Topic 5 review

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Topic 5 review
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Populations 5.3

• 5.3.1 Outline how population size can be
  affected by natality, immigration, mortality and
  emigration
• 5.3.2 Draw and label a graph showing the sigmoid
  (S-shaped) population growth curve
• 5.3.3 Explain reasons for the exponential growth
  phase, the plateau phase and the transitional
  phase between these two phases
• 5.3.4 List three factors which set limits to
  population increase

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• What determines population growth?
• Natality, Mortality, Immigration, Emmigration
• What type of species grow exponentially, with
  density independent growth?
• R-selected species
• What type of species shows density dependent
  growth that slows then plateaus over time?
• K-selected species

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So populations change by

• Natality and Immigration increasing them
• Mortality and Emigration decreasing them
• So
• Change (N I) (D E)

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Figure 52.8 Population growth predicted by the
exponential model
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Figure 52.11 Population growth predicted by the
logistic model
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Phases of an S curve

• Exponential phase population increases because
  natality rate is greater than mortality rate
• Resources abundant, diseases predation rare
• Transitional phase natality rate starts to slow
  /or mortality rate starts to increase. Natality
  still above mortality so population will still
  increase but less rapidly
• Resources decreasing /or Disease Predation
  increase
• Plateau phase Natality Mortality so
  population size remains constant
• Something has limited the population
• It has reached carrying capacity (K)

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What is Carrying Capacity?

• K the maximum number of individuals that a
  particular environment can support at a
  particular time with no habitat degradation
• What are the limiting factors that would cause
  carrying capacity?
• Limiting factors include Energy (food) available,
  shelters, predators, diseases or parasites, soil
  nutrients, water, suitable nesting roosting
  sites

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Ecosystems 5.1

• 5.1.1 Define ecology, ecosystem, population,
  community, species habitat
• 5.1.2 Distinguish between autotroph (producer)
  and heterotroph (consumer)
• 5.1.3 Distinguish between consumers,
  detritivores and saprotrophs
• 5.1.4 Describe what is meant by a food chain
  giving three examples, each with at least 3
  linkages (4 organisms)
• 5.1.5 Describe what is meant by a food web
• 5.1.6 Define trophic level
• 5.1.7 Deduce the trophic level of organisms in
  a food chain and food web
• 5.1.8 Construct a food web containing up to 10
  organisms given appropriate information

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• 5.1.9 State that light is the initial energy
  source for almost all communities
• 5.1.10 Explain the energy flow in a food chain
• 5.1.11 State that when energy transformations
  take place including those in living organisms,
  the process is never 100 efficient, commonly
  being 10 20
• 5.1.12 Explain what is meant by a pyramid of
  energy and the reasons for its shape
• 5.1.13 Explain that energy can enter and leave
  an ecosystem, but that nutrients must be recycled
• 5.1.14 State that saprophytic bacteria and
  fungi (decomposers) recycle nutrients

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Definitions

• Ecology
• ? the study of relationships between living
  organisms and between organisms and their
  environment
• Ecosystem
• ? a community and its abiotic environment
• Population
• ? a group of organisms of the same species who
  live in the same area at the same time
• Community
• ? a group of populations living and interacting
  with each other in an area
• Species
• ? a group of organisms which can interbreed and
  produce fertile offspring
• Habitat
• ? the environment in which a species normally
  lives or the location of a living organism
• Trophic level
• ? energy level in a food web / chain
• Autotroph
• ? organism which makes its own food from
  inorganic materials
• Heterotroph
• ? organism that depends directly or indirectly
  on producers for energy

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What is a

• Consumer?
• Eats another organism as an energy source
  heterotrophic
• Zebra, lion
• Detritivore?
• get their energy from detritus, nonliving organic
  material ? remains of dead organisms feces,
  fallen leaves, wood
• Dung beetles, earth worms
• Saprotroph?
• feed on dead organic material by secreting
  digestive enzymes into it and absorbing the
  digested products
• Bread mold, mushrooms

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Food chains are linear diagrams to show feeding
relationships and energy flow
Producer Passion Flower Carrot plant Sea lettuce
Primary Consumer Heliconius butterfly Carrot fly Marine iguana
Seconday Consumer Tegu lizzard Flycatcher Galapagos snake
Tertiary Consumer Jaguar Sparrowhawk Galapagos Hawk
Quarternary Consumer Goshawk
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An Antarctic marine food web no show
organisms at multiple trophic levels to indicate
the true complexity of the feeding relationships
and energy flowCan you deduce the trophic
level for each organism you see?
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Now create a food web remember the direction of
your arrows!
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The initial source of energy for most communities
is the

