Download Ecology is the study of the interactions between

CHAPTER 18 & 19 STUDY GUIDE
Ecology is the study of the interactions between organisms and their environment.
There are two parts of an environment which consist of the biotic part and the abiotic part.
The biotic part of the environment is all of the organisms that live together and interact with one
another.
The abiotic part of the environment includes all of the physical factors such as water, soil, light,
and temperature that affect organisms living in a particular area.
Organization in the environment: The environment is arranged into different levels.
Level 1- Organism – contains the individual organism.
Level 2 – Population – contains similar organisms, which form a population. A population is a group
of individuals of the same species that live together in the same area at the same time.
Level 3 – Community – contains different populations, which form a community. A community
consists of all of the populations of different species that live and interact in an area.
Level 4 – Ecosystem – contains a community and its ABIOTIC environment which form an
ecosystem. An ecosystem is made up of a community of organisms and its abiotic environment.
Level 5 – Biosphere – contains all ecosystems, which form the biosphere. The biosphere is the
part of the Earth where life exists. It extends from the deepest parts of the ocean to very high
in the atmosphere, where tiny insects and plant spores drift, and it includes every ecosystem.
Producers are organisms that use sunlight directly to make food.
EX: Plants, some algae and some bacteria
Consumers are organisms that eat producers or other organisms for energy.
There are several types of consumers.
A herbivore is a consumer that eats plants. (Examples of herbivores include large mammals such
as cattle, deer, sheep, and kangaroos, as well as smaller creatures such as leaf-eating insects and
crustaceans that graze upon aquatic algae.
A carnivore is a consumer that eats animals. Examples of carnivores are gray foxes, frogs, snakes,
hawks, and spiders.
Omnivores eat a variety of organisms, both plants and animals. Examples of omnivores are: Bears,
Turtles, Monkeys, and Squirrels
Scavengers are animals that feed on the bodies of dead animals. Examples of scavengers are:
Scavengers include many kinds of invertebrates (such as worms, insects, and crabs), vultures see,
and hyenas. Also any time you anything picking away at road kill, you are witnessing scavenging.
Decomposers are organisms that get energy by breaking down the remains of dead organisms.
Examples of decomposers are bacteria, and fungi.
Decomposers are very important to the ecosystem because they are nature’s recyclers.
A food chain represents how the energy in food molecules flows from one organism to the next.
A food web is a complex diagram representing the many energy pathways in a real ecosystem.
An energy pyramid is a diagram shaped like a triangle showing the loss of energy at each level of
the food chain.
An organism’s habitat is the environment in which it lives. A niche is an organism’s way of life. An
organism’s niche includes its habitat, its food, its predators, and the organisms with which it
competes. Its niche also includes how the organism affects and is affected by abiotic factors in
its environment. (light, temperature, water)
Carrying capacity is the largest population that a given environment can support over a long period
of time.
Prey is the organism that gets killed and is eaten.
Predator is the organism that kills and eats the prey.
Predator Adaptations - It is important for predators to be able to catch their prey if they are
going to survive. There are a wide variety of methods that predators use.
EX: the cheetah is able to run very fast, so that is an advantage it has over its prey. The
goldenrod spider uses a method of ambushing to catch its prey. It blends in so well with the
goldenrod flower that all it has to do is wait for its next meal.
Prey Adaptation – There are several methods prey use to escape being caught by their predator.
EX: Prey are able to run away, stay in groups, or camouflage themselves to protect themselves
against predators. Some prey are poisonous and show their poison with bright colors to warn their
predators.
Symbiosis is a close, long-term association between two or more species. There are 3 types of
symbiosis; Mutualism, commensalism, and parasitism.
Mutualism – is a symbiotic relationship in which both organisms benefit.
Commensalism – is a symbiotic relationship in which one organism benefits, and the other is
unaffected.
Parasitism – is a symbiotic relationship in which one organism benefits, and the other is harmed.
The organism that benefits is called the parasite. The organism that is harmed is called the host.
Coevolution is a long-term change that takes place in two species because of their close
interactions with one another.
The Water Cycle
Precipitation – water moves from the atmosphere to the land or ocean. Precipitation comes in the
forms of rain, snow, sleet, and hail.
91% of this precipitation falls into the ocean. The rest falls on land, which replenishes the
freshwater supply.
Evaporation – the sun’s heat causes the water to change from liquid to vapor.
Condensation– water vapor cools and falls as precipitation.
Ground water – provides water to soil, streams, rivers and oceans.
The Carbon Cycle
Moves between living things and the environment and back.
Photosynthesis – carbon dioxide is taken from the air by plants. These plants are eaten by
animals. Both the plant and animals receive carbon.
Respiration – Both the animal and plants respire. Carbon dioxide and water are returned to the
environment through respiration.
Decomposition – Decomposers break down dead materials.
Combustion – burning of fossil fuels.
The Nitrogen Cycle
*78% of the atmosphere is nitrogen
*Bacteria change nitrogen into forms that can be used
*Animals get nitrogen from eating plants.
Nitrogen fixation – When bacteria change nitrogen gas to a form that can be used by plants.
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3 places in the environment that you can find nitrogen
1. Animal waste
2. Atmosphere
3. Ocean
Succession – the gradual regrowth or development of a community of organisms over time
Pioneer species – the first organisms to grow in an area undergoing succession.
Ex: lichens