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ecosystems, populations and sustainability Flashcards

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1
Q

2 types of decomposer

A

bacteria and fungi

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2
Q

what do decomposers do?

A

feed on/break down dead plant and animal matter

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3
Q

detritivores example and what to they do?

A

e.g. woodlice, earthworms
speedy up decay process by breaking up dead matter onto smaller fragments
increase surface area for digestion

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4
Q

what is saprotrophic nutrition?

A

obtaining energy form dead organic material
used by fungi
thread-like hyphae secrete enzymes extracellularly, digest dead material and reabsorb soluble products e.g. glucose, amino acids

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5
Q

why does decomposition result in CO2 being released?

A

glucose released form digestion is respired and this process releases CO2 and water into the atmosphere

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6
Q

what are myrcorrhizae?
relationship w/ plants?

A

fungal networks underground
form a symbiosis with plant roots
fungi obtain sucrose from plants
plants obtain more magnesium ions and phosphates from fungi

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7
Q

why is nitrogen so important for living organisms?

A

required to make nucleic acids (DNA/RNA) and amino acids (proteins)

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8
Q

why can nitrogen not be directly absorbed by living organisms?

A

very difficult to break the triple bond
must be combined with H atoms and O atoms, which increases the ability of nitrogen-containing molecules to be absorbed

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9
Q

processes in the nitrogen cycle

A

nitrogen fixation
ammonification
nitrification
denitrification

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10
Q

nitrogen fixation description

A

anaerobic process
reduction reaction
nitrogen-fixing bacteria ude nitrogenase enzyme
N2 + 3H2 -> 2NH3
16ATP -> 16ADP +Pi

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11
Q

nitrogen fixation bacteria involved

A

azotobacter (free in soil)
rhizobium (live in root nodules of legumes)

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12
Q

ammonification description

A

decomposers break down dead plant or animal matter and/or their products of egestion/excretion
egested products= rich in cellulose (B glucose, respired), proteins digested into amino acids; excess amino acids converted to urea, which bacteria use to respire

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13
Q

ammonification bacteria involved

A

saprotrophic micoroorganisms e.g. fungi, bacteria

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14
Q

nitrification description

A

aerobic process
oxidation reactions
in well-drained soil
1. ammonium ions-> nitrites
2. nitrites ->nitrates

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15
Q

nitrification bacteria involved

A

nitrosomonas
nitrobacter
both free in the soil

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16
Q

denitrification description

A

anaerobic process
occurs in waterlogged soils
reduction reaction
nitrates are converted back into nitrogen gas
NO3- ->N2

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17
Q

denitrification bacteria involved

A

pseudomonas
denitrificans (use nitrates for respiration)

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18
Q

nitrites symbol

A

NO2 -

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19
Q

nitrates symbol

A

NO3 -

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20
Q

nitrogen gas symbol

A

N2

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21
Q

ammonium symbol

A

NH4 +

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22
Q

ammonia symbol

A

NH3

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23
Q

purposes of leghaemoglobin?

A

similar structure to haemoglobin
found in root nodules
plats produce it to absorb oxygen (removes excess O2 so nitrogenase enzymes can have anaerobic conditions to increase efficiency of enzyme action)
this O2 is transported to mitochondria

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24
Q

what does nitrogen reductase do?

A

denitrifying enzyme
returns N2 gas back to the atmosphere
found in pseudomonas denitrificans

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25
Q

oxidation vs reduction

A

oxidation= loss of electrons/hydrogen
reduction= gain of electrons/hydrogen

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26
Q

besides nitrogen fixation, how else is nitrogen gas converted to ammonium?

A

Haber Process
fertilisers

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27
Q

differences between carbon and nitrogen cycle?

A

N: decomposers produce ammonium ions
C: decomposers produce CO2
denitrifying bacteria produce N2 (gas) from nitrates
N2 gas reacts with lightning or with N-fixing bacteria whereas CO2 can react directly in plants

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28
Q

similarities between carbon and nitrogen cycle

A

both involve decomposers, micro-organisms e.g. saprotrophs
both involve micro-organisms returning inorganic gas to the atmosphere
both involve death, digestion and excretion so both release either C or N - containing compounds

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29
Q

processes in carbon cycle

A

decomposition
respiration
photosynthesis
death
excretion/egestion
combustion
fossilisation
feeding

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30
Q

stores in carbon cycle

A

producers
consumers
decomposers
fossil fuels
atmospheric CO2

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31
Q

describe the part played by soil bacteria in making the nitrogen in compounds in dead plants available to living plants

A

saprotrophic micro-organisms such as bacteria and fungi break down the seeds to produce ammonium (decomposition/ammonification)
nitrosomonas and nitrobacter then convert this into nitrates which can be taken up by plants

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32
Q

reasons for less growth in areas w more plants

A

interspecific competition for nitrates

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33
Q

compounds classified as organic nitrogen

A

amino acids
protein
DNA
ATP

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34
Q

suggest the advantage to cattle farmers of encouraging the growth of clover in a grassland

A

contain bacteria which can fix nitrogen
clover decays/dies and adds nitrogen compounds to the soil
no/less fertiliser needed

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35
Q

succession definition

A

the directional change in the composition of species in a community that occupy a given area through time

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36
Q

pioneer community definition

A

a species adapted to survive harsh or inhospitable conditions. they stabilise the environment and lead to soil development e.g. lichens and fungi

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37
Q

climax community definition

A

a final, stable community
stable state
very little change over time
few dominant plant/animal species

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38
Q

secondary succession description

A

faster than primary succession as minerals are already available in the soil
occurs on land that has been cleared of all plants and animals but soil remains e.g. after flooding, forest fire e.t.c.

