Holt Environmental Science Ch 5

when a plant uses sunlight to make sugar molecules
organisms that make their own food by photosynthesis
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organism that obtains its energy by feeding on other organisms
consumers that only eat plants
consumers that eat both plants and animals
consumers that only eat other animals
organisms that break down food to yield energy
process of breaking down food to yield energy
Cellular Respiration
Series of levels in which organisms transfer energy by eating and being eaten
Food Chain
Overlapping food chains
Food Web
each step in the transfer of energy, comes in the form of sugars which an organism breaks down for energy
Trophic level
Each time one organism eats another, a transfer of energy comes in the form of sugars which an organism breaks down for energy
How does energy get from one organism to another?
Plants need the sun to live. animals need plants and other animals need those animals. we need those animals to get our energy from our food and so everything come directly from the sun
why do scientists say that life on earth depends on the sun?
by converting carbon dioxide into oxygen during photosynthesis and by serving as a food source for other organisms
what do producers do in the ecosystem?
Herbivores get energy from eating plants
Omnivores get energy from eating plants and animals
explain the difference between an herbivore and an omnivore?
energy flows up a food chain. from primary producers to consumers the food chain the energy is transferred by heat and movement
compare energy transfer in a food chain to energy transfer in a food web
process by which carbon is cycled between the atmosphere, land, water, and organisms
carbon cycle
deposits of coal, oil, and natural gas underground
fossil fuels
organisms that can fix atmospheric nitrogen into chemical compounds
nitrogen-fixing bacteria
process in which nitrogen is cycled between the atmosphere, bacteria, other organisms
nitrogen cycle
movement of phosphorous from the environment to organisms and then back
phosphorous cycle
short term cycle – carbon dioxide in the atmosphere is absorbed by plants during photosynthesis to make carbohydrates/ animals eat plants producing carbon dioxide during cellular respiration/ decomposition of dead organisms also puts carbon dioxide back into the atmosphere
long term cycle – carbon is converted to carbonates and stored in shells, limestone and coral reefs/ some dead organisms are converted into fossil fuels
describe the short-term cycle and the long-term cycle of the carbon cycle
it increases the amount of carbon in the atmosphere and decreases the amount of carbon on earth
describe how the burning of fossil fuels affect the carbon cycle
washed from the land with run off water laden with fertilizer ends up in streams and ponds where it promotes plant growth called algal blooms. when these organisms die the action of bacterial decomposition uses up the available oxygen. organisms that require that dissolved oxygen die.
explain how the excessive use of fertilizer affects the nitrogen cycle and the phosphorous cycle
phosphorous rarely occurs as a gas and therefore the cycle takes longer to complete
explain why the phosphorous cycle occurs more slowly than both the carbon cycle and the nitrogen cycle
carbon cycle – acts as a decomposer, breaking down dead organisms and freeing nutrients so they may be reused
nitrogen cycle – special bacteria , nitrogen fixing bacteria convert atmospheric nitrogen to ammonia and nitrates for use by plants
phosphorous cycle – detrifying bacteria break down dead organisms and release nitrogen gas back into the atmosphere
why are bacteria so important in the carbon, nitrogen, and phosphorous cycles? What role do bacteria play in each?
carbon – proteins, fats, carbohydrates
nitrogen – build proteins
phosphorous – make up the cells
how are the following elements used in organisms?
solar power
what is one way that a person can help to reduce the level of carbon dioxide in the atmosphere?
gradual process of change and replacement of the types of species in a community
ecological succession
type of succession that occurs on a surface where no ecosystem existed before (rocks, sand, dunes)
primary succession
more common type of succession, occurs on surface where ecosystems existed before
secondary succession
the 1st organisms to colonize any newly available area and begin the process of ecological succession
pioneer species
a final and stable community
climax community
primary – starts from bare rock with no previous ecosystem and takes a very long time
secondary – starts from the remains of a previously existing ecosystem that had been wiped out by a catastrophic event & takes a relatively short time
what is the difference between primary and secondary succession?
they begin the process of modifying the environment so that the next organism can come in since they are one of the first organisms to arrive in an area
describe the role a pioneer species plays during the process of ecological succession?
1. some trees may need fire to weaken the wax holding their cones closed
2. some animals in the ecosystem depend on fire to burn out undergrowth
why is putting out forest fires damaging in the long run
lichens can grow without soil BUT can make soil so other organisms can grow
why are lichens good for primary succession? How are they similar to the weeds in old-field succession? How are they different?
secondary. the previously existing aquatic ecosystem is replaced by a terrestrial ecosystem
over a period of 1,000 years, a lake becomes a maple forest. is this process primary or secondary succession?

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