4. ecology and the environment Flashcards
done
define population
group of organisms of the same species living in the same place at the same time
define community
all of the populations living in the same area at the same time
what is interdependence
within a community, each species depends on others for food, shelter, pollination, seed dispersal etc- if one is removed it can affect the whole community
define habitat
the place where an organism lives
define ecosystem
all the biotic factors and all the abiotic factors that interact within an area at one time (non and living components)
define biodiversity
the range and variety of different species or organisms on earth, or within an ecosystem
why is biodiversity important?
- different species depend on each other for food, shelter and maintenance of the physical environment
- high biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for the reasons above
- populations with high diversity are also more likely to be resilient to sudden environmental impacts or disease
what is an abiotic factor?
non living
e.g. temperature, light intensity and wind speed
how does light intensity affect a community
light is needed by plants for photosynthesis, more light leads to an increase in the rate of photosynthesis and an increase in plant growth rate
how does temperature affect a community
affects the rate of photosynthesis in plants
how does moisture levels affect a community
plants and animals require water to survive
how does soil pH and mineral content affect a community
different species of plants are adapted to different soil pH levels and nutrient concentration levels
how does wind intensity and direction affect a community
wind speed affects transpiration rate in plants, transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves
how does carbon dioxide levels affect a community
co2 is required for photosynthesis in plants, so affects the rate of photosynthesis
how does oxygen levels affect a community
some aquatic animals (like fish) can only survive in water with high oxygen concentrations
what is a biotic factor
living factor
e.g. competition, predation and disease
how does availability of food affect a community
more food means organisms have a higher chance of surviving and reproducing, this means their populations can increase
how does new predators affect a community
in balanced ecosystems, predators catch enough prey to survive but not so many that they wipe out the prey population, if a new predator is introduced to the ecosystem, it may become unbalanced
how does new pathogens affect a community
if a new pathogen enters an ecosystem, the populations living there will have no immunity of resistance to it and the population may decline or be wiped out
how does competition affect a community
if 2 species compete for the same resource(s) and one is better adapted to take advantage, then the species will outcompete the other, this may continue until there are too few members of the lesser adapted species to breed successfully
what are trophic levels
- term used to describe the feeding relationships between organisms
- is the level occupied by an organism within a food chain or food web
what are producers
they produce their own organic nutrients usually using energy from sunlight
what are primary consumers
herbivores- they feed on producers (plants)
what are secondary consumers
predators that feed on primary consumers
what are tertiary consumers
predators that feed on secondary consumers
true or false:
animals can be at different trophic levels within the same food web as they may both eat primary, secondary and/ or tertiary consumers
true!
what are decomposers
bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste (such as faeces) by secreting enzymes to break them down
why are food webs are more realistic way of showing connections between organisms within an ecosystem instead of a food chain?
as animals rarely exist on just one type of food source
what does a food chain show
the transfer of energy from one organism to the next
fill in the blank:
a food web shows the _______________ of organisms
interdependence
what are most of the changes in populations or animals and plants a result of?
human impact- either by overharvesting of food species or by the introduction or foreign species to a habitat
what are pyramids of numbers
- shows the number of organisms at each trophic level
- the width of the bars represents the relative number of organisms at that trophic level
- the bottom bar will always be a producer
- not always pyramid shaped
what is a pyramid of energy
- shows the amount of energy at each trophic level
- always the shape of a pyramid- as energy is lost at each trophic level (about 10% transferred)
what is a pyramid of biomass
- represents the dry mass of organisms at each trophic level
- the unit is usually mas per surface area
- will always have a pyramid shape as biomass decreases
- represents quantity of organisms and interdependence more accurately
what is the equation for percentage efficiency transfer
percentage efficiency transfer = biomass in higher trophic level / biomass in lower trophic level x100
fill in the blanks:
_________ convert light energy into _______ energy- this occurs during ___________, when producers convert co2 and h2o into _______ and oxygen
producers use this glucose (during __________) to produce their own _______ (a store of chemical energy)
producers
chemical
photosynthesis
glucose
respiration
biomass
fill in the blanks:
when _______ consumers eat producers, they break down the biomass of the producer (________) and use the ______ energy to ______ or sustain their own biomass
(same thing occurs when ________ consumers eat primary consumers)
in this way chemical energy and _______ is _________ from one trophic level to the next
primary
digestion
chemical
increase
secondary
biomass
transferred
approximately what % of energy is transferred at each trophic level
10%
how is energy lost at each trophic level
- energy is used for movement
- used to generate heat
- for metabolic processes
- some is lost as waste (carbon dioxide, water, urea)
- not all the ingested material is digested and absorbed- some is egested as faeces
- some biological material is inedible (like bones and fur)
what do nitrogen fixing bacteria do in the nitrogen cycle
convert nitrogen gas and convert it into nitrates in the soil
found in soil and in the root nodules of certain plants like peas and beans
lightning also does this
can be called nitrogen fixation
what do nitrifying bacteria do
convert ammonium ions into nitrates, which can then be absorbed by plants
can be called nitrification
what do denitrifying bacteria do
take nitrates out of the soil and convert them back into nitrogen gas
can be called denitrification
what is the consequence of sulfur dioxide pollution
combines with water vapour to form acid rain, which damages plants, aquatic life and soil. can also cause respiratory problems in humans
what is the consequence of carbon monoxide pollution
binds irreversibly to haemoglobin, which reduces oxygen transport in blood, can lead to suffocation and death in high concentrations
name 5 greenhouse gases
water vapour, carbon dioxide, methane, nitrous oxides, CFCs
fill in the gaps!
