Presentation on theme: "Advanced Higher Biology"— Presentation transcript:
1Advanced Higher Biology Environmental Biology UnitAnderson High SchoolCR
2Environmental Biology The Environment and its ecosystems have political, economic and ethical dimensions due to their impact on the human speciesThis unit will help you to understand the interactions between organisms and their environment, and the human influence on the world around us
3Advanced Higher Assessment Environmental Biology is a 40 hour UnitInvolves lectures, tutorials, discussions, practical work, presentations and assessments all to help with the learning process and in preparation for University LifeNAB (sit in March after Prelims)Assessment – 2 ½ Hours (Feb & May)
4Environmental Biology 10 Topics 1 Energy Fixation2 Circulation of Nutrients3 Biotic Interactions4 Symbiotic Relationships5 Costs/Benefits of Competition6 Survival Strategies7 Succession8 Intensive Food Production9 Increase in Energy Needs10 Pollution
51. Energy Fixation Autotrophs Heterotrophs Saprotrophs Energy is required by all organisms for cellular activities, growth & reproductionThe fixation of energy occurs in photosynthesis by autotrophsAutotrophs (are producers) that change light energy into chemical energy to make organic moleculesHeterotrophs (are consumers) that must feed on other plants or animals to get a ready made supply of organic moleculesSaprotrophs (are decomposers) that use the organic materials from waste and dead organisms as an energy sourceAutotrophs Heterotrophs Saprotrophs
6Energy CalculationsGross Primary Productivity (GPP) is the total amount of light energy converted to chemical energy by autotrophsNot all energy produced by autotrophs is available for consumers as autotrophs use up some of the food in respiration for their own metabolic needsNet Primary Productivity (NPP)NPP= GPP – energy used in respiration.Therefore NPP is the energy available to all other organisms in an ecosystem after producer respirationPrimary productivity is measured using the biomass of vegetation added to a given area in a given time e.g. g/m2/year
7Feeding Relationships Herbivores feed on plant material & Carnivores feed on animalsDecomposers are organisms (e.g. bacteria and fungi) (saprotrophs) that breakdown organic matter by secreting digestive enzymesDetritivores are organisms (e.g. earthworms & woodlice) that feed on detritus (decomposing material)Primary consumers are herbivores that feed directly on producersSecondary consumers are carnivores that feed on primary consumersTertiary consumers are carnivores that feed on secondary consumersA trophic level is a feeding level present in a food chain or food webEnergy flow in a food chain or food web is represented by arrowsEnergy transfer is not very efficient. Only 10% of energy at one trophic level is passed on to the next level
8Biological PyramidsPyramids of numbers represent the number of organisms at each trophic levelPyramids of biomass represent the mass of organisms at each trophic levelPyramids of productivity represent the energy available at each trophic levelIn an ecosystem, productivity, biomass and numbers of organisms tend to decrease at each trophic levelThe ultimate loss of energy is in the form of HEAT (from respiration)
92. Circulation of Nutrients Decomposition is the breakdown of organic matter with the release of inorganic nutrients into the surrounding soilInorganic ions are released from decomposing matter in a process called mineralisationDecomposers and Detritivores are involved in decomposing organic matterUndecomposed material is called litterCompletely decomposed matter is called humusInvertebrate detritivores (e.g. worms) increase the decomposition rate as they reduce the particle size of the detritus, making it easier for the decomposers (bacteria & fungi) to break down detritus to form humusDecomposers are the ultimate releasers of energy and carbon dioxide fixed in photosynthesisNutrients must be recycled for the primary producers to useDetritivores (e.g. worms)Decomposers (e.g. wood fungi)
