Organisms and their Environment

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  • Created by: rachmhw
  • Created on: 10-04-19 09:59
what is the principle source of energy input to biological systems?
the sun
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why do living creatures need energy?
to maintain the metabolic reactions that keep them alive
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describe the flow of energy from the sun to animals
energy from sunlight is used by plants in photosynthesis (some energy as chemical energy), animals get energy by eat plants/ animals that eat plants, all energy is returned to environment in the form of heat
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what is a food chain?
a diagram that shows the transfer of energy from one organism to another, starting with the producer
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how is energy transferred between organisms in a food chain?
by ingestion
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how is energy transferred between trophic levels?
energy as chemical energy in organic nutrients (carbs, proteins, fats) in food
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what is a trophic level?
the position of an organism in a food chain, food web, pyramid of numbers or pyramid of biomass
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why does the amount of energy passed to each trophic level decrease?
the energy is used for respiration and lost as heat energy into environment, not all part of the organism are eat (bones), some energy is passed out as faeces
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why do food chains don't have more than 5 levels?
because the efficiency of energy transfer is about 10%, by the 5th level = very little energy left = very rare
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what is a food web?
a network of interconnected food chains
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what is a producer?
an organism that makes its own organic nutrients, usually using energy from the sun, through photosynthesis
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what is a consumer?
an organism that gets its energy by feeding on other organisms
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what are primary consumers?
a herbivore
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what is a secondary (tertiary) consumer?
a carnivore
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what is a herbivore?
an animal that gets its energy by eating plants
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what is a carnivore?
an animal that gets its energy by eating other animals
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what is a decomposer?
an organism that gets its energy from dead or waster organic material
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what is more efficient for humans; eating plants or animal products?
eating crop plants because there is more energy contained in a crop grown on that land than for a herd of animals grazing on that land
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what can food webs help predict?
what will happen if human activities affect the organisms
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what does a pyramid of numbers show?
the number of organisms at different trophic levels in a food chain. size represents number
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what does a pyramid of biomass show?
the mass of the organisms at each trophic level
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advantages of using a pyramid of biomass
if only 1 tree supplies energy for loads of insects, the producer bar would be smaller (a weird shape pyramid). Pyramid of biomass uses the mass which gives a normal shape
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what is the carbon cycle?
shows how carbon atoms move between different organisms and their environment
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what factors limit the carbon cycle?
combustion, photosynthesis , respiration, feeding, decomposition,
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what is the effect of the combustion of fossil fuels?
carbon in fossil fuels changes into carbon dioxide when burnt and goes into the air. increases amount of C02 in air
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what is the effect of cutting down forests?
cutting trees down = less photosynthesis, more C02 in air. concentration of C02 increases
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what factors limit the water cycle?
condensation, evaporation, transpiration and precipitation
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what is the nitrogen cycle?
shows how nitrogen atoms are cycled between organisms and their environment
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what is nitrogen like in the air?
as nitrogen molecules, stable, unreactive, not used by animals or plants
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what is nitrogen fixation?
changing nitrogen molecules into a more reactive form that plants can use
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how is nitrogen fixation done?
by lightning or nitrogen-fixation bacteria
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how does lightning cause nitrogen fixation?
it causes nitrogen and water in the air to combine to form nitrate ions.
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how does nitrogen-fixation bacteria work?
they change nitrogen gas into ammonium ions
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what is nitrification?
when the nitrifying bacteria change ammonium ions into nitrate ions in the soil
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how do plants use nitrate and ammonium ions?
they take them up in the roots. used to make amino acids, then to make protein
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how do animals use nitrate ions in plants?
they eat them, protein breaks down into amino acids and then built back up into different proteins
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what is deamination?
when decomposers break down dead animals and plants (and waste products) containing protein and amino acids into ammonium ions
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what is denitrification?
a group of bacteria in the soil break down nitrate ions to produce nitrogen gas
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what is population?
a group of organisms of one species, living in the same area, at the same time
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factors that affect the rate of population
limited food supply, predation and disease
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why has human population rapidly increased?
due to better access to medical treatment, a better diet, more access to clean water supply
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what are the social and environmental implications of a rapid population growth?
more demand for limited resources (water, food, land = conflict), more pollution (more C02 and more raw sewage entering waterways), crowded living conditions = disease , increased loss of habitats for other organisms
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what is community?
all of the populations of different species in an ecosystem
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what is an ecosystem?
a unit containing the community of organisms and their environment, interacting together, e.g. a decomposing log, or a lake
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what is the lag phase of a population growth curve?
start of graph, organisms are settling into their new environment
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what is the exponential (log) phase of a population growth curve?
the rapid growth of population, organisms reproduce rapidly, plenty of resources available to them, no limiting factors, birth rate > death rate
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what is the stationary phase of a population growth curve?
flat line on graph, population gets so big that resources begin to be in short supply, competition for resources, disease may spread quickly, lots of limiting factors, habitat reached its carrying capacity, death rate = birth rate
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what is the death phase of a population growth curve?
the decreasing part of the graph, usually remains steady but fluctuates from year to year, death rate > birth rate, population size rapidly falls
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what has resulted in increased food production?
agricultural machinery, chemical fertilisers, insecticides, herbicides, selective breeding
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how has agricultural machinery increased food production?
agricultural machinery to use larger areas of land and improve efficiency
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how have chemical fertilisers increased food production?
chemical fertilisers to improve yields
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how have insecticides increased food production?
insecticides to improve quality and yield
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how have herbicides increased food production?
herbicides to reduce competition with weeds
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how has selective breeding increased food production?
selective breeding to improve production by crop plants and livestock, e.g. cattle, fish and poultry
