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Module 6.5 Flashcards

Ecosystems

1
Q

what is an ecosystem

A

all the populations of animals plants fungus and bacteria interrelating with the physical and chemical environment of the habitat - influence by both biotic and abiotic factors

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2
Q

what is a habitat

A

the place where an organism lives

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3
Q

what is a population

A

all of the organisms of one species who live in the same place at the same time and who can breed together

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4
Q

what is a community

A

all the populations of different species who live in the same place at the same time and who can interact with each other

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5
Q

what are biotic factors in an ecosystem

A

the living organisms within the ecosystem

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6
Q

example of biotic factors

A

producers
consumers
decomposers

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7
Q

what are abiotic factors

A

non-living components of an ecosystem

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8
Q

example of abiotic factors

A

pH
humidity
temperature
concentration of pollutants

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9
Q

why are ecosystems described as dynamic

A

as the no-living elements change and the living elements frow and died with populations of particular species rising and falling

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10
Q

what are cyclic changes in ecosystems

A

changes that repeat in a rhythm e.g. movements of tides
the may and which predator prey species fluctuate is cyclic

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11
Q

what are directional changes in ecosystems

A

changes go in one direction and tend to last a long time
e.g. erosion of a coastline

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12
Q

what are unpredictable/erratic changes in ecosystems

A

have no rhythm or constant direction
e.g. the effect of lightning or hurricanes

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13
Q

examples of how ecosystems vary in size

A

rock pool
field
large tree

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14
Q

what is biomass transfer

A

transfer of biomass from one trophic level to another

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15
Q

what is a trophic level

A

the level at which an organisms feeds in a food chain

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16
Q

how do plants make up their biomass

A

energy captured in photosynthesis to produce organic molecules
some of the products of photosynthesis used immediately for respiration while some are incorporated into tissues and organs
inorganic components such as mineral ions combine with the organic molecules to make the biomass

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17
Q

how is the biomass from producers transferred to consumers

A

when a plant is eaten its biomass is consumed by the primary consumer

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18
Q

how is biomass lost through life processes

A

organisms need energy to carry out life processes
respiration releases energy from organic molecules like glucose
some of this energy is converted to hear and materials are lost in carbon dioxide and what

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19
Q

how is biomass lost through waste

A

dead organisms and waste material is lost from a food chain which is then only available to decomposers
waste material includes parts of animals and plant that cannot be digested by consumers such as bones and hair

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20
Q

what is a pyramid of number

A

represents how in a food chain where organisms about the same size there will be a large amount of producers and fewer consumers as you go up the trophic levels
each bar represents the number of individuals

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21
Q

what is a pyramid of biomass

A

provides a more accurate picture of how much biomass exists at each level that a pyramid of numbers
each bar is proportional to the dry mass of all the organisms at that trophic level

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22
Q

calculation for efficiency of biomass transfer

A

biomass transferred/biomass intake x 100

biomass at the higher trophic level/biomass at the lower trophic level x 100

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23
Q

what is productivity in an ecosystem

A

the rate of production of new biomass by producers

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24
Q

what is gross primary productivity

A

the rate at which plants convert light energy into chemical energy through photosynthesis

