Principles of Ecology Flashcards
Ecology
the study of the relationships between living organisms and their environment
Habitat
the place where an organism or group of organisms live
community
all the organisms in an ecosystem or habitat
population
all the organisms of the same species living in an area
ecosystem
organisms and their (non-living) environment together
biosphere
the part of the earth where life can exist
niche
the functional role of an organism in an ecosystem (or food chain) e.g green plants are producers
main feature of a desert ecosystem
low rainfall e.g sahara
main feature of a tropical rainforest ecosystem
high rainfall and warm summers e.g West Africa and Brazil
main feature of a temperate deciduous forest ecosystem
high rainfall and warm summers e.g eastern USA and western Europe
main feature of marine ecosystem
salt water e.g oceans and sea shorts
2 types of organisms in an ecosystem
producers
consumers
producers
autotrophs - organisms that make their own food using simple molecules (mainly green plants)
consumers
heterotrophs - organisms that cannot make their own food and take in and use food made by others
3 types of consumers
primary consumers
secondary consumers
tertiary consumers
primary consumers
herbivores - organisms that eat plants, e.g rabbits eat grass, bees eat pollen
secondary consumers
carnivores - organisms that eat animals (the primary consumers) e.g foxes eat rabbits, spiders eat flies
tertiary consumers
top carnivores - organisms that eat secondary consumers e.g thrushes eat spiders
omnivores
organisms that eat both plant and animal material e.g hedgehog, blackbird
decomposers
e.g saprophytic bacteria and fungi, these organisms live and feed on dead organisms
ecosystems can only flow if
energy is constantly taken in from an external force
primary source of energy for our planet
the sun and its ecosystems
what do feeding relationships in food chains and food webs show?
the pathway of energy flow in an ecosystem
food chain
a pathway along which food is passed from one species to another
a grazing food chain
a food chain that begins with a plant (a producer)
trophic level
each feeding stage
what is passed on from one trophic level to the next
a small amount of energy
most energy is lost as
heat in respiration
why are food chains generally short?
because of the loss of energy
food web
a number of interconnected food chains
pyramid of number shows
the number of organisms at each trophic level in a food chain
as you go up the pyramid 2
size of organism increases
number of organisms decreased
2 limitations of the pyramid of numbers
number of organisms may be difficult to count accurately
does not take size of organism into account
heat energy cannot be recycled and as a result
energy flows through ecosystems in one direction only
what can be continuously recycled and reused?
biomolecule such as carbon and nitrogen
biochemical cycles
biomolecules released from the bodies of dead organisms and taken in and reused by living organisms in these cycles
how much of living matter is made up by carbon?
about 18%
major source of carbon for living organisms
CO2
4 main events in the carbon cycle
photosynthesis
respiration
decay
combustion
photosynthesis
green plants take in CO2 and use it in photosynthesis to make carbohydrate, animals get carbon by eating plants and other organisms
respiration
all living organisms breakdown carbon compounds and release CO2
decay
microorganisms (decomposers) break down dead organisms and release CO2
combustion
burning of fossil fuels releases CO2
2 reasons why CO2 in atmosphere is increasing
increased combustion of fossil fuel
increased deforestation
2 effects of global warming
rising sea levels
rising deforestation
4 molecules with nitrogen
protein, DNA, RNA, ATP
composition of air - nitrogen
80%
plants take in nitrogen as
nitrate (NO3) dissolved in soil water
what does the nitrogen cycle ensure?
that nitrogen is available for use by living organisms
continued supply of nitrogen involves 2
nitrogen fixation
recycling of nitrogen
nitrogen fixation
nitrogen gas converted to nitrate and ammonia
what does nitrogen fixation
some bacteria e.g rhizobium
where do rhizobium live?
in nodules or swellings on the roots of legumes e.g clover, soya, peas
describe the symbiosis of nitrogen - fixing bacteria
bacteria take in N2 gas and convert it to nitrate which is given to the plant the plant in return gives food and shelter to the bacteria
recycling of nitrogen
nitrates and nitrogen gas are reformed from protein in dead organisms by different bacteria in the soil
3 types of bacteria in the soil
saprophytes
nitrifying bacteria
denitrifying bacteria
saprophytes recylce
protein
ammonia
nitrifying bacteria recycle
ammonia
nitrite nitrite nitrite
denitrifying bacteria recycle
nitrate
nitrogen (N2)
2 types of environmental factors affecting organisms
abiotic (non-living) and biotic (living)
abiotic factors
the non-living features of the environment that affect living organisms
2 types of abiotic factors
edaphic
climatic
edaphic factors
factors relating to the soil
main edaphic factors
particle size humus content water content air content mineral content pH
particle size of sandy soil
contains large sand particles - tend to lose water and minerals and relatively infertile
particle size of clay soil
contains a large amount of small clay particles - retain water and minerals but tend to waterlog and become infertile
particle size of loam soil
contains a mixture of sand and clay particles and is the most fertile soil
humus
decaying organic matter in the soil that provides food, retains water and minerals and helps bind soil particles together
where do earthworms thrive?