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39
Q

primary succession steps description

A

major disruption to ecosystem e.g. volcanic eruption, asteroid leaves bare rock without soil
lichens establish pioneer community, causing erosion of rock and providing dead material, which is decomposed and produces soil (humus)
shrubs and small plants e.g. ferns and mosses grow, which replace the pioneer community
plants establish themselves, reproduce, disperse seeds, die and decompose, adding minerals and water to soil
soil can support larger plant species, which outcompete smaller plants
continues until climax community forms

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40
Q

deflected succession description

A

when human activities halt succession from occurring e.g. agriculture (cattle farming, mowing, sustainable timber production)
STOPS climax community

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41
Q

plagioclimax definition

A

final community in a deflected succession ecosystem

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42
Q

what is the name of the stages in succession

A

seral stages

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43
Q

what causes succession?

A

changes in the community of organisms causes changes in the physical environment that allow another community to become established and replace the former community
therefore new community outcompetes former community: occurs in a number of seral stages: at each of these, key species can be identified that are responsible for changing the abiotic factors, particularly relating to soil (edaphic)

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44
Q

where are the pioneer species in sand dunes
why?

A

on the beach
they can tolerate harsh conditions e.g. high winds, high salt, high water

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45
Q

description of beach in sand dunes

A

bare sand
hostile environment: very salty so has low water potential. very windy. no organic matter
very low species diversity

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46
Q

description of mini dunes in sand dunes

A

embryo dunes
wind = blown sand builds up around base of pioneer plants
dunes increase in height as the plants grow
supports primitive species like MARRAM GRASS

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47
Q

young yellow dunes description in sand dunes

A

increased stability and more minerals therefore more marram grass growth
marram grass stabilises sand, some dies/decomposes, adding further organic matter to the sand

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48
Q

old grey dunes description in sand dunes

A

support intermediate plant species, these are able to outcompete pioneer species and increase species diversity
increased species diversity as you move further away from the sea

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49
Q

why do the dunes get darker as you go away from the sea?

A

soil depth and quality (mineral content) increases
larger root networks add to dark colour

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50
Q

marram grass is a xerophyte. what adaptations does it have? how does this help it to survive?

A

thick waxy cuticle reduces water loss by transpiration
rolled leaves (small) trap moist/humid air & decrease SA:vol ratio for transpiration
hairs on the lower surface reduce air movement to limit water loss
stomata are sunken so moisture trapped close to them to reduce water potential gradient

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51
Q

how would you measure change across a sand dune system?

A

an interrupted belt transect
does not lay flat along the ground
quadrats placed at regular intervals between 2 tape measures and number of organisms of each species is recorded
systematic sampling
take multiple reading at each interval and calculate mean
ensures sample is as representative as possible

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52
Q

what is a kite diagram?

A

allow frequencies of different species to be recorded along the length of a transect
the wider the kite, the greater the proportion of that species

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53
Q

advantage for pioneer species?

A

no competition

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54
Q

why can’t we predict the route which succession is going to take?

A

randomness
unpredictable variability (weather conditions e.t.c.)

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55
Q

what is the main way we can tell if an area is in a later stage of succession?

A

it has high biodiversity
lots of niches for species and many communities

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56
Q

what level of disturbance results in the greatest developmental change

A

mid-level disturbance: creates own habitat at its own stage of succession w/ its own unique niches
higher biodiversity and therefore a more stable and healthy ecosystem

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57
Q

why do people burn forests regularly?

A

undergo succession, creating an area of high biodiversity with a mosaic of habitats and communities

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58
Q

explain the role of pioneer plants in succession on a bare rock or sand dune

A

allows soil to hold more water and increase nitrogen content
reduces soil erosion
they stabilise the ecosystem by developing soil and increasing its quality so grasses can grow

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59
Q

how can deflected succession be caused

A

grazing of cattle
burning
herbicide use

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60
Q

explain how biomass changes during primary succession

A

plans in seral stages are larger
climax community= woody trees/shrubs appear

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61
Q

suggest how grazing by sheep could prevent a woodland climax community from developing

A

cause deflected succession so results in plagioclimax

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62
Q

outline the advantages of using a scale e.g. ACFOR scale

A

can be used with any species irrespective of size
quick to assess
doesn’t require distinguishing between individuals

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63
Q

outline the disadvantages of using a scale e.g. ACFOR scale

A

subjective. not objective
dominant species may be overestimated

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64
Q

outline 2 changes which occur between mid and late succession

A

topsoil becomes deeper and thicker
soil becomes richer in minerals
root networks become larger and more well-established
plant species become larger

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65
Q

conservation definition

A

maintaining biodiversity by actively managing ecosystems]
dynamic process involving human action

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66
Q

preservation definition

A

protecting an ecosystem by restricting all human access and use so it remains untouched

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67
Q

economic reasons why conservation is important

A

sources of raw materials for industries e.g. timber products from natural and plantation forests for the construction & paper industries
employment for people in transport, marketing & retailing; ecotourism also provides employment for many people in places of high biodiversity
sources of natural income from exporting biological resources e.g. timber, fish, paper products: the UK is a net importer of timber & fish, but exports of fish and shellfish are worth over £1bn

