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bio component 1 > populations and energy flow > Flashcards

populations and energy flow Flashcards

1
Q

what happens during the ‘lag phase’?

A

period of adaption to environment/time to reach sexual maturity

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2
Q

what happens during the ‘log phase’?

A

no.s increase exponentially as there are no limiting factors (reproductive rate>death rate)

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3
Q

what happens during the ‘stationary phase’?

A

carrying capacity is reached- pop. will fluctuate due to environmental changes and availability of resources (reproductive=death)

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4
Q

what happens during the ‘death phase’?

A

factors reducing pop. growth become more significant (death>reproductive)- cause pop. CRASH

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5
Q

define ‘carrying capacity’

A

the maximum population size that can be sustained over a period of time

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6
Q

define ‘species’

A

a group of organisms which can interbreed to produce fertile offspring

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7
Q

define ‘population’

A

the total no. of organisms of a single species occupying a particular area

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8
Q

define ‘ecosystem’

A

a characteristic community of interdependent species interacting with the abiotic components of their habitat (are dynamic- constantly changing in size)

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9
Q

what is meant by a ‘biotic factor’?
(factor being a feature that restricts population growth)

A

a part of the environment of an organism that is living (eg. pathogens/ predators)

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10
Q

what is meant by a ‘abiotic factor’?

A

a part of the environment of an organism that is non-living (eg. temp, oxygen availability)

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11
Q

what things cause environmental resistance?

A
  • competition for food and space
  • predation
  • parasitism
  • disease
  • accumulation of toxic waste
  • climate
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12
Q

what are the two types of factors that reduce population?

A

density DEPENDENT (biotic): pop. size increases, effect of factor increases- leads to slow down of pop. growth

density INDEPENDENT (abiotic): pop. size has no effect on factors so all members equally affected- can lead to pop. crash

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13
Q

what are the possible reasons for population fluctuation?

A
  • changes in light intensity/temp (due to time of year)
  • shortage of nutrients due to exceeding carrying capacity (effect of densitiy dependent factor increases, mortality increases)
  • once pop. falls below certain point, environmental resistance relieved
  • lack of natural predators/disease
  • build-up of toxic by-products
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14
Q

what are the two types of competition?

A
  • inTRAspecific: competition between individuals of SAME species (limits pop. size- natural selection)
  • inTERspecific: competition between individuals of DIFFERENT species
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15
Q

what practical is carried out to measure plant abundance?

A
  • use random no. generator to select random co-ordinates in a 10x10 area
  • put quadrat down at co-ordinate
  • count no.s of different species in area (how many squares contain it)
  • calculate % cover
    LIMITATIONS: small sample area, mis-identification of species
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16
Q

what practical is carried out to measure animal abundance?

A
  • kick sampling (use simpson’s diversity index to calculate)
    LIMITATIONS: organisms may not dislodge from bed, invertebrate’s too small so escape through mesh)
  • capture-mark-recapture (then count how many marked from before in now sample)
    LIMITATIONS: difficult to identify all species as similar-looking
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17
Q

what practical is carried out to measure distribution?

A
  • line transect
  • lay out line of tape across area, place quadrat at regular intervals of distance
  • count no./% cover of specific plant in each quadrat
  • draw kite diagram
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18
Q

why does not all light that lands on producer get absorbed?

A

light can reflect off plant/ transmit through or is absorbed by non-photosynthetic parts

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19
Q

why is energy lost between producers and primary consumers?

A

cellulose may not be able to be digested, not all of plant is eaten

20
Q

why is energy lost between primary and secondary consumers?

A
  • energy used in respiration (needed for synthesis of ATP, muscle contraction, temp regulation)
  • lost as urea
  • not all animal can be eaten (eg. bones) - some present in faeces
21
Q

what do food chains not show?

A
  • all the species at each trophic level (leads to calculated efficiency of energy transfer being low)
  • decomposers/denitrivores which are often a greater biomass
  • omnivores/organisms feeding at several levels
22
Q

what is meant by photosynthetic efficiency?

A

a measure of how well a plant is able to catch light energy
GPP/light energy falling on plant x 100

23
Q

what is meant by GPP?

A

Gross Primary Productivity
-rate of production of chemical energy in organic molecules by photosynthesis in a given area

24
Q

what is meant by NPP?

