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 Autotrophs Heterotrophs Saprotrophs
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
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

51. Alternative Energy Sources
We need to conserve fossil fuels and use alternative sources of energy such as:-
Nuclear
Solar
Wind
Hydro-electric
Wave
Tidal
Geothermal
Biofuels

52. Air Pollution & Greenhouse Gases
When Fossil fuels are burned they release acidic gases which cause air pollution
sulphur dioxide
nitrous oxide
carbon dioxide
Fossil fuels also release greenhouse gases:-
water
methane
CFC’s

53. Greenhouse Effect
Solar 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

54. Greenhouse Effect
Illustration 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.

55. Global Warming
Global warming may cause climate change (e.g. changes in temperature, rainfall levels, sea levels) which could affect the distribution of many different species
Scientists predict that climate change will happen too fast for organisms to adapt or move so it could result in a decrease in species diversity

56. Global Warming Effects on Animals
Increased storms damaging the breeding colonies of albatross, already facing heavy pressure from accidental capture on long-line fishing hooks
Sea level rise destroying beach nesting sites for sea turtles
Seals and wading birds also face destruction of their coastal habitats
Warmer seas could lead to some turtle species becoming entirely female, as water temperature strongly affects the sex ratio of hatchlings
The 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.

57. Coral 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 relationship
Temperature increase causes the algae zooanthellae to leave the coral, leaving just the white skeleton – thus called coral bleaching
If temperature increase is reversed zooanthellae may repopulate the reef and the coral may recover, of not the coral polyps eventually die.

58. Coral Bleaching Sun Coral in ideal temperatures
Coral bleaching in process

59. 10. Pollution
Pollution is the negative effect of a harmful substance on the environment
Pollution may cause the following biological effects:-
the appearance of a species
the disappearance of a species
changes in community structure and function
changes in behaviour
changes in productivity, energy flow and nutrient cycling
The 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)

60. Measuring Pollution
Freshwater can be polluted by organic material by the dumping of untreated sewage
This 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 waste
Ecosystems 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:-
Colour
Turbidity
Dissolved Oxygen levels PH
Biochemical Oxygen Demand (BOD)
Odour
Temperature
Ammonia, nitrate, chloride, phosphorus levels

61. BOD Testing
The 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 water
BOD 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.

62. Biological Monitoring
Indicator species give information about the environment that it is living in
Biological Monitoring is an indirect measure of water quality
A 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 dioxide
A favoured species can tolerate a wide range of environmental conditions, so cannot be used as an indicator species

63. Chemical 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 TRANSFORMATION
Sometimes chemical transformations can turn relatively safe chemicals into toxic ones
Biotransformation 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 humans
When a chemical accumulates in the tissues of an organism it is called BIOACCUMULATION
BIOMAGNIFICATION 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.

64. DDT
DDT (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 increases
DDT 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 resistant
Areas 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