Unit 10: Ecology
Mr. Nagel
Meade High School
Warm Up
Lifestyles of the Cells and Famous…
• Outline the differences between the behaviour
of the chromosomes in mitosis and meiosis.
two divisions in meiosis, only one in mitosis;
meiosis results in haploid cells, mitosis in diploid cells;
crossing over only occurs in meiosis;
no S phase precedes meiosis II;
chromosome behaviour in meiosis II and mitosis is similar / chromosome
behaviour in meiosis I and mitosis is different;
chiasmata only form during meiosis;
homologous chromosomes move to the equator in pairs only in meiosis;
Do not accept number of cells produced - it is a result not a behaviour.
IB Syllabus Statements
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5.1.1
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5.1.2
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State that energy transformations are never 100% efficient.
5.1.12
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Explain the energy flow in a food chain.
5.1.11
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State that light is the initial energy source for almost all communities.
5.1.10
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Construct a food web containing up to 10 organisms, using appropriate information.
5.1.9
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Deduce the trophic level of organisms in a food chain and a food web.
5.1.8
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Define trophic level.
5.1.7
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Describe what is meant by a food web.
5.1.6
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Describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms).
5.1.5
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Distinguish between consumers, detritivores and saprotrophs.
5.1.4
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Distinguish between autotroph and heterotroph.
5.1.3
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Define species, habitat, population, community, ecosystem and ecology.
Explain reasons for the shape of pyramids of energy.
5.1.13
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Explain that energy enters and leaves ecosystems, but nutrients must be recycled.
http://click4biology.info/c4b/5/eco5.1.htm
What is Ecology?
• Ecology is the study of the relationships
between organisms and their environment.
– Abiotic factors (non-living)
– Biotic factors (living)
Talking Points
• Should we be trying to prevent species
from becoming extinct? If so, why?
• Should emissions (carbon) be regulated?
Should these regulations be a condition for
developing countries to receive foreign
aid?
• Are global warming and ozone loss ‘real’
issues? What role does society have in
addressing them?
Essential Definitions
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Producer
Consumer
Detritivores
Saprotrophs
Autotroph
Heterotroph
Decomposer
Species
Niche
Habitat
Population
Community
Ecosystem
Food Chain
Food Web
Trophic Level
Essential Definitions
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Producer: an organism that is able to produce its own food from inorganic substances. (ex:
plant)
Consumer: a heterotrophic organism that feeds on other organisms in a food chain (ex:
primary, secondary, tertiary)
Detritivores: organism that uses organic waste as a food source (ex: certain insects)
Saprotrophs: organisms that consume inorganic foods
Autotroph: organism that synthesizes its organic molecules from simple inorganic
molecules
Heterotroph: organism that feeds on organic matter
Decomposer: organism that recycles nutrients (ex: fungus)
Species: organisms having common characteristics capable of mating with each other
Niche: status of an organism within its environment and community
Habitat: environment in which a species normally lives or the location of the living
organism
Population: organisms that occur in a specified habitat
Community: assemblage of two or more populations of different species occupying the
same geographical area
Ecosystem: system formed by the interaction of a community of organisms with their
physical environment
Food Chain: sequence showing the feeding relationships and energy flow between species
Food Web: complex of interrelated food chains in an ecological community
Trophic Level: group of organisms that occupy the same level of a food chain
Organisms and Relationships
Food Chains
• Create three distinctly DIFFERENT food
chains, each consisting of three or more
linkages (4+ organisms).
– Arrows indicate energy flow, NOT what
organisms are consuming other organisms.
Food Webs
• Create a model of Terrestrial or Oceanic
Food web – must contain a minimum of 10
organisms.
– Arrows indicate energy flow, NOT what
organisms are consuming other organisms.
Energy Pyramids
• The higher the level of organism…
– Less energy available.
– More ‘lower’ levels needed
to support it.
– Energy enters and leaves an
ecosystem, but nutrients
MUST be recycled!
IB Syllabus Statements
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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.
http://click4biology.info/c4b/5/eco5.2.htm
Cycles of Importance
• Water Cycle
• Carbon Cycle
• Nitrogen Cycle
Geochemical Cycles
• All molecules contribute to the movement
of nutrients through the environment.
Water Cycle
• Organisms lose water to the environment.
– Evaporation
– Transpiration
– Perspiration
• Clouds (In/Out).
– Condensation
– Precipitation
• Re-entry into organisms via land.
Carbon Cycle
• Atmospheric CO2
absorbed by plants.
• Photosynthesis turns
CO2 to sugar.
• Organisms undergo
respiration,
converting sugar to
CO2 gas.
• Dead organisms can
become fossil fuels,
which when burned,
produce CO2 .
• Bodies of water can
absorb CO2 .
Nitrogen Cycle
• Atmospheric nitrogen is
converted by bacteria into
nitrate.
• Plants use the nitrate to
create protein, along with
nitrogen found in animal
waste products.
• Animals consume plants
and produce proteins.
Excess nitrogen is excreted
as waste.
• Dead organisms are
broken down by bacteria,
converting nitrate back to
nitrogen gas.
Warm Up
Energy Pyramid
• The total solar energy received by a grassland is 5 × l05 kJ m–2 y–1. The
net production of the grassland is 5 × 102 kJ m–2 y–1 and its gross
production is 6 × l02 kJ m–2 y–1. The total energy passed on to primary
consumers is 60 kJ m–2 y–1. Only 10% of this energy is passed on to the
secondary consumers.
(a)
(b)
(a)
Calculate the energy lost by plant respiration.
Construct a pyramid of energy for this grassland.
plant respiration = gross production – net production /
6 × 102 kJ m–2 y –1 – 5 × 102 kJ m –2 y –1;
= 1 × 102 / 100 kJ m–2 y –1;
Units required.
(b)
correct pyramid shape;
6 kJ m–2 y–1 (correctly calculated as energy passed to secondary consumer);
producer and primary consumer values correctly inserted;
Award [2 max] if there are units omitted. Award [2 max] if a bar is included for the solar energy. Do not
deduct marks if the areas of the bars are not proportional to the values, although they should get
smaller going up.
(2)
(3)
IB Syllabus Statements
• 5.3.1
– Outline how population size is affected by natality, immigration,
mortality and emigration.
• 5.3.2
– Draw and label a graph showing a sigmoid (S-shaped)
population growth curve.
• 5.3.3
– Explain the reasons for the exponential growth phase, the
plateau phase and the transitional phase between these two
phases.
• 5.3.4
– List three factors that set limits to population increase.
http://click4biology.info/c4b/5/eco5.3.htm
Talking Points: Populations
• What factors work to increase a population
of a particular organism?
• What factors work to decrease a population
of a particular organism?
Let’s Study: Populations!
What happens in each of these steps?
I. Exponential Growth
II. Transition
Competition/Natural Selection
I. Plateau
Natality + Immigration =
Mortality + Emmigration
Consider the example of a bacterial
colony that has set up residence in
your throat.
Consider the germination of annual
plants in the spring time.
Let’s Study: Populations!
What are some environmental forms of
resistance that limit populations
from growing uncontrollably?
(Hint: Think Cancer)