A

Net Primary Production
- the chemical energy available to primary consumers in an ecosystem

25
Q

what is the equation that links GPP and NPP?

A

NPP= GPP-R (energy used by plant in respiration)

26
Q

why are herbivores less efficient than carnivores in energy transfer?

A
  • cellulose (and lignin) is more difficult to digest than protein
  • much more energy used in digestion of it
  • much more energy left in faeces of herbivore
27
Q

what do pyramids of numbers show?

A
  • no. organisms at each level (producer at bottom)
  • doesn’t take size into account (can be inverted)
28
Q

what do pyramids of biomass show?

A
  • show total weight of organisms
  • slightly more accurate
  • however difficult to measure as many organisms contain biomass that will not transfer to next trophic level)
  • doesn’t take lifespan into account
29
Q

what do pyramids of energy show?

A

amount of energy (eg. in J) transferred from one level to the next

30
Q

define ‘succession’

A

the change in structure and composition of species in a community over time

31
Q

what is ‘primary succession’?

A

succession in a habitat that has never before been colonised

32
Q

what is ‘secondary succession’?

A

the re-introduction of organisms into a habitat that was previously occupied by plants/animals before being destroyed/disturbed

33
Q

what are the different stages in a succession called?

A

seral stages

34
Q

what is meant by a ‘pioneer species’?

A

the first plants to grow in a new habitat (often highly adapted to harsh environment- xerophytes- and are nitrogen-fixing)

35
Q

what is meant by ‘climax community’?

A

the final, stable collection of plants and animals that succession produces and are the best adapted to those conditions

36
Q

why may the climax community have less biodiversity than the pioneer species?

A

the environment is dominated by a specific collection of species

37
Q

what occurs in the environment as succession occurs?

A
  • biomass increases: more soil allows bigger plants to grow
  • soil depth increases: plants die and create humus (dead accumulated plant matter)
  • soil nutrient and water content increases: increased depth means soil can hold onto more
  • biodiversity increases: more niches (roles of an organism in an ecosystem)
38
Q

what are the differences between primary and secondary succession?

A
  • p: surface is bare, s: soil is present
  • p: takes longer time to reach climax community (soil has to be created), s: quicker to reach
39
Q

what do the terms 1. ‘mutualism’ and 2. ‘commensalism’ mean?

A
  1. an interaction between organisms of two species from which both derive benefit
  2. an interaction between organisms of two species from which one benefits but the other is not affected
40
Q

what are the effects of human activity on the greenhouse effect, leading to the enhanced greenhouse effect?

A
  • cattle produce methane by belching
  • CFC’s in aerosol propellants/ coolants in fridges
  • deforestation/ combustion of fossil fuels releases CO2/ less trees taking it in (contributes to climate change)
41
Q

explain the greenhouse effect

A
  • radiation from sun reaches earth, some reflected back by atmosphere or is re-emitted back into space after hitting earth, and some is absorbed
  • reflected/re-emitted is then absorbed by insulating layer of greenhouse gases
  • this traps the heat in between the layer and earth
  • contributes to global warming
42
Q

what are the effects of global warming?

A
  • melting polar ice-> sea level rise-> coastal erosion and flooding OR desertification
  • increase in temp/ extreme weather events-> habitat changes-> migration/extinction
  • CO2 dissolves in ocean-> ocean acidification-> interferes with coral reefs and enzyme reaction in aquatic organisms
  • crop yield reductions-> farmers may need to move
43
Q

describe and explain the process of eutrophication

A
  • soluble nitrates (from use of nitrogen-rich fertiliser in farming) wash into water from fields
  • NO3- is leached from soil
  • causes an algal bloom due to excess nutrients in water
  • algae use up all nutrients and die, blocking light from penetrating water (plants can’t photosynthesise so die)
  • decomposed by saprotrophic bacteria which uses up all oxygen
  • more animals/plants die from lack of oxygen, causing a decrease in biodiversity
44
Q

which bacteria has a symbiotic relationship with the root nodules of leguminous plants?

A

rhizobium

45
Q

which bacteria is free-living in the soil?

A

azotobacter

46
Q

which bacteria is present during nitrification? (in order)

A

nitrosomonas, nitrobacter

47
Q

which bacteria is present during denitrification?

A

pseudomonas

bio component 1 (5 decks)

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