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
Primary Producers / Autotrophs
- “self feeders”
- can make their own food
- 1
st trophic level - e.g. plants, algae
Consumers / Heterotrophs
- can NOT make their own food
- must eat other organisms to get the matter
and energy they need to survive - e.g. animals,
humans
Primary consumers
- 2nd trophic level
- feed on producers / autotrophs directly
- herbivores
- e.g. cow, deer, mice
Secondary consumers
- 3rd trophic level
- feed on consumers / autotrophs
- omnivores, carnivores
- primary carnivores
Herbivores
These are animals that eat mainly plants
this includes leaves, grass, flowers, seeds, roots, fruits, bark, pollen and much more.
some herbivores are: deer ,horses, rabbits, cows, bees sheep, grasshoppers
Carnivores
These are animals that eat mainly meat.
This includes insects and all animals.
some carnivores are:
-felines(lions,tigers and all cats)
-birds of prey(eagles, hawks, owls etc.)
-sharks, frogs, spiders
top carnivore
- not eaten by any other animal
- top of the food chain/food web
Omnivores
These are animals able to eat plants and animals.
Some omnivores are:
-humans
-most bears
-raccoons
-most primates apes and monkeys)
-seagulls and other birds
Decomposers
They consume (eat) dead plants and animals and decomposes them-reduces them to simpler forms of matter
primary decomposers fungi and bacteria
Scavenger eats other animals that are already dead
striped hyena, crow, hag fish and vulture
3 categories of consumers:
herbivores
* eat only plants
* e.g. cow
carnivores
* eat only animals
* e.g. lion
* top carnivore: not eaten by any other animal
omnivores
* eat both plants and animals
* e.g. humans
Food Chain
– a feeding sequence in which each kind of
organism eats the one before it
– one way flow for energy
Food Web
– interaction of food chains
- Note: direction of arrow
indicates direction of energy
flow; may read as “is eaten by”
Arctic Food Wed
- lower biodiversity – fewer
organisms, fewer types of
organisms - number of producers is small
– less sun → less photosynthesis - more direct relationships between
organisms
– loss of any one member can have a
profound effect on all remaining
organisms – each is more vulnerable
Forest food Web
The forest food web consists of distinct components like producers, primary consumers, secondary consumers, scavengers, and decomposers. In the forest ecosystem, the producers are trees, which are of distinct kinds, the small plants and shrubs also produce their food. The primary consumers are deer, rhinoceros, etc.
Energy in Ecosystems THERMODYNAMICS:
- the study of energy transformations
- First Law of Thermodynamics: Energy cannot be
created or destroyed, it can only be changed form
one form to another. - Second Law of Thermodynamics: During any
energy transformation, some of the energy is
converted into an unusable form (e.g. heat =
thermal energy) that cannot be passed on
THEMODYNAMICS
- Every time energy is transferred within an ecosystem, some of it
changes form
– photosynthesis converts solar energy to chemical energy stored in
glucose - Every time energy is transferred within an ecosystem, some of it is
lost
– plants and animals use chemical energy (food) to sustain life
– once energy has been used, it is not available to be transferred
– the further up a food chain you travel, the less energy is available
– this limits the number of individuals that can be supported at the top
of the food chain
– because of the inefficiency of energy transfer among trophic levels,
there are usually fewer carnivores than herbivores, and fewer
herbivores than plants
ENERGY PYRAMID:
- graph showing how energy flows from one
trophic level to the next in a food chain
TROPHIC EFFICIENCY
- measure of how much of the energy stored in
organisms at one trophic level is transferred to
the next higher trophic level - usually only
10% can be
passed onto
the next
trophic
level.
Why is trophic efficiency less than 100%
- herbivores may not eat all parts of a plant (e.g. eat
top; leave the roots) - not everything eaten is digested (e.g. fur)
- energy is lost as body heat
- energy is used to carry out life functions (moving,
breathing, reproducing, etc.) - waste is produced
Other Pyramids:
- Pyramid of Numbers: shows the number of
organism at each trophic level in an ecosystem - Pyramid of Biomass: shows the dry mass
(after water has been removed) of the dry
tissue in the organisms at each trophic level in
an ecosystem
BIOMASS
- total mass of living organisms (cells, tissues) in
a defined group or area
Pyramid of Numbers
- This type of
pyramid does not
always have the
same shape as the
other pyramids. - Depending on the
ecosystem, it can
have a variety of
shapes.
BIOACCUMULATION
- ingestion of toxins (e.g. PCBs, DDT, mercury, lead) at a
faster rate than they are eliminated - greatest health problems show up at highest trophic
levels
BIOACCUMULATION
➢Bioaccumulation is defined as the increase in
concentration of a substance(s) in an organism or
a part of that organism.
➢Bioaccumulation takes place within an organism
when the rate of intake of a substance is greater
than the rate of elimination (excretion or
metabolic transformation) of that substance.
➢Toxic substances are lipophilic or fat-loving; these
substances are deposited and concentrated in the
fat tissues of the organisms.
BIOACCUMULATION 2
As the fish eats more of the smaller
organisms, the amount of heavy metals
increases. The heavy metals build-up in
concentration in the larger living things
(pelicans).
The presence of mercury in tuna has
lead to a great deal of concern about
the safety of canned tuna.
BIOMAGNIFCATION
➢Biomagnification is also called Bioamplification.
➢It is the increase in concentration of a substance
in a food chain, not an organism.
➢Persistent organic pollutants (POPs) are chemical
substances that stay in the environment.
➢These substances bioaccumulate through the
food web and pose risk not only to humans but
also other living organisms because of their
adverse effects.
GREENHOUSE GASES
- atmospheric gases
that prevent heat
from leaving the
atmosphere, thus
increasing the
temperature of the
atmosphere - e.g. water vapour,
carbon dioxide (CO2
),
methane (CH4
), ozone
(O3
), nitrous oxide
(N2O), CFCs.
GREENHOUSE GASES
GREENHOUSE EFFECT
- the warming of the Earth as a result of
greenhouse gases, which trap some of the
energy that would otherwise leave Earth
