IB Biology Chapter 4 Ecology Species ,communities, and ecosystems Interdependence of Living Organisms 1980-eruption @ Mt St. Helens-see p.172
What is a species? Defined as a _____________________ Made up of organisms that Have similar physiological and morphological (ie. Size and shape of an organism and/or its parts) characteristics that can be observed or measured Have the ability to interbreed and produce fertile offspring Are genetically distinct from other organisms
Have a common phylogeny(ie.family tree) That can interbreed and produce fertile offspring Challenges to this definition: Sometimes members of separate but similar species mate and
succeed in hybrid offspring-eg.horse+zebra-produces---zebroidsboth parents belong to Equidae family-related but not same species-do not have same # csomes-why offspring usually infertile Some populations may be able to interbreed,but do not do so because they are in different niches or separated by long distances How do we classify organisms that reproduce asexually What about infertile offspring-Do we exclude humans unable to reproduce from species? What about in vitro fertilization
Domesticated dogs-while different breeds-are same species and can interbreed Hybrids To understand fertile offspring-(female) horse + (male) (female) horse + (male) (male) produce_____-mules cannot mate to make more mulesmule is called_____________________________________
(male) lion and (female) horse + (male) tiger produce liger hybrid Challenges hybrids face cont as a population inc.infertilty, Other hybrids: (female) horse + (male) horse + (male) donkey=mule (female) horse + (male) horse + (male) zebra=zorse (female) horse + (male) tiger + (male) lion=liger mule
Interspecific hybrid Populations can become isolated Grp from a species separated from rest of species may evolve differently when compared w/rest of populationeg.mice have inadvertently crossed oceans on board ships-as they searched for food-may even end up islands away-mice
produced on new islands are reproductively isolated-may end up w/ a different frequency of certain alleles-eg fur color Other things can produce isolation-such as mt. ranges-tree snails in Hawaii-present on only one side of volcano Also temporal isolation-early migrating birds may have genes isolated from later arrivals Behavioral isolation-such as different mating calls from same
species of birds Over time-some of these may result in speciation_________________________________(refer to ch 10.3) New species formed from old Autotrophs and heterotrophs Autotrophs-capable of ________ -synthesize organics from simple inorganics-usually by photosynthesis
Because the food they make is eaten by others __________ Examples-cyanobacteria,algae,grass,trees photosynthesis producers Heterotrophscannot make own food from inorganics-but
must get from other organisms-from autotrophy and heterotrophy-called ____________________because rely on others, ingest organic matter -Examples-zooplankton, fish, sheep, insects consumers E. Consumers
Heterotrophs-whether we from autotrophs or products of other heterotrophs Take in energy-rich C-compounds, such as sugars,proteins,and lipids Only part of humans diet that we synthesize is Vitamin D cholesterol molecule in our skin is modified by light into Vitamin D Detritivores
Eat non-living organic matter-dead leaves, feces, carcasses-eg. Earthworms,woodlice Saprotrophs Live on or in non-living organic matter, secreting enzymes and absorbing the products of digestion Fungi, some bacteria-decomposers
Communities Group of populations living and interacting with each other in an area 1 species may interact by feeding on another or being eaten May provide vital nutrients for another(e.g.-N-fixing
bacteria) One species may provide protection for another-e.g.aphids protected by ants One may rely on another for its habitat-e.g.-parasites Ecosystems abiotic
______________-non-living components of environment(air,water,rocks)such measurements include _______________-often using electronic probes and data-logging techniques These things have a large influence on living things ________________-living factors Random sampling using quadrats(to determine the frequency and distribution of a species)-see page 178 Systematic sampling-using a transect= a line traced from one environment to another-may be a 1,25-50 m long-may set up quadrat
every meter along transect or at specific intervals along transect-counting the organisms that hit each quadrat and then counting organisms found in each quadrat-no random numbers.see p. 179 Temp,pH,light levels,and relative humidity
biotic Where do autotrophs get their nutrients? From inorganic surroundings Photosynthetic organismsphytoplankton,cyanobacteria,and plants--photosynthesis Producers and start of food chain Nutrient Cycling
Find need nutrients w/in own habitat-C,N,etc Decomposers Accessing nutrients through decay Saprophytes and detritivores break down body parts of dead organisms Digestive enzymes convert organic matter into more usable forms for themselves