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68
Q

social reasons why conservation is important

A

human communities in rural areas w/ little industry or commerce gain stability from the employment provided by fishing or forestry
areas set aside for forestry provide spaces for recreation: the Forestry Commission & private forestry owners manage their forests as an amenity for people to enjoy the visual appeal of forested areas, the opportunities to take exercise and observe wildlife

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69
Q

ethical reasons why conservation is important

A

the duty we have to conserve resources for the livelihoods and wellbeing of future generations
the support of indigenous people across the world who maintain their traditional ways of living relying on certain biological resources e..g Inuit people in the Arctic rely on seals and whales & Amazonian communities depend on foods harvested from the rainforest

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70
Q

3 reasons why tropical rainforest have been destroyed

A

timber products/timber as fuel
clearance for agriculture
urban growth and development

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71
Q

describe the importance of tropical rainforests an why their disappearance is concerning

A

carbon sinks: remove CO2 from atmosphere
release stored carbon when burnt and stop photosynthesising, decreasing oxygen production
deforestation disrupts water cycle, by decreasing transpiration
more soil erosion
soils are nutrient deficient and cannot sustain agriculture
decreased gene pool
new medicines only in rainforests may be lost
conserve for later generations
extinction of species
high species diversity in small area of rainforest

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72
Q

how can international measures be taken to try and halt decline of tropical rainforests

A

ITTS
ecotourism
educaiton
reserves
rio CBD
IUCN/REDD
debt reduction

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73
Q

what is a sustainable resource

A

a renewable resource that is being economically exploited in such a way that it does not diminish/run out

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74
Q

uses of timber

A

in construction
as a fuel
in paper manufacturing

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75
Q

advantages of sustainable timber production

A

ecosystem not destroyed
biodiversity maintained
aesthetic and amenity value retained
long term financial benefit available from timber

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76
Q

what is sustainable timber harvesting

A

removing timber from a forest or woodland in a manner that allows similar amounts to be removed year after year
maintains the forest ecosystem, allowing all the different habitats and species to survive

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77
Q

how long do coppiced trees live

A

hundreds of years

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78
Q

describe the process of coppicing

A

tree that has been previously coppiced is cut at an angle so water runs off (less chance of fungal infection) and wood is harvested
in the following year lots of new stems are produced
after 9 years a few stems have produced significant growth
wood is harvested gain
wood is divided into 9 areas; each year, one area is coppiced (some trees grown to maturity= standard)

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79
Q

what does coppicing allow for

A

allows wood to be taken each year
most deciduous trees do not die when they are cut down and regrow form the base

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80
Q

examples of trees which are coppiced

A

sweet chestnut
ash
lime
hazel

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81
Q

issues with coppicing

A

labour intensive
small scale only
doesn’t work with coniferous trees
new growth of coppice trees= several stems, narrow (limited use BUT okay for paper, fencing or burning to generate electricity)

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82
Q

coppicing vs pollarding

A

coppicing- cutting trees to ground level: encourages more growth
pollarding- cutting higher up the trunk, useful if deer population is high

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83
Q

how does coppicing increase biodiversity

A

open glades promote wildflowers: different habitats created (trees never grow tall enough to block out light so succession halted)

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84
Q

small scale
management technique
size of timber
use of timber
habitat destruction
biodiversity
soil erosion
planting new trees

A

coppicing
smaller
paper, fencing, electricity
less
increases
none
no

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85
Q

large scale
management technique
size of timber
use of timber
habitat destruction
biodiversity
soil erosion
planting new trees

A

felling
larger
construction industry
more
decreases
yes
yes

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86
Q

clear felling is on what scale?

A

large

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87
Q

issues with clear felling

A

destroys habitats
reduces soil mineral levels
increases soil erosion
increase flood risk

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88
Q

what is selective felling

A

cutting only trees which are commercially viable/ diseased/unwanted trees

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89
Q

where is selective felling important and what is the rotation time

A

on slopes (trees prevent soil erosion)
long rotation time of 100 years to ensure regeneration

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90
Q

what does selective felling maintain

A

nutrients in forest soil (role in C and N cycles)

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91
Q

selective felling issue

A

difficult to carry out with large machinery

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92
Q

what is strip felling

A

small patches or strips of forest are cleared completely leaving other patches untouched to cut many years later

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93
Q

what does strip felling avoid

A

loss of species and soil erosion avoided as large areas not felled at the same time

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94
Q

making the most of each tree: if each tree supplies more wood, less trees are needed
what are the benefits of this?

A

control pests and pathogens
uses every part of felled trees e.g. small branches chipped

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95
Q

if management is stopped, what would woodlands go through

A

a process of natural succession (reach a climax community in which biodiversity would be much lower than in a managed woodland)

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96
Q

outline the use of coppice w/ standards in sustainable woodland managememt

A

trees cut to sloping stump close to ground
new shoots form
harvest periodically in same way
rotational coppicing to maximise age and size range of trees/maximise habitats
increase light intensity for seed germination/seedling/growth/creates varied abiotic conditions
increases habitats and biodiversity
provides continuous source of products/fencing/poles/furniture/charcoal
standards provide larger planks/more valuable timber

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97
Q

what are the marine stewardship council principles for sustainable management of fisheries

A

fishing must take place at a level which allows it to continue indefinitely
fishing must be managed to maintain structure, productivity and diversity of the ecosystem
a fishery must adapt to changes in circumstances and comply with local and international regulations

