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Biology Comp 1 > Population Size And Ecology > Flashcards

Population Size And Ecology Flashcards

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1
Q

What are density dependant factors?

A

factors that INCREASE as pop. density increases.

all BIOTIC factors sow pop. growth eg disease, parasites

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2
Q

What are density independent factors?

A

factors that DO NOT INCREASE as pop. density increases.

effect is same regardless of pop. size as ABIOTIC factors cause pop. crash eg flood, fire

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3
Q

Describe population fluctuations

A

mainly due to BIRTH RATE and DEATH RATE.
hover around set point (above= density dependant increases death rate, below= environmental resistance relieved- death rate decreases)

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4
Q

Define abundance

A

measure of how many individuals exist in a habitat

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5
Q

Two ways to assess animal abundance

A

1) Capture- mark- recapture

2) Kick sampling (streams)

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6
Q

Two ways to assess plant abundance

A

1) quadrat- mean no. of individuals in several quadrats of known area (no/m^20
2) estimate percentage

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7
Q

Define distribution

A

Area or volume individuals are found

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8
Q

One way to measure plant distribution and what does it provide readings for?

A

1) Belt transect (tape through area & quadrat at regular intervals.
readings for: density of chosen species, % freq species, % area cover of species

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9
Q

One way to measure animal distribution

A

1) direct observation

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10
Q

Define species

A

group of organisms that share some characteristics and can interbreed to produce fertile offspring

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11
Q

Define population

A

group of organisms of same species which occupy particular habitat

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12
Q

Define birth-rate

A

no. of new organisms produced by reproduction per unit time

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13
Q

Define immigration

A

movement of population into same species

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14
Q

Define emigration

A

movement of individuals of one species out of population

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15
Q

Define equilibrium species

A

species that control pop. size by competition rather than reproduction or dispersal

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16
Q

factors that control pop size

A

1) energy flowing through ecosystem
2) biological cycles
3) succession
4) emigration
5) immigration
6) birth-rate
7) death-rate
8) new species

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17
Q

Describe the LAG phase

A
  • slow growth
  • time taken to adapt to environment
  • BACTERIA- enzyme synthesis
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18
Q

Describe the LOG (exponential) phase

A
  • birth-rate > death-rate
  • BACTERIA- cell production > cell death
  • rate does not continue to increase rapidly due to environmental resistance
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19
Q

Define environmental resistance

A

All factors that may limit the growth of a population ( BIOTIC OR ABIOTIC)

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20
Q

4 environmental resistance factors of bacteria in a flask

A
  • food availability,
  • overcrowding,
  • intraspecific competition,
  • toxic waste
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21
Q

4 environmental resistance factors of rabbits on a island

A
  • predation
  • parasitism
  • disease
  • intraspecific competition (food, nests)
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22
Q

Describe the STATIONARY phase

A
  • birth-rate = death-rate
  • BACTERIA- cell production = cell death
  • carrying capacity reached- pop. fluctuates around this in response to environmental change
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23
Q

Define carrying capacity

A

Max. pop. size that can be maintained over a period of time by an environment

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24
Q

Describe the DEATH/ DECLINE phase

A
  • environmental resistance slows growth until…
  • birth-rate < death-rate
  • BACTERIA- cell production < cell death
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25
Q

Describe the predator- prey cylcle (fluctuates around carrying capacity because….)

A
  • large no of predator predates prey, prey pop decreases (INCREASE ENVIONMENTAL RESISTANCE FOR PREY)
  • not enough food for predator, pop decreases (INCREASE ENVIONMENTAL RESISTANCE FOR PREDATOR)
  • less predation on prey, pop increases (DECREASE RESISTANCE FOR PREY)
  • more prey for predator, pop increases (DECREASE RESISTANCE FOR PREDATOR)
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26
Q

Define intraspecific competition

A

competition between individuals of SAME species

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27
Q

Define interspecific competition

A

competition between individuals of DIFFERENT species

- two species cannot occupy same niche of same habitat (GAUSIAN EXCLUSION PRINCIPLE)

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28
Q

Define community

A

Interacting populations of two or more species in the same place at the same time

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29
Q

Define ecosystem

A

Community of independent species interacting with the abiotic factors of their habitat

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30
Q

Define habitat

A

place where an organism lives

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31
Q

Define niche

A

role of a organism in its ecosystem, may include:

  • may include microhabitat, food, nocturnal
  • no two species have same niche- interspecfic competition leads to outcompeting one
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32
Q

Define producer

A

uses light energy to fix inorganic CO2 into organic molecules
-Phototrophs or chemoautotrophs

