tugas

1. 14th MEETING
DEPARTEMEN PENDIDIKAN NASIONAL
UNIVERSITAS NEGERI SURABAYA
JURUSAN BIOLOGI - FMIPA
2012

2. • You should be able to:
1. Define the terms habitat, niche, population,
community and ecosystem, and describe
examples of each;
2. Explain the term producer, consumer and
trophic level, and state examples of these in
specific food chain and food webs;
3. describe how energy is transferred through
food chain and food webs;
4. explain how energy losses occur along food
chains, and understand what is meant by
efficiency of transfer;

3. Food Chains
and
Food Webs
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4. What is a Food Chain?
• A food chain is the path
by which energy passes
from one living thing to
another.
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5. What’s in a Food Chain?
•Producers
•Consumers
•Decomposers
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6. Producers
• Producers make their
own food
• Green plants use
energy from the sun
to make food
• Producers are on the
bottom of the food
chain
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7. Consumers
• Consumers hunt, gather,
and store food because
they cannot make their
own.
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8. Three Types of Consumers
•Herbivores
•Carnivores
•Omnivores
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9. Herbivores
• Animals who eat plants
such as:
–grasshoppers
–rabbits
–squirrels
–deer
–pandas
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10. Carnivores
• Animals who only eat
other animals such as:
–tigers
–lions
–hawks
–wolves
–cougars
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11. Omnivores
• Animals who eat both
plants and animals such
as:
–humans
–bears
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12. Decomposers
• Microorganisms that are
able to break down large
molecules into smaller
parts
• Decomposers return the
nutrients that are in a
living thing to the soil
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13. Let’s Look
at a
Food Chain
• A food chain is a
simplified way to
look at the energy
that passes from
producers to
consumers.
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14. Types of Food Chains
• Aquatic- Water-related
food chains with sea
plants and animals
• Terrestrial- Land-related
food chains with land
plants and animals
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15. Predator & Prey
• Predator- An animal that
captures and eats other
animals
• Prey- The animal that is
captured and eaten
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16. What is a Food Web?
• A more realistic way of looking at
the relationship of plants and
animals in an environment
• Several food chains linked
together
• A predator from one food chain
may be linked to the prey of
another food chain
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17. Food Webs
• How many food chains can
you make from this food
web?
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18. NUTRIENT CYCLES

19. NUTRIENT CYCLES:
ECOSYSTEM TO
ECOSPHERE
• Nutrient cycling occurs at
the local level through the
action of the biota.
• Nutrient cycling occurs at
the global level through
geological processes, such
as, atmospheric circulation,
erosion and weathering.

20. NUTRIENT CYCLES
• The atoms of earth and life are the same; they
just find themselves in different places at different
times.
• Most of the calcium in your bones came from
cows, who got it from corn, which took it from
rocks that were once formed in the sea.
• The path atoms take from the living (biotic) to the
non-living (abiotic) world and back again is called
a biogeochemical cycle.

21. Nutrients: The Elements of Life
• Of the 50 to 70 atoms (elements) that
are found in living things, only 15 or so
account for the major portion of living
biomass.
• Only around half of these 15 have been
studied extensively as they travel
through ecosystems or circulate on a
global scale.

22. A GENERALIZED MODEL OF
NUTRIENT CYCLING IN AN
ECOSYSTEM
• The cycling of nutrients in
an ecosystem are
interlinked by an a number
of processes that move
atoms from and through
organisms and to and from
the atmosphere, soil
and/or rocks, and water.
• Nutrients can flow between
these compartments along
a variety of pathways.

23. Nutrient Compartments in a
Terrestrial Ecosystem
• The organic compartment consists of the
living organisms and their detritus.
• The available-nutrient compartment consists
of nutrients held to surface of soil particles or
in solution.
• The third compartment consists of nutrients
held in soils or rocks that are unavailable to
living organisms.
• The fourth compartment is the air which can
be found in the atmosphere or in the ground.

24. Uptake of Inorganic Nutrients
from the Soil
• With the exception of CO2
and O2 which enter though
leaves, the main path of all
other nutrients is from the
soil through the roots of
producers.
• Even consumers which find
Ca, P, S and other elements
in the water they drink,
obtain the majority of these
nutrients either directly or
indirectly from producers.

25. The Atmosphere Is a Source of
Inorganic Nutrients
•
•
•
The atmosphere acts as a
reservoir for carbon dioxide
(CO2), oxygen (O2) and water
(H2O).
These inorganic compounds
can be exchanged directly
with the biota through the
processes of photosynthesis
and respiration.
The most abundant gas in
the atmosphere is nitrogen
(N2);about 80% by volume.
Its entry into and exit from
the biota is through bacteria.