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98
Q

methods of fishing control

A

set up exclusion zones (no catch zones) fish migrate into and out of these areas (spawning/nursery grounds)
beginning fishing at certain times of year (e.g. during spawning, so allows fish numbers to recover)
rules of type of fishing gear e.g. larger mesh size to allow younger fish to escape, allowing them to reach breeding age/ limit number of boats in area
quotas: certain mass or number of fish per fisherman each year and inspect
restocking sea with young fish
international agreements
fish farms (aquaculture) rather than wild populations

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99
Q

how are fish stocks increased

A

brith of fish
growth of fish

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100
Q

how are fish stocks decreased

A

death of fish by natural means e.g. age, disease
humans catching fish

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101
Q

what is ICES

A

an independent intergovernmental scientific body providing advice on fisheries in NE Atlantic to National Governments

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102
Q

how is overfishing prevented

A

limit areas where fishing can take place
decrease total net size
increase net mesh size
set minimum landing sizes e.g. min. size of fish that can eb brought into port
reduce/stop subsidies for increasing size of fleet

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103
Q

suggest 3 reasons why quotas are not always effective in preserving fish stocks

A

inaccurate estimate of size of fish populations
fish caught above quota have to be returned to sea (but are unlikely to survive)
quotas exceeded illegally
small fish may be caught
fish not caught may be eaten by predators

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104
Q

describe the LT ecological effects of overfishing

A

disruption to food chains/webs
reduced productivity of ecosystem
loss of biodiversity
loss of nutrients from ecosystem

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105
Q

what assumptions foes the capture/recapture technique make?

A

no immigration/emigration
tagging has no effect on predation/likelihood of capture/survivorship

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106
Q

what is peat

A

consists of the remains of fallen trees/branches/leaves/plants and other carbon matters that have built up in waterlogged conditions over 1000s of years
no/slow decomposition (carbon stays in solid state)

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107
Q

what happens to peat when drainage ditches are dug?

A

water that was previously stored in the peat starts to flow out of the ditch
sunlight enters the forest so more temps
oxygen enters peat so it begins to decompose
carbon converted to CO2, which moves away
large scale= issue
water table lowers so peat dome subsides
fire accelerates smokinh

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108
Q

how many billions of tonnes of carbon is stored by the UKs peat bogs

A

3

109
Q

why should bogs be conserved

A

provide habitats e.g. for sphagnum moss, bog cotton, lichens, sundew
abundance of insects e.g. butterflies attracted by a wide variety of plants or damselflies and dragonflies
habitat for birds e.g. snipe, skylark
frogs, lizards, hares foes e.t.c. live at bogs
store CO2
archaeologists use to analyse past
part of heritage
flood management

110
Q

how much water can sphagnum moss store?

A

20 times its own weight

111
Q

when does peat form

A

when plant material is inhibited from fully decaying by acidic and anaerobic conditions
normally occurs ion wet ares so peat is mainly composed of wetland vegetation e.g. mosses

112
Q

what is a bog

A

a wetland area which is waterlogged only by direct rainfall

113
Q

why is peat being destroyed

A

peat extraction to use as fuel
afforestation of area
agricultural intensification
drainage ditches
garden compost

114
Q

describe conservation of lowland bogs

A

organisations like wildlife trusts and rspb carry out conservation work
ensures that peat and vegetation of bog surface is undisturbed and as wet as possible
ditch blocking to raise water table
removal of seedling trees
controlled grazing

115
Q

why has human population not changed much throughout history

A

due to limiting factors preventing increase e.g. food availability, predation, disease, climate

116
Q

what recent developments led to exponential increase in global human population

A

industrial revolution, scientific revolution, public health revolution and development of agriculture

117
Q

what does exponential increase mean

A

as time doubles, population more than doubles

118
Q

population definition

A

members of the same species in the same place at the same time able to interbreed w each other

119
Q

population size definition

A

number of individuals in a population

120
Q

population density definition

A

number of individuals per unit area

121
Q

limiting factor definition

A

a factor whose magnitude slows down the rate of a natural process

122
Q

abiotic factor definition

A

non living
e.g. soil pH, moisture, temperature, light intensity

123
Q

biotic factor definition

A

living
e.g. predation, competition, disease

124
Q

interspecific competition definition

A

competition between organisms of different species

125
Q

intraspecific competition definition

A

competition between organisms of same species

126
Q

what is a growth curve

A

if the growth of a population over time is plotted on a graph, regardless of the organism, most natural populations will show the same characteristics

127
Q

stages of a population growth curve

A

lag phase
log phase
stationary phase
death phase

128
Q

describe the lag phase of a population growth curve
(period of slow growth)

A

acclimatising to habitat (i.e. adjusting to nutrients, genes switched on to make appropriate enzymes)
only a few individuals, so low rate of reproduction
birth rate greater than death rate but growth in population size is slow

129
Q

describe the log phase of a population growth curve (population increases rapidly)

A

can only be maintained if resources are plentiful and conditions are good
numbers double each generation (=max rate of reproduction every 20 mins)
birth rate much greater than death rate (maximum rate of reporduction)

130
Q

describe the stationary phase of the population growth curve (population levels out at carrying capacity)

A

birth rate equal to death rate
population remains stable/ fluctuates slightly
fluctuations are due to variations in environment (limited/changing food supply/outbreaks of disease i.e. abiotic and biotic factors which decrease BR or increase DR)