and other organisms-e.g. proteins from dead organisms are broken down into ammonia(NH3) and then, in turn ammonia has its N converted into nitrates(NO3-) by bacteria. This recycles nutrients so they are available to other organisms-instead of locked into carcasses or waste products Decomposers help w/formation of soil ________-rich black layer composed of organic debris and nutrients released by decomposers
Decomposers form humus in compost piles compost The sustainability of ecosystems Through recycling of nutrients, ecosystems can contribute to be productive and successful for long periods of time Convert CO2 to C6H12O6-by producers-used then to make complex carbs-like
cellulose or lipids and proteins Consumers eat producers, and digest the complex organic compounds into simple building blocks---amino acids and sugars,eg,for growth and energy When the consumers die,their cells and tissues are broken down by decomposersminerals retd to soil---for producers ,once again-completing cycle N-cycle-N important for nucleotides and amino acidsessential to DNA and proteins-essential to existence Cycle starts w/ N in gas form in atmosphere(N2)Plants and animals cant use N2 some bacteria transform it by N-fixing Then absorbed by plant roots(some plants
have N-fixing nodules attached to roots)----Plants and animals return N to soil in variety of wayse.g. ,retd by decomposition,byurine,feces Energy Flow Importance of sunlight to ecosystems Best studied ecosystems on earths surface, relying on sunlight-are the focus here All life relies directly or indirectly on sun
B. Role of photosynthesis Take CO2 and convert to C6H12O6 Light energy converts into chemical energy(food)-rich in energy due to chemical bonds between C and other atoms Chemical energy measured in calories or kilocalories(kilocalories on pkging)
Release energy by digesting,also to burn Food chain Process of passing energy from one organism to another
Food chain defined as _______-arrow shows direction of energy flow Trophic level=indicates how many organisms the energy has flowed through 1st trophic level has autotrophs or prodcers;next level primary consumers; next secondary consumers Sequence showing
feeding relationships band energy flow between species Cellular respiration and heat As grasshoppers consume grass, chemical energy is used for cellular respiration/glucose converted
to CO2 and H2O This takes a sm amount of heat in each of grasshoppers cellsheat lost to environment/thee nutrient and energy passed on to next consumers Cells of decomposers also do cellular respiration and thus release heat to environment Heat cannot be recycled
Heat not actually lost due to law of conservation of energy, but cannot be used again as biological energy source Where does the heat go? Heat lost from ecosystem, radiates into surrounding
environment/ecosystem cannot take back heat to use itnot recycled like nutrients Food chain only adversely affected by the lost heat if sun is lost-thus affecting food chains Only chemical energy can be used by next trophic level and only a small amount of energy absorbed is converted into chemical energy No organism can use 100% of energy in organic molecules-typically only 10-20% used from previous
step~ 90% lost Main reasons not all energy in n organism can be used by all other trophic levels: Not all of an organism is swallowed as a food sourcesome parts rejected and decay Not all food swallowed can be absorbed and used in body(e.g.-owl pellets)
__________________ There is considerable heat loss from cellular respiration @ all trophic levels-most animals have to moverequiring more energy than plants-Warm blooded animals use much more Some organisms die w/ o having been eaten by member of next
trophic level see p.188 Pyramid of energy Used to show how much and how fast energy flows from one trophic level to the next in a
community Units=energy per unit area per time=kilojoules per square meter per year(kjm-2yr-1)take into account rate of energy produced as well qty Because energy is lost-each level smaller than previouscannot have higher level wider than lower level
Food webs and energy levels in trophic levels # of organisms in a chain as well as qty sunlight energy available @ start decide length of chain Biomass of a trophic level=estimate of mass of all organisms w/in that levelexpressed in mass units, but also take into account area or volume eg.3tons acre 1yr-1 Amount of sunlight reaching fields affects biomass, therefore sunnier region produce more biomass wheat
Some molecules along the way cannot participate in biomass because they re lost-e.g. CO2 lost in cellular respiration, water during transpiration evapoartion from skin,urea lot in excretion not all energy passed to next trophic level and not all biomass passed on Sometimes foodweb rather than chain is used because there may be many feeding relationships going on III. Carbon cycling Crucial element to life
Life on earth is referred to as C-based In biosphere as carbs, lipids, nucleic acids and proteins Also in atmosphere as CO2 and lithosphere ____________________________ i.e.-places where rocks are found .
