Advanced Higher Biology

1. Advanced Higher Biology Environmental Biology Unit Anderson High School CR

2. Environmental Biology • The Environment and its ecosystems have political, economic and ethical dimensions due to their impact on the human species • This unit will help you to understand the interactions between organisms and their environment, and the human influence on the world around us

3. Advanced Higher Assessment • Environmental Biology is a 40 hour Unit • Involves lectures, tutorials, discussions, practical work, presentations and assessments all to help with the learning process and in preparation for University Life • NAB (sit in March after Prelims) • Assessment – 2 ½ Hours (Feb & May)

4. Environmental Biology 10 Topics 1 Energy Fixation 2 Circulation of Nutrients 3 Biotic Interactions 4 Symbiotic Relationships 5 Costs/Benefits of Competition 6 Survival Strategies 7 Succession 8 Intensive Food Production 9 Increase in Energy Needs 10 Pollution

5. 1. Energy Fixation • Energy is required by all organisms for cellular activities, growth & reproduction • The fixation of energy occurs in photosynthesis by autotrophs • Autotrophs (are producers) that change light energy into chemical energy to make organic molecules • Heterotrophs (are consumers) that must feed on other plants or animals to get a ready made supply of organic molecules • Saprotrophs (are decomposers) that use the organic materials from waste and dead organisms as an energy source Autotrophs Heterotrophs Saprotrophs

6. Energy Calculations • Gross Primary Productivity (GPP) is the total amount of light energy converted to chemical energy by autotrophs • Not all energy produced by autotrophs is available for consumers as autotrophs use up some of the food in respiration for their own metabolic needs • Net Primary Productivity (NPP) • NPP= GPP – energy used in respiration. • Therefore NPP is the energy available to all other organisms in an ecosystem after producer respiration • Primary productivity is measured using the biomass of vegetation added to a given area in a given time e.g. g/m2/year

7. Feeding Relationships • Herbivores feed on plant material & Carnivores feed on animals • Decomposers are organisms (e.g. bacteria and fungi) (saprotrophs) that breakdown organic matter by secreting digestive enzymes • Detritivores are organisms (e.g. earthworms & woodlice) that feed on detritus (decomposing material) • Primary consumers are herbivores that feed directly on producers • Secondary consumers are carnivores that feed on primary consumers • Tertiary consumers are carnivores that feed on secondary consumers • A trophic level is a feeding level present in a food chain or food web • Energy flow in a food chain or food web is represented by arrows • Energy transfer is not very efficient. Only 10% of energy at one trophic level is passed on to the next level

8. Biological Pyramids • Pyramids of numbers represent the number of organisms at each trophic level • Pyramids of biomass represent the mass of organisms at each trophic level • Pyramids of productivity represent the energy available at each trophic level • In an ecosystem, productivity, biomass and numbers of organisms tend to decrease at each trophic level • The ultimate loss of energy is in the form of HEAT (from respiration)

9. 2. Circulation of Nutrients • Decomposition is the breakdown of organic matter with the release of inorganic nutrients into the surrounding soil • Inorganic ions are released from decomposing matter in a process called mineralisation • Decomposers and Detritivores are involved in decomposing organic matter • Undecomposed material is called litter • Completely decomposed matter is called humus • Invertebrate 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 humus • Decomposers are the ultimate releasers of energy and carbon dioxide fixed in photosynthesis • Nutrients must be recycled for the primary producers to use Detritivores (e.g. worms) Decomposers (e.g. wood fungi)

10. Nitrogen Cycle There are 4 main stages – Fixation, Nitrification, Denitrification and Ammonification 1. Fixation is when Atmospheric Nitrogen is converted to Ammonia • Free living cyanobacteria in the soil fix nitrogen • Rhizobium bacteria in the root nodules of legumes fix nitrogen • Cyanobacteria & Rhizobium bacteria have an enzyme complex called nitrogenise which converts atmospheric nitrogen to ammonia with the use of ATP • The 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 process 2. Nitrification is when Ammonium is converted to Nitrites then to Nitrates • Nitrosomonas and Nitrobacter bacteria carry out this process • The 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 Nitrogen Denitrifying bacteria (Agrobacterium) are involved 4. 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

11. The Nitrogen Cycle

12. The Nitrogen Cycle (again)

13. Nitrogen Cycle

14. Nitrogen Fixation • Fixation is when Atmospheric Nitrogen is converted to Ammonia • Free living cyanobacteria in the soil fix nitrogen • Rhizobium bacteria in the root nodules of legumes fix nitrogen • Cyanobacteria & Rhizobium bacteria have an enzyme complex called nitrogenise which converts atmospheric nitrogen to ammonia with the use of ATP • The 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 process Cyanobacteria Rhizobium Root Nodules Clover