in humus rich soil
why is water content significant ?
water is needed for photosynthesis, transpiration and general metabolism. minerals enter plats dissolved in water
air content
this provides oxygen for plant root, microorganism and animal respiration, plants don’t grow well in oxygen-poor soils e.g waterlogged soil
mineral content
minerals like magnesium and nitrogen are needed by plants for healthy growth, lack of magnesium causes yellowing of leaves or chlorosis, lack of nitrogen causes stunted growth
pH
plants and animals have certain pH requirements e.g bog mosses and heathers need an acid soil
most plants prefer neutral soil
the major climactic factors that affect the distribution and behaviour of organisms
temperature rainfall light intensity humidity day length
temperature
affects the rate of metabolism in living this. higher temperatures cause rapid plant growth in summers
lower temperatures cause the hibernation of some animals during the winter and the death of others
rainfall
provides water - essential for life and determines the distribution of terrestrial life. only plants such as cacti can live in places with low rainfall such as deserts. plants in tropical rain forests need a lot of rain
light intensity
affects the rate of photosynthesis. woodland plants e.g bluebell, flower in the spring before the leaves come on the trees and block the light
plankton in the sea grow best in the upper layers due to the higher light intensity
humidity
water vapour content of air
effect on transpiration rate of plants
high humidity in the air reduces transpiration
woodlice only live in humid conditions under rooting leaves
day length
this affects flowering and germination in plants, hibernation and reproduction in animals
5 abiotic factors that affect aquatic environments
light currents wave action salt content oxygen concentration
abiotic factors that affect aquatic environments
light
water stops light penetrating
plants confined to upper layers
rock seashore - Fucus can photosynthesis underwater because it has fucoxanthin
fucoxanthin
a pigment that traps light that filters through the water
other thing that fucus also has
air bladders that keep the plant upright in the water close to the light
abiotic factors that affect aquatic environments
currents
moving water will carry away any organisms not attached
fucus has a holdfast to attach it to rocks
abiotic factors that affect aquatic environments
wave action
this can cause physical damage to organisms, seaweeds living on a rocky seashore have flexible stalk that can withstand wave action
abiotic factors that affect aquatic environments
salt content
this causes problems relating to the movement of water in and out of organisms. in rock pools, some seaweeds and marine snails only survive due to the effect of rainwater
abiotic factors that affect aquatic environments
oxygen concentration
water has a lower concentration of oxygen than air. animals and plants living in water must have a large surface area for gaseous exchange
what are biotic factors
the influence of living organisms on each other
3 biotic factors
competition
predation
symbiosis
competition
the struggle between two or more organisms for a resource that is in short supply
what do organisms compete for?
food, space, water, light, minerals, shelter and mates
what is competition significant in?
