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biology - component 1 > population size and ecosystems > Flashcards

population size and ecosystems Flashcards

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1
Q

name the things which change in an ecosystem

A
  • species composition
  • population sizes
  • biological cycles
  • successional changes
  • energy flow
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2
Q

what do population numbers in an ecosystem depend on

A
  • birth rate
  • death rate
  • immigration into the population
  • emigration away from the population
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3
Q

what causes population size to increase

A

if birth rate + immigration rate > death rate + emigration rate

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4
Q

what is meant by carrying capacity

A

maximum population size that can be maintained over a period of time in a particular habitat/environment

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5
Q

give some examples of limiting factors in an environment that restrict population size

A
  • competition for food
  • disease
  • predation
  • competition for living space and mates
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6
Q

describe what is happening in the lag stage of an animal population growth curve

A
  • takes a while to reproduce
  • only a few individuals are initially present
  • period of adaptation to new environment
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7
Q

describe what is happening in the log stage of an animal population growth curve

A
  • resources are plentiful
  • population grows at maximum rate
  • no limiting factors
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8
Q

describe what is happening in the stationary phase of an animal population growth curve

A
  • slows as organisms start to compete
  • organisms dying in equal numbers to those produced by reproduction
  • environmental resistance
  • carrying capacity has been reached
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9
Q

describe what is happening in the death phase of an animal population growth curve

A
  • death rate greater than rate of production
  • may occur when all plants are eaten
  • new diseases
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10
Q

describe what is happening in the lag stage of a bacterial population growth curve

A
  • bacteria / yeast synthesising new enzymes and proteins
  • rate of cell division is slow
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11
Q

describe what is happening in the log phase of a bacterial population growth curve

A
  • plenty of nutrients
  • cells divide at maximum rate (binary fission / budding)
  • doubling in s unit time
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12
Q

describe what is happening in the stationary phase of a bacterial population growth curve

A
  • cells dying at same rate they are being produced
  • nutrients running out becomes a limiting factor
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13
Q

describe what is happening in the death phase of a bacterial population growth curve

A
  • cell death greater than rate of production of new cells
  • build up of toxic waste (ethanol/yeast, acid for bacteria)
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14
Q

define the term population

A

interbreeding group of organisms of the same species in one place at a time

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15
Q

define the term community

A

interacting population of more than one species in the same habitat

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16
Q

define the term ecosystem

A

balanced biological system where community and non-living components interact in a particular location
there’s energy flow and nutrient cycling within the ecosystem

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17
Q

define the term habitat

A

place where an organism lives

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18
Q

define the term niche

A

role of an organism within the place that it lives

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19
Q

define the term ecology

A

study of relationships between living organisms and their physical environment

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20
Q

define the term environment

A

factors in a habitat that affect an organism

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21
Q

define the term biotic

A

part of the environment that is living

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22
Q

define the term abiotic

A

part of the environment that is non-living

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23
Q

what is meant by a density dependent factor

A

effects of these factors increase as the population increases and lead to a slow down in population growth

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24
Q

give some examples of density dependent factors

A
  • disease
  • accumulation of toxic waste
  • food availability
  • predation
  • space
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25
Q

what is meant by a density independent factor

A

effects of these factors do not depend on population size and all members of a population are equally affected

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26
Q

give some examples of density independent factors

A
  • soil pH
  • light availability
  • mineral availability
  • freezing / fire
  • flooding
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27
Q

give some examples of what plants compete for

A
  • light
  • space
  • water
  • nutrients
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28
Q

give some examples of what animals compete for

A
  • food and water
  • shelter
  • space
  • reproductive partners
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29
Q

what is meant by interspecific competition

A
  • competition between individuals of different species
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30
Q

why does interspecific competition occur

A
  • two species cannot occupy the same niche in the same habitat
  • the bigger the niche overlap, the more competition
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31
Q

what is meant by intraspecific competition

A

competition between animals of the same species and limits population size

32
Q

what assumptions do you have to make when using the capture mark recapture technique

