Gabrielle Korn
Biology 9
Mr. Holzinger
Self-Study
Study of Ecology:
I. Chapter 16: pages 339-352:
Section 1: What is Ecology? What is an Ecosystem?
1. Ecology is the study on how living organisms interact and the environments that
they occupy. An organisms’ habitat is where their population of the specie lives.
The physical aspects of a habitat are called abiotic factors, like water, soil, and
weather. The living aspects of a habitat, the organisms themselves, are called the
biotic factors.
2. When one habitat is inhabited by multiple species it is referred to as a community.
A community of organisms and their abiotic environment together create an
ecosystem. Biodiversity is the term used to reference the variations of organism in
their environments.
a. Biodiversity is the term used to reference the variations of organism living
in their environment.
B. How do ecosystems change over time?
1. After a volcano creates a new island, a glacier recedes to uncover a new ground a
new habitat is left, empty, and available for organisms to settle in. Pioneer species
are organisms that settle in uninhabited areas to start an ecological cycle, or
ecosystem, so other species can later become established.
2. Ecosystems change through the process of succession. A new specie settling or
replacing in a community is called succession. There are two types of succession:
a. When no previous life has existed that succession is called primary
succession.
b. Succession in areas of previous growth, such as abandoned fields or forests,
is called secondary succession.
Section 2: How does energy move through ecosystems?
1. The majority of life relies on photosynthetic organism. These organisms acquire
some of the sun’s energy to store it as chemical energy in organic molecules, or
food. How quickly organic material is produced in an ecosystem is called
primary productivity, which determines the amount of energy available in an
ecosystem.
a. Producers, the organism that first capture the energy from the sun, are
usually plants, algae, and some bacteria.
b. The remaining organisms in an ecosystem are consumers. Consumers
consume plants or other organisms to attain the energy needed to make
molecules.
3. Trophic levels enable ecologists to study the movement of energy in an ecosystem
based on the organism’s source of energy.
Example:
a. The pathway of energy transfer through the trophic levels of an ecosystem is
called a food chain. The lowest trophic level of an ecosystem is always the
producer such as bacteria, algae, and plants.
b.
Herbivores, animals that eat plants are at the second trophic level. A
herbivore must be able to breakdown a producers’ molecule into usable
compounds. Most herbivores depend on microorganism in their gut like
protists to help digest the cellulose.
c. Secondary consumer, animals that eat animals are at the third level of the
trophic levels and are called carnivores. Animals such as snakes, lions and
wolves are carnivores. Some animals such as bears eat plants and animals
and are called omnivores.
d. Detrivores are organisms that acquire their energy from organic wastes and
dead bodies that are produced at all trophic levels (ex: worms, fungal, etc.).
Bacteria and fungi are referred to as decomposers. Decomposition of bodies
and waste releases nutrients back into the environment.
e. Many ecosystems have a fourth trophic level of only carnivores that eat
other carnivores are called tertiary consumers. In most ecosystems, energy
doesn’t follow one straight path, because animals often feed from different
trophic levels. This interconnected group of food is called a food web.
3. The Pyramid of Energy
Ecologists use energy pyramids to illustrate the flow of energy through and
ecosystem. An energy pyramid is a diagram of each trophic level with the lowest on
the bottom. The width of each block of the diagram is based on the amount of energy
stored in the organisms at that trophic level.
4. W hat are the limitations of Trophic Levels?
1. The number if trophic levels that can be maintained in a community are limited
by dispersal of potential energy. Too much energy is lost at each level to have
more than three to four different levels.
2. However, some organisms may be larger than others and therefore use more
energy. The number of organisms doesn’t always form a pyramid when the
trophic levels are compared. Biomass is the dry weight of tissue and other
organic matter in an ecosystem. Each higher level only has 10% of the biomass
in the trophic level below it.
Section 3: The Cycling of Materials in Ecosystems:
1. Biogeochemical Cycle is the circulation of substances (water, soil, trees) through
living organisms from or to the environment.
2. The sun, which drives the water cycle, heats water in the oceans. Water evaporates
as vapor into the air. Transpiration is water transpired from plants and evaporated
from the soil.
3. Carbon enters the living portion of the carbon cycle through photosynthesis.
Organisms release carbon through cellular respiration. Carbon trapped in rocks and
fossil fuels are released by erosion and burning.
4. Phosphorus appears in soil and rock as calcium phosphate. It is absorbed by the
roots of the plants to build organic molecules. When herbivores or omnivores eat
the plants, they are re-using the organic phosphorus. This is the Phosphorus Cycle.
5. Most organisms are unable to use nitrogen in its N form as nitrogen gas. Bacteria
are able to break the triple covalent bond between the two nitrogens and re-bind the
nitrogens with hydrogen to make NH , or nitrogen fixation. The nitrogen cycle
has four important stages:
a. Assimilation: the absorption and incorporation of nitrogen into organic
compounds by plants.
b. Ammonification: the production of ammonia by bacteria during the decay
of organic matter.
c. Nitrification: the production of nitrate from ammonia.
d. Denitrification: the conversion of nitrate to nitrogen gas. ]
II. Chapter 17: pages 361-378:
Section 1: How do organisms interact in communities?
1. Species within communities coevolve, making evolutionary adjustments to living
together. The prey evolves to escape being eaten and predators evolve to overcome
the defenses of the prey.
a. Predation is when one animal kills another animal for food.
b. Paratism is when an organism feeds and/or lives on another organism.
c. All plants have defensive compounds (against herbivores) called secondary
compounds. Each type of plant has a different chemical.
2. In symbiosis two or more species have a relationship that benefits both species
leaving them both unharmed/unaffected.
a. Mutualism: is a relationship where both species benefit.
b. Commensalism: is a relationship where one specie benefits and the other is
affected.
Section 2: How does competition shape communities?
1. When two species use the same resource, they interact through competition to use
that limited resource. Competition can limit how that resource is used.
2. To understand the competition of the species, you must focus on the daily activity
within the community, the niche of the organism. A niche is the role the organism
plays in its ecosystem.
a. The largest ecological niche where an organism can live without
encountering competition with other species is called the fundamental
niche.
b. An organism’s realized niche is its functional roles, the conditions it can
handle, and the range of the resources they can use.
3. Competitive exclusion is the exclusion of one speice by another due to
competition.
Section 3: Major Biological Communities
1. The climate and genes largely determine where species live.
2. The temperature and moisture are key factor in determining where biomes
occur.
3. The seven major biomes are:
a. Tropical rain forest: has the most species out of all the biomes. Have a high
primary productivity even on infertile lands, because the nutrients are in the
plants.
b. Desert: less than 25 cm of rain fall in a desert. Sparse vegetation.
c. Savana: found in tropical areas with low annual precipitation levels. Open
landscape, with few trees.
d. Temperature deciduous forests: mild climates, a lot of rain. Grow in areas
with hot summers and cold winters.
e. Temperate grasslands: moderate climates, soil very fertile.
f. Taiga: cold, wet climate. Many coniferous trees.
g. Tundra: perma-frost. Precipitation occurs in the summer.
4. Freshwater communities have three zones of life:

