Transcript Biology - Marric.us

Biology
CST Review PowerPoint in
Ecology
ACCORDING TO THE
BLUEPRINTS…
6. Stability in an ecosystem is a balance between competing effects. As a basis
for understanding this concept:
a. Students know biodiversity is the sum total of different kinds of organisms
and is affected by alterations of habitats.
b. Students know how to analyze changes in an ecosystem resulting from
changes in climate, human activity, introduction of nonnative species, or changes
in population size.
c. Students know how fluctuations in population size in an ecosystem are
determined by the relative rates of birth, immigration, emigration, and death.
d. Students know how water, carbon, and nitrogen cycle between abiotic
resources and organic matter in the ecosystem and how oxygen cycles through
photosynthesis and respiration.
e. Students know a vital part of an ecosystem is the stability of its producers
and decomposers.
f. Students know at each link in a food web some energy is stored in newly made
structures but much energy is dissipated into the environment as heat. This
dissipation may be represented in an energy pyramid.
Biodiversity
•Biodiversity is the variation of life
forms within a given ecosystem,
biome, or on the entire Earth.
Biodiversity is often used as a
measure of the health of biological
systems. The biodiversity found on
Earth today consists of many millions
of distinct biological species.
•Today there is concern about the
mass reduction in biodiversity
caused primarily by the impact
humans are having on the
environment, particularly the
destruction of plant and animal
habitats.
Question: Name some
ecosystems that show high
biodiversity and low
biodiversity.
Question: Why are
ecosystems “healthy” if
they exhibit high
biodiversity?
Question: What human
practices can lead to a
reduction in biodiversity?
Question: Why should a
loss in biodiversity be of
great concern to us?
Introduction of Non-native Species
•An introduced, alien, exotic, non-indigenous, or
non-native species, or simply an introduction, is a
species living outside its native distributional
range, which has arrived there by human activity,
either deliberate or accidental.
•Some introduced species are damaging to the
ecosystem they are introduced into, others
negatively affect agriculture and other human
uses of natural resources, or impact on the health
of animals and humans.
•The greatest impact is caused by introduced
species that change an entire habitat, because
many native species thrive only in a particular
habitat.
•Other invaders, though they do not change a
habitat, endanger single species or even entire
groups of them in various ways.
Water hyacinth from
South America
POPULATIONS
-A population is a group of organisms of the same species that
live in a particular area.
-The number of organisms in a population changes over time
because of the following: births, deaths, immigration, and
emigration.
-Births and immigration increase the size of the population;
whereas, deaths and emigration decrease the size.
Immigration:
Individuals
arrive at the
habitat.
Emigration:
Individuals
leave the
ecosystem.
Population growth
is the change in a
population over
time, and can be
quantified as the
change in the
number of
individuals of any
species in a
population using
"per unit time" for
measurement.
Many factors influence population growth, for
example, availability of resources, presence of
predators, diseases, etc.
Population
Density
Population density may
be defined as simply the
number of individual
organisms per unit
area.
Distribution can be
uniform, random, or
clumped.
Uniform
Random
Clumped
Energy in the Ecosystem
•The source of all food is the activity of autotrophs, mainly photosynthesis
by plants.
•They are called producers because only they can manufacture food from
inorganic raw materials.
•This food feeds herbivores, called primary consumers.
•Carnivores that feed on herbivores are called secondary consumers.
•Carnivores that feed on other carnivores are tertiary (or higher)
consumers.
•Such a path of food consumption is called a food chain.
•Each level of consumption in a food chain is called a trophic level.
GRASS
GRASSHOPPER
TOAD
SNAKE
HAWK
Decomposers (or saprotrophs) are
organisms that break down the
dead or decaying organisms, and
in doing so carry out the natural
process of decomposition. Like
herbivores and predators,
decomposers are heterotrophic,
meaning that they use organic
substrates to get their energy,
carbon and nutrients for growth
and development. Decomposers
use deceased organisms and nonliving organic compounds as their
food source. The primary
examples are bacteria and fungi.
Pyramids of Energy and Biomass
An ecological pyramid is a
graphical representation designed
to show the biomass at each
trophic level in a given ecosystem.
Biomass pyramids show the
abundance or biomass of
organisms at each trophic level.
Ecological pyramids begin with
producers on the bottom (such as
plants) and proceed through the
various trophic levels (such as
herbivores that eat plants, then
carnivores that eat herbivores, then
carnivores that eat those
carnivores, and so on). The highest
level is the top of the food chain.
Loss of Matter and Energy - At
each trophic level along a food
chain, there is always a 'loss' of
matter and energy in the forms of
waste (e.g. carbon dioxide, feces),
and heat and kinetic energy (e.g.
constant body temperature of
mammals, the energy used to
move). Up to 90% of matter and
energy can be 'lost' at each level.
10% Efficiency in
Energy Transfer!
Loss of Matter and Energy - At each trophic level along a food chain, there is
always a 'loss' of matter and energy in the forms of waste (e.g. carbon dioxide,
feces), and heat and kinetic energy (e.g. constant body temperature of
mammals, the energy used to move). Up to 90% of matter and energy can be
'lost' at each level.
Carbon Cycle
Five major
reservoirs of
Carbon:
a. Atmosphere
b. The
terrestrial
biosphere (soil,
freshwater).
c. Oceans
d. The
sediments
including fossil
fuels.
e. The earth's
interior, carbon
from the
earth's mantle
and crust
The Carbon Cycle
-Plants “fix” the Carbon from
CO2 into glucose through
photosynthesis using light
energy.
-Oxygen gas is one of the
products of photosynthesis.
-Cell Respiration in both animals
and plants break down glucose
to yield energy, producing CO2
as a by-product.
-O2 and CO2 cycles from plants
and animals via the
complementary processes of
photosynthesis and respiration.
Decomposition and
combustion are two other
processes that contribute
CO2 gas into the atmosphere.
The Nitrogen Cycle
Key processes:
1. Nitrogenfixation
2. Nitrification
3. Denitrification
2
1
3
1. Nitrogen fixation- is the process by which nitrogen (N2) in the atmosphere
is converted into ammonia. This process is essential for life because fixed
nitrogen is required to biosynthesize the basic building blocks of life, e.g.
nucleotides for DNA and amino acids for proteins.
Nitrogen Cycle, continued…
-Certain bacteria, called Nitrogenfixing bacteria, live in nodules found in
the roots of some plants. These
bacteria possess the enzymes that can
fix nitrogen gas into ammonia.
2. Nitrification- Nitrifying bacteria from
the soil, can convert the ammonia
produced by decay, into nitrates, a
process called ‘nitrification.’ Plants
can directly use N in the form of
nitrates.
3. Denitrification- Denitrification
reduces nitrates to nitrogen gas, thus
replenishing the atmosphere.
Legumes such as peas,
clover, and beans have
nitrogen-fixing bacteria in
their roots. This enables
them to grow in nitrogenpoor soil. Plants take up
nitrates through their
roots, and convert them
into proteins and other
compounds.
Ecological Relationships
Organisms within ecosystems may be involved in any of
these relationships…
1. Symbiosis- interaction between two organisms where at
least 1 benefits.
a. Commensalism- one species benefits, the other
species is not affected.
b. Mutualism- both species benefit.
2. Parasitism-one species benefits, the other
species is harmed.
3. Predation- one species ‘preys’ (kills for food)
This is an example of
another species.
commensalism- he
4. Competitionbarnacle gains a
exists when species
place to live and,
fight for food and
presumably, the
other resources.
scallop is not
This may be intraharmed.
or inter-specific.
A lamprey, is an ectoparasite.