10Nitrogen CycleThere are 4 main stages – Fixation, Nitrification, Denitrification and Ammonification1. Fixation is when Atmospheric Nitrogen is converted to AmmoniaFree living cyanobacteria in the soil fix nitrogenRhizobium bacteria in the root nodules of legumes fix nitrogenCyanobacteria & Rhizobium bacteria have an enzyme complex called nitrogenise which converts atmospheric nitrogen to ammonia with the use of ATPThe plant (legume) and the Rhizobium bacteria produce a molecule called Legheamoglobin. This molecule binds with oxygen which is really important as nitrogen fixation is an anaerobic process2. Nitrification is when Ammonium is converted to Nitrites then to NitratesNitrosomonas and Nitrobacter bacteria carry out this processThe nitrates are then used by plants to make proteins & nucleic acids (assimilation)Nitrates can be lost by leaching and denitrifying bacteria (Pseudomonas)3. Denitrification is when Nitrates are converted back to Atmospheric NitrogenDenitrifying bacteria (Agrobacterium) are involved4. Ammonification is when organic nitrogen in Proteins is converted into ammonia by decomposers (bacteria & fungi)Water saturation and anaerobic conditions affect the cycling of nitrogen
14Nitrogen FixationFixation is when Atmospheric Nitrogen is converted to AmmoniaFree living cyanobacteria in the soil fix nitrogenRhizobium bacteria in the root nodules of legumes fix nitrogenCyanobacteria & Rhizobium bacteria have an enzyme complex called nitrogenise which converts atmospheric nitrogen to ammonia with the use of ATPThe plant (legume) and the Rhizobium bacteria produce a molecule called Legheamoglobin. This molecule binds with oxygen which is really important as nitrogen fixation is an anaerobic processCyanobacteriaRhizobiumRoot NodulesClover
15NitrificationNitrification is when Ammonium is converted to Nitrites then to NitratesNitrosomonas and Nitrobacter bacteria carry out this processThe nitrates are then used by plants to make proteins & nucleic acids (assimilation)Nitrates can be lost by leaching and denitrifying bacteria (Pseudomonas)
16DenitrificationDenitrification is when Nitrates are converted back to Atmospheric NitrogenDenitrifying bacteria (Agrobacterium) are involvedNitrates Atmospheric NitrogenAgrobacteria
17Ammonification Ammonification is when organic nitrogen in Proteins is converted into ammonia bydecomposers (bacteria & fungi)Nitrogen Ammonia
19Phosphorus Cycle Phosphorus Cycle Phosphorus is added to the soil by the weathering of rocks, taken up by primary producers and returned by decompositionPhosphorus is a main component of nucleic acids, phospholipids, ATP, bones, teethPhosphorus is organic, doesn’t have a gaseous form, so the only inorganic form is phosphatePhosphate is a limiting factor in the productivity of aquatic ecosystemsPhosphate enrichment can lead to eutrophication (algal blooms)Eutrophication is when plant and algal growth is over stimulated in a water ecosystem.Fertilisers running into water systems, added nitrogen or phosphate to lochs etc can cause this over stimulationThe plants and algae eventually die, which reduces the oxygen in the water, so fish and other organisms eventually die
213. Biotic InteractionsBiotic components of an ecosystem are living factors e.g. predation, disease, food supply, competitionAbiotic components of an ecosystem are non-living factors e.g. temperature, light intensity, soil pH, availability of waterDensity dependent factors are factors that can regulate a population. These factors increase as population size increases e.g. predation, disease, food supply, competitionDensity independent factors are factors that can regulate a population. These factors are independent of population size e.g. hurricanes, forest firesInterspecific Competition is interactions between individuals of different speciesIntraspecific Competition is interactions between individuals of the same species and is more intense that Interspecific CompetitionPredator/Prey interactions are cyclical, but slightly out of phase with each other due to the changes in predator numbers lagging behind those of the prey (e.g. Lynx – Snowshoe Hare)Predators have a role in maintaining species diversity in ecosystems by controlling the numbers of more dominant competitors in an ecosystem, thus allowing weaker competitors to survive
22Defence Against Predation 3 Main Defences:-1. Camouflage Camouflage is when the organisms colouring or pattern allows it to merge into the backgrounda) Crypsis – hiding to reduce the risk of predationb) Disruptive Colouration – patterns on body don’t match outline2. Warning Colouration Warning Colouration is when organisms are brightly coloured to warn predators that they are dangerous to eat3. Mimicry Mimicry is when an organism bears a resemblance to a harmful speciesa) Batesian mimicry is when an edible or harmless species mimics a poisonous or harmful speciesb) Mullerian mimicry is when 2 or more species have evolved to have the same or similar warning signals
