Food chains

Question 1

what are the levels of a food chain known as

Answer 1

• trophic levels

Question 2

what is the first level

Answer 2

• primary producer

Question 3

what is the thing that eats the primary producer

Answer 3

• primary consumer

Question 4

why is energy lost at each stage of the chain

Answer 4

• excretion
• respiration

Question 5

what is gpp

Answer 5

• gross primary productivity the rate of production of chemical energy in organic molecules by photosynthesis

Question 6

whatt is npp

Answer 6

gpp - respiration = npp

Question 7

what does npp stand for

Answer 7

net primary productivity which is the energy in the plant’s biomass

Question 8

What is primary productivity

Answer 8

the rate at which energy is converted by producers into biomass

Question 9

what is secondary productivity

Answer 9

the rate at which consumers convert the chemical energy of their food into biomass

Question 10

When calculating gpp and npp your answer should roughly be what

Answer 10

gpp = 1% npp = 0.5%

Question 11

what are the 3 ways energy is lost into the environment

Answer 11

energy in molecules that are egested

energy lost as heat following processes fuelled by the energy generated in respiration including muscles contraction

energy remains in molecules in parts of an animal that may not be eaten such as horns

Question 12

the efficiency of energy transfer =

Answer 12

energy incorporated into biomass after transfer

———————————————————————— x100

energy available in biomass before the transfer

Question 13

what is an ecological pyramid

Answer 13

diagram that shows a particular feature of each trophic level in an ecosystem

Question 14

what does an ecological pyramid not account for

Answer 14

organisms functioning at multiple trophic levels

Question 15

what are 3 common forms of pyramids

Answer 15

numbers

energy

biomass

inverted biomass

Question 16

what are the issues with the pyramid of numbers

Answer 16

• Doesn’t take into account of the size of organisms
• Doesn’t recognise the difference between juvenile and adult forms
• The range of numbers may be so large that it may be difficult to draw to scale
• The pyramid of part of it may be inverted if one trophic level has more organisms than the previous trophic level

Question 17

what is the most accurate way of representing feeding relationships is to

Answer 17

use a pyramid of energy

Question 18

why is a pyramid of energy the most accurate way of representing feeding relationships

Answer 18

as the material passes up through the food chain energy is lost from the ecosystem so the area of the bars decreases accordingly

Question 19

what are the issues with a pyramid of biomass

Answer 19

• pyramids of biomass are difficult to measure accurately
• they do not indicate productivity or the amount of energy flowing through the ecosystem
• pyramids of biomass may be inverted
• in a pyramid of biomass, a trophic level may seem to contribute more to the next trophic level than it actually does
• species with similar biomass may have different lifespans
• direct comparison of their total biomasses is therefore misleading

Question 20

what is succession

Answer 20

the change in structure and species composition of a community over time

Question 21

what is climax community

Answer 21

a stable self perpetuating community that has reached equilibrium with its environment and no further change occurs

Question 22

what is a primary succession

Answer 22

the change in structure and species composition of a community over time in an area that has not been colonised

Question 23

what is a sere

Answer 23

sequence of communities with the different species and structure

Question 24

what is a xerosphere

Answer 24

very dry environment is a xerosphere

Question 25

what is a seral stages

Answer 25

the stages of a sere

Question 26

what is a pioneer species

Answer 26

first organisms to colonise the bare rock are algae and lichens

Question 27

a xerosere sequence

Answer 27

pioneer herbs and grasses shrubs and small trees large trees

Question 28

what dictates the type of succession animals undergo

Answer 28

plant types present at each stage

Question 29

as xerosere progresses what is increased

Answer 29

* soil thickness * availability of water * biomass * biodiversity * resistance to invasion by new species * stability to disruption by environmental challenges

Question 30

what is secondary succession

Answer 30

the changes in a community following the disturbance or damage to a colonised habit

Question 31

what is disclimax

Answer 31

human interference can affect a succession and may prevent the development of the climatic climax community

Question 32

what are the 3 factors that impact succession

Answer 32

migration competition facilitation

Question 33

how does migration affect succession

Answer 33

arrival of spores seeds and animals is vital for succession to occur immigrating non-native species may spread themselves widely altering the community and the soil

Question 34

what does facilitate mean

Answer 34

enables something to happen

Question 35

what is symbiosis

Answer 35

association between individuals of two species

Question 36

what is mutualism

Answer 36

the interaction between species that is beneficial to both such as the relationship between bird eating insects of a deer so the bird feeds and the deer becomes insect free in a loose association

Question 37

what is commensalism

Answer 37

described as a loose interaction between organisms of two species in which one benefits and one is unaffected