15. Nitrification • Nitrification is when Ammonium is converted to Nitrites then to Nitrates • Nitrosomonas and Nitrobacter bacteria carry out this process • The nitrates are then used by plants to make proteins & nucleic acids (assimilation) • Nitrates can be lost by leaching and denitrifying bacteria (Pseudomonas)

16. Denitrification • Denitrification is when Nitrates are converted back to Atmospheric Nitrogen • Denitrifying bacteria (Agrobacterium) are involved Nitrates Atmospheric Nitrogen Agrobacteria

17. Ammonification Ammonification is when organic nitrogen in Proteins is converted into ammonia by decomposers (bacteria & fungi) Nitrogen Ammonia

18. Bacteria involved in Nitrogen Cycle Nitrogen Fixation - Cyanobacteria & Rhizobium(legumes) Nitrogen Ammonia Nitrification - Nitrosomonas and Nitrobacter Ammonium Nitrites Nitrates Denitrification – Agrobacterium & Pseudomonas Nitrates Atmospheric Nitrogen Ammonification – Bacteria & Fungi Nitrogen Ammonia

19. Phosphorus Cycle • Phosphorus Cycle • Phosphorus is added to the soil by the weathering of rocks, taken up by primary producers and returned by decomposition • Phosphorus is a main component of nucleic acids, phospholipids, ATP, bones, teeth • Phosphorus is organic, doesn’t have a gaseous form, so the only inorganic form is phosphate • Phosphate is a limiting factor in the productivity of aquatic ecosystems • Phosphate 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 stimulation • The plants and algae eventually die, which reduces the oxygen in the water, so fish and other organisms eventually die

20. Phosphorus Cycle

21. 3. Biotic Interactions • Biotic components of an ecosystem are living factors e.g. predation, disease, food supply, competition • Abiotic components of an ecosystem are non-living factors e.g. temperature, light intensity, soil pH, availability of water • Density dependent factors are factors that can regulate a population. These factors increase as population size increases e.g. predation, disease, food supply, competition • Density independent factors are factors that can regulate a population. These factors are independent of population size e.g. hurricanes, forest fires • Interspecific Competition is interactions between individuals of different species • Intraspecific Competition is interactions between individuals of the same species and is more intense that Interspecific Competition • Predator/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

22. Defence Against Predation 3 Main Defences:- 1. Camouflage Camouflage is when the organisms colouring or pattern allows it to merge into the background a) Crypsis – hiding to reduce the risk of predation b) Disruptive Colouration – patterns on body don’t match outline 2. Warning Colouration Warning Colouration is when organisms are brightly coloured to warn predators that they are dangerous to eat 3. Mimicry Mimicry is when an organism bears a resemblance to a harmful species a) Batesian mimicry is when an edible or harmless species mimics a poisonous or harmful species b) Mullerian mimicry is when 2 or more species have evolved to have the same or similar warning signals

23. Camouflage Camouflage is when the organisms colouring or pattern allows it the merge 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)

24. Warning Colouration Warning Colouration is when organisms are brightly coloured to warn predators that they are dangerous to eat! e.g. yellow and black markings of wasps

25. Mimicry Mimicry is when an organism bears a resemblance to a harmful species a) Batesian mimicry is when an edible or harmless species mimics a poisonous or harmful 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 or similar warning signals (e.g. social wasps and caterpillars of cinnabar wasps) Harmless Robber fly Harmful wasp Wasp Cinnabar Caterpillar

26. Grazing A grazer is defined as any species that moves from one victim to another, feeding on a part of each victim but doesn’t actually kill it Moderate grazing can increase the biodiversity of species present as grazing reduces the number of dominant grasses and other plants with basal meristems, which allows weaker competitors to survive

27. Competition 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 resource Exploitation Competition results when two or more species use the same resources, thus reducing the resources available for all.