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33
Q

Define consumer

A

Obtains energy and complex organic molecules from tissues of other living organisms
- heterotrophs

34
Q

Define biotic factor

A

ecological factor that is LIVING and may affect organisms in an ecosystem
-environmental resistance

35
Q

Define abiotic factor

A

ecological factor that is NOT LIVING and may affect organisms in an ecosystem
- soil pH, temp, soil nitrate conc

36
Q

Define edaphic factor

A

aspects of soil that may affect an organism in ecosystem

- pH, % humus, nitrate level

37
Q

Define food chain

A

diagram showing simple, unbranched feeding relationship with only one organism at each position

38
Q

Define trophic levels

A

position of an organism in food chain

  • T1= producer= plant
  • T2= primary consumer= herbivore
  • T3= secondary consumer= carnivore
39
Q

What do food chains NOT SHOW?

A
  • all species at each trophic level
  • detrivores and decomposers often greater biomass
  • omnivores or organisms feeding at multiple tropic levels
    Food webs show these
40
Q

Define biomass

A

mass of biological material in living or recently living organisms

41
Q

Describe biomass transfer

A
  • Photosynthetic organisms convert sunlight into chemical energy which passes between organisms
  • energy available to tropic level contributes to biomass
42
Q

Define decomposition and give examples of decomposers

A

when dead energy remains in organic compounds

- detrivores & decomposers are SAPROBIONTS (get organic molecules from dead/ decaying organisms)

43
Q

Define detrivores

A

eg earthworms

feed on small fragments of remains of dead organisms

44
Q

Define decompers

A

eg bacteria, fungi

obtain nutrients from organisms and animal waste

45
Q

Define photosynthetic efficiency

A

measure of how much light energy a plant captured by the sun

46
Q

What is the typical loss between each trophic level?

A

10%

47
Q

Why is photosynthetic efficiency not 100%

A
  • reflected
  • passes through
  • absorbed by non-photosynthetic parts
  • much is wrong wavelength
48
Q

Define Gross Primary Productivity (GPP)

A

rate of production of chemical energy by photosynthesis

GPP= Plant respiration + NPP

49
Q

Define Net Primary Productivity (NPP)

A

energy left in plants biomass and available to primary consumers
NPP= GPP - plant respiration

50
Q

define primary productivity

A

rate at which producers convert energy into biomass

51
Q

define secondary productivity

A

rate at which consumers convert chemical energy into biomass

52
Q

define secondary production

A

total energy transferred to biomass

53
Q

4 reasons energy is lost between trophic levels

A

1) inedible tissue. 2)

54
Q

4 reasons energy is lost between trophic levels

A

1) inedible tissue. 2) indigestible food. 3) respiration. 4) excretory products

55
Q

what is the pyramid of numbers?

A

No of organisms at each trophic level of food chain (proportional to size of group)

56
Q

what is the pyramid if biomass?

A

dry mass of organisms present at each trophic level (usually actually pyramid shaped)

57
Q

define succession

A

change in structure and species composition over time in a community

58
Q

define primary succession

A

succession on land that has not been previously colonised. stages= seral stages. one seral stage improves environment for next

59
Q

define pioneer species

A

first species to colonise new area

60
Q

define climax community

A

final, stable community has reached equilibrium with environment- no further change

61
Q

Describe primary succession on bare rock

A
  • sere on dry environments= xerosere
  • pioneer species= algae and lichens
  • able tolerate desiccation and nutrients
  • slowly erodes rock—> soil
62
Q

Describe the process of primary succession

A

1) bare rock
2) spores allow mosses to gow
3) dies and forms soil- roots for plants
4) deeper soil= more water
5) over time, large trees–> climax community
ANIMAL BIODIVERITY CONSTANTLY INCREASES

63
Q

What increases as xerosere progress?

A
  • soil thickness
  • humus, water, mineral content
  • biomass
  • biodiversity
64
Q

Define secondary succession

A

Series of community changes that takes place on a previously colonised habitat that has been disturbed or damaged

65
Q

Why is secondary succession quicker than primary succession?

A
  • existing seed bank
  • vegetable reproductive organs
  • root systems
  • fertility and structure of soil
66
Q

How do humans impact succession?