controlling population size
2 main types of competition
contest competition
scramble competition
contest competition
involves active physical contest, one wins it all, e.g birds compete for territory
scramble competition
struggle for limited resource and resource is shared by all e.g rabbits in a field sharing available plants
3 animals in grassland
spiders
snails
earthworms
adaption of spiders
carnivores with strong mouthparts to crush their prey
adaption of snails
herbivores with a shell for protection against predators and drying out
adaption of earthworms
live in damp soil, feeding on dead organic matter
3 plants in grassland
dandelion
daisy
clover
adaption of dandelion
leaves spread out close to ground, blocking the light and prevent grass from growing. seeds are dispersed by wind
adaption of daisy
leaves spread out close to ground. new plants form from stem of parent and prevent grass from growing
adaption of clover
can grow in nitrogen-poor soil
predator
an organism that kills and eats another living organism
prey
an organism that is killed and eaten
example of predation
foxes prey on rabbits
where is predation important
in population control
what is interrelated in predation
numbers of predators and prey
increase in prey
increase in predators
increase in predators
decrease in prey
3 predators
foxes
spiders
hawks
adaption of foxes
sharp pointed teeth and very good eyesight, run very fast
adaption of spiders
strong mouthparts and release venom, use webs
adaption of hawks
sharp talons and beaks and very good eyesight
3 prey
greenfly
mice
snails
adaption of greenfly
green bodies for camouflage
adaption of mice
have large eyes and sensitive ears - furs blends into surroundings and they run and hide from predators
adaption of snails
shells for protection
symbiosis
where two organisms of different species live together and at least one benefits
organisms involved in symbiosis
symbionts
3 types of symbiosis
mutualism
parasitism
commensalism
mutualism
two organisms of different species live together and both benefit
2 examples of mutualism
bacteria in large intestine of humans produce vitamin K
nitrogen-fixing bacteria in root nodules in clover plants
parasitism
two organisms of different species live together; one called the parasite loves in or on the other (host), feeds on it and causes harm
4 examples of parasitism
fleas on skin of cats and dogs
greenfly (aphids) on rose bushes
disease - causing bacteria in humans e.g tetanus
liver fluke, flatworm that lives on cattle and sheep
where are parasites important
in controlling wild populations
commensalism
two organisms of different species live together where one benefits and the other neither benefits nor is it harmed
example of commensalism
birds nesting on a tree
population dynamics
the factors that affect the size of a population
examples of population dynamics
food availability, predators, birth, death, disease/parasite, migration in or out of an area , human activity, climate
3 ways in which humans impact on ecosystems
pollution
conservation
waste management
pollution
any harmful addition to the environment
substances that cause pollution
pollutants
3 examples of pollutants
industrial waste enters rivers and kills fish and plants
untreated sewage released into lakes and rivers can contaminate drinking water supplies and cause disease
one air pollutant
CO2
CO2 contributes to
greenhouse effect
CO2 levels rising due to
increased combustion of fossil fuels
increased deforestation
2 effects of global worming
rising sea levels
rising temperatures
control of CO2
power stations
change from burning fossil fuels to renewable energy sources such as wind power, solar energy or hydroelectricity
control of CO2
transport
change from private transport to public transport
control of CO2
electricity
reduce consumption of electricity in commercial places and in homes
control of CO2
plants
plant more trees to absorb carbon dioxide
4 pollutants from fossil fuels and their effects
CO2
SO2
smoke particles
CO
CO2
increasing levels causing global warming
SO2
causes acid rain
effects of acid rain
kills plants and animals, human breathing problems , reduced soil fertility, damage to buildings
smoke particles
may irritate human lungs and cause cancer
block sunlight and reduce photosynthesis
CO
combines with haemoglobin and reduced amount O2 carried in blood, may cause headaches
conservation
the management of the environment
benefits of conservation
maintains biodiversity prevents extinction maintains source of valuable chemicals (medicine) promotes recreation and tourism prevents pollution of air and water
one conservation practice
forestry
forestry
cutting down trees is regulated
new tees planted
deciduous and coniferous trees planted for variety
what does a variety or trees do?
encourages different birds and insects to survive
destruction of forest
brought to public awareness by the use of visitor centres and educational programmes
why are forests important
dependence
many organisms depend on the trees for food and shelter
why are forests important
erosion
trees prevent soil erosion, prevents topsoil from being washed away in rain water, this topsoil ends up in river beds as silt
why are forests important
greenhouse gases
trees reduce the greenhouse effect by absorbing carbon dioxide from the air
why are forests important
floods
absorb rainwater and prevent flooding
why is waste management necessary
to prevent pollution as much as possible
rising population has led to
huge increase in the amount of waste
3 ways to dispose of waste
stored in landfill sites
recycled
destroyed in incinerators
2 problems associated with waste disposal
shortage of landfill sites
landfill sites are unsightly, smelly and pollute local H2O
waste products in forestry
small branches, roots, tree stumps and sawdust
2 methods of waste disposal in forestry
spread on floor and allowed to rot down naturally
large branches reduced to sawdust and used to make MDF
3 roles of microorganisms in waste management
anaerobic digestion (digestors)
composting
treatment of sewage
3 products of anaerobic digestion
methane gas (fuel)
solid (sludge) for compost
liquid rich in nutrients (fertiliser)
composting
the breakdown of plant waste under aerobic conditions by bacteria and fungi.
what is sewage made up of?
waste domestic water treated in a sewage plant
what is increasing human population due to?
increase in birth rate and decrease in death rate
4 factors affecting growth in human population
disease
famine
war
contraception