131
Q

what is carrying capacity

A

the maximum population size that can be maintained over a period of time in a particular habitat with a particular set of conditions
further growth stopped by environmental resistance e.g. abiotic and biotic factors which reduce BR or increase DR

132
Q

describe the death/decline phase of a population growth curve (population decreases in size)

A

death rate greater than birth rate
lack of resources
buildup of toxic waste
not usually shown in natural populations

133
Q

what is a niche

A

the role of each species in an ecosystem
role refers to position in food chain and how it interacts with the environment and other species

134
Q

why is a food web more useful than a food chain

A

a food web is more realistic than a food chain: each trophic level usually consists of more than one species of organisms and most consumers will eat more than one type of organism

135
Q

why is a pyramid of biomass more useful than a pyramid of numbers

A

pyramid of numbers does not reflect the varying sizes of organisms at each trophic level
a pyramid of biomass provides a more accurate picture of how much biomass exists at each trophic level

136
Q

GPP definition

A

the rate at which plants convert light energy into chemical energy through photosynthesis

137
Q

8 ways that farmers can increase NPP

A

plant crops earlier to increase length of growing season
use light banks to grow plants
irrigate crops
introduce drought-resistant strains
grow plants in glasshouses to provide a warmer temperature
pesticide use
crop rotation
selective breeding to resist fungal infections
use of herbicides

138
Q

4 ways farmers can improve secondary productivity

A

harvesting animals just before adulthood
selective breeding to increase animal growth rate/ egg production/ milk production
treatment of animals with antibiotics
zero grazing for pigs/cattle

139
Q

describe how selective breeding and GM can increase primary and secondary productivity

A

by producing consumers or primary producers that are more efficient at increasing their biomass

140
Q

describe how saprotrophs feed

A

secrete extracellular enzymes onto dead and waste material
enzymes digest the material into small molecules, which are then reabsorbed

141
Q

explain why all stages of succession are visible on a sand dune

A

the sea deposits sand on the beach
the sand closets to the sea is deposited more recently than the sand further away
this means the sand nearest to the sea is at the start of succession whereas the sand further away may have already reached its climax community

142
Q

describe what is meant by the competitive exlcusion principle

A

2 species have exactly the same niche, so one is outcompeted by the other and dies out or becomes extinct in the habitat

143
Q

describe how the terai region has made resource use more sustainable

A

created forest corridors
counteracted poaches and illegal felling
introduced biogas plants and wood-efficient stoves
constructed waterholes
monitored endangered species
eradicated invasive species

144
Q

describe how the Maasai mara region has made resource use more sustainable

A

created conservancies that allow limited grazing and tourism opportunities to co-exist

145
Q

state the similarities between the strategies adopted in the terai region and the Maasai mara

A

both strategies acknowledge the importance of local people and work with them
both have conservation with developmental aspects

146
Q

explain why both the terai and Maasai mara projects have involved the local community

A

both area provide homes to many local people and those people depend on the habitat for their existence
it makes sense to improve conditions for local people at the same time as conserving the habitat
it is important to involve local people so they do not act against the conservation aims

147
Q

describe the positive and negative consequences in terai

A

forests provide local people with a sustainable source of fuel, animal feed, food, building materials, agricultural and household tools as well as medicines
tiger populations appear to be increasing
increasing tiger populations may tempt back poachers

148
Q

describe the positive and negative consequences in Maasai mara

A

positive partnerships between conservancies and tourism organisations
sustainable farming and tourism opportunities for locals
landowners are forced to move their livestock out of the conservancies during the tourist seasoned can be forced to re-settle elsewhere

149
Q

producer definition

A

organism that converts simple inorganic source of carbon into complex organic molecules
supply chemical energy to all other organisms either directly or indirectly

150
Q

how to sample (different methods)

A

random sampling
systematic sampling
stratified sampling
opportunistic sampling

151
Q

how to carry out random sampling

A

set out 10m x 10m Grid using tapes
use random number table to generate pairs of random no.s and then put bottom left corner of quadrat at co-ordinate

152
Q

random sampling use

A

used to compare 2 or more areas
avoids bias

153
Q

how to calculate population size of whole area from random sampling

A

mean number of individuals of a species in a quadrat/fraction of total habitat covered by 1 quadrat

154
Q

systematic sampling use

A

to investigate changes along an environmental gradient

155
Q

types of systematic sampling

A

line transect
belt transect

156
Q

describe line transect

A

a line across a habitat from one end to another
sample at regular intervals and only count what touches the tape

157
Q

describe belt transect

A

parallel tapes with a quadrat at regular intervals
can be continuous or interrupted

158
Q

belt transect vs line transect

A

belt transect takes longer
belt= more data, more representative

159
Q

continuous vs interrupted belt transect

A

continuous is higher number of quadrats so more data and more representative

160
Q

stratified sampling use

A

to investigate a habitat which has distinct different areas
sample each area proportionally to its size as a percentage of whole habitat (STRATA=GROUPS)

161
Q

what are opportunistic sample sites based on

A

prior knowledge e.g. safe areas w particular species
(may not be representative so weakest form of sampling)

162
Q

what are cyclic changes in an ecosystem w examples

A

changes that repeat in a rhythm
e.g. movement of the tide, changes in day length, fluctuations in predator-prey species