23CamouflageCamouflage is when the organisms colouring or pattern allows it themerge into the background. 2 Types:-a) Crypsis – hiding to reduce the risk of predation (e.g. stick insects)b) Disruptive Colouration – patterns on body don’t match outline (e.g. zebra)
24Warning Colouration Warning Colouration is when organisms are brightly coloured to warn predators that theyare dangerous to eat!e.g. yellow and black markings of wasps
25Mimicry Mimicry is when an organism bears a resemblance to a harmful speciesa) Batesian mimicry is when an edible or harmless species mimics a poisonous orharmful species (e.g. harmless robber fly has similar colourings to a wasp)b) Mullerian mimicry is when 2 or more species have evolved to have the same orsimilar warning signals (e.g. social wasps and caterpillars of cinnabar wasps)Harmless Robber flyHarmful waspWaspCinnabar Caterpillar
26Grazing A grazer is defined as any species that moves from one victim to another, feeding on apart of each victim butdoesn’t actually kill itModerate grazing can increasethe biodiversity of speciespresent as grazing reduces thenumber of dominant grassesand other plants with basalmeristems, which allows weakercompetitors to survive
27Competition Competition is when organisms require the same resource Interference Competition results when two or more species actually fight over resources and one species prevents another species from using the resourceExploitation Competition results when two or more species use the same resources, thus reducing the resources available for all.
28Niche For A’Higher the term Niche means:- “the feeding role that a species plays within acommunity”A fundamental niche is the set of resources aspecies is capable of using if there is nocompetitionA realised niche is the set of resourcesactually used by the species due toResource partitioning is the dividing up ofeach resource by species specialisation andadaptation (e.g. different lengths of beaks inwading birds)Competitive Exclusion Principle is when twospecies compete for the same resource, butone species will dominate and the otherspecies will move away
30Exotic SpeciesExotic species are species that have been introduced deliberately or by accident and it may have damaging effects on native species e.g. New Zealand Platyhelminth (flatworm)This worm has a detrimental effect on earth worms and thus effects soil ecosystems
314. Symbiotic Relationships Symbiosis is the relationships between organisms of different species that show an intimate association with each other, involving at least one species gaining a nutritional advantageExamples of Symbiosis areParasitism, Commensalism, and Mutulaism
32ParasitismParasitism is a biotic interaction which is beneficial to one species (the parasite) and detrimental to the other species (the host) e.g. tapeworm and humansAn obligate parasite cannot survive without the host organismA facultative parasite can live with or without the hostEndoparasites live within a hosts body e.g. tapeworms, liver flukes, malarial parasitesEctoparasites live on the surface of the host e.g. ticks, fleas, leechesEctoparasite – Dog TickEndoparasite – human tape worm
33Host-Parasite Balance A balance exists between the parasite and the host so that there is a relatively stable relationshipParasites can be transmitted to new hosts can be by: -direct contact e.g. head lice and humans touching each otherresistant stages e.g. liver fluke in snail hosts are dormant in water, then sheep drink water and the fluke becomes activesecondary hosts (vectors) e.g. mosquitoes transmit the malarial parasiteHost-parasite specificity gives evidence of evolutionary adaptation e.g. immunity
34CommensalismCommensalism is a biotic interaction beneficial to one species (commensal) and the other species in unaffectedEgrets feed on the ectoparasites on back of elephantClownfish feed on scraps of dead prey of sea anemone
35MutualismMutualism is a biotic interaction beneficial to both species.The anemone is taken to new habitats when the crab moves so the crab gets to new food sourcesThe crab gains protection from predators from the anemones stinging cells
365. Costs/Benefits of Interactions Competition (-/-)Predation (+/-)Parasitism (+/-)Commensalism (+/0)Mutualism (+/+)The health of the host and environmental factors can change the balance of symbiotic relationshipsHumans can manage environmental factors by the use of drugs and pesticides to help improve human, animal and plant health.Herbicides are used in the management of plant competition
