Ecosystems and Ecology

Unit Review Sheet

Facts and Definitions

Lesson 1: What Is in an Ecosystem?

• An ecosystem consists of the organisms and non-living components found within a very specific area.
• Ecology is the study of the relationships of living organisms with one another and their natural surroundings.
• A biome is a large geographical area defined in part by its climate, soil, and living organisms.
• A biotic factor is a living organism (such as plants, animals, fungi, microscopic organisms).
• An abiotic factor is a non-living component (soil, temperature, weather, light, elements like oxygen or nitrogen, compounds like water).
• Producers are organisms that produce living material using sunlight, carbon dioxide, and water. They are sometimes also referred to as autotrophs, meaning they are self feeding.
• Consumers are organisms that rely on other organisms for energy. They are sometimes also referred to as heterotrophs, meaning they cannot create their own food.
• Decomposers are organisms that break down waste and dead and decaying material and return minerals and other elements to the ecosystem by the process of decomposition.

Lesson 2: Diversity within Ecosystems

• Diversity is the degree of variation of life forms within a given ecosystem.
• Aquatic means of or dealing with water.
• Terrestrial means of or dealing with land.

Lesson 3: Energy Transfer in Ecosystems

• Photosynthesis is a process where energy from sunlight is captured and used to make carbohydrates.
• Carbohydrates are energy-storing molecules that contain carbon, hydrogen, and oxygen; carbon dioxide + water + energy produces carbohydrates + oxygen.
• Biomass is the total mass of living material within a given area or trophic level.
• The position or stage that an organism occupies in a food chain or energy pyramid (producer, consumer, etc.) is its trophic level.
• A food chain is a group of organisms that depend upon one another for survival; the organisms are organized based upon their relationships; one organism provides food for another organism.
• A food web is a collection of food chains that have organisms interacting with organisms associated with other food chains.
• An energy pyramid is a graphic that demonstrates the transfer of energy from one trophic level to another.
• Producers are plants (such as trees, grasses, seaweed, algae) that use sunlight to make carbohydrates.
• Consumers get their nutrients by eating producers or other consumers. Herbivores eat plants, carnivores prey upon and eat other consumers, and omnivores consume both plants and animals.

Lesson 4: Ecosystem Relationships

• Niche refers to an organism's behavior or habits (such as what it eats or where it makes its home) in a particular area.
• Competition is a conflict between organisms for essential resources like territory or food. The competition can occur between individuals of the same species or between different species.
• Symbiosis is a close and often long-term relationship/interaction between two different species in an ecosystem; the interaction can be beneficial, harmful, or neutral.
• Parasitism is a symbiotic relationship where one organism, the parasite (such as a tick or mosquito), benefits at the expense of its host.
• Commensalism is a symbiotic relationship where one organism benefits but the other is neither harmed nor helped.
• Mutualism is a symbiotic relationship that benefits both species (bees and flowers, for example).

Lesson 5: Ecological Succession

• Natural succession is a process of changes that take place in an ecological community after a disaster or disturbance.
• Primary succession is a process that occurs after disruptions in the environment have been strong enough to destroy and/or eliminate any living organisms from the site; organic matter is destroyed, which means that primary succession usually occurs in a place lacking soil.
• Secondary succession is a process started by an disturbance, such as a forest fire or flood, that decreases an already-established ecosystem to a smaller population of species; organic matter remains, and soil is present.
• Pioneer species describes the first organisms to start the chain of events leading to a livable ecosystem; land that does not have any living organisms may have very poor soil, and poor soil means poor plant life; pioneer species eventually die, making new soil that contains nutrients for secondary succession.
• Herbaceous plants are plants that have leaves and stems that die down at the end of the growing season to the soil level.
• Climax community is the final stage in ecological succession in which a relatively constant environment is reached and the types of species present do not change.
• A cycle is a process that returns to its beginning and repeats itself in the same sequence; in ecology, cycles are the result of relationships between organisms and their environment.

Lesson 6: Natural Hazards and Natural Disasters

• A natural disaster is a major disruption in an environment that impacts organisms.
• A natural hazard is an environmental event or situation that has the potential to cause great harm (such as a storm, earthquake, or tornado).
• The Earth's ancient history includes periods of explosions — when the number and diversity of organisms dramatically increased — and extinctions — when environmental change led to the death of large number of organisms.

Lesson 7: Succession and Natural Disasters

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Lesson 8: A Carbon Journey

• The carbon cycle describes the movement of carbon throughout the Earth.
• Decomposition is a breakdown of organic matter that releases nutrients back into the environment.
• Carbon fixation is a process, like photosynthesis, in which an organism converts carbon dioxide to carbohydrates.
• Cellular respiration is a process where the cells of plants or animals "burn" carbohydrates for energy; carbon dioxide is released as a result.

Lesson 9: Ecosystems and Their Environments

• A habitat is the place where an organism naturally lives.
• An adaptation is a trait that improves an organism's function in its environment; it also refers to the evolutionary process that helps organisms better survive in their habitat.
• Evolution involves changes in the characteristics of populations of organisms over very long spans of time.
• Specialized species are ones that can fit into a limited environment (usually specific certain climates or food sources).
• Generalized species are ones that have the flexibility to live in different environments or eat varied food sources.
• An extremophile is an organism that has developed the ability to thrive in harsh conditions, such as very high temperatures or pressures or in an area without oxygen.

Lesson 10: Cause and Effect in the Ecosystem

• Biomagnification is an increase in the concentration of a substance as it moves from one trophic level to another.
• Bioaccumulation is an increase in concentration of a substance in an organism over time.
• A pollutant is a substance that has the potential to make air, soil, water, or other natural resources harmful or unsuitable for living organisms.
• A toxicant is a chemical compound that has a negative effect on organisms.

Lesson 11: Matter and the Food Web

• The Law of Conservation of Matter and Energy states that, in a closed system, the amount of energy and matter remains constant; neither mass nor energy can be destroyed, yet both can change form.

Lesson 12: Adaptability and Survival

• Extinction is the death or end of all organisms in a species.

Lesson 13: Invasive Species

• Native species are organisms that are normally found in a geographic region; the organisms occupy a niche within the local ecosystem.
• Invasive species are organisms introduced by human action to an area where it did not previously occur naturally; the species becomes capable of establishing a breeding population in the new location and becomes a pest, directly threatening agriculture or the local biodiversity.
• Invasive generalists are invasive organisms that can grow just about anywhere.
• Invasive specialists are invasive organisms that live within a narrow range of conditions.
• Biodiversity is the degree of variation of life forms within a given ecosystem.