Phys 102: Natural Systems

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Phys 102 Natural Systems
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Ecology Intro
Lecture 8
Phys 102 Natural Systems
Introduction

• The ecosphere is finite but also very diverse
• So far we have been looking at the abiotic
  (non-living) components of the ecosphere.

• Now we will look at the living organisms in the
  ecosphere (the biosphere).
• This next part of the course falls mainly into
  the field of ecology. This is the study of the
  distribution and abundance of organisms, and the
  interactions of organisms with biotic and abiotic
  environment.

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Lecture 8
Phys 102 Natural Systems
Physical and Chemical Factors that Influence Life

• Solar Energy
• powers most ecosystems.(are there any
  exceptions?)
• plantlike organisms convert the solar energy into
  forms life can use.
• Shading by trees forest/jungle can create intense
  competition for light at ground level.

• Water
• As we already know is fundamental constituent of
  many natural systems and is essential for life.
• Main threat for terrestrial organisms is of
  drying out
• Aquatic organisms may face problems of water
  balance, ie changing concentrations of dissolved
  substances in the water.

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Soil Oxygen WInd
Lecture 8
Phys 102 Natural Systems
Physical and Chemical Factors that Influence Life

• Soil
• Important factors are its structure, pH and
  inorganic nutrients.
• Variations in soil account for the many
  differences in types of plants in difference
  ecosystems
• Oxygen
• Plentiful in the air, so rarely limits cellular
  respiration on terrestrial organisms.
• Due to small amount dissolved in water, it is
  often in short supply for aquatic organisms.
• Wind
• Organisms can depend on nutrients blown by the
  wind (eg insects that live on snow covered
  mountain peaks.)
• It increases an organisms rate of water loss by
  evaporation. Can be advantageous in summer,
  dangerous in winter.

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Temperature Fires
Lecture 8
Phys 102 Natural Systems
Physical and Chemical Factors that Influence Life

• Temperature
• Is very important because of its effect on
  metabolism.
• 50 degrees destroys enzymes in most living
  organisms.
• Few organisms can maintain active metabolisms at
  0 degrees
• There are extraordinary adaptations that allow
  some species to live outside this temp range

• Fires and catastrophic events
• Includes hurricanes, volcanic eruptions etc.
• Mostly these events are infrequent and highly
  unpredictable.
• Can have a large impact in living organisms.
• Fire occurs in many terrestrial ecosystems in
  Australia and has had a significant influence on
  their biotic composition, structure, function and
  evolution.
• The effect of fires on ecosystems is complex.
• In Australia biodiversity loss has been
  associated with both high fire frequency and fire
  exclusion. Conversely, certain fire regimes are
  essential for the survival of some native
  species.

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Australian Biomes
Lecture 8
Phys 102 Natural Systems
Australian Biomes

• Savanna
• This is typically, grassland and scattered trees.
• Have a simple structure compared with tropical
  forests
• Grasses wind pollinated
• Are home to many of worlds large herbivores
  (plant eating animals).
• Typical inhabitants in Australia include emus,
  red kangaroos, rabbit bandicoots, and parrots.
• Temperate Broadleaf and Mixed Forests
• (called Tropical'' in picture).
• This consists of a closed-canopy rain forest or
  eucalyptus forests with mountain ash and gum
  trees.
• There are cold tropical rain forests in the
  Melbourne area and in Tasmania.
• Marsupials include koalas, possums, platypus,
  flying foxes, lyre birds.

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Australian Biomes
Lecture 8
Phys 102 Natural Systems
Australian Biomes

• Desert
• An area where little or no life exists because of
  a lack of water.
• About one-fifth of the earth's land surface is
  desert.
• Intense heat or cold also make this biome
  inhospitable to most life forms.
• Plants include varieties of eucalyptus and
  acacia.
• Animals living here include the marsupial moles,
  devil lizards, and parakeets.
• Notice that the desert barrier of the interior of
  Australia isolates the four corners of Australia.

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Other Biomes
Lecture 8
Phys 102 Natural Systems
Other Biomes

• Tropical rainforests
• forest of tall trees in a region of year-round
  warmth.
• Mostly found near the equator.
• About half of the world's tropical rainforests
  are in the South American country Brazil.
• Northern Australia has a dry rainforest, it
  experiences a dry season each year.
• Tundra
• cold, vast, treeless area of low, swampy plains
  in the far north around the Arctic Ocean.
• Taiga
• consists of coniferous forest south of the Arctic
  tundra. It stretches from Alaska straight across
  North America to the Atlantic Ocean and across
  Eurasia.
• Chaparra
• a biome found in areas across the world. Summers
  in the chaparral are arid whilst winters are
  cool and damp. Dense thickets of evergreen shrubs
  and small trees

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Major Biomes
Lecture 8
Phys 102 Natural Systems
Major Biomes
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Lecture 8
Phys 102 Natural Systems
Cells
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Classification of The Earths Organisms
Lecture 8
Phys 102 Natural Systems
Cells

• Cells are the smallest living unit of an
  organism.
• Cells contents are encased in a outer membrane
  that separates it from its environment.
• They contain genetic material in the form of DNA
  and many other components necessary for life
• Two main types have evolvedProkaryotic and
  Eukaryotic.
• Prokaryotic cells are small and structurally
  simple.
• Eukaryotic cells are larger and have a complex
  structure.