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25
why is gross primary productivity inefficient
not all of the energy from the sun is used not all of this energy is involved in glucose production not all of the glucose produced is used for production of biomass contributing to growth e.g. starch and cellulose
26
what is net primary productivity
the amount of energy from the sun that remain to enter the food chain
27
how can humans increase net primary productivity
make energy conversion more efficient reduce energy loss increase the amount of biomass incorporated into plants
28
examples of increasing primary productivity
growing crops under light banks irrigation growing in greenhouses crop rotation and fertiliser pesticides herbicides fungicides
29
what is gross secondary productivity
the amount of biomass and energy transferred from producers to consumers through consumption
30
why is gross secondary productivity inefficient
consumers do not make full use of plants biomass some plants die not every part of the plant is eaten not everything is digested
31
why is net secondary productivity inefficient
a large amount of the biomass digested in respired as consumer are metabolically active only a small amount of energy contributes to a increase in biomass which can be transferred to the next consumer in the food chain
32
how can humans manipulate secondary productivity
harvesting animals just before adulthood - in adulthood not much energy is dedicated to growth selective breeding for increased growth rate or egg/milk production antibiotic treatment zero grazing keeping temperature constant
33
what are the 4 stages of the nitrogen cycle
ammonification nitrogen fixation nitrification denitrification
34
what bacteria is responsible for nitrogen fixation in free soil
azotobacter
35
what is nitrogen fixation
taking nitrogen gas from the atmosphere and "fixing" it into ammonium ions or nitrate ions
36
what bacteria is responsible for nitrogen fixation in root nodules
rhizobium
37
what plants are nitrogen fixing
legumes e.g. peas, beans and clover
38
how do rhizobium and nitrogen fixing plants have a mutualistic relationship
the bacteria provide the plant with fixed nitrogen and receive carbon compounds such as glucose in return
39
what is leghaemoglobin
protein similar to haemoglobin that is in the root nodules to absorb oxygen keeping the conditions for rhizobium anaerobic to allow for nitrogen fixation
40
what bacteria's are responsible for nitrification
nitrobacter and nitrosomonas
41
what is ammonification
where decomposers break down organic nitrogen compounds e.g. proteins into ammonia or ammonium ions
42
what does nitrosomonas bacteria do
oxidises ammonium ions to nitrites
43
what do nitrobacter bacteria do
oxidise nitrites to nitrates
44
what is nitrification
when bacteria convert ammonium ions or ammonia into nitrites then nitrates
45
what is denitrification
when bacteria convert nitrates back into nitrogen gas
46
what do animals, plants and microorganisms contribute to the carbon cycle
as they respire they release carbon dioxide microorganisms decompose organic waster
47
what do plant contribute to the carbon cycle
terrestrial plants use gaseous carbon dioxide in photosynthesis aquatic plants use dissolved carbonates
48
how is carbon exchanged between the air and water
carbon dioxide dissolves in water and forms carbonic acid weathering of limestone and chalk provides releases hydrogen carbonate into rivers
49
how do fossil fuels contribute to the carbon cycle
combustion of fossil fuels increases the amount of atmospheric carbon dioxide
50
what is succession
progressive change in a community of organisms over time
51
what is a pioneer species
the species that begin begin the process of succession often colonising an area as the first thing living there
52
what is a climax community
the final stable community that exists after the process of succession has occurred
53
what is primary succession
the development of a community from bare ground
54
what is the pioneer species in sand dunes and what do they do
sea rocket tolerates salt, lack of fresh water and unstable sand sand builds up around their base forming mini sand dunes and nutrients from dead and decaying plants enter the sand allowing for bigger plants to colonise
55
example of what species can colonise after sea rocket and what they do
sea couch grass has underground stems to stabilise the sand marram grass shoots trap wind blown sand nutrients build up as more plants colonise
56
example of leguminous plants which can colonise sand dunes after sea couch grass and marram grass
hares foot clover convert nitrogen to nitrate allowing more species to colonise and further stabilise the dune until a climax community is reached
57
what is deflected succession
when succession is stopped or interfered with so often does not reach a climax community
58
example of how deflected succession can occur
mowing grass grazing application of fertiliser or herbicide
59
what do deflected succession communities reach instead of a climax community
plagioclimax
60
what is sampling
selecting small portions of a habitat and studying them carefully to try and get an accurate estimate of the number of individuals of every species in a habitat
61
what is distribution of a species
presence or absence of a species
62
what is abundance of a species
number of individuals of each species
63
how can distribution and abundance be measured
quadrats
64
how to calculate population size of a species from a quadrat
mean number of individuals of the species in each quadrat / fraction of the total habitat area covered by a single quadrat
65
what is a transect
a line taken across a habitat
66
what is a transect used for
looking at changes in vegetation across a habitat
67
what are the two types of transect
line transect belt transect

Biology (25 decks)

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