376. Survival StrategiesRegulators maintain their internal environment regardless of the external environmentregulators have homeostatic controlosmoregulators can maintain a stable internal water concentrationshomeotherms can maintain a stable internal temperateExamples are mammals, insects & birdsConformers cannot maintain their internal environmentconformers do not have homeostatic controlosmoconformers are isotonic to their surroundingspoikilotherms internal temperature varies with the external environmentExamples are snakes, lizards and marine fishRegulators can occupy a wide range of habitats due to homeostatic mechanisms but conformers have a restricted habitat occupation
38DormancyDormancy is a way that many organisms can resist or tolerate environmental conditionsPredictive dormancy occurs before the adverse conditions. It is triggered by environmental conditions e.g. decreasing temperature or photoperiod (and is largely under genetic control)Consequential dormancy occurs immediately as a direct result of changing environmental conditionsDifferent forms of dormancy include:- resting spores, diapause, hibernation & aestivation
39Types of DormancyResting spores – dormancy in seeds. A hard case surrounds the dehydrated seed or spore until conditions are beneficial (e.g. warmer temperatures)Diapause – dormancy in insects and deer. Insects won’t develop until better conditions in spring and deer mate at a particular time so the young are born in spring.Hibernation – bears, squirrels. Inactivity time used to escape cold weather conditions and scarce food suppliesAestivation – inactivity time associated with hot, dry periods. Organism remains in a state of torpor with a reduced metabolic rate e.g. desert frogs & lungfish
407. SuccessionEcological succession is the name given to a repeatable series of changes in the types of species which occupy a given area through time from a pioneer to a climax communityAutogenic Succession is the changes in environmental conditions which leads to changes in species composition in an ecosystem caused by the biological processes of the organisms themselves2 Types of Allogenic Succession are – Primary & Secondary Succession
42Primary & Secondary Succession Primary succession occurs when plants become established on land which has not previously been inhabited and where no soil exists e.g. barren rockSecondary succession occurs when plants invade a habitat which was previously inhabited by other plants and which therefore has existing soil and some organic material present e.g. a forest destroyed by firePrimary succession takes longer than secondary succession because in primary succession the soil has to be formed
43Pioneer to Climax Communities Pioneer species are first to colonise and can withstand difficult environmental conditions e.g. drying out (e.g. lichens)Climax community is a relatively stable community in which no further succession takes placeDuring succession from a pioneer to a climax community all of the following increase:-- complexity- species diversity- habitat variety- productivity- food webs- stability
44Degradative Succession Degradative succession (or Heterotrophic succession) is the sequence of changes associated with the decomposition process. For instance, when organisms die and begin to decompose, a characteristic sequence of certain species appear associated with that type of organism.This chain can be used by Forensic entomologistsDead Cow > Bacteria>Flies lay eggs on body>Larvae hatch & feed on body> Beetles feed &lay eggs>Spiders feed on insects
45Loss of Complexity of Ecosystems Loss of complexity can be brought about by:- monoculture- eutrophication- toxic pollution- habitat destruction
468. Intensive Food Production Monoculture is when a single species is grown over a large areaThe aim of monoculture is to reduce the complexity of the ecosystem to a single species in order for the farmer to gain highest yields at minimal costs to get maximum profitPopulation sizes throughout the world are increasing and we thus need more foodHedgerows and fences are taken down to make large fields so machinery can plough them easily. This removes habitats and shelters and reduces organisms living thereA monoculture is not a climax community so it is unstable and is at risk from competition from other plant species. Therefore humans remove these additional plants by hand (organic farming) and by the use of herbicides.
