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YEAR 2 BIO > population size and ecosystems > Flashcards

population size and ecosystems Flashcards

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Biology 101 flashcards
1
Q

define ecology

A

study of the ecosystem

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2
Q

define ecosystem

A

a definable area with its own community of organisms and physical environment, all interacting as a relatively self sustaining unit

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3
Q

define community

A

all the populations of all the species that live together in a particular ecosystem

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4
Q

define habitat

A

the part of an ecosystem in which particular organisms live

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5
Q

define population

A

all the interbreeding organism of one species living in a particular habitat at the same time

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6
Q

define environment

A

term used for surroundings. term for the external conditions affecting the existence of organisms

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7
Q

define biotic factor

A

effects of the activities of living organisms on other organisms e.g. food availability

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8
Q

define abiotic factors

A

non living, physical conditions in an ecosystem e.g. temp,light,soil

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9
Q

define niche

A

how it feeds and where it lives

the role that each species plays in an ecosystem

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10
Q

what is the carrying capacity

A

as a population increases it begins to experience environmental resistance as space and resources are reduced and so competition increases
population stabilised at a level which ecologists call the carrying capacity

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11
Q

what is the lag phase

A

little or no pop growth. period of adaptation for preparation for breeding

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12
Q

what is the log phase

A

exponential growth. a period of no constraint on pop growth with adequate supplies

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13
Q

what is the linear phase

A

a decelerating phase when growth rates become limited

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14
Q

what is the stationary phase

A

the population size is maintained at a constant level

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15
Q

what are some factors affecting population

A
  • immigration
  • emigration
  • variation in birth or death rate
  • sudden physical or chemical environment change
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16
Q

when will a population increase

A

when birth and immigrants > death and emigrants

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17
Q

what are density dependant factors

A

factors that increase as the size of population increases = biotic factors

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18
Q

what are density independent factors

A

unrelated to the size of the population = abiotic factor

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19
Q

describe a brine shrimp ecosystem

A 
algae - for photosynthesis 
brine shrimp - for respiration 
competition for space 
competition for resources 
mineral in sand
reproduction 
competition for a mate
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20
Q

what does a food chain show

A

how energy is transferred from one living organism to another

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21
Q

what is a trophic level

A

the level at which an organism feeds

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22
Q

what is energy transfer measured in

A

KJ m^-2 year

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23
Q

how is energy lost

A

lost from each trophic level as heat and some remains stored in dead organisms

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24
Q

what does a pyramid of biomass show

A

area of bars is proportional to the dry mass of all organisms at the level but different organisms may release difference amounts of energy per unit mass

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25
Q

what is a pyramid of energy

A

burning the organisms to measure calories and work out heat energy release per unit mass

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26
Q

what is photosynthetic efficiency

A

measure of the ability of a plant to trap light energy

27
Q

how can light energy be lost and what %

A

due to reflection conversion inefficiencies

20-40% exuded into soil to feed the microbes

28
Q

what is gross primary productivity

A

the rate at which plants convert light energy into chemical energy
as energy is lost when the plant respires, less energy is available to the primary consumer
the energy remaining is called the net primary productivity (NPP)

29
Q

how much GPP is lost to respiration

A

60%

30
Q

how much GPP is used for growth and respiration (NPP)

A

40%

31
Q

what do consumers have a conversion efficiency of

A

10%

32
Q

how can energy transfer between each trophic level be calculated

A

(energy available after transfer)/(energy available before transfer) X 100

33
Q

why does life require nitrogen

A

protein and nucleic acids

34
Q

what is the major reservoir of nitrogen

A

79% in the air (inert in this form )

35
Q

how must plants reserve nitrogen and where do they get it from

A

in a fixed form
nitrate ions (NO3^2-)
ammonia (NH3)
ammonium (NH4+)

36
Q

where do animals get nitrogen from

A

plants

they digest absorb and assimilate different forms of nitrogen from their food

37
Q

what four biological processes participate in the cycling of nitrogen

A
  • nitrogen fixation
  • decomposition
  • nitrification
  • denitrification
38
Q

what is nitrogen fixation

A

the nitrogen molecule is inert and uses substantial amounts of energy to break it apart
three processes
-biological fixation by certain microbes
-atmospheric fixation by lightning
-industrial fixation by the haber process

