ecosystems Flashcards
(83 cards)
1
Q
define ecosystem
A
all the interacting living organisms and the non-living conditions in an area
2
Q
define community
A
all the populations of living organisms in a particular habitat
3
Q
define habitat
A
the natural home or environment of an animal, plant or other organism
4
Q
define population
A
a group of organisms of the same species that live in the same place at the same time
5
Q
define species
A
the smallest and most specific taxonomic group. can breed to produce fertile offspring
6
Q
define ecology
A
the study of relations of organisms to each other and their physical surroundings
7
Q
what is meant by “ecosystems are dynamic”
A
dynamic ecosystems are constantly changing
8
Q
define biotic factor
A
the living components of an ecosystem
9
Q
define abitotic factor
A
non-living conditions of a habitat
e.g rainfall, temperature, light intensity
10
Q
define edaphic factor
A
factors to do with soil
11
Q
define food web
A
many interconnected possible routes of energy and biomass through an ecosystem
12
Q
define food chain
A
a single possible route of energy and biomass through a food web
13
Q
define trophic level
A
each stage in a food chain
14
Q
what do the arrows represent in a food web
A
direction of energy flow
15
Q
define heterotroph
A
another name for a consumer
16
Q
define consumer
A
organisms that obtain their organic molecules and energy by feeding on other organisms
17
Q
define primary consumer
A
animals that eat producers in a food chain
18
Q
define secondary consumer
A
animals that eat primary consumers in a food chain
19
Q
define tertiary consumer
A
animals that eat secondary in a food chain
20
Q
define herbivore
A
animals that eat plants - primary consumers
21
Q
define carnivore
A
animals that eat other animals - secondary consumer or higher
22
Q
define omnivore
A
animals that eat both plants and other animals
23
Q
define detritivore
A
animals that feed on detritus (dead and decaying material)
24
Q
define decomposer
A
an organism that feeds on dead organic matter, turning the organic molecules into inorganic ions
25
role of detritivores in food webs
speed up decay by breaking down dead material into smaller pieces, increasing the surface area of decomposers to work on
26
role of decomposers in food webs
decomposers break down dead organisms releasing nutrients back into the ecosystem
27
define biomass
the mass of living material present in a particular place or in particular organisms
28
define dry mass
the mass of living material remaining once all the water has been removed
29
why is dry mass is a better indicvator of biomass than fresh mass
dry mass is a more reliable measure of mass as it exculdes fluctuating water concentrations
30
how to calculate the dry mass of each trophic levels in a food chain
organisms killed and placed in an oven until water has all evaporated - 2 identical mass readings
31
how to measure the energy content of organic matter
using calorimeter - burn matter and measure temperature rise of water
32
suitable units in a terrestrial ecosystem
gm^-2 grams per metre squared
33
suitable units in an aquatic ecosystem
gm^-3 grams per metre cubed
34
how does a pyramid of numbers represent data about an ecosystem
show number of each organism in a food chain - not always pyramid shaped
easy to count, hard to draw due to variation
35
how does a pyramid of biomass represent data about an ecosystem
shows mass at each trophic level in a food chain - almost alwats pyramid shaped
easier to draw, might be skewed due to time of year or reproduction rate
36
how does a pyramid of energy represent data about an ecosystem
shows energy available from each level - always pyramid
hard to calculate
37
suitable units for the energy at each trophic level in a food chain
kJm^-2yr^-1 Kilojoules per metre squared per year
38
how is energy transferred from one trophic level to the next
transferred between trophic levels as organisms feed on eachoteher.
