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Ecosystems Flashcards

1
Q

What is ecology?

A

The name given to the study of relationships between organisms and the environment

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2
Q

What is the study of ecology important?

A

So scientists can understand interdependence between living organisms and therefore help the survival of earths biodiversity

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3
Q

What is an ecosystem?

A

The interaction between all the biotic and abiotic element living in a defined area

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4
Q

Ecosystems are dynamic.
What does this mean?

A

They are constantly changing

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5
Q

What are the two factors that affect an ecosystem?

A
  1. Biotic factors (living)
  2. Abiotic factors (non-living)
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6
Q

What do animals compete for?

A
  1. Food
  2. Space
  3. Partners
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7
Q

What are the 3 main types of soil?

A
  1. Clay
  2. Loam
  3. Sandy
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8
Q

What is an edaphic factor?

A

Soil

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9
Q

What are the 5 main abiotic factors affecting an environment?

A
  1. Light
  2. Temperature
  3. Water availability
  4. Oxygen availability
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10
Q

What 2 adaptations do plants have to cope with low light levels?

A
  1. Larger leaves
  2. Photosynthetic pigments requiring less light
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11
Q

What is the source of energy for most ecosystems on earth?

A

The suns light energy

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12
Q

What do food webs and food chains show?

A

The transfer of biomass

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13
Q

What is each stage in a food chain known as?

A

A trophic level

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14
Q

What does the first trophic level always consist of?

A

A producer

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15
Q

What does a producer do?

A

It is an organism that converts light energy into chemical energy by photosynthesis

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16
Q

What are the subsequent levels of a food chain called after the producer?

A

Consumers

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17
Q

What are consumers?

A

Organisms that gain their energy by feeding on other organisms

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18
Q

What is the second trophic level occupied by?

A

A primary consumer - an animal that eats the producer

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19
Q

What is the role of decomposers?

A

They breakdown dead organisms releasing nutrients back into the ecosystem

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20
Q

What does a pyramid of numbers depict?

A

The number of individuals at each trophic level

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21
Q

What is biomass?

A

The mass of living material present in a particular place or in particular organisms

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22
Q

Why is biomass an important measurement in food chains?

A

It can be equated to energy content

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23
Q

How can biomass be presented?

A

Pyramid of biomass

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24
Q

How do scientist calculate the ‘dry mass’ of an organism to calculate biomass?