163
Q

what are directional changes in an ecosystem w examples

A

these changes tend to go in one direction ie a particular variable continues to increase/decrease
tend to last longer than the lifetime of an organism in an ecosystem
e.g. deposition of silt in an estuary , deposition of sand forming a dune, coastal erosion

164
Q

what are unpredictable/erratic changes in an ecosystem w examples

A

no rhythm or constant direction
e.g. effect of lightning, hurricanes, pollution

165
Q

examples of how living organisms respond to changes in ecosystems

A

hibernation in cold months
changes in thickness or colour of coat
migration to warmer areas
loss off leaves to avoid water loss
dormancy of seeds until warmer months
flowering (delayed until pollinators are around)

166
Q

step by step sand dune succession

A

bare ground colonised by pioneer species e.g. marram grass that can tolerate the dry, salty condiitons
marram grass stabilises the sand due to its dense roots
as the marram grass decays it makes the sand less hostile, adding humus and improving water retention
this allows other plants to grow e.g. grasses, ragwort, restharrow
as plants build up and then decay, soil depth and quality improve further allowing taller plants to establish- firstly small shrubs and then trees
this greater variety increases biodiversity encouraging the presence of insects and birds
eventually a stable woodland may develop
damage to dunes by rising sea levels, storms or trampling may reverse succession. these are deflecting factors.

167
Q

biomass definition

A

mass of living material (including organic and inorganic components)
can be used to determine energy content

168
Q

is biomass expressed as wet or dry mass
why?

A

dry mass bc gives a better representation of energy content (but it is destructive)
this is bc plant wet matter varies considerably due to fluctuations in water uptake and transpiration

169
Q

how to get dry mass of an organism

A

put in oven at 80C until constant mass

170
Q

how to calculate biomass of a population (so can measure change over time)

A

measure dry mass of a small representative sample of population and scale up for the whole population

171
Q

what is biomass measured in

A

gm^-2 for land organisms
gm^-3 for aquatic organisms

172
Q

how to calculate efficiency of transfer between trophic levels

A

biomass of higher trophic level /
biomass of lower trophic level x100

173
Q

GPP definition

A

rate at which plants convert light energy into chemical energy through photosynthesis
total production of organic material in a given time and area

174
Q

why is energy los between sun and producers

A

some light misses leaves/plant (e.g. bark cannot photosynthesise)
some light reflected
some light transmitted and not trapped (passes straight through leaf and doesn’t hit chlorophyll molecule)
only certain wavelengths can be absorbed:blue & red (plant does not possess enough pigments to absorb all wavelengths)
energy losses occur in p/s reactions
there may be other factors which limit the rate of p/s (e.g. temp)

175
Q

what % of solar energy do producers convert into chemical energy and hence biomass

A

0.5-3%

176
Q

where is GPP higher

A

at equator than at poles

177
Q

why is GPP higher at equator than at poles

A

higher light intensity
higher temp so higher enzyme activity
faster rate of p/s
more glucose made so more organic material produced in a given time/area

178
Q

NPP definition

A

energy which remains as chemical energy after the plants have supplied their own needs in respiration
energy released in respiration is used to drive metabolic reactions

179
Q

what % of energy generated in p/s do producers use for other processes eg. respiration

A

20-50%

180
Q

equation liking NPP and GPP

A

GPP=NPP +R
NPP=GPP-R

181
Q

biomass losses between producers and primary consumers

A

not all parts of the plant are eaten e.g. roots/woody tissue
large proportion of the parts eaten are undigestable e.g. cellulose and lignin

182
Q

what % of energy is transferred between producers and primary consumers

A

5-10%

183
Q

biomass losses between primary consumers and secondary consumers

A

greater proportion of organism is digestible (but cannot digest all parts e.g. bones)
primary consumers use some biomass in respiration for movement
primary consumer loses heat energy to surroundings
primary consumer loses biomass in urine/faeces (egestion)

184
Q

what % of energy is transferred between primary and secondary consumers

A

10-20%

185
Q

what is production by heterotrophs called

A

secondary production

186
Q

positive of using pyramid of numbers

A

easy to collect data and to draw

187
Q

negatives of using pyramid of numbers

A

range of numbers may be v big e.g. 500,000 grass plants may only support a single top carnivore so drawing may be tricky to do scale
doesn’t account for size of organism

188
Q

pyramid of biomass positives

A

eliminates the inversion and scale problems of a pyramid of numbers

189
Q

issues w a pyramid of biomass

A

destructive bc use dry mass
doesn’t take into account seosnal changes

190
Q

how to measure energy content

A

dry sample and burn in calorimeter
calculate energy released in kJkg^-2yr^-1
multiply by biomass at each trophic level

191
Q

advantages of pyramid of energy

A

comapres productivity bc a itme factor is incorporated
no inverted pyramids obtained

192
Q

how does LI limit productivity

A

lower LDR so lower rate of p/s
slower production of biomass

193
Q

how to limit effect of LI on productivity

A

plant crops earlier and use light banks

194
Q

how does water limit productivity

A

decreased photolysis so lower rate of p/s
slower production of biomass

195
Q

how to limit effect of water on productivity

A

irrigation
GM drought resistant strains

196
Q

how does temp limit productivity

A

decreased enzyme activity of rubisco
decreased rate of p/s
decreased production of biomass

197
Q

how to limit effect of temp on productivity

A

plant crops earlier
grow plants in a glasshouse

198
Q

how do mineral ions limit productivity

A

decreased growth e.g. magnesium and nitrates
decrease chlorophyll and amino acids
slower production of biomass

