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Biology > ECOSYSTEM > Flashcards

ECOSYSTEM Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is an ecosystem?

A

the relationship between all living and non-living components of a habitat

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1
Q

what are the component of an ecosystem?

A

Habitat = place where organism lives
Population = all of the organism of one species, who live in the same place at the same time, who can breed together
Community = all the populations of different species, live in the same place at the same time

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2
Q

what are two characteristic of ecosystems?

A

vary in size
very dynamic

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3
Q

what are the 2 groups of factors affecting ecosystem?

A

abiotic and biotic factors

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4
Q

list biotic factors

A

producers
consumer (primary, secondary and tertiary)
decomposers
predation
competition
hunting

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5
Q

list abiotic factors

A

light
temperature
pH

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6
Q

what are 3 types of change in ecosystem that affect population size?

A

cyclic changes - changes repeat themselves in a rhythm (tides), the way in which predator and prey species fluctuate is cyclic

directional changes - changes are not cyclic
unpredictable/erratic changes - have no rhythm and no constant direction

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7
Q

what is biomass?

A

mass of all living materials in an ecosystem

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8
Q

what is the first source of energy in an ecosystem?

A

sunlight.

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9
Q

explain what happens to sunlight?

A

only a small percentage of light (1-3%) is absorbed by plants and used by them. The rest of the sunlight might not be absorbed to to light not hitting the chloroplast or due to wrong wavelength of light which makes it reflect.

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10
Q

what is total amount of energy USED by the plant to make biomass called?

A

gross production

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11
Q

what might be the energy use for in plants?

A

for respiration

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12
Q

what is meant by net production?

A

the remaining energy, the energy that is going to be transferred to the next consumer

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13
Q

how is net production calculated?

A

gross production - respiratory losses

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14
Q

how do consumers get energy?

A

by ingesting producers, however only 10% of th energy is transferred to the consumer as some of the biomass might be digested and released into faeces, urine and respiration, released as heat.
less available at higher trophic levels

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15
Q

what is the formula to calculate ecosystem efficiency?

A

(biomass transferred : biomass intake) x 100
(biomass at higher level : biomass at lower level) x 100
(biomass of primary consumer : biomass of producer) x 100

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16
Q

what makes up the biomass?

A

organic and inorganic components

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17
Q

what is a trophic level?

A

each level in the food chain

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18
Q

what is meant by productivity?

A

the rate at which energy passes through each trophic level in the food chain

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19
Q

what is gross primary productivity ?

A

the rate at which plant convert light energy into chemical energy

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20
Q

how do human manipulate environmental factors to increase the amount of biomass in plants?

A
  • grow plant under light banks and crops planted early to provide longer growing season to harvest more light , thus increasing the rate o photosynthesis and biomass production
  • grow plant in greenhouses which provides warmer temperature increasing photosynthesis rate and biomass production
  • crop rotation can stop the reduction of inorganic materials in soil (nitrate or potassium), thus plant will have more nutrients available to carry out more photosynthesis
  • use of pesticides and fungicides and herbicides to kill insects that may feed on plants removing biomass from food chain
    -competition of weed for light, water and nutrients, reduces crop
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21
Q

how do human manipulate environmental factors to increase the amount of biomass in animals?

A
  • harvesting animal just before adulthood

-selective breeding to produce improved animal

-animals treated with antibiotics to avoid unnecessary loss of energy

  • preventing animals from moving to look for food, food is directly supplied to them and environmental temp is kept constant
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22
Q

why does the carbon cycle occur?

A

because there is a limited availability of carbon, therefore it is recycled

23
Q

describe the carbon cycle.

A

-carbon dioxide present in the atmosphere
-carbon dioxide uptaken by plants
-carbon dioxide is used for photosynthesis
-carbon dioxide is converted into carbon containing compounds = carbon fixation
-carbon dioxide is also released into the atmosphere via respiration
-consumers feed off from producers, therefore the carbon containing compounds are passed on the food chain
-consumers also release carbon dioxide via respiration
-when producers and consumers die, the carbon containing compound remain in their waste matter.
-these waste matters and compound are broken down by decomposers in a process called decomposition , this process releases carbon back in the atmosphere
- the waste matters that are not decomposed become fossil fuels
- when fossil fuels are burnt, via the process of combustion, this releases carbon dioxide into the atmosphere.

24
Q

what is the process of converting nitrogen gas into ammonia called?

