CP Environmental Science
2013-2014
KEY
Unit 2A Notes Packet: Ecosystems, Biogeochemical Cycles, and Succession
Note: Vocabulary terms are in italics
Chapter 4, Section1: Ecosystems: Everything is Connected
I. Defining an Ecosystem:
Ecosystem- all of the organisms living in an area together with their physical
environment.
A. Ecosystems are Connected: they do not have clear boundaries (ex. birds
migrating, pollen blows from forest into a field, animal goes from forest to a
lake).
II. The Components of an Ecosystem:
-
Every ecosystem needs 5 components in order to survive: energy (from the sun),
mineral nutrients, water, oxygen, and living organisms.
A. Biotic and Abiotic Factors:
Biotic Factor: Are the living and once living parts of an ecosystem (including all
plants and animals).
Abiotic Factor: The nonliving parts of the ecosystem (air, water, rocks, send,
light and temperature).
B. Organisms:
Organism- is an individual living thing.
Species- a group of organisms that are closely related and that can mate to
produce fertile offspring (ex: Homo sapiens).
C. Population- is all the members of the same species that live in the same place at
the same time. The members of one population usually breed with one another
rather that with members of other populations.
CP Environmental Science
2013-2014
D. Community- a group of various species that live in the same place and interact
with each other.
III. Habitat
-
The place where an organism lives.
Chapter 5, Section 1: Energy Flow in Ecosystems
I.Life Depends on the Sun:
Photosynthesis: A process where the plant is using sunlight to make sugar molecules
(carbohydrates). These sugars are energy-reach molecules that the rest of the
heterotrophic organisms use to carry out daily activities.
A. From Producers to Consumers:
Producers: An organism that makes its own food. They are also called autotrophs
(self-feeders).
Consumers: Organisms that get their energy by eating other organisms. They
are also called heterotrophs (other-feeders).
B. An Exception to the Rule: Deep-Ocean Ecosystems
-The areas on the bottom of the ocean where sunlight do not reach the bottom.
Since there is no sunlight, it means that photosynthesis can NOT occur.
However, some bacteria are able to use the hydrogen sulfide (that comes from
the thermal vents located on the ocean floor), to make their own food.
II. What Eats What:
Consumers that eat only producers are called herbivores (plant eaters). Consumers that
eat only other consumers are called carnivores. If the consumers eat both, plants and
animals, they are called omnivores.
-Decomposers- consumers that get their food by breaking down dead organisms
(bacteria and fungi).
III. Cellular Respiration: Burning the Fuel
Cellular Respiration: The process of breaking down food to yield energy. This
process occurs inside the cells of most organisms.
CP Environmental Science
2013-2014
IV. Case Study: DDT in an Aquatic Food Chain
DDT, during the 1950’s and 1960’s were used for pest control (mosquitos). However,
the scientists discovered that as the DDT (poison), is being absorbed by the algae in
the water, once the other organisms (fish, and then the birds) consumed the algae, the
poison dissolves into the fat of the fish and the birds. This poison had the greatest
effect on organisms at the top of the food chain. As a result, the U.S. government had
stopped the selling of the DDT and the aquatic food chain immediately started to
recover.
V. Energy Transfer
- A transfer of energy occurs when each time one organism eats another organism. We
can follow the energy traveling in an ecosystem by studying food chains, food webs and
trophic levels.
A. Food Chains and Food Webs
Food Chains: is a sequence in which energy is transferred from one organism to
the next as each organism eats another organism.
Food Web: shows many feeding relationships that are possible in a particular
ecosystem.
B.Trophic Level
-Each step in the transfer of energy through a food chain or food web in an ecosystem
is known as a trophic level.
C. Energy Pyramids
The drawing of an energy pyramid helps us to visualize the loss of energy from one
trophic level to the next trophic level. The producers form the base of the energy
pyramid (the lowest trophic level) which contains the most energy. The primary,
secondary and tertiary consumers follow, where the tertiary consumers have the least
energy.
D. How Energy Loss Affects an Ecosystem
- The decreased amount of energy at each trophic level affects the organisms of an
ecosystem. Because of the lost of energy as we go up on the pyramid, there are fewer
organisms at the higher trophic levels.
CP Environmental Science
2013-2014
Chapter 5, Section 2: The Cycling of Materials
I. The Carbon Cycle – is a process by which carbon is cycled between the
atmosphere, land, water, and organisms.
A. How Humans Affect the Carbon Cycle
-
By burning fossil fuels, carbon gets released into the atmosphere as carbon
dioxide. Vehicles and factories need fossil fuels derivatives in order to run.
II. The Nitrogen Cycle
Nitrogen-fixing bacteria- The species of bacteria that can fix atmospheric nitrogen
into chemical compounds. All organisms depend on these bacteria to supply
nitrogen.
Nitrogen cycle- a process in which nitrogen is cycled between the atmosphere,
bacteria, and other organisms.
A. Decomposers and the Nitrogen Cycle:
-
In the nitrogen cycle, the nitrogen moves between the atmosphere and living
organisms. Nitrogen is transferred into the atmosphere with the help of bacteria,
which brake down decaying plants and animals and return the nitrogen into the
soil. After this process, the bacteria transfers a small amount of that nitrogen
into nitrogen gas, which gas returns back to the atmosphere and completes the
cycle.
III. The Phosphorus Cycle
-Is the movement of phosphorus from the environment to organisms and then back
to the environment. Phosphorus doesn’t enter the atmosphere. Only the biosphere,
the geosphere and the hydrosphere.
A. Fertilizers and the Nitrogen and Phosphorus Cycles
- In order to stimulate and maximize plant growth, we apply fertilizers. They contain
both nitrogen and phosphorus. If we overuse the fertilizers, they could enter the
aquatic ecosystems through runoff, which can cause access algae growth (algal
bloom). The algal bloom can deplete an aquatic ecosystem from important nutrients
such as oxygen.
CP Environmental Science
2013-2014
B. Acid Precipitation
- Every time we burn oil, wood and coal, we affect the nitrogen cycle by releasing large
amounts of nitric oxide into the atmosphere. The nitric oxide (harmful gas), combines
with oxygen and water vapor to form nitric acid. The nitric acid can dissolve in the rain
or the snow, which results in acid precipitation.
Chapter 5, Section 3- How Ecosystems Change
I. Ecological Succession
-
A gradual process of change and replacement of the types of species in a
community.
Primary Succession- a type of succession that occurs on a surface where no
ecosystem existed before (on rocks, cliffs, and send dunes).
Secondary Succession- is a more common type of succession that occurs of a
surface where an ecosystem has previously existed.
Pioneer Species – the first organisms to colonize any newly available area and begin
the process of ecological succession.
Climax Community- a final and stabile community.
B. Fire and Secondary Succession:
-
The natural fire caused by lightning are a necessary part of secondary
succession.
C. Old Field Succession:
-A type of secondary succession which occurs when farmland is abandoned. When
farmers abandon their land, grasses and weeds start growing. Over time, these
grasses and weeds will be overgrown by taller plants. This taller plants will be
overgrown by taller trees….
D. Primary Succession
- On new islands created by volcanic eruptions, in areas exposed when a glacier
retreats, or on any other surface that has not previously supported life, primary
succession can occur.