199
Q

how to limit effect of mineral ions on productivity

A

crop rotation
nitrogen-fixing crops e.g. legumes like clover
selective breeding crops t respond to high levels of fertiliser

200
Q

how do pests limit productivity

A

eat and damage crops to decrease biomass

201
Q

how to limit effect of pests on productivity

A

spray w pesticides
selectively breed to be pest-resistant
GM to be pest-resistant

202
Q

how do fungal diseases limit productivity

A

damage roots to decrease volume of water absorbed
damage xylem so decrease water transport
damage foliage so decrease leaf area for p/s
damage phloem so decrease translocation
damage flowers/fruit so decrease reproduction and biomass

203
Q

how to limit effect of fungal diseases on productivity

A

spray w fungicides
selectively breed resistances
GM to be resistant

204
Q

how does competition from weeds limit productivity

A

decreased p/s
decreased production of biomass

205
Q

how to limit effect of competition from weeds on productivity

A

use herbicides to kill weeds

206
Q

how to improve secondary productivity

A

harvest animal before adulthood (young invest greater % of their energy into growth)
zero grazing max. energy allocated to growth
treatment w antibiotics avoids unnecessary energy losses during disease
limit space for movement, food supply, keep temp constant (warm means less energy lost to surroundings as heat)
select and produce breeds w higher growth rates incl. egg/milk production

207
Q

how to measure energy content of a sample

A

measure biomass and dry in oven at 80C until constant mass
burn in O2 in calorimeter and measure temperature increase
calculate energy content using equation

208
Q

why are there usually no more than 4 or 5 trophic levels in a food chain

A

proportion of energy transferred at each trophic level is small <20%
energy losses e.g. heat loss from resp/movement & faeces limit % energy transfer
after 4/5 tropical levels, insufficient energy to support large enough breeding population

209
Q

similarities between carbon and nitrogen cycles

A

involve inorganic gases CO2 and N2 in atmosphere
involve these elements being returned to the atmosphere by microorganisms such as decomposers releasing CO2 and N2 released by dentrifying bacteria
involve elements being fixed to organic compounds e.g. C and N both form proteins/nucleic acids
compounds are incorporated into producers and consumers
animals obtain element N or C by feeding
decomposer m/o’s e.g. bacteria/fungi
involve decomposition of organic macromolecules and the release of inorganic molecules e.g. ammonia

210
Q

differences between C and N cycles

A

C fixation provided by p/s but N fixation provided by N fixing bacteria
COI2 converted to glucose/sugars by plant, NH3 ions converted to amino acids/proteins in plants
fixed C is released into atoms by combustion/resp, N is released by denitrification
inorganic mols taken up differently by plants in each cycle: CO2 via stomata and NH3/NO3 via AT in roots
p/s only in C cycle
C cycle includes combustion of fossil fuels
N cycle involves nitrifying and N fixing bacteria
N cycle shows symbiotic mutualistic relationship between legumes and Rhizobia

211
Q

aspects of ecological niche occupied by clovers in plant comminities

A

have N fixing bacteria in root nodules
clovers decay releasing NH3 into soil
symbiotic relationship
not dependent on taking N compounds from soil (provided by Rhizobia)

212
Q

suggest factors that may prevent a plant species from colonising other habitats

A

pollution from vehicles
interspecific competiton
needs good drainage
difference in soil depth/type
cannot tolerate grazing/mowing
cannot tolerate disturbance
different nutrient levels
different light levels
agricultural activity

213
Q

suggest 2 ways in which leg haemoglobin improves performance of nitrogenase enzyme

A

transports O2 for resp/to generate ATP in Rhizobium
removes excess O2 to decrease inhibition of enzyme
anaerobic conditions for N fixation

214
Q

shape of curve for when a plant or animal starts a population in a new place

A

s shaped (sigmoid)

215
Q

describe sigmoid curve when an animal or plant starts population in a new place

A

exponential growth in first part
followed by population regulation as number of plants or animals approaches carrying capacity and negative feedback takes over
fluctuates in vicinity of carrying capacity
SOMETIMES grows so rapidly it overshoots CC before -ve feedback can stop the increase. this depletes food so severely that the -ve feedback in the form of more deaths and fewer births quickly reduced it below CC

216
Q

types of limiting factors preventing a population from increasing in size

A

density dependent factors
density independent factors

217
Q

what is a density dependent factor

A

effects depend on the density of the population (larger effect on larger pop (regulatory effect))
e.g. factor that causes an increase in deaths when pop density increases

218
Q

are density dependent factors usually abiotic or biotic

A

biotic

219
Q

examples of density dependent factors

A

food (e.g. prey more difficult to find)
oxygen conc
CO2 conc (if plant)
territory/shelter
^^ all increase competition
predation (predators are more attracted to higher density prey pops bc easier to catch)
disease (spreads more easily at higher densities)
IN EXAM Q BE SPECIFIC TO FOOD CHAIN GIVEN

220
Q

what is a density independent factor

A

factors with similar effects regardless of population density
e.g. a factor that causes deaths irrespective of the number in the population

221
Q

are density independent factors usually biotic or abiotic

A

abiotic

222
Q

examples of density independent factors

A

climate change
fire
volcano

223
Q

2 types of species

A

k and r
(k- carrying capacity)
(r- growth rate of pop)

