Biology
Populations, Communities, and Ecosystems
Fall 2015
Objectives: to define ecosystems and populations and discuss how organisms interact in different types of each. To
compare and contrast Earth’s seven major biomes.
Areas of interaction: approaches to learning
Criteria A and C : Knowledge and Understanding of Science, one world
The Biggest Ecosystem
Earth:
Extension: How can Earth be considered a closed system? Is this accurate?
Ecosystem:
Factors in Ecosystems:
Biotic:
Examples:
Abiotic
Examples:
Soil:
Communities
Population:
Community:
Resources:
Competition:
Niche:
Dispersion:
Realized niche:
Density-dependent factors in an ecosystem:
Pioneer species:
Climax communities:
Mortality
Natality:
Immigration:
Emigration:
Extension: Draw the three types of dispersion and give an example for each
Population Studies
Population density:
Population Model:
Exponential Growth rate:
Carrying Capacity:
Extension: what factors contribute to population density?
Growth Patterns
Rapidly growing populations (r- strategists):
Examples:
Slowly growing populations (K- strategists)
Examples:
Extension: What is the Hardy Weinberg Principle and how does it explain how populations change over
time? (5 principle evolutionary forces)
Energy sources and trophic levels (Food Chains/Food Webs)
Examples:
Trophic Levels:
Extension: What are some specific examples of how humans alter food webs?
Symbiotic Relationships (3 types)
Symbiosis:
1.
Predation:
Example:
2.
Mutualism
Example:
3.
Commensalism
Example:
*****These are all examples of ______________________________!!!
Extension: Find another example of a symbiotic relationship
Succession (2 Types)
a. Primary Succession:
b. Secondary succession
Extension: Please explain how succession is occurring in summit County as a result of the MTN Pine Beetle
infestation.
Ecosystems Cycle Material
The water cycle:
The carbon cycle:
The carbon cycle is a process where carbon is recycled through the ecosystem. The concentration of
carbon in living matter (18%) is almost 100 times greater than its concentration in the earth (0.19%). So
living things extract carbon from their nonliving environment. For life to continue, this carbon must be
recycled.[2] See the diagram for a detailed look at the carbon cycle. An example of a route carbon takes in
this cycle is carbon dioxide in the atmosphere is absorbed by plants and used in photosynthesis to
produce sugars which the plant uses for energy. When the plant dies, it decomposes and the carbon
stored in the plant will, over millions of years, form into coal (a fossil fuel). The coal is burnt and gives off
carbon dioxide which goes into the atmosphere. Also the carbon cycle has to relate to quantum
mechanics due to the restoration of water.
At the moment, the carbon cycle, and how human activity is affecting it, is a big topic in international
news. Fossil fuels are a non-renewable resource which means that they cannot be replaced easily. Our use
of fossil fuels has nearly doubled every 20 years since 1900.[3] Also, the burning of fossil fuels produces
pollution which contributes to the greenhouse effect and acid rain.
The nitrogen cycle:
Nitrogen makes up 78% of the troposphere.
Nitrogen cannot be absorbed directly by
the plants and animals until it is converted
into compounds they can use. This process
is called the Nitrogen Cycle.
How does the nitrogen cycle work?
Step 1- Nitrogen Fixation- Special bacteria convert the nitrogen gas (N2 ) to ammonia (NH3) which the
plants can use.
Step 2- Nitrification- Nitrification is the process which converts the ammonia into nitrite ions which the
plants can take in as nutrients.
Step 3- Ammonification- After all of the living organisms have used the nitrogen, decomposer bacteria
convert the nitrogen-rich waste compounds into simpler ones.
Step 4- Denitrification- Denitrification is the final step in which other bacteria convert the simple nitrogen
compounds back into nitrogen gas (N2 ), which is then released back into
the atmosphere to begin the cycle again.
How does human intervention affect the nitrogen cycle?
Nitric Oxide (NO) is released into the atmosphere when any type of fuel is burned. This includes
byproducts of internal combustion
engines.
Nitrous Oxide (N2O) is released into the atmosphere through bacteria in livestock waste and commercial
fertilizers applied to
the soil.
Removing nitrogen from the Earth’s crust and soil when we mine nitrogen-rich mineral deposits.
Discharge of municipal sewage adds nitrogen compounds to aquatic ecosystems
Biological Communities (7 main biomes)
1. tundra
2. taiga
3. temperate grasslands
4. temperate deciduous forests
5. savannas
6. deserts
7. tropical rain forests