• Sun

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Explain the energy flow in one of these food
chains What percent of the energy in zooplankton
could be expected to be transferred to the small
carnivorous fish? If there are 20 Joules of
energy in a grasshopper, how much of that is left
for the hawk?
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Energy pyramids
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So energy and matter move differently

• Energy flows through the system in from the sun
  out by heat
• Matter must be recycled though because there is
  no new matter coming in to replace used matter

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Syllabus statements

• 5.4.1 Define evolution
• 5.4.2 Outline the evidence for evolution
  provided by the fossil record, selective breeding
  of domesticated animals, and homologous
  structures
• 5.4.3 State that populations tend to produce
  more offspring that the environment can support
• 5.4.4 Explain that the consequence of the
  potential overproduction of offspring is a
  struggle for survival
• 5.4.5 State that the members of a species show
  variation
• 5.4.6 Explain how sexual reproduction promotes
  variation in a species
• 5.4.7 Explain how natural selection leads to
  evolution
• 5.4.8 Explain two examples of evolution in
  response to environmental change one must be
  multiple antibiotic resistance in bacteria

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Evolution Basics

• Evolution The change in the genetic composition
  of a population over time
• Changes in gene frequency over time

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Evidence for evolution

• Evidence indicates that species evolve by natural
  selection over longer time periods
• Evolution is validated by evidence from
• homology ? similarities between species due to
  common ancestry
• Selective breeding ? Breeding organisms for
  specific traits
• Biogeography ? distribution of living species
• Fossils ? Form and distribution validate the
  theory

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Principles of Evolution

1. Populations tend to produce more offspring that
   the environment can support
2. Members of a species show variation
3. The resources in the environment are limited
4. The consequence of the potential overproduction
   of offspring is a struggle for survival
5. Some variations are favorable in this struggle
6. Those individuals with favorable variations will
   pass on their genes to the next generation in
   higher numbers
7. Gene frequency changes to represent the fittest
   organisms SURVIVAL OF THE FITTEST

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Consequences of Overproduction of Offspring

1. Food might become scarce
2. Territories might be limiting for both mating and
   reproducing
3. Density might get so great that disease and
   parasites would become epidemics
4. Predator populations will also grow because of
   the increase in population size of prey, and
   begin to whittle down the herd.

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Role of Sex

• Living organisms vary as a result of sexual
  reproduction
• Meiosis allows a large variety of genetically
  different gametes to be produced by each
  individual (2n)
• This occurs through segregation of maternal and
  paternal chromosomes and crossing over in
  prophase I of meiosis
• Fertilization allows alleles from 2 different
  individuals to be brought together in one new
  individual

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Evolution in response to environmental change
antibiotic resistence
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Evolution in response to environmental change
pesticide resistence
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Taxonomy syllabus statements

• 5.5.1 Outline the binomial system of
  nomenclature
• Define species
• 5.5.2 List the seven levels in the hierarchy of
  taxa kingdom, phylum, class, order, family,
  genus, species using an example from two
  different kingdoms for each level
• 5.5.3 Distinguish between the following phyla of
  plants, using simple external recognition
  features bryophyta, filicinophyta, coniferophyta
  and angiospermophyta.
• 5.5.4 Distinguish between the following phyla of
  animals, using simple external recognition
  features porifera, cnidaria, platyhelminthes,
  annelida, mollusca and arthropoda.
• 5.5.5 Apply and/or design a key for a group of
  up to eight organisms

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Binomial Nomenclature System

• Created by C. Linneaus
• Each species has 2 part Latin name
• Genus species (computer)
• Genus species (handwritten)
• E.g. Homo sapiens humans
• Felis sylvestris house cat
• Ranunculus acris buttercut

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Remember KPCOFGS(memorize the following
examples)
Levels Domestic Cat Common Buttercup Human
Kingdom Animalia Plantae Animalia
Phylum Chordata Anthophyta Chordata
Class Mammalia Dicotyledons Mammalia
Order Carnivora Ranunculales Primates
Family Felidae Ranunculacae Hominidae
Genus Felis Ranunculus Homo
Species sylvestris acris sapiens
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• Organisms that are in a particular level of the
  taxonomic hierarchy together share all the levels
  above and may or may not share the levels below