Petroleum-from which gasoline, kerosene, and plastics are made-rich in C having come from decomposed organisms of millions of years ago Constantly cycled between living organisms and inorganic processes making C available-e.g. C atoms composing the flesh of a giraffe come from the vegetation it ate When cellular respiration is complete-CO2 released into atmosphere
When organisms die, scavengers eat decomposers break downwhich release CO2 back into atmosphere from cellular respiration Glucose also starting point for other organicse.g. lipids and amino acids-which go into cell membranes and proteins-enzymes Other elements added to glucose-such as N
C in aquatic ecosystems CO2 water soluble Absorbed by bodies of water Organisms living in water also produce CO2 (by cellular respiration) ____________________________
As CO2 is dissolve in water it forms an aciddecreasing waters pH The H+ influences pH The HCO3 important inorganic C-based molecule that participates in C-cycle Cycling of CO2 Absorbed by photosynthetic autotrophs such as bacteria,
phytoplankton, plants, and trees. They are eaten by consumers, using C in their bodies Cellular respiration (hereby abbreviated as cr) from all trophic levels produce CO2releasing it back into environment
Methane in C-cycle Members of Archaea include methanogensanaerobic ___________________________ Methanogens also common in wetlands, where they produce marsh gas (may glow) Also produce CH4 in digestive tract of mammals-inc. humans-hence the concern
w/cattle herds-contribute to greenhouse effect (next section) When they metabolize food, they produce CH4 (g)-a waste gas The oxidation of methane CH4 main ingredient in fossil fuel__________________
The C found in CH4 borrowed from CO2 molecule removed from atmosphere MYA-during photosynthesis, it then took CH4(g) millions of years to form and accumulate underground When we burn natural gas, we return C to atmosphere as CO2 What would normally take millions of years to be cycled is thus released rapidly released
Natural gas Peat as a fossil fuel ____________=partially decomposed plant matter Waterlogged, found in certain wetlands-e.g. Mires and bogs in British Isles, Scandanavia, N. Russia, some of E.
Europe, N. Canada, N. China, Amazon River basin, Argentina, N. USA9esp.Alaska), ans some of S.E Asia Dark in color and only certain types of vegetation can grow on its surface-such as Sphagnum moss Heterogeneous but at least 30% of its dry mass must be composed of dead organic material peat
Soil that forms peat is called a _______________-typically 10-40 cm thick Spongy---The high levels of water on peatland force out the air that would normally be between the particles of soil-creates anaerobic conditionsThis allows microorganisms to grow but prevents growth of microorganisms that would help in plant matter
decomposition the energy rich molecules that would have been fed upon by decomposers are left behind and transformed, over thousands of years, into energy rich peat. histosol pH of waterlogged histosol-very acidic
not conducive to decomposers this contributes to the accumulation of non-decomposed material within the pools of acidic water- in these wetlands are unique organisms such as some aquatic beetles to be usable as fuel, cut peat is dried out to reduce humidity. It is then cut into slabs, granules, or blocks and moved where needed
takes a long time to form and considered nonrenewable energy when oil prices are high, peat can be a competitive energy source many wetlands have been drained to replace w/forests and farmland concern about wetland preservation has
hindered some harvesting of peatbut also because of concern about unique species also preserve because trapped pollen can reveal info about past climate Oil and gas as fossil fuels
When left in the correct conditions, partially decomposed peat can be further transformed into coal Over millions of years, sediments can accumulate above the peat and weight and pressure of those sediments compress it Under ideal conditions, sedimentation cont. until Crich deposits are both under huge pressure and exposed to high temperatures (since they have been