Littoral: a shallow area where light reaches the bottom and nurtures
the plants.

Limnetic: an area that is away from the shore but still close to the
surface.

Profundal: an area where little sunlight penetrates.
5. The three major marine communites are:

shallow ocean water

open sea surface

deep-sea waters
III. Chapter 18: pages 386-400:
Section 1: Global Change:
1. Acid rain, which is caused by airborne pollutants that lower the pH of rain, has
damaged many forests and lakes.
2. Destruction of the ozone layer is cause by chlorofluorocarbons (CFCs) and several
other manufactured chemicals.
3. The greenhouse effect occurs when greenhouse gases, such as carbon dioxide, trap
heat in Earth’s atmosphere.
4. Many believe that increased concentration of CO and other greenhouse gases in the
atmosphere have led to the start of global warming.
Section 2: Effects on Ecosystems:
1. When toxic chemicals are released into our environment they can severe effects,
especially when their concentration is magnified by the food chains.
2. There are three nonreplaceable resources in our environment: species of living
things, ground water, and topsoil. All of these resources are being destroyed very
quickly.
3. The overwhelming growth of the human population is hurting the Earth’s
ecosystems.
Section 3: Solving Environmental Problems:
1. Worldwide efforts to reduce pollution are being made but they are only part of the
solution to the growing pollution problem.
2. Taxing products that create pollution and creating laws requiring pollution control
devices are two methods that have been used to reduce pollution.
3. Each of the world’s many environmental problems can be solved if seriously
addressed. A combination of scientific investigation and public action can solve
many environmental problems.