A

DISCLIMAX
human interference may deflect natural climax community
- deforestation, planting fast growing trees
- grazing animals or moving
- farming and planting monocultures
final disclimax= golf courses, lawns, managed moor land, hedgerows

67
Q

How is moorland managed? use grouse and grazing as an example

A
  • fire= standard way of deflecting succession
  • pre climax habitat preserved so specialised plants and animals preserved
    GROUSE
    -feed on young heather
    1) pioneer stage (growing from seed)
    2) building stage (rapid growth)
    BURN TO RESTART GROWTH
    3) mature stage (growing but gaps- not good for nests)
    4) degenerate stage (branches break/ plant dies)
    GRAZING
    rabbits- prevent succession on chalk land
    sheep- maintain open habitats
68
Q

Define migration in terms of ecosystems

A
  • arrival of spores, seeds, animals
  • vital for succession
  • non- native species have huge effect
69
Q

When does competition occur in the development of habitats?

A
  • all seral stages
  • leads to one species outcompeting another (2 species cannot occupy same niche)
  • best advantage wins
70
Q

What is meant by facilitation? what are the two types?

A

POSITIVE INTERACTION BETWEEN ORGANISMS

1) mutualism
- interaction between species that benefit BOTH
2) commensalism
- interaction between species that BENEFITS ONE AND LEAVES OTHER UNAFFECTED

71
Q

Describe the role of minerals in food chains

A
  • short supply as from finite resources in crust/ atmosphere
  • taken up by plants, manufactures biochemical molecules
  • passed along food chain through trophic levels
  • minerals released from dead organisms by decomposers
72
Q

Describe the process of organic breakdown

A
  • one organism source of nutrition for another
  • detrivores & decomposers break down organism–> nutrients and minerals return to soil for plants to take up again
  • saprobionts secrete enzymes onto organism matter to digest it & free minerals in process
73
Q

LEARN CARBON CYCLE DIAGRAM

A

LEARN CARBON CYCLE DIAGRAM

74
Q

Describe the 5 processes in the carbon cycle

A

1) PHOTOSYNTHESIS
- CO2 removed by plants to form C compound
2) RESPIRATION
- CO2 returned to atmosphere (plants, animals, decomposers)
3) DECOMPOSTION
- CO2 released from dead organisms by saprobionts
4) FOSSILISATION
- formation of fossil fuels from dead organisms which have not decayed
- limestone from skeletons and shells
5) COMBUSTION
- C from fossil fuels released as CO2

75
Q

What is the greenhouse effect?

A
  • radiation usually reaches earth from sun and some is reflected back to space
  • radiation that reaches earth is absorbed and reemitted as a longer wavelength
  • absorbed by greenhouse gases (CO2, CH4)
  • contributes to global warming
76
Q

Four factors that are increasing CO2 levels

A

1) CFC’s
2) DEFORESTATION
3) COMBUSTION OF FOSSIL FUELS
- increasing pop. 70% increase
4) METHANE
- rice crops (anaerobic respiration)
- cattle
- rotting material in landfill sites

77
Q

What are the consequences of global warming?

A
  • melting polar ice caps and thermal expansion of water (flooding)- increased droughts, hurricanes, forest fires
  • serious effects on food production- reduction of grain crops, economic and political consequences
78
Q

Define and describe carbon footprint

A

TOTAL AMOUNT OF CO2 RELEASED BY AN INDIVIDUAL PER YEAR
either:
- direct (home/ transport)
- indirect (CO2 resulting from goods and services consumed)

79
Q

LEARN NITROGEN CYCLE DIAGRAM

A

LEARN NITROGEN CYCLE DIAGRAM

80
Q

Name and describe the four stages in the nitrogen cycle

A

1) NITROGEN FIXATION
- converts atmospheric O2 into ammonia or ammonium compounds
- achieved by: nitrogen fixing bacteria, haber process, lightening
2) AMMONIFICATION
- decomposers secrete protease which hydrolyses decaying compounds into amino acids
- also secrete deaminase to produce ammonia then reduced to ammonium ions
3) NITRIFICATION
- ammonium ions—> nitrite ions by nitrosomonas
- nitrite ions—> nitrate ions by nitrobacter
- oxidation (o gained)
4) DENITRIFICATION
- nitrates lost from ecosystems and converted back to N2 by pseudomonas
- reduction
- bad for farming- anaerobic conditions- water logged soil lacks oxygen

81
Q

What are the two types of nitrogen fixing bacteria and what do they do?

A

1) free living in soil (AZOTOBACTER)
- N2–> ammonium ions
- reduce nitrogen ions
- make own amino acids
- aerobic conditions but still reduction as high metabolic rate so low O2
2) mutualistic (RHIZOBIUM)
- root nodules of legumes
- synthesise nitrogenase
- combine ammonium ions with organic acids to form amino acids- translocated
- leg-haemoglobin- formed by nodules and absorb oxygen. keeps O2 partial pressure low for nitrogenase to carry out reduction, oxygen would inhibit reduction

Biology Comp 1 (10 decks)

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