A
  • no emigration or immigration
  • no births or deaths
  • marked individuals distribute evenly
  • marking process in non toxic and doesn’t make the population more susceptible to predation
33
Q

outline the process of kick sampling

A
  • stand in river with net downstream
  • kick river bottom and collect species in net
  • repeat for at least 3 positions along the river
  • identify each species present and number of each
34
Q

outline the limitations of kick sampling

A
  • difficult to identify all species due to similarity
  • hard to count total number of each species
  • may count more than once due to movement
  • only gives snapshot of population - need to repeat throughout the year
35
Q

what is photosynthetic efficiency

A

a measure of how well a plant is able to capture light energy

36
Q

why is the photosynthetic efficiency percentage usually so small

A
  • sunlight misses the leaves
  • light may be reflected from leaves (green)
  • only certain wavelengths absorbed by chloroplasts
  • light passed through leaves (transmission)
  • light absorbed by non-photosynthetic parts
37
Q

define gross primary productivity

A

rate of production of chemical energy inorganic molecules by photosynthesis in a given area

38
Q

define net primary productivity

A

represents the rate of production of potential food available to primary consumers

39
Q

define net primary production

A

amount of energy in organic molecules stored in plants, which is available for herbivores or primary consumers

40
Q

why is energy transfer between plants and herbivores very inefficient

A
  • plants made of cellulose which is not easily digested
  • not all of the plant is eaten eg. roots
41
Q

why is energy transfer between herbivores and carnivores more efficient

A
  • animals made of protein and fat which is more easily digested
  • less energy lost in faeces
42
Q

what terms are given to the trophic levels of organisms in a food chain

A
  • producer
  • primary consumer
  • secondary consumer
  • tertiary consumer
43
Q

give three reasons why energy in plants is not passed on to the animals who eat them

A
  • used in plant respiration
  • not all of plant is eaten
  • cellulose hard for animals to digest so passes through body
44
Q

why is energy in animals not passed on to the predators that eat them

A
  • lost through egestion
  • undigested waste
  • excretion
  • metabolic waste
45
Q

what is meant by succession

A
  • change in structure and composition of species in a community over time
  • species replaced by others overtime as environment changes or as a better adapted species arives
46
Q

what are the different stages in a succession called

A

seral stages

47
Q

what is meant by pioneer species

A
  • first species to grow in new habitat
  • highly adapted to harsh conditions
  • lichens: able to tolerate total desiccation + low nutrients
  • mosses: able to root in first soil formed by decomposing lichen, could not survive on bare rock alone
48
Q

what is meant by the grassland community

A
  • decomposing moss and lichen produce soil that the roots of low growing herbaceous plants and grasses can grow in
  • seeds blown into habitat establish the grassland
  • outcompete moss and lichens for sunlight
49
Q

what are meant by the shrubs

A
  • perennial woody plants that outcompete grasses and block sunlight from reaching them
  • grow throughout the year and stop grasses growing underneath
50
Q

what is meant by the climax community

A
  • dominated by trees
  • wide variety of plants and animals growing at variety of heights
  • final stable collection of plants and animals that succession produces, which is the best adapted to the conditions
51
Q

give the definition of a primary succession

A

habitat never before colonised, eg. bare rock

52
Q

outline the gradual changes that take place during succession

A
  • soil becomes deeper
  • mineral nutrient content goes up
  • biodiversity and environmental stability increase
  • number of woody plants increase
  • organisms live at variety of heights
  • pioneer plants usually lost due to competition
53
Q

give the definition of a secondary succession

A

series of community changes which take place on a previously colonised, but disturbed or damaged habitat

54
Q

explain why a secondary succession is usually quicker than primary succession

A
  • already existing seed bank in soil
  • root systems undisturbed so plants can rapidly regenerate
  • fertility and structure of soil has been substantially modified by previous organisms to make it more suitable for growth and colonization
55
Q

outline how human intervention may divert the climax

A
  • ploughing
  • fire
  • trampling
  • poor quality soil
  • grazing
  • mowing
  • mineral extraction and building
56
Q

give the definition of facilitation

A

presence of an initial species that aids and increases the probability of growth of a second species