28. Niche For A’Higher the term Niche means:- “the feeding role that a species plays within a community” A fundamental niche is the set of resources a species is capable of using if there is no competition A realised niche is the set of resources actually used by the species due to competition Resource partitioning is the dividing up of each resource by species specialisation and adaptation (e.g. different lengths of beaks in wading birds) Competitive Exclusion Principle is when two species compete for the same resource, but one species will dominate and the other species will move away

29. Resource Partitioning

30. Exotic Species • Exotic 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

31. 4. 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 advantage Examples of Symbiosis are Parasitism, Commensalism, and Mutulaism

32. Parasitism • Parasitism is a biotic interaction which is beneficial to one species (the parasite) and detrimental to the other species (the host) e.g. tapeworm and humans • An obligate parasite cannot survive without the host organism • A facultative parasite can live with or without the host • Endoparasites live within a hosts body e.g. tapeworms, liver flukes, malarial parasites • Ectoparasites live on the surface of the host e.g. ticks, fleas, leeches Ectoparasite – Dog Tick Endoparasite – human tape worm

33. Host-Parasite Balance • A balance exists between the parasite and the host so that there is a relatively stable relationship • Parasites can be transmitted to new hosts can be by: - • direct contact e.g. head lice and humans touching each other • resistant stages e.g. liver fluke in snail hosts are dormant in water, then sheep drink water and the fluke becomes active • secondary hosts (vectors) e.g. mosquitoes transmit the malarial parasite • Host-parasite specificity gives evidence of evolutionary adaptation e.g. immunity

34. Commensalism • Commensalism is a biotic interaction beneficial to one species (commensal) and the other species in unaffected • Egrets feed on the ectoparasites on back of elephant • Clownfish feed on scraps of dead prey of sea anemone

35. Mutualism • Mutualism 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 sources • The crab gains protection from predators from the anemones stinging cells

36. 5. Costs/Benefits of Interactions • Competition (-/-) • Predation (+/-) • Parasitism (+/-) • Commensalism (+/0) • Mutualism (+/+) • The health of the host and environmental factors can change the balance of symbiotic relationships • Humans 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

37. 6. Survival Strategies • Regulators maintain their internal environment regardless of the external environment • regulators have homeostatic control • osmoregulators can maintain a stable internal water concentrations • homeotherms can maintain a stable internal temperate • Examples are mammals, insects & birds • Conformers cannot maintain their internal environment • conformers do not have homeostatic control • osmoconformers are isotonic to their surroundings • poikilotherms internal temperature varies with the external environment • Examples are snakes, lizards and marine fish • Regulators can occupy a wide range of habitats due to homeostatic mechanisms but conformers have a restricted habitat occupation

38. Dormancy • Dormancy is a way that many organisms can resist or tolerate environmental conditions • Predictive 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 conditions • Different forms of dormancy include:- resting spores, diapause, hibernation & aestivation

39. Types of Dormancy • Resting 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 supplies • Aestivation – inactivity time associated with hot, dry periods. Organism remains in a state of torpor with a reduced metabolic rate e.g. desert frogs & lungfish

40. 7. Succession • Ecological 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 community • Autogenic 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 themselves • 2 Types of Allogenic Succession are – Primary & Secondary Succession

41. Succession

42. Primary & 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 rock Secondary 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 fire Primary succession takes longer than secondary succession because in primary succession the soil has to be formed

43. Pioneer 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 place • During succession from a pioneer to a climax community all of the following increase:- - complexity - species diversity - habitat variety - productivity - food webs - stability

44. Degradative 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 entomologists • Dead Cow > Bacteria>Flies lay eggs on body> Larvae hatch & feed on body> Beetles feed & lay eggs>Spiders feed on insects

45. Loss of Complexity of Ecosystems • Loss of complexity can be brought about by: - monoculture - eutrophication - toxic pollution - habitat destruction

46. 8. Intensive Food Production • Monoculture is when a single species is grown over a large area • The 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 profit • Population sizes throughout the world are increasing and we thus need more food • Hedgerows and fences are taken down to make large fields so machinery can plough them easily. This removes habitats and shelters and reduces organisms living there • A 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.

47. Problems with Monoculture • Monocultures are highly unstable and are vulnerable to:- • disease caused by bacteria, fungi and viruses • attacks from pests (weeds, insects and animals) • soil erosion • adverse weather conditions • The 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 chemicals • Pesticides (kill pests) and Herbicides (reduce competition by weeds) also contain substances which are toxic to organisms other than those they are intended to kill • Industrial 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

48. Eutrophication • Waterways 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 fields • This pollution increases the nitrates and phosphates in the water system • The 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 respiration • Algae 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

49. Eutrophication Loch Eutrophication Coastline Eutrophication

50. 9. Increase in Energy Needs An increase in the human population as resulted in an increase in our energy needs Fossil Fuels (coal, oil and gas) are finite and will soon run out if we continue to use them at the present rate