only a small proportion of the food is converted into a new tissue and therefore only a small proportion of the energy is available for next level to eat
39
define ecological effiency
the efficiency with which energy or biomass is transferred from one trophic level to the next
energy or biomass available after the transfer / energy or biomass available before the transfer x 100
40
why is 1-3% of sunlight is converted into chemical energy in producers
not all energy used for photosynthesis - 90% reflected, some transmitted, some is unusable wavelength
other limiting factors eg water availability
proprtion of energy lost as it is used for photosynthetic reactions
41
define gross production
total solar energy that plants convert to organic matter
42
define net production
the energy converted into biomass and therefore available to the next trophic level
43
define respiratory losses
energy used in respiration so not available to next trophic level
44
define primary production
generation of biomass in a producer
45
define secondary production
generation of biomass in a consumer
46
why consumers convert only a small amount of the biomass
not all biomass eaten
energy transferred to environment - movement and respiration
some parts eaten but indigestible - lost as faeces
some energy lost from animal in excretory matierals
47
why does biomass decreases at each trophic level in a food chain
each level receives less energy than the level before due to energy losses such as in respiration
48
why are food chains with more than 4 trophic levels rare
not enough energy available as biomass to sustain another tier of organisms
49
how have humans manipulated energy transder in farming to our advantafe
provide abiotic conditions needed ot thrive
remove competition from other species
remove threat of predators
minimise trophic levels so least amount of energy is lost
50
importance of decomposers
decomposers break down the organic matter into small inorganic molecules that can then be used by producers
51
importance of detritivores
speed up decay process by breaking down organic material into smaller pieces
52
define nitrogen fixation
conversion of nitrogen gas to ammonium compounds
53
define nitrification
conversion of ammonium compounds into nitrites and nitrates
54
define denitrification
conversion of nitrates into nitrogen gas
55
define ammonification
conversion of nitrogen compounds in dead organic matter or waste into ammonium compounds by decomposers
56
microorganisms involved in the nitrogen cycle
nitrogen fixing: rhizobium
nitrifying: nitrosomonas (ammonia to nitrites)
nitrobacter (nitrires to nitrates)
dentrification: pseudomonas dentrificians (nitrates to nitrogen)
57
why does co2 levels vary throughout time
rate of photosynthesis, so rate of use of co2 fluctuates with light intensity.
at night - co2 levels are higher as respiration continues but photosynthesis doesn't.
co2 levels lower in summer - more light = more photosynthesis
58
why have co2 levels increased over last 200 years
industry - increased burning of fossil fuels
deforestation - fewer large areas of trees - less photosynthesis removed
59
how do scientists gather data about co2 levels thousands of years ago
looking at ice at poles that formed 1000s of years ago but has never melted. - air bubbles trapped in ice
60
define succession
progressive replacement of one dominant type of species or community, until climax community is established
61
define primary succession
occurs on land that has been newly formed, no soil or organic material to begin with.
62
define secondary succession
occurs on land where soil is present but contains no plant or animal species
63
define deflected succession
when the direction of succession is affected by farming or other human activities
64
define pioneer species
the first organisms to colonise an area
65
define sere
the steps in succession
66
define climax community
final stage in succession, where community is in a stable state
67
define plagioclimax
stage in succession where artificial or natural factors prevent natrual climax community from forming
68
adaptations species have for being pioneer species
produce large number of seeds/spores to spread
seeds that germinate rapidly
able to photosynthesise
tolerance to extreme environments
ability to fix nitrogen from atmosphere - adds to mineral content of soil
69
describe effect of pioneer species on envrionment
if they die, their organic matter makes the environment more able to support other species.
70
describe how conditions of soil change as succession occurs.
weathering of bare rock produces particles that form the basis of soil.
pioneer species die and decompose = release organic product into soil
71
why does succession occur
result of changes to the environment, causing plant and animal species to change
72
define dominant species
most abundant species in an ecosystem
73
describe change in niche number and number of species as succession progresses
niche number and biodiversity increases as succession continues.
niche - role organism plays.
as succession continues, more organisms available to eat/be eated
biodiversity can dip as climax community forms if dominant species outcompetes others
74
why secondary succession is likey to occur more quickly than primary succession
soil is already present so time not spent eroding rock to form it
75
why deflected succession might occure
grazing and trampling of vegetation
removing existing vegetation to plant other crops
burning to clear forests - often leads to increase of biodiversity - nutrtient-rich ash
76
define lithosphere
plant succession that begins life on newly exposed rock surface
77
define psammosere
succession that began life on newly exposed coastal sand
78
define halosere
succession in a saline environment
79
define hydrosere
succession which occures in an area of fresh water
80
how can the abundance of plants be estimated
sampling with quadrats then multiplying up to size of whole area
81
what is capture-mark-recapture and how to estimate pop. size with it
capture as many as possible and mark them
reslease and recapture as many as possible
proportion marked will be the same as for the entire population
82
lincoln index to estimate the population size of a species
pop size = number marked x numver recaptured / number recaptured marked
83
what are the assumptions made when using capture-mark-release-recapture
population is closed - no immigration or emmigration
no deaths between samples
marked organisms must mix completely with the rest of the population between sampling.