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Plants

• Bryophyta mosses, liverworts, hornworts
  short, nonvascular, no roots, live in moist and
  harsh environments,
• Filicinophyta ferns, clubmosses, wiskferns,
  horsetails - vascular, spores, need water for
  reproduction, simple leaves,
• Coniferophyta conifers, cycads, ginkgo, and the
  gnetophytes small waxy leaves, naked seeds,
  larger,
• Angiospermophyta flowering plants fruits,
  flowers, most diverse, monocots and dicots

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Animals

• Porifera sponges sessile, lack tissues,
  filter feeders
• Cnidaria anemones, corals, hydra, jellies
  nematocysts, radial symmetry, polyp or medusa
• Platyhelminthes flatworms bilateral symmetry,
  flat, only one GI tract opening
• Annelida segmented worms (oligocheates,
  polycheates, hirudinea) repeated segments on
  bilaterally symmetrical body
• Mollusca bivalves, cephlopods, gastropods,
  chitons bilateral symmetry, 3 body parts? foot,
  visceral mass, mantle
• Arthropoda insects, crustaceans exoskeletons
  and jointed appendages

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Create Apply A Dichotomous Key
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Syllabus Statements

• 5.2.1 draw and label a diagram of the carbon
  cycle to show the processes involved
• 5.2.2 Analyse the changes in concentration of
  atmospheric carbon dioxide using historical
  records
• 5.2.3 Explain the relationship between rises in
  concentrations of atmospheric carbon dioxide,
  methane and oxides of nitrogen and the enhanced
  greenhouse effect
• 5.2.4 Outline the precautionary principle
• 5.2.5 Evaluate the precautionary principle as a
  justification for strong action in response to
  the threats posed by the enhanced greenhouse
  effect
• 5.2.6 Outline the consequences of a global
  temperature rise on arctic ecosystems

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Figure 54.17 The carbon cycle
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Greenhouse Effect Global Warming

• Incoming short wave radiation (visible and UV) is
  transmitted through the atmosphere
• Much of solar radiation that strikes the planet
  is reflected back into space
• Although CO2 and water vapor in the atmosphere
  are transparent to visible light, they absorb
  much of the reradiated long wave radiation
  (infrared radiation)
• Some reflected back and retained to heat up the
  earth
• If not for the natural Greenhouse effect the
  earths surface temperature would be 18 oC ? most
  life would not exist

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So

• Main atmopsheric gases involved are CO2, methane,
  water vapor, CFCs
• If we put more of those gases into the atmosphere
  from our activities, we should expect a
  corresponding increase in temperature
• Do we put in more?

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Human activities increase the Greenhouse Effect

• Gases CO2, methane, water vapor, CFCs
• CO2 Released from combustion of fossil fuels
  (coal, oil natural gas)
• Burning of wood from deforestation
• Methane release from the digestive tracts of
  ruminants (cows)
• Swamps, rice paddies, landfills
• CFCs used as refrigerants, propellants in cans,
  gas blown plastics

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Historical Records

• We see trends of increased CO2 emissions in
  measures taken since 1950s
• Mona Loa and Cape Grim Tazmania, show
  fluctuating increase
• Peaks in our winter, dips in our summer depends
  on photosynthesis
• Longer term trends in CO2 seen in ice core data

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Consequences for Arctic ecosystems

• Increased decomposition rates of organic material
  trapped in the ice caps
• Expansion of temperate species into the polar
  habit
• Loss of ice habitat Polar bears threatened
• Changes in prey distribution, effecting top
  predators
• Increased success of pests and pathogens.

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The Precautionary Principle

• If the effects of human induced climate change
  would be large or catastrophic
• Those responsible for the changes must prove that
  they are not harmful before proceeding
• This is the reverse of the normal condition

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The Precautionary Principle

• In other words if Human disturbances are
  disrupting ecosystem processes
• Our ignorance of long term effects means we
  should be cautious
• Thus, When there is considerable evidence that
  and activity threatens human and ecosystem
  health, we should take precautions to minimize
  harm, even if the effects are not fully known.
• Better safe than sorry

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• Does the economic harm of measures taken now to
  limit global warming, offset the potentially
  greater harm that inaction would present to
  future generations?
• The ethics of it
• Is it right to jeopardize the health welfare of
  future human populations?
• Is it right to do damage to habitats and drive
  species to extinction?

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