47Problems with Monoculture Monocultures are highly unstable and are vulnerable to:-disease caused by bacteria, fungi and virusesattacks from pests (weeds, insects and animals)soil erosionadverse weather conditionsThe same crops are used year after year so the soil has the same nutrients taken from it consistently. Also, after harvesting, the field is cleared of plant debris (so nutrient cycles don’t occur).To increase the fertility of the soil fertilisers are used.Organic fertilisers are manure and composts, whereas inorganic fertilisers are made from chemicalsPesticides (kill pests) and Herbicides (reduce competition by weeds) also contain substances which are toxic to organisms other than those they are intended to killIndustrial sites are often polluted with heavy metals such as lead, cadmium and mercury which can lead to the death of many organisms, leading to the decrease in complexity of ecosystems
48EutrophicationWaterways near the fields can become polluted by excess nutrients e.g. by adding untreated sewage, runoff of animal waste from farms, leaching of fertilisers from fieldsThis pollution increases the nitrates and phosphates in the water systemThe increase in nutrients leads to an explosion of algal growth (algal blooms).Algal blooms increase oxygen levels in the day by photosynthesis, but oxygen depletion occurs at night due to respirationAlgae die and accumulate at bottom of water system, and decomposers feed on them, which decreases the oxygen levels even further, so water plants and larger animals die due to lack of oxygen. Eventually species diversity in the water is drastically reduced
509. Increase in Energy Needs An increase in the human population as resulted in an increase in our energy needsFossil Fuels (coal, oil and gas) are finite and will soonrun out if we continue to use them at the present rate
51Alternative Energy Sources We need to conserve fossil fuels and use alternative sources of energy such as:-NuclearSolarWindHydro-electricWaveTidalGeothermalBiofuels
52Air Pollution & Greenhouse Gases When Fossil fuels are burned they release acidic gases which cause air pollutionsulphur dioxidenitrous oxidecarbon dioxideFossil fuels also release greenhouse gases:-watermethaneCFC’s
53Greenhouse EffectSolar energy passes through the atmosphere striking the earth’s surface and thus warms it up, producing infrared radiation (heat). Most of this radiation is reflected back to space but some greenhouse gases absorb some of this heat, making the earth warmer – this is called the greenhouse effect.Called the greenhouse effect because in a real greenhouse, glass acts as the atmosphere and traps some of the heat energy.When too much heat is absorbed by greenhouse gases, global warming may occur
54Greenhouse EffectIllustration 1 The earth is covered by a blanket of gases which allow light energy from the sun to reach the earth's surface, where it is converted to heat energy. Most of the heat escapes our atmosphere, but some is trapped. This natural effect keeps the earth warm enough to sustain life. Illustration 2 Human activity such as burning fossil fuels (coal, oil and natural gas) and land clearing is creating more greenhouse gases. This traps more heat, so the earth becomes hotter.
55Global WarmingGlobal warming may cause climate change (e.g. changes in temperature, rainfall levels, sea levels) which could affect the distribution of many different speciesScientists predict that climate change will happen too fast for organisms to adapt or move so it could result in a decrease in species diversity
56Global Warming Effects on Animals Increased storms damaging the breeding colonies of albatross, already facing heavy pressure from accidental capture on long-line fishing hooksSea level rise destroying beach nesting sites for sea turtlesSeals and wading birds also face destruction of their coastal habitatsWarmer seas could lead to some turtle species becoming entirely female, as water temperature strongly affects the sex ratio of hatchlingsThe spreading extent of the Sahara desert could threaten long-range travellers such as the swallow, as they will be unable to "fuel up" in previously fertile regions on the desert's edge.
57Coral Bleaching“Coral Bleaching” is an example of how global warming might affect the distribution and diversity of different species.Colourful Coral reefs are made up of a symbiotic relationships of coral polyps (which secret a skeleton of white calcium carbonate) and a unicellular-coloured algae called zooanthellae.Zooanthellae provides the coral polyps with nutrients produced from photosynthesis and the coral polyps provide the zooanthellae with a protected environment and lots of carbon dioxide for photosynthesis – a mutualistic relationshipTemperature increase causes the algae zooanthellae to leave the coral, leaving just the white skeleton – thus called coral bleachingIf temperature increase is reversed zooanthellae may repopulate the reef and the coral may recover, of not the coral polyps eventually die.