A

nitrogen fixation

25
Q

what are the bacteria that carry out nitrogen fixation called? give 2 examples

A

nitrogen-fixing bacteria : Azotobacter (lives freely in the soil) ( nitrogen gas- ammonia - ammonium ions)
rhizobium ( roots nodules) ( nitrogen gas - ammonia)

26
Q

in what condition can nitrogen fixation occur?

A

anaerobic conditions

27
Q

what is the process of converting ammonium ions into nitrate known as? describe the steps

A

denitrification : ammonium ions - nitrite - nitrate

28
Q

by what type of bacterias is nitrification carried out? give example in each step

A

nitrifying bacteria.
ammonium ions into nitrite = nitrosomonas

nitrite into nitrate = nitrobacter

29
Q

what is required for nitrification, why?

A

oxygen - bacteria need oxygen for aerobic respiration to ensure their survival, oxygen used in nitrification

30
Q

how is nitrogen returned to the soil?

A

by death and excretion of plants and animals

31
Q

what happens to dead organisms and excretion containing nitrogen? and what does it result to?

A

broken down by decomposers (saprobionts) , results in ammonia formation

32
Q

what happens to ammonia?

A

released into the soil to make ammonium ions

33
Q

what is ammonification?

A

the process of obtaining nitrogen form the decomposition of dead organism and excretion, producing ammonia which is then converted into ammonium ions

34
Q

how is thereduction of nitrogen gas availability in the atmosphere avoided?

A

by the process of denitrification

35
Q

explain the process of denitrification

A

denitrifying bacteria convert NITRATE into nitrogen gas in anaerobic conditions

36
Q

when can denitrifying bacteria carry out denitrification?

A

when they carrying out anaerobic respiration

37
Q

what processes can occur under anaerobic conditions?

A

nitrogen fixation an denitrification

38
Q

what processes reduce or oxidise nitrogen?

A

nitrogen fixation - reduction
nitrification - oxidation
denitrification - reduction

39
Q

what is succession in ecosystem?

A

when a habitat/ ecosystem changes from simple to complex over time

40
Q

how does succession occur?

A

via seral (intermediate) stages.

41
Q

what is the first stage of seral stages, describe it.

A

PRIMARY SUCCESSION : when there is an inhabited land, which is colonised by an initial species (mousse or lichen - PIONEER SPECIES), usually in the form of seeds or spores
these species are often adapted for colonisation eg tolerant to extreme conditions and reproduce asexually.
-primary succession

42
Q

what do pioneer species cause?

A

change the environment making it less hostile and enabling the survival of other species

43
Q

what is the second stage of seral stages?

A

INTERMEDIATE COMMUNITY : the growth of an intermediate community such herbs and grass, shrubs and trees.
When these intermediate organisms decompose, they release nutrients into the soil making the environment less hostile
secondary succession

44
Q

what is the last stage of seral stages?

A

CLIMAX COMMUNITY - when the environment becomes stable and no more succession occurs,present at the end of primary succession

45
Q

what is meant by deflected succession?

A

when human activities interfere or stop succession, such as agriculture and farming.
the habitat doesn’t reach t eh climax so it is called plagioclimax community.

46
Q

what is primary succession?

A

colonisation of uninhabited terrain over time by a living organism

47
Q

what is secondary succession?

A

recolonisation of an area after earlier community has been removed

48
Q

pioneer species

A

A species that can colonise barren terrain.

49
Q

ways to measure / sample ecosystem

A

using quadrants and transects

50
Q

what can be calculated using quadrants?

A

abundance and distribution of species

51
Q

what should be decided before starting to sample? (quadrants)

A
  • where to place the quadrats : to random sampling , coordinates , systematic sampling at regular distance
  • how many samples to take : take samples from across the habitat, make a cumulative frequency against quadrat number. The point where the curve levels off tell you how many quadrants to use
52
Q

what is the equation to estimate the size of the population of each species in the whole habitat?

A

mean number of individual of the species in each quadrat : fraction of the total habitat area covered by a single quadrat

53
Q

what method of sampling is used to look for changes in abundance and distribution of a species across a habitat?

A

transect

54
Q

what are the 2 approaches of using a transect?

A

line transect =at regular intervals make a note of which species is touching the tape

belt transect = at regular intervals , place a quadrat next the line (interrupted belt transect) , or place a quadrate and move it along the line (continuous belt transect)

Biology (18 decks)

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