6.3.1: Ecosystems Flashcards

(63 cards)

1
Q

Ecosystem

A

Any group of living organisms and non-living things occurring together, and the interrelationships between them.

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2
Q

Ecosystems are affected by what?

A

Biotic and abiotic factors

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3
Q

Abiotic factors

A

non-living components e.g. pH, temperature, soil type

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4
Q

Biotic factors

A

living components e.g. food supply, predation and disease

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5
Q

Habitat

A

the place where an organism lives

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6
Q

Population

A

all organisms of 1 species living in the same place at the same time, can breed together.

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7
Q

Community

A

All populations of species living in the same place at the same time and can interact together

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8
Q

Niche

A

role each species plays in an ecosystem e.g. through feeding, excretion and reproduction etc. No two species can occupy exactly the same niche.

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9
Q

Why do diagrams of biomass give a pyramid shape?

A

1) Not all of the previous trophic level is eaten
2) Some parts not digested so not all absorbed
3) Small fraction of materials end up as new cells in the next organisms (this happens at each trophic level)

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10
Q

Limits of a pyramid of energy

A

It is a snapshot of an ecosystem at 1 moment in time (ecosystems are dynamic)
Population sizes can fluctuate over time

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11
Q

How is the energy in an organism calculated?

A

Dry weight organism
Burn organism in calorimeter
Change in temp. of water –> work out from this energy released per gram

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12
Q

Ecological efficiency (definition)

A

the efficiency with which biomass or energy is transferred from one trophic level to the next

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13
Q

Ecological efficiency (formula)

A

(energy or biomass available after transfer / energy or biomass available before transfer ) x 100

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14
Q

Edaphic factors

A

soil factors, e.g. type of soil, particle size, drainage

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15
Q

Gross (primary) production

A

the rate at which a plant converts light energy into chemical energy

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16
Q

Denitrification

A

the conversion of nitrate ions into nitrogen gas

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17
Q

the conversion of nitrate ions into nitrogen gas

A

Denitrification

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18
Q

A bacterium that fixes nitrogen

A

Rhizobium

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19
Q

The conversion of ammonium ions into nitrite ions

A

Nitrification

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20
Q

Nitrification

A

The conversion of ammonium ions into nitrite/nitrate ions

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21
Q

Bacterium that carries out denitrification

A

Clostridium

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22
Q

Bacterium that carries out nitrification

A

Nitrosomonas, Nitrobacter

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23
Q

Clostridium

A

Bacterium that carries out denitrification

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24
Q

Nitrosomonas, Nitrobacter

A

Bacterium that carries out nitrification

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25
Denitrifcation requires
anaerobic conditions
26
Nitrogen fixing (often) requires
anaerobic conditons so the enzyme nitrogen reductase can work
27
Ammonification
conversion of nitrogen compounds in dead organic matter or waste into ammonium compounds by decomposers.
28
What do plants need nitrogen for?
DNA, RNA, amino acids, ATP, protein synthesis
29
% of nitrogen in the air?
71%
30
Why can't plants use nitrogen gas?
It is insoluble; cannot be absorbed
31
What is the main point of/why do we care about the nitrogen cycle?
To create nitrate ions --> the form of nitrogen that plants can absorb
32
Nitrate ions =
NO3-
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Example of free-living (nitrogen-fixing) bacteria
Azobacter
34
Nitrogen fixing bacteria that lives in root nodules
Rhizobium
35
What gases do denitrifying bacteria release?
nitrogen and nitrous oxide
36
What does nitrogen reductase do?
Catalyses the breakdown of N-N triple bond, adding 3 H atoms to each N
37
Succession
Directional changes in the species of organisms living in a community that occur over time due to changes in the environment.
38
Types of succession
Primary | Secondary
39
What is primary succession?
Development of a community from bare ground Pioneer community colonise first e.g. algae and lichen on bare rock Build up of dead organisms and rock erosion forms soil for large plants e.g. mosses
40
What is secondary succession?
Development of a community on previously colonised but disturbed/damaged habitat (e.g. after forest fire) Soil is present but there are no plant/animal species
41
Different communities (stages)
Pioneer community --> Intermediate community --> climax community
42
Plagioclimax
the final stage that is formed when succession is halted artificially (i.e. when humans prevent the ecosystem from reaching a climax community) e.g. clearing scrubland to grow crops, burning for deforestation
43
Features of a pioneer community
Low species biodiversity Instability Small
44
Carrying capacity
the maximum population size that can be maintained over a period of time in a particular habitat
45
Different phases of population growth
1: lag phase 2: log phase 3: stationary phase
46
When do limiting factors have the most effect?
As population size gets closer to carrying capacity
47
Density independent factors
Affect populations equally regardless of size | e.g. earthquakes, volcanoes, fires, storms
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Density dependent factors
Affect populations differently according to size | e.g. disease spreads quicker in more dense populations
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Conservation
maintenance of biodiversity through human action or management e.g. controlled grazing, sustainable timber Can use resources but not beyond the point of recovery
50
Preservation
completely halting human activity (in an effort to preserve an area) e.g. building a fence around it
51
Reclamation
restoring ecosystems that have been damaged or destroyed. | Can include use of controlled burning of forest which can stop succession and increase biodiversity
52
Economic reasons for conservation
``` Ecosystems conduct valuable processes: • Nutrient cycling • Cleaning water • Providing an atmosphere/cleaning the air • Provision of food • Provision of building materials ```
53
Social reasons for conservation
Ecosystems provide pleasant environments that can have mental and physical health benefits
54
Ethical reasons for conservation
* All organisms have a right to exist * Humans have been responsible for destructive of habitats/hunting of species to extinction --> now have a duty of care to preserve ecosystems * Moral responsibility to future generations
55
Conservation - how?
• Legal protection to endangered species • Zoos/botanic gardens (ex situ conservation) • Manage ecosystems ⟶ Raise carrying capacity by providing food for some species ⟶ Control poachers and predators ⟶ Prevent pollution ⟶ Restrict succession by coppicing/grazing ⟶ Eradicate unwanted species that have been introduced ⟶ National Parks, green belts, SSSIs
56
Sustainability
Resources are exploited in a way that means they won't run out and will be available for future generations
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Aims of sustainability
* Conserve environment * Ensure resources are available fo future generations * Allow people to live comfortably * Allow LEDCs to develop through exploitation of their natural resources
58
Population size of species (Lincoln index)
No. of individuals in 1st sample x no. individuals in second sample / number recaptured marked individuals
59
Main principles of ecotourism
Balancing human needs with the needs of the ecosystem Type of sustainable development No exploitations Consultation with local people Infrastructure must be available for use by local people as well as tourists
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Why to conserve/preserve peat bogs?
Biodiversity Erosion control Carbon storage Flood management
61
Human activites that lead to destruction of peat bogs
Afforestation Peat extraction Agricultural intensification Pollution--> acid rain (kills moss, peat underneath washed away)
62
How to conserve peat bogs?
Removal of seedlings from an area Use of controlled grazing Ensure peat and vegetation of bog as undisturbed as possible
63
Nitrogen fixing
conversion of atmospheric nitrogen gas into ammonium ions