ECosystems Flashcards
Sustainablity
An ecosystem is described as being all
the interacting parts of a biological
community and its environment.
A sustainable ecosystem is one that is
capable of withstanding pressure and
giving support to a variety of organisms.
As noted by the Easter Island example on
page 7 of the text, humans have the
potential to inflict catastrophic changes on
an ecosystem. These changes can greatly
affect an ecosystem’s sustainability.
Parts Of An Ecosystem
Every ecosystem has biotic and abiotic parts.
* Biotic refers to the living parts of an ecosystem (including
plants, animals, and micro-organisms).
* Abiotic refers to the non-living parts of an ecosystem
(including water, oxygen, light, nutrients, and soil).
Cycling Of Matter And Earth’s Sphere
Ecological processes move matter from the biotic and abiotic parts of
an ecosystem and back again in continuous cycles.
*The lithosphere is the hard
part of Earth’s surface.
*The hydrosphere is all of the
water found on Earth (lakes,
oceans, and ground water).
*The atmosphere is the layers
of gas above Earth’s surface.
*The biosphere is the regions
of Earth where living
organisms exist.
Nutrient Cycles:Water
Nutrients are chemicals that are needed by living things and
are continually cycled through ecosystems.
The water cycle moves water through the hydrosphere,
atmosphere, and lithosphere.
This occurs by way of:
evaporation: the change of state from a liquid to a
gas.
condensation: the change of state from a gas to a
liquid.
precipitation: rain, snow, sleet, dew, formed by
condensation of water vapour in the atmosphere.
The Water Cycle
The Earth’s water is stored in rivers, lakes and oceans
and as ground water under the surface of the land.
The Sun’s light energy turns the water from the oceans
and other bodies of water into vapour through
evaporation and evapotranspiration.
The vapour rises into the atmosphere and condenses
into water droplets to forming clouds.
The clouds eventually drop the water in the form of
precipitation which could be rain, snow or ice pellets.
The rain drains back into the rivers, lakes, oceans and
the ground water. Water from melting snow and ice
eventually joins the run-off.
Carbon Cycle
The carbon cycle moves carbon through all of Earth’s
spheres.
Carbon exists as a gas—carbon dioxide (CO2
)—in the
atmosphere. This gas is used by plants to make sugars.
Sugars are broken down by organisms to release energy
and CO2
.
Carbon is stored in fossil fuels buried within Earth and
in carbonate (CO3
2-
) rock found in the lithosphere.
The largest carbon sink is in the oceans contained in
sedimentation and rock within these bodies of water.
(Page 15)
The Nitrogen Cycle
- Nitrogen is used by life forms to carry
out many of the functions of life.
Nitrogen in its gaseous form is almost
entirely unusable to life forms. It must
first be converted or ‘fixed’ into a more
usable form. The process of converting
nitrogen is called fixation. - There are specialized nitrogen fixing
bacteria whose function it is to convert
nitrogen so that it can be used by
plants. - Denitrifying bacteria do the reverse;
they return nitrogen to its gaseous
form. - After nitrogen is fixed, it can be
absorbed, and used by plants, and
subsequently by animals.
Nutirent Cycle: Nitrogen
The nitrogen cycle moves nitrogen through Earth’s spheres
(atmosphere, lithosphere, hydrosphere).
nitrogen (N2
) is stored in the atmosphere - Earth’s atmosphere is
78% nitrogen.
N2 must be converted to a form organisms can use.
bacteria in the soil (terrestrial ecosystem) or cyanobacteria
(aquatic ecosystem) convert N2
into ammonium (NH4
+
).
decomposers also breakdown dead organisms into ammonium.
other bacteria convert ammonium to nitrate (NO3
-
).
plants absorb both forms of nitrogen (ammonium and nitrate)
through roots nodules.
organisms eat plants to use nitrogen.
denitrifying bacteria convert nitrates to nitrogen gas (N2.)
nitrogen can enter aquatic and terrestrial ecosystems when humans
fertilize soil.
volcanic eruptions release nitrogen into the atmosphere.
burning of fossil fuels releases nitrogen into the atmosphere.
