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Unit 15 – Ecology and
Plant Life Functions
Ecology – the study of living organisms
and their interactions in the
environment.
Ecosystem – community of living and
nonliving things interacting as a system
Abiotic vs Biotic Factors

Abitoic (non-living) and Biotic (living) factors are what make-up an
Ecosystem.

Organisms are placed into a food chain and then ecological levels.


organism level of study: studying one specific organism in a food
chain
The following are a few of the major ecological levels:

Population – a group of organisms that are members of the same
species and share a common gene pool

Community – the various populations of living organisms in an
ecosystem

Biosphere – all areas of the Earth that sustain life
Ecological Levels in Order
Life Influences Life

There are many different types of relationships within ecosystems.

Symbiosis- the relationship between two different species.
Examples are #1 mutualism, #2 parasitism, and #3 commensalism.

Mutualism- both species benefit from each other. +/+
- Example: algae and fungus. Algae makes the food for both,
fungus provides shelter for both

Parasitism- one species is harmed where the other is benefited.
+/-
- Example: ticks and humans. Ticks bite humans and suck out the
blood
Predator vs Prey

Predators are organisms who hunt to kill other organisms, their prey.
If the prey population increases  predator population will increase
If the prey population decreases  predator population will decrease
If the predator population decreases  prey population will increase
If the predator population increases  prey population will decrease

Habitat: where an organism lives

Niche: the organism’s role in the environment.

Ants gathering food for their ant family back home.
Population Studies

Ecologists use sampling to obtain a total count of
the population by counting the organisms in a
small area and multiplying that by the total area.
 Example:
# of organisms in a small area = 50
and total area = 100 sq meters. The total # of
organisms in the total area is 5,000.

Ecologists use quadrant studies to study the
species diversity in an area, otherwise known as
biodiversity.
Examples of Growth Patterns:
Limiting Resources – energy, water, nutrients
Exponential
Population
Growth
Dynamic Equilibrium –
staying near Carrying
Capacity
Max amount of
Organisms in
One ecosystem.
Human Age Structure Graphs- showing stable or rapid growth
Rapid growth: large number of children
Slow growth: shaped like a tower – even distribution – stable
Food and Energy Pyramid
5 cal
50
calories
500
calories
5,000
calories
Note: Decomposers recycle the nutrients
at every trophic level.
Carbon Cycle
Cellular Respiration breaks down
glucose with oxygen to produce
Carbon dioxide, water, and ATP.
Plants use sunlight and carbon
dioxide to create photosynthesis
for food and energy.
Photosynthesis removes carbon
dioxide from the atmosphere.
Carbon Dioxide is released into
the atmosphere by animals.
Global Warming – the imbalance of the
carbon cycle that leads to increase
temperatures on Earth.


Decrease in global forests
– less photosynthesis
occurring to remove
carbon dioxide from the
atmosphere.
Increase in fossil fuels –
more carbon dioxide
released into the
atmosphere.
Nitrogen Cycle
Bacteria recycles nitrogen from
the atmosphere and dead
organisms from the soil.
Nitrogen is an important part of
nucleic acids and proteins (two of
the four macromolecules).
Human Impact on the Environment
Cause

Pesticide use

Fossil Fuel use

Human growth

Non-native species
Effect

Bioaccumulation – accumulation in
an organism. Pesticides are
increasing as you get higher in the
food chain.

Acid precipitation – chemicals
attach to water molecules and fall
as rain/snow. Sulfur and Nitrogen
are the chemicals from fossil fuels.

Habitat destruction – natural
habitats destroyed for growth to
create more space/room.

Invasive species kill and crowd out
important species natural to the
ecosystem.
Plants Illustrating Evolution of Life

Plants today have evolved from algae that lived in the ocean.
Moss
Ferns
-non-vascular
-vascular tissue
Gymnosperms
-vascular tissue
-spores, not seeds
-spores, not seeds
- vascular tissue
-seeds
-seeds
-flowers
-no flowers
-no flowers
Angiosperms
-no flowers
Self Pollination vs Cross Pollination
5 Methods of Seed Dispersal