A

Kill the organic and good at 80 degrees until all water is evaporated

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25
What tends to happen to biomass as you move up the pyramid?
It usually decreases
26
What is ecological efficiency?
The efficiency in which biomass is transferred through trophic levels
27
Producers only convert 1-3% of sunlight into biomass, why? [3]
1. Not all energy can be used in photosynthesis 2. Limiting factors of photosynthesis 3. Energy is lost as it is used for photosynthetic reactions
28
What is the calculation of energy transferred to the next trophic level?
Net production = gross production - respiratory loss
29
Consumers at each trophic level convert around 10% of the biomass in their food. Why? [3]
1. Not all matter is eaten (bones, plant roots) 2. Movement and respiration will cause energy loss 3. Some parts of the organism are indigestable
30
How do we calculate ecological efficiency of the energy transfer between trophic levels?
Ecological efficiency = energy after transfer / X100 energy before transfer
31
How are food chains affected by agriculture?
They become very simple as competition and predators are removed Producer > primary consumer > secondary consumer Animal feed > cow > human
32
What does the simplified agricultural food chain mean?
Minimum energy is lost and as much energy as possible is transferred for humans to eat
33
What are the main decomposers?
Fungi and bacteria
34
What is a saprotroph?
An organism obtaining their energy from dead waste material e.g a decomposer
35
What is a detrtivore?
An organism that speed up decay by feeding on dead and decaying material e.g wood lice
36
What are two forms of nitrogen fixing bacteria?
Azotobacter (free in soil) and rhizobium (inside root nodules)
37
What is nitrogen fixation?
The process in which nitrogen fixing bacteria use the enzyme nitrogenase to combine atmospheric nitrogen N2 with H2 to produce NH3 that can be used by plants
38
What are root nodules?
Growths that grow in leguminous plants
39
How does rhizobium bacteria have a symbiotic mutualistic relationship with the plant?
Both organisms benefit: - plant gains amino acids from Rhizobium - bacteria gain carbohydrates from plants to use as an energy source
40
What is nitrification?
The process in which ammonium compounds in the soil are converted into nitrogen containing molecules that be used by plants
41
What type of reaction is nitrification, and therefore what conditions are needed?
It is an oxidation reaction so soil needs to be aerated
42
What are the 2 stages of nitrification?
1. Nitrosomas oxidise ammonium compounds to nitrites NO2- 2. Nitrobacter oxidises nitrites into nitrates NO3-
43
What is denitrification and what conditions are needed?
Denitrification is the conversion of nitrates back to nitrogen gas This only happens in anaerobic conditions
44
How do atmospheric levels of carbon dioxide fluctuate?
Levels are higher at night than in the day as plants do not photosynthesise at night but still respire
45
How do carbon dioxide levels fluctuate seasonally?
As days are longer and photosynthesis rates are higher in summer carbon dioxide levels will be lower
46
Why have global atmospheric carbon dioxide levels increase in the last 200 years?
1. Combustion of fossil fuels 2. Deforestation
47
How does the atmospheric temperature affect the absorption of carbon dioxide in the ocean?
The higher the temperature of water the less gas can dissolve
48
what us succession?
The process by which ecosystems change over time
49
What is primary succession?
This occurs on a newly formed area of of land, no soil or organic matter present
50
What is secondary succession?
Occurs on an area of land where soil is present but no animal o plant species E.g after a forest fire
51
When does primary succession occur?
1. Volcanoes erupt 2. Sand is deposited to make new dunes 3. Mud is deposited at river estuaries 4. Glaciers retreating
52
What is each stage of succession known as?
Seral stage
53
What are the main 3 stages of succession?
1. Pioneer community 2. Intermediate community 4. Climax community
54
What is a pioneer species?
The species that colonise an inhospitable environment
55
What are the adaptations of pioneer species?
1. Produce large quantities of seeds or spores 2. Germinate rapidly 3. Photosynthesise 4. Tolerance to environment 5. Can fix nitrogen form environment
56
What is humus?
Organic component of soil
57
What is a climax community?
The stable community that will show little change over time
58
Why is biodiversity levels higher in the intermediate stage than the climax stage of succession?
Dominant species will out compete other species
59
What is plagioclimax?
When succession is stopped artificially (usually by humans)
60
Why does agriculture cause deflected succession?
1. Grazing and trampling of vegetation 2. Removing vegetation to plant crops 3. Burning to clear Forrest’s
61
What is distribution of organisms? And what is it like in an ecosystem?
Distribution of organism is where organisms are fond within an ecosystem They are usually uneven
62
Where are organisms usually found within an ecosystem?
Where abiotic and biotic factors favour their survival
63
Why may abundance of organism fluctuate?
Immigration and birth will increase individual numbers and emigration and death will decrease individual numbers
64
What is abundance of organisms?
The number of individuals of a species present in an area at a given time
65
What is used to measure distribution of organisms in an environment?
Line or belt transect
66
What is the calculation for measuring plant abundance?
Estimated population (m2)= number of individuals in sample / area of sample
67
How do we measure abundance of plants?
Using random placement of quadrants in an area
68
What technique is used to measure animal abundance?
Capture, mark, release, recapture
69
What is the calculation for Animal abundance?
Estimated population = individuals in first sample x individuals in second sample / number of recaptured marked individuals
70
What Do we use to calculate biodiversity in a habitat?
Simpsons index of diversity (D) D = 1 - (sum of) (n/N)2 N = total number of organisms in ecosystem, n = total number of species

Biology (26 decks)

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