Nutrient Cycle:Phosphorus
The phosphorus cycle moves phosphorus from the
lithosphere to the hydrosphere:
phosphorus is stored in the lithosphere (rocks, sediment on
ocean floor)
weathering breaks down rocks releasing phosphate (PO4
3-
)
into the soil
humans mine Earth for phosphate rock – used for
fertilizers and detergents
plants absorb phosphate via roots
animals eat plants
decomposer bacteria break down dead organisms releasing
phosphate back into soil
PO4
3- enters aquatic ecosystem via leaching and runoff
from land
Human Activities And Nutrient Cycles
Aquatic ecosystems suffer when run-off contains high
amounts of agricultural fertilizers (which are high in nitrates
and phosphates).
Eutrophication is a process in
which nutrient levels in aquatic
ecosystems increase, leading to
an increase in the populations of
primary producers, such as
algae.
Eutrophication eventually
leads to a reduction in the
oxygen content of the water.
Human Activities And Nutrient Cycles:2
Aquatic ecosystems suffer when run-off contains high
amounts of agricultural fertilizers (which are high in nitrates
and phosphates).
All Activities Require A Source Of Energy
eg.
– campfire needs wood
– car needs gasoline
– hummingbird needs sugars
All energy comes from the sun
- organisms in biosphere trap
solar energy and use it to
make food - organisms use energy for life
processes
– locomotion, reproduction,
respiration, circulation,
ingestion, excretion, etc.
Facts about Photosynthesis
- is a process that changes SOLAR ENERGY into
CHEMICAL ENERGY (food – glucose/sugar) - synthesis –
Greek
“putting
together” - photo –
Greek
“light” - without light energy, photosynthesis can NOT
occur - sugars (glucose) are carbohydrates (carbon,
hydrogen and oxygen)
– plants get hydrogen from water, H2O via their roots
– plants get carbon and oxygen from carbon dioxide gas,
CO2
from the atmosphere via tiny pores in their leaves
called stomata
Chlorophyll
- pigment that gives
leaves their green
colour
– chloros – Greek
“green”
– phyllon – Greek
“leaf” - perform
photosynthesis - inside chloroplasts
Benefits of Photosynthesis
- animals eat plants
and both use
glucose for energy
– to live - adds oxygen to the
atmosphere which
many organisms
breathe - removes carbon
dioxide from the
atmosphere to
maintain balance
in carbon cycle
Sense of scale
- Photosynthesis produces the equivalent of
100 000 000 000 to 200 000 000 000 tones of
sugar each year. This amounts of sugar is
enough to make about 3.0 x 1017 or
300 000 000 000 000 000 sugar cubes
ENERGY – Cellular Respiration
- NOT all
organisms
undergo
photosynthesis - but ALL
organisms get
energy from
glucose
2 ways organisms break down glucose
to release its energy:
- Cellular Respiration
- Fermentation
1.Cellular Respiration
- oxygen is present (aerobic conditions)
- humans, plants, animals, fungi
- most common and most efficient
- occurs in mitochondria in cells of organisms
- O2
comes from breathing it in from atmosphere
- glucose comes from eating plants
- oxygen and glucose react in cells
- producing H2O, CO2
and energy
Cellular Respiration
VS. Photosynthesis
CELLULAR RESPIRATION
* consumes oxygen
* consumes glucose
* produces carbon dioxide,
water and energy
* in mitochondria
PHOTOSYNTHESIS
* produces oxygen
* produces glucose
* consumes carbon and water
dioxide, water and
energy
* in chloroplasts
-produces water
- Fermentation
- oxygen is absent
- also known as
anaerobic respiration - takes place in the
cytoplasm - bacteria
(cyanobacteria), some
fungi
Plants and algae undergo BOTH
photosynthesis and cellular respiration
ENERGY – Trophic Levels
- a category of organisms
that is defined by how
the organisms gain
energy - “feeder”
- matter moves though
the biosphere by
travelling from one
trophic level to the next
in a cycle - e.g. producer, consumer