pushed below Earths surface) Pressure and heat cause chemical transformations associated w/lithification____________________ During lithification, the molecules are compacted and rearranged The hydrocarbons-long chains-are of particular interest to industry due to the large amount of energy they holdready to be released by burning
Coal must be extracted from below ground to be used for energy-mining Found in seams, where layers of sediments were deposited, covered, and then transformed and other twisted/deformed by geological forces over millions of years Which is the transformation of sediments into solid rock
The C-H bonds hold a significant amount of energy, and because there is many-much energy to be released by burning In addition to coal, the chemical transformations underground can produce other petro products such as crude oil and natural gas
During the __________________________period MYA, some places in the world that are now dry were underwater-hosted much aquatic or marine life-inc. algae and zooplankton The dry deserts of Saudi Arabia used to be under the Tethys ocean-in the time of Pangea At that time, under ideal conditions for petro formation, dead remains of organisms in the water
did not fully decompose @ the bottom of the oceaninstead forming layers of sediment w/silt Carboniferous In ________-no O2 conditions-the decaying material started to form sludge, as parts of organisms cells decayed and others didnt The lipid component of cells not easily broken down-the accumulated lipid trapped in sediments from a waxy substance called kerogen Kerogen is also rich in hydrocarbons and also is transformed by
pressure and heat as sediments accumulate above it and cause it to rearrange Natural production of kerogen-long process Over millions of years and after geological transformation, kerogen in porous sedimentary rock becomes crude oil or natural gas (in g state)both being less dense than rock, rising through the cracks to the surface Anoxic conditions
In order to be used by humans, petroleum products must be trapped and pooled under non-porous rock, preferably one bent by tectonic movement into a dome-as seen abovethis allows large qtys of useful gas and oil to collect together in a productive reservoir Geologists study which parts of the world might contain exploitable gas and oil reserves
CO2 is produced when fossil fuels are used Substances rich in hydrocarbons can be oxidized using O2 gas from atmosphere when they are burned Wood, animal dung, can be used-inc. for cooking Fresh, wet dung can be mixed w/other refuse from a farm and put into lg container, where methane producing microorganisms will decompose and
ferment it to produce CH4(g) Biofuels made in biogas generator take millions of years to form In efforts to reduce fossil fuel consumption, some countriese.g. USA and Brazil-have introduced biofuel programs using ethanol made from crops like corn and soybeans The plant material is fed to microorganisms that ferment it and release ethanol-which is added to gasoline for carsreduces gasoline use Standard vehicles cannot use more than 25% ethanol (need
75% or more gasoline)-gasohol Esp. adapted vehicles can run solely on ethanol w/a different technique, biodiesel can be made from vegetable oil or animal fat-such as from deep-fat fryers Limestone marine organisms remove CO2 from water and some is used to make carbonate shells
C can be in form of [email protected] dissolved in water or HCO3- ions Coral polyps build coral reefs-they absorb 2 ions from seawater to build the reef-HCO3and Ca 2+---forming CaCO3(calcium carbonate)-basis for coral reef-sturdy Other organisms also use CaCO3 to build shells about their bodies-mollusks-snails, clams, oysters, and musselswhen
they die their shells accumulate at bottom of ocean Microscopic foraminifera are usually on ocean floor and build shells---their shells accumulating in sediment after millions of years through lithificationforming limestone A bldg. material Carbon sequestration-taking C out of environment and locking-up in a substance for an extended period of timeif natural its bio- sequestration-helps maintain balance in c
cycle Through biosequestration-accumulation of foraminifera shells as sediment at bottom of ocean can trap C in limestone for millions of years Making of cement by people sues limestone-releases C back to atmosphere as CO2
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