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Biology Hope > Ecosystems > Flashcards

Ecosystems Flashcards

1
Q

what is an ecosystem

A
  • all organisms living in a certain area
  • dynamic system
  • self-contained community of interacting organisms and the environment they live/interact in
  • flow of energy + nutrients
  • abiotic and biotic factors
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2
Q

what are biotic factors

A
  • living features of the environment
  • predators, competition, disease, mankind
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3
Q

what are abiotic factors

A
  • non living features
  • water, light, temperature, humidity
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4
Q

what are the impact of factors on rock pools

A

Biotic
- seaweed acts as a food source for consumers
- intense competition for food can limit no. organisms present

Abiotic
- influenced by tides
- hight tide = submerged by ocean
- low tide = extreme conditions

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5
Q

what are the impact of factors on a playing field

A

Biotic
- producers attract organisms to use them as a food source

Abiotic
- rainfall / sunlight affect growth
- very wet = waterlogged soil
- poor plant growth = decrease number of consumers the ecosystem can support

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6
Q

what are edaphic factors

A
  • soil factors
  • provides minerals for growth
  • water for photosynthesis
  • anchorage for roots
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7
Q

what is biomass

A
  • mass living material of the organism or tissue
  • chemical energy stored within
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8
Q

how to measure biomass

A
  • dry mass
  • mass of carbon it contains
  • chemical energy content of the organism when burned in pure energy
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9
Q

what is dry mass

A
  • mass of an organism/ tissue after all water had been removed
  • used to calculate the total biomass of a total population of organisms
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10
Q

what is calorimetry

A
  • estimate chemical energy stored in biomass
  • burning sample of dry biomass in a piece of equipment
  • burning sample heats a known volume of water
  • change in temperature of water provides an estimate of chemical energy
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11
Q

how is energy transferred through an ecosystem

A
  • energy enters through photosynthesis
  • primary producers convert light energy to chemical energy
  • storing the chemical energy as plant biomass makes a certain amount of energy available to the next trophic level
  • energy transfers through trophic levels
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12
Q

where does the energy go

A
  • 60% of available energy not taken in
  • plants cannot use all light energy that reaches the leaves
  • some light hits bark

40% absorbed
- 30% lost to the environment
- 10% becomes biomass

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13
Q

how do human activities increase the transfer of energy

A
  • herbicides kill weeds - reduce competition means crops receive more energy
  • fungicides kill fungal infections that damage agriculture - crops use more energy for growth
  • fertilisers provide crops with minerals needed for growth
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14
Q

what are saprobionts

A
  • decompose waste and dead matter via extracellular digestion
  • inorganic ions available to other organisms
  • ammonification
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15
Q

what is nitrogen fixing bacteria

A
  • convert atmospheric nitrogen gas into nitrogen containing compounds
  • forms ammounium ions in soil
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16
Q

what is nitrifying bacteria

A
  • convert ammonium ions in the soil to nitrogen compounds that can be used by plants
  • convert ammonium ions into nitrites
17
Q

what is denitrifying bacteria

A
  • uses nitrates during respiration
  • release nitrogen gas
18
Q

what is mycorrhizal fungi

A
  • increase surface area of root systems
  • help plats absorb water and scarce mineral ions from soil
19
Q

what are the stages of the nitrogen cycle

A
  • nitrogen fixation
  • ammonification
  • nitrification
  • denitrification
20
Q

what is the process of nitrogen fixation

A
  • nitrogen gas in the atmosphre is turned into ammonia by bacteria
  • ammonia used by plants
  • Rhizobium found inside root nodules and form a mutualistic relationship with plants - provide plant with nitrogen compounds
21
Q

what is the process of ammonification

A
  • nitrogen compounds from dead organisms are turned into ammonia by decomposers to form ammonium ions
  • animal waste contains nitrogen compounds
22
Q

what is the process of nitrification

A
  • ammonium ions in the soil are changed into nitrogen compounds then used by plants (nitrates)
  • nitrifying bacteria (Nitrosomonas) change ammonium ions into nitrites
  • Nitrobacter change nitrites into nitrates
23
Q

what is the process of denitrification

A
  • nitrates in soil converted into nitrogen gas by denitrifying bacteria
  • use nitrates in the soil to carry out respiration and produce nitrogen gas
24
Q

what is the process of the carbon cycle

A
  • carbon is absorbed by plants when they carry out photosynthesis
  • carbon passed on to primary consumers
  • eat plants and passed to secondary
  • carbon compounds in dead organisms are digested by microorganisms called decomposers
  • carbon is returned to the air for respiration
25
Q

what is succession

A
  • process by which an ecosystem changes over time

Primary = happens on newly exposed land

Secondary = happens on land cleared of all plants

26
Q

what are the stages of succession

A
  • pioneer species colonise a new land surface
  • harsh abiotic conditions
  • pioneer species change abiotic conditions - die and microorganisms decompose the dead organic material
  • basic soil formed
  • conditions less hostile
  • as succession goes on the ecosystem becomes more complex
  • new species move alongside existing species
  • biomass increases
27
Q

what is a climax community

A
  • ecosystem supports the largest and most complex community of plants and animals
28
Q

example of primary succession

A
  • pioneer species colonise rocks
  • lichens grow and break down the rocks releasing minerals
  • lichens die and decompose to form a new soil
  • soil thickens as organic material grows
  • larger plants that need more water can move in as soil deepens
  • soil deepens as larger plants die and decompose
  • shrubs and trees grow
29
Q

how can succession be managed

A
  • human activities can prevent effects
  • regularly mown lawn won’t develop woody plants
30
Q

how to manage succession - conservation

A
  • protecting an area from reaching a climax community
  • ecosystems at an intermediate succession stage
  • hold distinct diversity
31
Q

how to prevent succession

A
  • grazing animals introduced temporarily
  • managed burning - controlled fires burn away shrubs and trees to reset succession process

Biology Hope (27 decks)

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