Download Energy Transfer

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Topic 5.2
https://www.youtube.com/watch?v=joZ1EsA5_NY
Ecosystems rely on
energy transfer
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Introduction
 An
ecosystem is:
 A self-sufficient system consisting of a community of
interacting organisms and the abiotic factors of their
habitat
 What does self-sufficient mean?
 The organisms are interdependent and ALL rely on
Producers
 Producers are autotrophs: what does this mean?
 They are able to produce their own food, they
convert inorganic substances to organic substances.
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 What
are the 2 types of autotrophs- give examples:
 Photosynthetic: plants, phytoplankton and some
bacteria
 Chemosynthetic: some bacteria: synthesis organic
molecules using energy released from exergonic
reactions
 When might chemosynthesis be useful?
 Deep in the ocean where there is not enough light
 Is a link between productivity and biodiversity?
 Usually a direct correlation, but not always
(exception - when eutrophication occurs)
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Energy flow through the
ecosystem
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Feeding relationships
grass  grasshopper  frog  snake  hawk
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Give examples of the following terms from the food chain above Autotroph,
 heterotroph,
 producer,
 consumer,
 prey,
 predator,
 carnivore,
 omnivore,
 herbivore,
 trophic level
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Recycling
 What
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They ingest small pieces of dead plant or animal or waste like
leaves, antlers, skin.
Earthworms, woodlice, freshwater shrimps
 What
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are detritivores? Give examples.
are decomposers ? Give examples.
They breakdown dead organic material or waste by living on
their food- releasing enzymes which digest externally and then
absorb the breakdown products
Bacteria and Fungi
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Decomposers and detritivores
 What
niche do they have in an ecosystem?
 They are important as they recycle
organic compounds by breaking them
down into small, inorganic compounds
which can be used by producers.
 Checkpoint
the blanks
5.4: Ecology definitions fill in
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Activity 5.7 Constructing Food
Webs
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Activity 5.7 Constructing Food
Webs
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Photosynthesis converts light
energy into chemical energy.
 How
much of the light
energy available to
plants is actually
converted into
chemical energy?
 Very
little estimated 5%
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Energy Transfer
 What
happens to the rest of the light energy?
 Is reflected
 Is used in evaporating water- transpiration
 Is transmitted through the leaf
 Only about 40% of light hitting a leaf gets absorbed
by the chloroplast
 What happens to the 40% which is absorbed?
 some is converted into organic molecules in
photosynthesis
 some is lost in the process of photosynthesis. Why?
 It is not 100% efficient and light may not be the
limiting factor
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Energy Flow through a food chain
 The
flow of energy from one trophic level to
another is not 100% efficient either. Usually
<10% of the energy from producers is used to
produce biomass in primary consumers.
 Why?
 Some
parts of the plants don’t get eaten, e.g.
roots,
 some are indigestible and pass out (egested)
in faeces (cellulose for example),or lost in
urine
 some energy used in respiration to provide
energy to move, stay warm, active transport etc.
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Energy Transfer
1.
The transfer of energy from herbivores to
carnivores is MORE efficient
 no cellulose, more protein= more digestible,
more parts of the organism are eaten
 Law
of conservation of energy: energy can not be
created or destroyed, it can just be converted
/transferred.
energy entering = energy lost +
the trophic level
in respiration
 page
29. Q 5.21
energy lost
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in faeces + urine
energy in
new biomass
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Energy flow through an ecosystem
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Productivity
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Define GPP: gross primary productivity
 the rate at which energy is converted into organic molecules in an
ecosystem measured in kJ or MJ per m2 or ha per year
(megajoule= 1 million joules. UNITS ARE IMPORTANT IN THE
DEFINITION.
Calculate the percentage efficiency of photosynthesis:
(GPP/light energy striking the plant) x 100
What happens to the carbohydrates produced during
photosynthesis?
 Respiration, or building other organic molecules, proteins etc
Define biomass.
 The amount of living (organic) material present, it is produced
by the organism and does not include water
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Productivity
 Define
NPP: net primary productivity
 the rate at which energy is transferred into the
organic molecules that make up new plant
biomass is called net primary productivity
(NPP).
 What
is the relationship between NPP and GPP?
 NPP = GPP – R
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Net primary productivity terrestrial
Many factors influence primary productivity rates, but the most important on
land are temperature and water availability.
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Ocean net primary productivity
In contrast to land, where vascular plants carry out most primary production,
most primary production in the oceans is done by microscopic algae.
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Pyramids of Energy
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What does each bar
represent?
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Why are food chains rarely
more than 5 organisms?
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Since energy transfer
from one trophic level to
another is so inefficient,
food chains rarely have
more than 5 organisms
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Activity 5.08 Energy Flow in a
Ecosystem
Q 1-read the question.
 Which letter represents the energy
available to the bullock?
 C (3056)
 Which represents the energy used
to make its new biomass?
 P (125)
 What happened to the rest of the
energy?
 Egested or excreted or used in
respiration.
 How efficient was the energy
transfer from the producer to this
primary consumer?
 P/C * 100%
Complete Q 1
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Activity 5.08 Energy Flow in a
Ecosystem
A 1000 units falls on the plant per unit time.
F 400 units are absorbed by chloroplasts.
B 500 units are of wavelengths not used in
photosynthesis.
G 308 units are used in the reactions of
photosynthesis. This energy is lost to the
environment.
C 500 units have wavelengths in the range 400–
700 nm so it can be used in photosynthesis.
H 92 units are converted to carbohydrate in
photosynthesis (gross primary production).
D 50 units available for photosynthesis are
reflected.
I 55 units become plant biomass (net primary
production).
E 50 units available for photosynthesis pass straight
through the plant.
J 37 units are released in cell respiration in the
mitochondria. This energy is lost to the
environment.
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Activity 5.08 Energy Flow in a
Ecosystem
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