2.5.1 Explain the role of producers,
consumers, and decomposers in the
ecosystem.
 2.5.2 Describe photosynthesis and
respiration in terms of inputs, outputs,
and energy transformations.
 2.5.3 Describe and explain the transfer
and transformation of energy as it flows
through an ecosystem.

2.5.4 Describe and explain the transfer
and transformation of materials as they
cycle within an ecosystem.
 2.5.5 Define the terms gross productivity,
net productivity, primary productivity,
and secondary productivity.
 2.5.6 Define the terms and calculate
values of both gross primary productivity
(GPP), and net primary productivity
(NPP).


2.5.7 Define the terms and calculate
values of both gross secondary
productivity (GSP), and net secondary
productivity (NSP).


Producers – basis of
ecosystem,
supporting them
through constant
input of energy and
biomass.
Consumers – Obtain
energy, minerals,
and nutrients by
eating other
organisms.

Decomposers –
Break down dead
organic matter for
food, thereby
releasing nutrients
ready for
reabsorption by
producers. Also
build up hummus
and improve nutrient
retention capacity of
soil.

Photosynthesis
› Inputs: Sunlight,
carbon dioxide, and
water
› Outputs: Glucose,
and oxygen
› Transformation: Light
energy into stored
chemical energy

Respiration
› Inputs: Glucose,
and oxygen
› Outputs: Carbon
dioxide, water, and
release of energy
for work and heat
› Transformation:
Stored chemical
energy to kinetic
energy and heat

Not all solar radiation
ends up as biomass.
Losses include:
› Reflection from
›
›
›
›
leaves
Not hitting
chloroplasts
Wrong wavelength
Transmission of light
through the leaf
Inefficiency of
photosynthesis

Energy comes into
the ecosystem as
light energy, which is
converted into
chemical energy by
producers. That
chemical energy is
transferred as
organisms are eaten,
with energy being
lost as heat and
respiration.

Carbon cycle –
Carbon is fixed by
producers. They
respire returning
some to the
atmosphere, with the
rest going to
biomass. When they
die they are eaten
by decomposers,
returning CO2 to air.

Carbon cycle –
Producers that died
a long time ago are
turned into fossil fuels
and release CO2
when burned.
Shellfish fix CO2 in
their shells and
release it after a long
time thru weathering
volcanism.

Nitrogen cycle –
Nitrogen is fixed by
bacteria and absorbed
by plants. Plants are
eaten by consumers and
decomposers, with
decomposers and
lightning changing it to
ammonia and nitrifying
bacteria oxidizing it to
nitrates for plants to
absorb. It is also
denitrified by bacteria to
return to the
atmosphere.

Nutrient cycle –
Nutrients are dissolved
in rain going to litter
with some run off. This
mineralizes into soil
and some lost thru
leeching and gained
via weathering of rock.
Plants absorb the
nutrients and return it
to litter through decay.

Water cycle – Rain falls
as precipitation, it is
absorbed into
vegetation, surface
water, soil, ground
water, and water
channels with some
leakage to deep
basins. It goes to the
ocean via runoff, and
returns to the
atmosphere via
evapotranspiration.


Gross Productivity –
total gain in energy
or biomass per unit
area per unit time
Net Productivity –
Gain in energy or
biomass per unit
area per unit time
after allowing for
respiration losses


Primary Productivity –
gain by autotrophs in
energy or biomass per
unit area per unit time
Secondary
Productivity – biomass
gained by
heterotrophs thru
feeding and
absorption, measured
in units of mass or
energy per unit area
per unit time
Gross Primary
Productivity – Gain in
energy or biomass thru
photosynthesis per unit
area per unit time.
 Net Primary
Productivity – The gain
by producers in
energy or biomass per
unit area per unit time
remaining after
respiration losses.



Gross Secondary
Productivity (Gross
Assimilation) – Gain in
energy or biomass thru
absorption per unit
area per unit time.
Net Secondary
Productivity (Net
Assimilation) – The gain
by consumers in
energy or biomass per
unit area per unit time
remaining after
respiration losses.