39
Q

what is biological fixation

A

-free living bacteria such as AZOTOBACTER
-symbiotic bacteria RHIZOBIUM in root nodules of legumes
contain an enzyme called nitrogenase that converts nitrogen and hydrogen into ammonia -the ammonia is used to make amino acids which the legume can use to make proteins in return for supplying the bacteria with carbs

40
Q

what is decomposition

A

the proteins made by plants enter and pass through food webs just as carbs do
at each trophic level their metabolism produces organic nitrogen compounds that return to the environment chiefly in excretions
the final beneficiaries of these materials are microorganisms of decay
they break down the molecules in excretions and dead organisms into ammonia

41
Q

what is nitrification

A

ammonia can be taken up directly by plants usually through their roots
most of the ammonia produced by decay is converted into nitrates
1) bacteria of the genus NITROSOMONAS oxidise NH3 to nitrites N02-
OR
2)nitrobacter oxidise the nitrites to nitrates (NO3-)

42
Q

what is denitrification

A

reduced nitrates to nitrogen gas, replenishes the atmosphere and closes the nitrogen cycle
bacteria =PSEUDOMONAS live deep in soil and in aquatic sediments where conditions are anaerobic
use nitrates instead of 02 for final electron acceptor

43
Q

why do we need fertilisers

A

contain nitrogen nd other mineral ions - obtain from the soil, if farming is intensive then minerals are lost from the soil
nitrogen and mineral ions increase growth and yield

44
Q

what are the different types of fertilisers

A

NATURAL - dead and decaying plants
ARTIFICIAL - mined from rocks and blended to give the right mix of nutrients
NPK - nitrogen, phosphorous and potassium

45
Q

what are the consequences of using fertilisers

A

reduced species diversity - NPK fertilisers favour the growth of grass and nettle species
leaching - excess nitrogen in soil due to excess fertilisers and causes leaching in rivers
eutrophication - excess fertilisers in lakes cause increase in algae and decreases the amount of sunlight

46
Q

advantages of organic fertilisers

A 
steady supply go nutrients 
contain macro and micro nutrients 
add structure to soil 
use for disposing farm waste 
nutrients not readily leached from soil l
47
Q

disadvantages of organic fertilisers

A

offensive smells
difficulty spreading
mineral release low

48
Q

advantages of inorganic fertilisers

A 
nutrients in concentrated form 
can be in smaller amounts 
nutrients released rapidly 
easy to apply 
clean chemicals lack odour
49
Q

disadvantages of inorganic fertilisers

A

readily leached
increased eutrophication
expensive
risk of spreading to other areas

50
Q

what happens during eutrophication

A 
plants and animals die 
saprotrophs secrete hydrolytic enzymes 
enzymes digest organic molecules 
saprotrophs absorb amino acids and sugars 
sugars are respired for energy and release co2 into the atmosphere 
amino acids used for growth 
excess amino acids are respired 
carbon is returned to the carbon cycle
51
Q

what is succession

A

gradual change in species at a defined location over time

52
Q

what happens to a community during succession

A

constantly changing and dynamic unit which passes through a number of stages from its origin to its climax
the transition from one stage to the next is called succession

53
Q

what is primary succession

A

plants grow where no plants have grown before

54
Q

what is secondary succession

A

plants grow where there has been a previous population. these will have been destroyed

55
Q

what are pioneer species

A

the first species to colonise

often opportunistic species which are able to rapidly exploit a sudden new opening in ground plant cover

56
Q

what is the climax community

A

the ultimate species to colonise

57
Q

what is bare rock succession

A

weathering will start to erode the rock forming crevices and breaking down mineral particles
no plant competition
soil mobile and liable to erosion

58
Q

what is a sere

A

the sequence of communities with the different species and structures

59
Q

what is a xerosere

A

a sere in a dry environment

60
Q

what is global warming

A

he increase of average global temp in excess of the greenhouse gas effect caused by the atmospheres conc of co2

61
Q

what causes an increase in co2

A

= burning fossil fuels

=deforestation

62
Q

what is the greenhouse effect

A

carbon dioxide, methane, nitrous oxides, cdc’s, ozone and water vapour
allow high energy short wave length solar radiation to pass through earths surface
re-emits lower energy longer wavelength infrared radiation
so the surface warms up

63
Q

what is global warming caused by

A

high concentrations of greenhouse gases

64
Q

consequences of global warming

A 
melting polar ice 
increased frequency of extreme weather 
increased forest fires 
decrease in availability of water 
world food production may decrease 
increase in  CO2 in oceans will decrease pH which threatens organisms.

YEAR 2 BIO (11 decks)

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