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45 Cards in this Set
- Front
- Back
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What is the principal source of energy input to biological systems? |
THE SUN |
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Describe the flow of energy through living organisms |
light energy from the sun chemical energy in organisms: 1) producer 2) consumer 3) decomposer eventual transfer to the envrionment |
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Define food chain |
as showing the transfer of energy from one organism to the next, beginning with a producer |
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How is energy transferred between organisms in a food chain? |
ingestion |
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Ingestion in food chains is how...? |
energy is transferred between organisms |
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Describe how energy is transferred between trophic levels |
- |
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Define trophic level |
as the position of an organism in a food chain, food web, pyramid of numbers or pyramid of biomass |
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Define food web |
as a network of interconnected food chains |
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Define producer |
an organism that usually makes it own organic nutrients, usually using energy from sunlight, through photysnthesis |
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Define consumer |
as an organism that gets its energy by eating other animals |
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What may consumers be classed as? |
-primary -secondary -tertiary according to their position in a food chain |
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Define herbivore |
animal that gets its energy by eating other plants |
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Define carnivore |
as an animal that gets its energy by eating other animals |
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Define decomposer |
as an organism that gets it energy from dead or waste organic material |
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Identify producers, primary consumers, secondary consumers, tertiary consumers and quaternery consumers as the trophic levels in food webs, chains and pyramids of numbers and biomass |
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Explain why the transfer of energy from one trophic level to another is inefficient |
energy is lost in transfer from one level to another -as heat energy to the environment -consumers lose energy in faeces and urine, not digested |
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Energy losses in ecosystem diagram |
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Explain why food chains usually have fewer than five trophic levels |
on average 90% of energy is lost at each level -very little energy entering the chain through the producer is available to the top consumer |
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Explain why there is a greater efficiency in supplying plants as human food, and that there is a relative inefficiency in feeding crop plants to livestock that will be used as food |
energy losses can be reduced, as you are removing a trophic level and feeding the producers directly to the top consumers |
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Effects of over-harvesting |
-causes reduction in numbers of species to a point where the species becomes endangered or made extinct |
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Effects of introducing a foreign species to a habitat |
-food chains and webs disrupted |
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Draw describe and interpret pyramids of biomass |
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Pyramid of numbers |
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Discuss the advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain |
-pyramid of numbers does not take into account the size of organisms at each tropic level -pyramid of numbers can be inverted |
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What is the biomass of an organism? |
mass of living material |
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The CARBON CYCLE |
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Effects of combustion of fossil fuels |
-increase in concentration of carbon dioxide in atmosphere -causing a rise in the Earth's temperature (global warming) |
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Effects of cutting down of forests |
-increase in atmospheric carbon dioxide -trees are responsible for removing gaseous carbon dioxide and trapping carbon in organic molecules -when trees are cut down the amount of photosynthesis globally is reduced |
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THE WATER CYCLE |
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THE NITROGEN CYCLE |
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State the roles of micro-organisms in the nitrogen cycle |
decomposition -when plant/animal dies its tissues decompose as a result of bacteria nitrification -bacteria oxidise ammonium comounds to nitrates, and other bacteria oxidise nitrites to nitrates nitrogen fixation -bacteria that can absorb nitrogen as a gas from air spaces in the soil and build it into compounds of ammonia denitrification -bacteria obtain their energy by breaking down nitrates to nitrogen gas, which then escapes from the soil into the atmosphere |
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Define population |
as a group of organisms, of the same species, living in the same area, at the same time |
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Define community |
as all of the populations of different species in an ecosystem |
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Define ecosystem |
as a unit containing the community of organisms and their environment, interacting together a decomposing log, or a lake |
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State the factors affecting the rate of population growth for a population of an organism |
food supply -good food supply, population increases, enable orgnisms to produce mroe offspring -food shortage can result in starvation leading to death, decreasing the population predation -heavy predation means that organisms may not be able to reproduce enough to replace those that have been eaten disease -spreads easily from one individual to another |
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Factors affecting the increase in size of the human population |
increase in life expectancy reduction in death rate -agricultural development, improvements in nutrition -housing and sanitation improvements reduce infections and diseases -new medication |
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Population pyramid |
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Sigmoid population growth curve |
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Label phases in the sigmoid population growth curve in an environment with limited resources |
A- lag phase (population is small, although numbers double at each generation this does not lead to a huge change) B- exponential (log) phase (cont. doubling of population at each generation, considerable competition for food and space, growth rate starts to slow) C- stationary phase (resources no longer support an increasing population, limiting factors start to have an effect) D- death phase (mortality rate is greater than the reproduction rate, population begins to drop, fewer offspring live to reproduce) |
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What does the sigmoid curve show? |
the characteristic growth pattern of a population where food is abundant at first |
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Limiting factors of population growth |
competition PLANTS: -abiotic limiting factors (non-biological_ -biotic limiting factors (biological) |
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What are abiotic limiting factors to population growth? |
NON-BIOLOGICAL FACTORS plant populations affected by: -rainfall, temperature change, light intensity animals affected by: -seasonal changes |
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What are biotic limiting factors to population growth? |
BIOLOGICAL FACTORS plant populations affected by: -eaten by grazing animals, spread of fungus diseases animals affected by: -availability of food, competition for nest spaces, predation, parasitism and disease |