human activities have led to increasing levels of ______ _______ and ______ in the atmosphere
CO2 is produced during the __________ of fossil fuel
methane is produced by _____ as they digest grass, and released by rice paddy fields
carbon dioxide
methane
combustion
cattle
describe the greenhouse effect process
- the sun emits rays that enter the earth’s atmosphere
- heat bounces back from the earth’s surface
- some heat is reflected back out into space
- some heat is absorbed by greenhouse gases and is trapped within the earth’s atmosphere- this is normal
the enhanced greenhouse effect happens when increasing levels of greenhouse gases from human activities cause the earths average temperature to rise above normal- leading to global warming
when does the enhanced greenhouse effect happen
when increasing levels of greenhouse gases from human activities cause the earths average temperature to rise above normal- leading to global warming
what are the consequences of global warming?
- ocean temperatures increasing (causes polar ice caps to melt, rising sea levels- flooding, coral bleaching)
- increasing temperatures (causes extreme weather like super storms, flooding, droughts)
- changes in or loss of habitats
- decreases in biodiversity (as food chains are disrupted and extinction rates increase)
- increases in migration of species to new places, including increased spread of pests and disease
what is the uptake of carbon by living organisms
- carbon dioxide is taken out of the atmosphere in the form of carbon dioxide by plants during photosynthesis
- the carbon is used to make glucose, which can be turned into carbohydrates, fats and proteins within the biomass of plants
what is the transfer of carbon between living organisms
- carbon is passed from plants to animals when herbivores feed
- carbon passes between animals when carnivores feed
what is the release of carbon into the atmosphere
- carbon returns to the atmosphere in the form of carbon dioxide during respiration (respiration occurs in plants and animals, microorganisms such as bacteria and fungi use dead and waste material to fuel respiration releasing CO2 during decomposition)
- if animals and plants die in conditions where decomposers are not present the carbon in their bodies can be converted into fossil fuels; these can be burned to release carbon dioxide into the atmosphere by combustion
what are the stages of the carbon cycle
respiration, photosynthesis, decomposition and combustion
what is eutrophication
the process when minerals from agricultural fertilisers leach into water bodies (such as lakes and streams)
what happens after eutrophication (what are the biological consequences of eutrophication)
- fertilisers are high in nitrogen (essential mineral for plant growth) so can result in the overgrowth of aquatic plants and algae at the water surface
- aquatic plants below the surface die due to reduced light levels and are broken down by decomposers
- decomposers increase, and the increased respiration of them uses up oxygen in the water- reducing dissolved oxygen levels
- the water no longer contains enough oxygen so many aquatic organisms die
when can water pollution occur
- when sewage is washed into waterways
- e.g. when sewers overflow or agricultural waste is washed off fields due to heavy rain
- can result in an increase in the number of pathogenic bacteria present
what are the effects of sewage pollution
- causes an increase in growth of aerobic bacteria, which feed on biological waste
- these reduce the availability of dissolved oxygen in water
- aquatic organisms that are sensitive to oxygen levels die, leaving only organisms that can survive at low concentrations of oxygen
- therefore the aquatic ecosystems decrease in biodiversity
what are the effects of deforestation
- leaching
- soil erosion
- disturbance of evapotranspiration (water cycle disturbance)
- disturbance of the carbon cycle (+ increased global warming/ balance of atmospheric gases)
what is leaching as an effect of deforestation
soil minerals are not taken up by trees and are instead washed away by rain into nearby bodies of water
what is soil erosion as an effect of deforestation
soil is not held together by tree roots and organic matter, so is more likely to be washed and/ or blown away
what is water cycle disturbance as an effect of deforestation
the removal of trees reduces the release of water vapour into the atmosphere by transpiration, reducing cloud formation and rainfall
what is carbon cycle disturbance and increased global warming as an effect of deforestation
- the removal of trees reduces photosynthesis, so less carbon dioxide is removed from the atmosphere and stored in plant tissues
- combustion of felled trees increases release of carbon dioxide into the atmosphere
