Biology Unit 4: Ecology

Ecology

the study of relationships between living organisms and between organisms and their environment 

Population

a group of organisms of the same species livin in the same area at the same time

Ecosystem

a community and its abiotic (no living) environment

Community

group of populations living and interacting with each other in an area

Habitat

the environment in which  species normally lives (location of living organism)

Species

a group of organisms that can interbreed or produce fertile offspring

Why do species only interbreed and not cross species boundaries

• Mating and courtship rituals: birds of paradise species have distinctive rituals 

• Species species cues: release of pheromones that signal that an individual is ready to mate 

• Structural adaptations: plant species have specifically shaped flowers that ensure they are pollinated by specific pollinators 

• Mechanical isolation: different species will have structurally different genetalias that prevalent successful mating between species 

autotrophs

synthesise their own organic molecules

• Covert carbon dioxide into organic compounds (photosynthetic autotrophs) 

• Plant synthesis sugars → converted into organic compounds such as complex carbs (starch, cellulose), lipids, amino acids

heterotrophs

• obtain organic molecules from other organisms known as consumers 

• Range of food sources and feeding machanimss, the cobo can be used to classify consumers 

  • Herbivores: feed on producers 

  • Omnivores: combo of producers and consumers  

  • Carnivores: feed on other consumers only 

Scavengers: specialised carnivores and feed off of dead and decaying animals

mixotrophs

plants and algae that use different modes of nutrition (mix of euro and heterotrophic)

detritivores

type of heterotroph that obtain nutrients by consuming non living organic sources like detritus and humus

saprotroph

live on or in non living organic matter and secrete digestive enzymes on to the organic matter and absorb the products of digestion

mesocosm

biological systems that contain the abiotic and biotic features of an ecosystem but are restricted in size and or under controlled conditions

null hypothesis

no correlation between distribution of two species (distribution is random)

alternative hypothesis

significant different between the distribution of species (species are associated)

predator prey relationship

• Positive association

  • Prey pop increases, predator pop increases (more food available, increasing natality and decreasing mortality rates)

• Prey population will spike before the predator population 

symbiosis

close and persistent interaction between two species in close proximity, in which at least one species benefits

obligate symbiotic

• essential for survival of at least on species

  • Lichen consists of algae (photosynthesis) of/and fungi (which protects, absorbs water and nutrients) 

facultative symbiotic

• advantageous to survival 

  • Oxpeckers and large animals 

  • Oxpeckers have food source and provide a service to the large animals removing ticks 

mutualism

• both species benefit from interaction 

  • Sea anemone (protection) and clown fish (provides faecal matter for food) 

commensalism

• one species benefits but the other is unaffected 

  • Barnacles and whales 

  • Barnacles attach to whales and benefit from constant flow of water rich in phytoplankton  

parasitism

• one species benefits and the other is harmed 

  • Tapeworms and humans 

  • Tapeworms attach to lining of digestive tract and absorb nutrients which can harm the host 

  • Weight loss, digestive issues

methanogen

archean microorganism that produce methane as a byproduct in anaerobic conditions

carbon sinks

anything that accumulates and stores carbon for an extended period of time 

carbon fluxes

transfer of carbon between sinks or reservoirs (rate of carbon flux depends on processes involved)

examples of carbon fluxes

• Photosynthesis 

• Respiration 

• Decomposition: releases carbon product into air or sediment 

• Gaseous dissolution: exchange of carbon gases between the ocean and atmosphere 

• Lithification: compression of carbon containing sediments into fossils and rocks within earth's crust 

• Combustion: releases carbon gases when organic hydrocarbons (coal, oil, gas9 or vegetation are burned as fuel source

negative flux

transfer results in reduction in amount of carbon in that particular sink

positive

transfer resulting in increase in amount of carbon in that particular sink

carboniferous period

most of the coal was formed during this period as there was a cyclical change where the sea level suddenly fell and then rose

main greenhouse gases

carbon dioxide, water vapour

methane

• 25 times more potent than carbon dioxide 

  • Found in swamps, waterlogged environment, and landfills 

  • Released through fossil fuel extractions and the melting of ice in polar regions 

  • It is removed by oxidation in the atmosphere  

    • Does not stay as long in the atmosphere as the breakdown process is simpler, meaning even though it is more potent than carbon dioxide, it doesn't do much harm

nitrous oxide

• 300 times more potent than carbon dioxide 

• Found in agriculture due to use of fertilisers, bacteria during nitrification and denitrification, as well as combustion of fossil fuels

carbon dioxide

• produced during cellular respiration and burning of fossil field and biomass

  • Removed by photosynthesis and can be dissolved in oceans 

water vapour

formed due to evaporation from oceans and transpiration in plants