26. Some Processes By Which
Nutrients Are Recycled
• Cycling within an
ecosystem involves a
number of processes.
• These are best
considered by
focusing attention on
specific nutrients.

27. CARBON, HYDROGEN AND
OXYGEN CYCLES IN
ECOSYSTEMS
• C, H & O basic elements of life; making up
from about 98% of plant biomass.
• CO2 and O2 enter biota from the atmosphere.
• Producers convert CO2 and H2O into
carbohydrates (CH2O compounds) and
release O2 from water.
• Producers, consumers and decomposers
convert CH2O compounds, using O2, back into
CO2 and H2O.

28. CARBON, HYDROGEN AND OXYGEN
CYCLES IN ECOSYSTEMS
• Carbon and oxygen cycle come out of the air as carbon
dioxide during photosynthesis and are returned during
respiration.
• Oxygen is produced from water during photosynthesis
and combines with the hydrogen to form water during
respiration.

29. PHOSPHOROUS CYCLE IN
ECOSYSTEMS
• Phosphorus, as phosphate (PO4-3),
is an essential element of life.
• It does not cycle through
atmosphere, thus enters producers
through the soil and is cycled
locally through producers,
consumers and decomposers.
• Generally, small local losses by
leaching are balanced by gains
from the weathering of rocks.
• Over very long time periods
(geological time) phosphorus
follows a sedimentary cycle.

30. NITROGEN CYCLE IN
ECOSYSTEMS
• Nitrogen (N2) makes up
78% of the atmosphere.
• Most living things, however,
can not use atmospheric
nitrogen to make aminoacids and other nitrogen
containing compounds.
• They are dependent on
nitrogen fixing bacteria to
convert N2 into NH3(NH4+).

31. Biological Sources of Soil
Nitrogen
• Only a few species of
bacteria and
cyanobacteria are
capable of nitrogen
fixation.
• Some are fee-living and
others form mutualistic
associations with plants.
• A few are lichens.

32. Atmospheric Sources of Soil
Nitrogen
• Lightning was the major source
of soil nitrogen until recent times
when the burning of fossil fuels
became a major source of
atmospheric deposition.
• Nitrogen oxides come from a
variety of combustion sources
that use fossil fuels. In urban
areas, at least half of these
pollutants come cars and other
vehicles.

33. Agricultural Supplements to Soil
Nitrogen
• Various forms of
commercial fertilizer are
added to agricultural fields
to supplement the nitrogen
lost through plant harvest.
• Crop rotation with legumes
such as soybeans or alfalfa
is also practiced to
supplement soil nitrogen.

34. Biological Nitrogen Fixation
•
Nitrogen fixation is the largest
source of soil nitrogen in
natural ecosystems.
• Free-living soil bacteria and
cyanobacteria (blue-green
“algae”) are capable of
converting N2 into ammonia
(NH3) and ammonium (NH4+).
•
Symbiotic bacteria (Rhizobium)
in the nodules of legumes and
certain other plants can also fix
nitrogen.
QuickTimeª and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

35. Nitrification
• Several species of
bacteria can convert
ammonium (NH4+) into
nitrites (NO2-).
• Other bacterial
species convert
nitrites (NO2-) to
nitrates (NO3-).

36. Uptake of Nitrogen by Plants
•
Plants can take in either
ammonium (NH4+) or nitrates (NO3-)
and make amino acids or nucleic
acids.
• These molecules are the building
blocks of proteins and DNA, RNA,
ATP, NADP, respectively.
• These building blocks of life are
passed on to other trophic levels
through consumption and
decomposition.

37. Ammonification
• Decomposers convert
organic nitrogen (CHON)
into ammonia (NH3) and
ammonium (NH4+).
• A large number of
species of bacteria and
fungi are capable of
converting organic
molecules into ammonia.

38. Denitrification
• A broad range of
bacterial species can
convert nitrites, nitrates
and nitrous oxides into
molecular nitrogen (N2).
• They do this under
anaerobic conditions as
a means of obtaining
oxygen (O2).
• Thus, the recycling of N
is complete.

39. GLOBAL NUTRIENT
CYCLES
• The loss of nutrients
from one ecosystem
means a gain for
another. (Remember
the law of conservation
of matter.)
• When ecosystems
become linked in this
manor, attention shifts
to a global scale. One is
now considering the
ECOSPHERE or the
whole of planet earth.

40. THANK YOU