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Lecture 8
Phys 102 Natural Systems
Bacteria
Bacteria Protist Fungi Plants Animals

• Bacteria
• Are single cell organisms with prokaryotic cell
  structure.
• In activity and potential for rapid unchecked
  growth, bacteria are unrivaled among living
  organisms. About 10,000 different forms have been
  described as "species'
• Some can survive very low temperatures, well
  below freezing, for years others thrive in
  boiling hot springs and still others even grow
  in very hot acid or live by deriving hydrogen and
  carbon dioxide from rocks.
• Many are decomposers which get their nutrients
  from breaking down complex organic compounds.
  Vital for functioning ecosystems.
• Cyanobacteria are aquatic and photosynthetic,
  that is, they live in the water, and can
  manufacture their own food. They often grow in
  colonies large enough to see (eg blue green
  algae)

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Lecture 8
Phys 102 Natural Systems
Protist
Bacteria Protist Fungi Plants Animals

• Protist
• cells have nuclei and other characteristically
  eukaryotic features.
• Comprises the eukaryotic microorganisms and their
  immediate descendants all algae, including the
  seaweeds and the slime molds and other water
  molds etc.
• Can be single celled.
• They produce their own nutrients via
  photosynthesis (like Cyanobacteria).
• Many are decomposers, some feed on bacteria.

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Classification of The Earths Organisms
Lecture 8
Phys 102 Natural Systems
Fungi
Bacteria Protist Fungi Plants Animals

• Fungi
• Are eukaryotic mostly multicelled organisms such
  as mushrooms, moulds and yeasts.
• Of the estimated 1,500,000 species of fungi
  estimated to exist, about 60,000 have been
  described most are terrestrial, although a few
  truly marine species are known.
• They are decomposers. They secrete enzymes that
  break down the organic matter in the tissue of
  living or dead organisms.
• They absorb the resulting nutrients.

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Classification of The Earths Organisms
Lecture 8
Phys 102 Natural Systems
Plants
Bacteria Protist Fungi Plants Animals

• Plants
• Eukaryotic and develop from embryos -
  multicellular structures enclosed in maternal
  tissue. Because all plants form embryos, they are
  all multicellular
• Furthermore, because embryos are the products of
  the sexual fusion of cells, all plants
  potentially (although not always in reality) have
  a sexual stage in their life cycle.
• All plants that photosynthesize produce oxygen
  and organic nutrients for themselves.
• Examples are mosses, ferns, flowers, cacti,
  grasses, beans, trees etc.
• Plants are adapted primarily for life on land,
  although many dwell in water during part of their
  life history.
• Water and other inorganic nutrients are obtained
  from the soil (terrestrial plants) or water
  (aquatic plants)

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Classification of the Earths orgnii
Lecture 8
Phys 102 Natural Systems
Animals
Bacteria Protist Fungi Plants Animals

• Animals
• Eukaryotic, multicellular organisms capable of
  locomotion (sponges, jelly fish, insects fish,
  reptiles, birds mammals etc..)
• They can get their nutrients from feeding on
• plants (herbivores)
• other animals (carnivores)
• plants and animals (omnivore)
• They either have backbones (vertebrates) or no
  backbones (invertebrates).
• Can be cold blooded (fish, reptiles) or warm
  blooded (mammals, birds)

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Food Webs
Lecture 8
Phys 102 Natural Systems
Food Webs
Food webs allow us to track the flow of energy
through an ecosystem and study the dynamics of
populations.
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Lecture 8
Phys 102 Natural Systems
Food Webs

• The biotic components of an ecosystem are usually
  classified as producers and consumers.
• Producers
• Are the base level of all food webs, undergo
  photosynthesis to produce food.
• Producers are autotrophs, which literally means
  self-feeding
• ("auto"self, "troph"to nourish).
• In most terrestrial ecosystems the producers are
  plants. In aquatic ecosystems they are mostly
  phytoplankton (various species of drifting
  bacteria and protists)

• Consumers
• Obtain their food from other organisms.
• They are heterotrophs, or "other feeders".
• Since herbivores take their food directly from
  the producer level, they are also called primary
  consumers.
• Carnivores feed on other animals and are
  secondary consumers.
• Carnivores can also be tertiary consumers, ie
  they feed on other animal eating animals.

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Food Webs
Lecture 8
Phys 102 Natural Systems
Food Webs

• Decomposers and Detritus Feeders
• Decomposers are mostly bacteria and fungi.
• They live off detritus, which are parts of dead
  organisms, cast off fragments and wastes of
  living organisms.
• They break down the complex molecules in detritus
  material and converting them into simpler
  inorganic compounds. Thus they are very important
  as they recycle nutrients.
• Also in this category are detritus feeders.
• There are organisms like termites earthworms and
  crabs that extract nutrients from decomposed
  particles of organic matter.

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Thermodynamics Food Webs
Lecture 8
Phys 102 Natural Systems
Energy in the Food Web
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Phys 102 Natural Systems