophic levels?

Answer 27

not all of the organism is consumed
some parts of an organism are lost in faeces if they cannot be digested
some energy lost in excretory materials

Question 28

what is the formula for net production of consumers?

Answer 28

net production=

chemical energy ingested in food - (chemical energy lost in faeces/urine/respiration)

Question 29

what is the net production of consumers also called?

Answer 29

secondary production/productivity

Question 30

why do most food chains only have 4/5 levels?

Answer 30

insufficient energy to support a large enough breeding population at a higher trophic level than this

Question 31

is the mass of organisms higher/lower at a higher trophic level?

Answer 31

lower

Question 32

how does the energy available change as you go higher up the food chain?

Answer 32

decreases

Question 33

what is the equation for percentage efficency?

Answer 33

(energy available after the transfer/ energy available before the transfer) x 100

Question 34

what are two methods farmers use to increase the efficency of energy transfer?

Answer 34

reduce the energy lost to other organisms

reduce the energy lost through respiration

Question 35

how can a food web be simplified?

Answer 35

by getting rid of pests

Question 36

what are methods of pest control?

Answer 36

use chemical pesticides and biological agents

Question 37

how can respiration loss be reduced?

Answer 37

keep animals in pens to restrict their movement

keep pens indoors and warm- less energy lost by generating body heat

Question 38

how do pens increase energy conversion rate?

Answer 38

movement restricted so less energy used in muscle contraction

environment kept warm to reduce heat loss

feeding controlled so max growth with no waste

predators excluded- no loss in food web