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negative impacts to an ecosystem of large-scale monocultures of crop plants
number of variety of species is very small, destroy natural ecosystem
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negative impacts to an ecosystem of intensive livestock production
cause overgrazing of land, soil erosion by wind and rain, faeces build up and cause disease, pollute waterways
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what factors contribute to famine?
extreme weather (drought, flooding) more common with climate change, growth in human population > growth in food production, poverty stopping people buying things for farming, unequal distribution of food
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what is a habitat?
a place where organisms live
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what factors contribute to habitat destruction?
increased area for food crop growth, livestock production and housing / extraction of natural resources / marine pollution
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how can humans damage/alter food webs?
by introducing a new species or by killing some species
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what are the effects of deforestation?
loss of habitat, loss of soil, increased flooding, increased carbon dioxide in the atmosphere
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explain the effect of loss of habitat
plant and animal adaptation to an area = they will not survive when the forest is cut down = extinction
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explain the effect of loss of soil
plant roots help hold soil in place, when trees are lost = soil is easily eroded by wind or water
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explain the effect of increased flooding
tree leaves help slow down rain falling to the ground = better absorption into the soil, no trees = water hits ground directly = more water runoff. also no trees to take up water from the ground
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explain the effect of increased carbon dioxide in the atmosphere
no trees = less photosynthesis to remove carbon dioxide in air. if trees are burnt = produces carbon dioxide
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what are sources of pollution?
insecticides, herbicides, nuclear fallout, chemical waste, untreated sewage
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what are the effects of using insecticides?
may kill beneficial insects (bees), slows down reproduction of plants with insect-pollinated flowers, reduce flood supplies for animals = population falls, washed into rivers/lakes = harmful to aquatic organisms
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what are the effects of using herbicides?
may kill not just weeds, harmful to insects, washed into rivers/lakes = harmful to aquatic organisms
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what are the effects of nuclear fallout?
causes radiation burns, sickness and mutations, remains for a long time
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What are the effects of chemical waste?
toxins that harm living organisms, rubbish may look bad / contain toxins
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what are the effects of untreated sewage?
can spread diseases such as cholera, contain nutrients that cause plant growth e.g. algal blooms = produce toxins that kill animals
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describe the events of eutrophication?
1.increased number of nitrate /other ions 2. increased no. of producers 3. increased decomposition after death of producers 4. increased aerobic respiration by decomposers 5. less dissolved oxygen 6. death of organisms requiring oxygen in water
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effects of non-biodegradable plastics
no broken down by decomposers, remain in area for long time, harm to living organisms, get trapped in plastic, eat plastic, block alimentary canals = death
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effects of female contraceptive hormones
get into rivers/ lakes/ sea = feminisation = male fish become female. also reduce sperm count in men
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types of pollution
land, water, air
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effects of greenhouse gases
carbon dioxide and methane = earth's temperatures to increase = climate change
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how is carbon dioxide created?
burning fossil fuels
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how is methane produced?
leakages of natural gases, produced by micro-organisms that break down rubbish, intestines of cattle
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what happens to cause the enhanced greenhouse effect?
C02 and CH4 in atmosphere = short-wave radiation from sun to go to ground = heat ground + re-emitted as longer-wave radiation = doesn't return to space = long wave radiation absorbed by C02/ CH4 = raising temps
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what is another cause of air pollution?
sulphur dioxide
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what are the effects of sulphur dioxide?
gas dissolves in water making rain water acidic = acid rain
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what does acid rain cause?
it decrease pH of water in rivers/lakes = kills animals and plants / damages trees
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when is sulphur dioxide produced?
when burning fossil fuels (especially coal)
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how can we reduce amount of sulphur dioxide?
reducing use of coal for electricity generators (renewable energy), use 'scrubbers' to extract sulphur dioxide from waste gases before released into atmosphere
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what does conservation mean?
caring for the environment
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what does sustainable resource mean?
one which is produced as rapidly as it is removed from the environment so that it does not run out
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what is sustainable development?
development providing for the needs of an increasing human population without harming the environment
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why must we conserve non-renewable resources?
because they will eventually run out
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examples of resources that we can keep renewable
planting a tree every time we cut one down OR taking right amounts of fish from sea so fish can reproduce fast enough to replace the ones taken
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how can we ensure the forests are sustainable?
by replanting at least one tress for every one cut down OR leaving enough of the trunk to all regrowth OR only cutting down some trees
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how can we ensure that harvesting fish from the sea is sustainable?
by drawing up international agreements about where and how many allowed to fish OR limiting areas and times (breeding areas / seasons) OR imposing quotas OR having license/permit system OR educate about fish OR restocking
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how can we reduce quantity of resources taken from Earth?
by recycling paper, glass, plastic, metal
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how can water be recycled?
sewage treated and returned back to waterways
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what is an endangered species?
a species that is at risk of becoming extinct
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reasons for species becoming extinct
climate change, human destruction of habitat, hunting, pollution, introduced species
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why is there a greater risk of extinction once the population sizes drop?
because the variety of alleles in the population decrease = loss of genetic variation = hard to adapt to changing environment through natural selection
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how can we conserve endangered species ?
monitoring and protecting species and habitats, education , captive breeding programmes, seed banks
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what are the reasons for conservation programmes?
reducing extinction / protecting vulnerable environments / maintaining ecosystem functions, limited to nutrient cycling and resource provision, e.g. food, drugs, fuel and genes
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what is often involved in sustainable development?
management of conflicting demands / planning and cooperation at local, national and international levels
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Card 2

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why do living creatures need energy?

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to maintain the metabolic reactions that keep them alive

Card 3

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describe the flow of energy from the sun to animals

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Card 4

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what is a food chain?

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Card 5

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how is energy transferred between organisms in a food chain?

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