57
Q

what is the significance of the pyramidal shape of a biomass pyramid

A

to show energy lost between each trophic level

58
Q

outline what food chains do not show

A
  • all the species at each trophic level, only one
  • detritivores and decomposers which are often a greater biomass than other consumers
  • omnivores or other species feeding at several trophic levels
59
Q

draw an annotated diagram of the carbon cycle

A

s

60
Q

outline the main reasons for the increase in the greenhouse effect

A
  • the burning of fossil fuels
  • deforestation
  • methane increases from different sources
  • CFCs
61
Q

what is meant by the carbon footprint

A

total amount of carbon dioxide released into the atmosphere due to the actions of individuals over the course of a year

62
Q

outline the consequences of global warming

A
  • melting of polar ice caps and thermal expansion of water which could cause coastal erosion or flooding
    -increased frequency of droughts and forest fires
  • serious effects on food production which would have economic and political connsequences
63
Q

explain the process of the greenhouse effect

A
  • radiation from sun reaches earth but some reflected back by atmosphere
  • radiation that reaches earth is absorbed and re-emitted as longer wavelength radiation
  • radiation absorbed by greenhouse gases which contributes to warming of the earth
64
Q

what do plants need nitrogen for

A
  • building amino acids to build proteins
  • building organic bases to build nucleotides
  • chlorophylls
65
Q

draw and annotate a diagram of the nitrogen cycle

A

see poster

66
Q

explain the process of nitrification and why it is so important to soil fertility

A
  • nitrosomonas convert ammonium ions to nitrites
  • nitrobacter convert nitrites to nitrates
  • plant can absorb them
67
Q

outline the function of azobacter and the process they are involved in

A
  • nitrogen fixation
  • free living nitrogen fixing bacteria
  • absorb nitrogen from air and produce ammonium ions
  • can leach into soil or used by bacteria themselves to synthesise amino acids
68
Q

outline the function of rhizobium and the process they are involved in

A
  • nitrogen fixation
  • found in root nodules of legumes
  • bacteria benefit by getting sucrose
  • plants benefit by having amino acids produced by the bacteria
69
Q

explain the advantage of legumes having root nodules

A
  • nitrogen fixing bacteria found in root nodules produce amino acids which pass to the plant which allows them to grow in poor soils
70
Q

outline the function of putrefying bacteria and fungo and the process they are involved in

A
  • decay
  • decompose proteins in dead organisms
  • proteins digested to amino acids which are deaminated to produce NH2 which is reduced to produce ammonium ions
71
Q

outline the function of pseudomonas and the process they are involved in

A
  • de-nitrification
  • found in boggy, waterlogged soils
  • convert nitrates back to nitrogen gas so few plants can grow in these soils
72
Q

outline and explain the process of eutrophication

A
  • nitrates applied to soil and leached out as a result of rain - ending up in bodies of water
  • causes an algal bloom where high levels of nutrients cause rapid growth of algae which cut off light to photosynthesising plants which die
  • saprotrophic bacteria decompose the dead plants and respire aerobically using the dissolved oxygen
  • this gives the water a high biological demand
  • biodiversity of plants and animals in the water decreases
73
Q

outline another effect of using fertilisers

A

reduces biodiversity by encouraging the growth of nettles and grasses which have a high demand for nitrogen, these outcompete other plants for nitrogen

74
Q

outline some ways in which we can reduce problems caused by fertilisers

A
  • restrict amount of fertiliser used
  • only use fertiliser when crops are actively growing
  • leave a strip of land at least 10m wide next to watercourses
  • avoid leaving the land bare as it can lead to soil erosion and fertilisers go with it
75
Q

outline how we can aerate soil

A
  • ploughing increases oxygen content of soil
  • installing drainage systems reduces waterlogging
  • both of these encourage nitrifying bacteria and discourage denitrifying ones
76
Q

give some reasons for loss of lowland raised bog habitat

A
  • landfill development
  • built development
  • afforestation

biology - component 1 (2 decks)

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