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Biology > Ecosystems > Flashcards

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
Q

What tends to happen to biomass as you move up the pyramid?

A

It usually decreases

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26
Q

What is ecological efficiency?

A

The efficiency in which biomass is transferred through trophic levels

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27
Q

Producers only convert 1-3% of sunlight into biomass, why? [3]

A
  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
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28
Q

What is the calculation of energy transferred to the next trophic level?

A

Net production = gross production - respiratory loss

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29
Q

Consumers at each trophic level convert around 10% of the biomass in their food.
Why? [3]

A
  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
Q

How do we calculate ecological efficiency of the energy transfer between trophic levels?

A

Ecological efficiency = energy after transfer / X100 energy before transfer

31
Q

How are food chains affected by agriculture?

A

They become very simple as competition and predators are removed

Producer > primary consumer > secondary consumer
Animal feed > cow > human

32
Q

What does the simplified agricultural food chain mean?

A

Minimum energy is lost and as much energy as possible is transferred for humans to eat

33
Q

What are the main decomposers?

A

Fungi and bacteria

34
Q

What is a saprotroph?

A

An organism obtaining their energy from dead waste material e.g a decomposer

35
Q

What is a detrtivore?

A

An organism that speed up decay by feeding on dead and decaying material e.g wood lice

36
Q

What are two forms of nitrogen fixing bacteria?

A

Azotobacter (free in soil) and rhizobium (inside root nodules)

37
Q

What is nitrogen fixation?

A

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
Q

What are root nodules?

A

Growths that grow in leguminous plants

39
Q

How does rhizobium bacteria have a symbiotic mutualistic relationship with the plant?

A

Both organisms benefit:
- plant gains amino acids from Rhizobium
- bacteria gain carbohydrates from plants to use as an energy source

40
Q

What is nitrification?

A

The process in which ammonium compounds in the soil are converted into nitrogen containing molecules that be used by plants

41
Q

What type of reaction is nitrification, and therefore what conditions are needed?

A

It is an oxidation reaction so soil needs to be aerated

42
Q

What are the 2 stages of nitrification?

A
  1. Nitrosomas oxidise ammonium compounds to nitrites NO2-
  2. Nitrobacter oxidises nitrites into nitrates NO3-
43
Q

What is denitrification and what conditions are needed?

A

Denitrification is the conversion of nitrates back to nitrogen gas

This only happens in anaerobic conditions

44
Q

How do atmospheric levels of carbon dioxide fluctuate?

A

Levels are higher at night than in the day as plants do not photosynthesise at night but still respire

45
Q

How do carbon dioxide levels fluctuate seasonally?

A

As days are longer and photosynthesis rates are higher in summer carbon dioxide levels will be lower

46
Q

Why have global atmospheric carbon dioxide levels increase in the last 200 years?

A
  1. Combustion of fossil fuels
  2. Deforestation
47
Q

How does the atmospheric temperature affect the absorption of carbon dioxide in the ocean?

A

The higher the temperature of water the less gas can dissolve

48
Q

what us succession?

A

The process by which ecosystems change over time

49
Q

What is primary succession?

A

This occurs on a newly formed area of of land, no soil or organic matter present

50
Q

What is secondary succession?

A

Occurs on an area of land where soil is present but no animal o plant species
E.g after a forest fire

51
Q

When does primary succession occur?

A
  1. Volcanoes erupt
  2. Sand is deposited to make new dunes
  3. Mud is deposited at river estuaries
  4. Glaciers retreating
52
Q

What is each stage of succession known as?

A

Seral stage

53
Q

What are the main 3 stages of succession?

A
  1. Pioneer community
  2. Intermediate community
  3. Climax community
54
Q

What is a pioneer species?

A

The species that colonise an inhospitable environment

55
Q

What are the adaptations of pioneer species?

A
  1. Produce large quantities of seeds or spores
  2. Germinate rapidly
  3. Photosynthesise
  4. Tolerance to environment
  5. Can fix nitrogen form environment
56
Q

What is humus?

A

Organic component of soil

57
Q

What is a climax community?

A

The stable community that will show little change over time

58
Q

Why is biodiversity levels higher in the intermediate stage than the climax stage of succession?

A

Dominant species will out compete other species

59
Q

What is plagioclimax?

A

When succession is stopped artificially (usually by humans)

60
Q

Why does agriculture cause deflected succession?

A
  1. Grazing and trampling of vegetation 2. Removing vegetation to plant crops 3. Burning to clear Forrest’s
61
Q

What is distribution of organisms? And what is it like in an ecosystem?

A

Distribution of organism is where organisms are fond within an ecosystem They are usually uneven

62
Q

Where are organisms usually found within an ecosystem?

A

Where abiotic and biotic factors favour their survival

63
Q

Why may abundance of organism fluctuate?

A

Immigration and birth will increase individual numbers and emigration and death will decrease individual numbers

64
Q

What is abundance of organisms?

A

The number of individuals of a species present in an area at a given time

65
Q

What is used to measure distribution of organisms in an environment?

A

Line or belt transect

66
Q

What is the calculation for measuring plant abundance?

A

Estimated population (m2)= number of individuals in sample / area of sample

67
Q

How do we measure abundance of plants?

A

Using random placement of quadrants in an area

68
Q

What technique is used to measure animal abundance?

A

Capture, mark, release, recapture

69
Q

What is the calculation for Animal abundance?

A

Estimated population = individuals in first sample x individuals in second sample / number of recaptured marked individuals

70
Q

What Do we use to calculate biodiversity in a habitat?

A

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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