224
Q

what is a k-strategist species

A

species whose population size is determined by the carrying capacity
limiting factors exert more and more significance as the pop size gets closer to CC, causing pop to level out

225
Q

what is an r-strategist species

A

species whose population increases so quickly it exceeds the carrying capacity before limiting factors have an effect (boom)
once carrying capacity exceeded, lack of resources and toxins lead to death/decline (bust)

226
Q

are all species k or r strategists

A

no: continuous spectrum
k and r species are the 2 ends of the spectrum: many species show characteristics of each

227
Q

examples of species w part k and part r strategist characteristics

A

sea turtle
trees

228
Q

examples of r-selected species

A

pioneer species
frogs

229
Q

examples of k-selected species

A

elephant
human
tree

230
Q

lifespan of r-selected species

A

short

231
Q

lifespan of k-selected species

A

long

232
Q

time to reproductive maturity: r selected species

A

short

233
Q

time to reproductive maturity: k selected species

A

long

234
Q

number of reproductive events: r selected species

A

many

235
Q

number of reproductive events: k selected species

A

few

236
Q

number of offspring: r selected species

A

many

237
Q

number of offspring: k selected species

A

few

238
Q

size of offspring: r selected species

A

small

239
Q

size of offspring: k selected species

A

large

240
Q

parental care: r selected species

A

none/little

241
Q

parental care: k selected species

A

lots/significant

242
Q

population growth rate: r selected species

A

fast

243
Q

population growth rate: k selected species

A

slow

244
Q

competitors: r selected species

A

poor

245
Q

competitors: k selected species

A

good

246
Q

population dynamics: r selected species

A

highly variable

247
Q

population dynamics: k selected species

A

stable near carrying capacity

248
Q

environment: r-selected species

A

unstable environment
low nitrogen content
low shade

249
Q

environment: k-selected species

A

stable environment
high nitrogen content
low light intensity

250
Q

where do predators often specialise on a single prey species

A

northern climates
e.g. Canadian lynx on snowshoe hares or Goshawks on ruffled grouse

251
Q

describe interrelationship between predator and prey population sizes

A

when pred pop increases, more prey get eaten
prey pop decreases so less food for preds
less food so fewer preds survive and pop size reduces
fewer predators so less prey eaten so pop size increases
more prey so pred pop increases and cycle restarts
PREDATOR CURVE FOLLOWS PREY CURVE

252
Q

why is no. of predators generally smaller

A

higher in food chain

253
Q

why is there a delay in change of predator pop after prey pop changes

A

takes time for the BR to respond to changing conditions

254
Q

why predator pop not competely depleted when prey pop drastically lower

A

found other food source

255
Q

other factors involved in predator prey relationship

A

higher species diversity in ecosystem means more difficult to see predator prey relationships
predator eats several kinds of prey so can switch to another if 1st species pop declines
other limiting factors (correlation not always causation, competition for food, space, mates also play a role in pop dynamics)

256
Q

what does removal of a strong competitor prey population by predators enable

A

weaker competitors to survive
reduces effect of competitive exclusion

257
Q

ecosystem benefits after reduced effect of competitive exclusion

A

increased species diversity
increases stability
ability to adapt to env change
reintroduction of wolves to Yellowstone park increased biodiversity (conservation strategy)

258
Q

what is a niche

A

species role in its ecosystem e.g. the feeding role in food chain (producer, parasite, predator), habitat, reproduction method, behaviour

259
Q

do members of same pop have same or different niche

A

same
well adapted to niche e.g. nectar feeding birds have long thin beaks

260
Q

describe infraspecific competition

A

between members of same species who share same niche
competition for food, water, territory, mates, light
comp slows growth and pop enters stationary phase
pop fluctuates around carrying capacity (stabilising effect on pop size)

261
Q

describe interspecific competition

A

between individuals of different species when their niche overlaps
greater the overlap, greater the competition
can affect pop size and distribution in an ecosystem

262
Q

example of interspecific competition: squirrels

A

Red squirrels= native species (nimble, light, put on less fat in winter, struggle to digest acorns before ripe)
Grey squirrels= introduces in 1800s (wider food range, twice as heavy, store more fat, can decimate crops of acorns before ripe and become viable food source for reds)

263
Q

competitive exclusion principle definition

A

if 2 species have exactly the same niche, one always outcompetes the other which then dies out
OR
one species may be pushed into another niche (niche partitioning)

264
Q

examples of competitive exclusion principle

A

paramecium (microscopes single celles Protozoan)
flour beetles

265
Q

competitive exclusion principle Paramecium

A

grow P.aurelia and P.caudatum together and separately
when grown separately, P.aurelia has highest pop
when grown together, competition for food, P.aurelia obtains food more efficiently, P.caudatum less so and dies out in 20 days, P.aurelia pop increases and is eventually only remaining species, P.caudatum competitively excluded

266
Q

competitive exclusion principle flour beetles

A

if Tribolium confuseum and Tribolium casteaneum grown together, one species will competitively exclude the other
small changes in temp determine which species will survive
>29C: T.casteaneum survives
<29C T.confusum survives

267
Q

describe niche partitioning barnacles example

A

Chthalamus is able to live high up and low down the shore
Balanus can only survive low down and always outcompetes Chthalamus and eventually replaces it completely
this is bc Balanus grows faster, occupies the limited space more quickly, can grow over the other barnacles or under them to lift them off the rock

268
Q
A

biology (27 decks)

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