58Coral Bleaching Sun Coral in ideal temperatures Coral bleaching in process
5910. PollutionPollution is the negative effect of a harmful substance on the environmentPollution may cause the following biological effects:-the appearance of a speciesthe disappearance of a specieschanges in community structure and functionchanges in behaviourchanges in productivity, energy flow and nutrient cyclingThe 4 ecosystems that can be effected by pollution are:-sea (oil spills, dumping of radioactive waste, dumping of toxic waste)air (emissions from cars, planes, industry)land (landfill sites, domestic rubbish)freshwater (agricultural run off, organic sewage)
60Measuring PollutionFreshwater can be polluted by organic material by the dumping of untreated sewageThis organic sewage provides a rich food source for microorganisms that feed, reproduce and use up the oxygen in the water. Other organisms such as fish die.Biodegradable organic pollutants include sewage, farm waste and industrial wasteEcosystems need continually monitoring to ensure they are free from harmful levels of pollutants. Water can be tested directly or indirectly.Direct methods of water testing are:-ColourTurbidityDissolved Oxygen levelsPHBiochemical Oxygen Demand (BOD)OdourTemperatureAmmonia, nitrate, chloride, phosphorus levels
61BOD TestingThe BOD (Biochemical Oxygen Demand) test is a water quality test that measures the levels of dissolved oxygen in the water. It is used to estimate the levels of biodegradable organic material there is.High BOD levels indicate a high level of organic pollution in the water, and a low BOD level indicates a low level of organic pollution in the waterBOD Test – 2 samples of water are taken from the same site. Sample 1 is tested immediately, and Sample 2 is incubated for 5 days in the dark at 20°C and then the BOD is taken.The difference in dissolved oxygen content of the 2 samples shows the amount of oxygen consumed by microbial respiration as bacteria break down the organic matter in the sample.
62Biological Monitoring Indicator species give information about the environment that it is living inBiological Monitoring is an indirect measure of water qualityA susceptible species can be used as an indicator species, as their disappearance from a habitat that they were in previously indicates that the environmental conditions have changed. For example, lichens disappearing indicates increased levels of sulphur dioxideA favoured species can tolerate a wide range of environmental conditions, so cannot be used as an indicator species
63Chemical Transformations Once chemicals have been released into the environment, their chemical nature changes due to their interactions with each other and the environment, this is called CHEMICAL TRANSFORMATIONSometimes chemical transformations can turn relatively safe chemicals into toxic onesBiotransformation of the heavy metal mercury by Clostridium, Neurospora and Pseudomonas. These organisms can all methylate metallic mercury changing it from a moderately toxic chemical into a highly toxic one that change damage kidney, liver and brain tissue in humansWhen a chemical accumulates in the tissues of an organism it is called BIOACCUMULATIONBIOMAGNIFICATION is when some toxins become very harmful because they become more concentrated in successive trophic levels of a food web. This is due to the fact that some chemicals (e.g. chlorinated hydrocarbons) accumulate in specific tissues, especially fat.
64DDTDDT (Dichlorodiphenyltrichloroethane) is an insecticide that was commonly used during the 1940’s & 1950’s. It was used to kill insects like mosquitoes that carried malaria and saved many lives.DDT is no longer used due to its long-term lethal side effects.DDT bioaccumulates in the body fats of organisms.DDT is biomagnified through the food chain, so at each tropic level the concentration of DDT increasesDDT breaks down to form a stable compound called DDE which thins the shells of many birds reducing the survival rate of many birds (e.g. osprey)Large scale resistance to DDT has evolved with 35 species of malarial mosquitoes now resistantAreas of the world that did not use DDT show high levels of the chemical. Inuit people from Greenland have high levels of DDT in the tissues acquired from consuming seals that had visited DDT regions