APES Study Guide

Abiotic

Nonliving

Accuracy

How close a measured value is to the actual or true value

Biotic

Living

Control group

In a scientific investigation, a group that experiences exactly the same conditions as the experimental group, except for the single variable under study.

Deductive reasoning

The process of applying a general statement to specific facts or situations.

Dependent variable

A variable that is dependent on other factors.

Ecosystem

A particular location on Earth with interacting biotic and abiotic components.

Environment

The sum of all the conditions surrounding us that influence life.

Environmental science

The field of study that looks at interactions among human systems and those found in nature.

Environmental studies

The field of study that includes environmental science and additional subjects such as environmental policy, economics, literature, and ethics.

Environmentalism

A social movement that seeks to protect the environment through lobbying, activism, and education.

First law of thermodynamics

A theory with no known exception that states that energy is neither created nor destroyed but it can change from one form to another.

Hypothesis

A testable conjecture about how something works.

Independent variable

A variable that is not dependent on other factors.

Inductive reasoning

The process of making general statements from specific facts or examples.

Natural experiment

A natural event that acts as an experimental treatment in an ecosystem.

Null hypothesis

A prediction that there is no difference between the groups or conditions that are being compared.

Precision

How close the repeated measurements of a sample are to one another.

Replication

The data collection procedure of taking repeated measurements.

Sample size (n)

The number of times a measurement is replicated in data collection.

Scientific method

An objective method to explore the natural world, draw inferences from it, and predict the outcome of certain events, processes, or changes.

Second law of thermodynamics

The physical law stating that when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes.

Sustainability

Living on Earth in a way that allows humans to use its resources without depriving future generations of those resources.

Theory

A hypothesis that has been repeatedly tested and confirmed by multiple groups of researchers and has reached wide acceptance.

Uncertainty

An estimate of how much a measured or calculated value differs from a true value.

Variable

Any categories, conditions, factors, or traits that differ in the natural world or in experimental situations.

Aerobic

An environment with abundant oxygen.

Aerobic respiration

The process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Algal bloom

A rapid increase in the algal population of a waterway.

Anaerobic

An environment that lacks oxygen.

Anaerobic respiration

The process by which cells convert glucose into energy in the absence of oxygen.

Aphotic zone

The deeper layer of ocean water that lacks sufficient sunlight for photosynthesis.

Aquatic biome

An aquatic region characterized by a particular combination of salinity, depth, and water flow.

Assimilation

A process by which plants and algae incorporate nitrogen into their tissues.

Benthic zone

The muddy bottom of a lake, pond, or ocean beneath the limnetic and profundal zones.

Biogeochemical cycle

The movements of matter within and between ecosystems involving cycles of biological, geological, and chemical processes.

Biomass

Biological material that has mass.

Biome

The plants and animals that are found in a particular region of the world.

Biosphere

The region of our planet where life resides.

Carbon cycle

The movement of carbon around the biosphere among reservoir sources and sinks.

Carnivore

A consumer that eats other consumers.

Cellular respiration

The process by which cells unlock the energy of chemical compounds.

Chemosynthesis

A process used by some bacteria to generate energy with methane and hydrogen sulfide.

Climate

The average weather that occurs in a given region over a long period of time.

Commensalism

An interaction between two species in which one species benefits and the other species is neither harmed nor helped.

Community ecology

The study of interactions among species.

Competition

The struggle of individuals, either within or between species, to obtain a shared limiting resource.

Competitive exclusion principle

The principle stating that two species competing for the same limiting resource cannot coexist.

Consumer (Heterotroph)

An organism that is incapable of photosynthesis and must therefore obtain its energy by consuming other organisms.

Coral bleaching

A phenomenon in which algae inside corals die, causing the corals to turn white.

Coral reef

Represents Earth's most diverse marine biome, and are found in warm, shallow waters beyond the shoreline in tropical regions.

Dead zone

When oxygen concentrations become so low that it kills fish and other aquatic animals.

Decomposers

Fungi and bacteria that complete the breakdown process by converting organic matter into small elements and molecules that can be recycled back into the ecosystem.

Denitrification

The conversion of nitrate (NO3) in a series of steps into the gases nitrous oxide (N2O) and, eventually, nitrogen gas (N2O), which is emitted into the atmosphere.

Detritivore

An organism that specializes in breaking down dead tissues and waste products into smaller particles.

Ecological efficiency

The proportion of consumed energy that can be passed from one trophic level to another.

Estuary

An area along the coast where the fresh water of rivers mixes with salt water from the ocean.

Eutrophic

Describes a lake with a high level of fertility.

Evapotranspiration

The combined amount of evaporation and transpiration.

Exotic species (Alien species)

A species living outside its historical range.

Food chain

The sequence of consumption from producers through tertiary consumers.

Food web

A model of how energy and matter move through two or more interconnected food chains.

Freshwater biomes

Categorized as streams and rivers, lakes and ponds, or freshwater wetlands.

Freshwater wetland

An aquatic biome that is submerged or saturated by water for at least part of each year, but shallow enough to support emergent vegetation.

Global warming

The increase in global temperatures due to humans producing more greenhouse gases.

Greenhouse gases

Gases in Earth's atmosphere that trap heat near the surface.

Gross primary productivity (GPP)

The total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time.

Habitat

An area where a particular species lives in nature.

Herbivore (Primary consumer)

A consumer that eats producers.

Herbivory

An interaction in which an animal consumes plants or algae.

Hot desert

A biome located at roughly 30° N and 30° S, and characterized by hot temperatures, extremely dry conditions, and sparse vegetation.

Hydrologic cycle

The movement of water around the biosphere among reservoir sources and sinks.

Hypoxic

Low in oxygen.

Intertidal zone

The narrow band of coastline that exists between the levels of high tide and low tide.

Invasive species

A species that spreads rapidly across large areas and causes harm.

Leaching

A process in which dissolved molecules are transported through the soil via groundwater.

Limiting nutrient

A nutrient required for the growth of an organism but available in a lower quantity than other nutrients.

Limnetic zone

A zone of open water in lakes and ponds as deep as the sunlight can penetrate.

Littoral zone

The shallow zone of soil and water in lakes and ponds near the shore where most algae and emergent plants such as cattails grow.

Mangrove swamp

A swamp that occurs along tropical and subtropical coasts, and contains salt-tolerant trees with roots submerged in water.

Mesotrophic

Describes a lake with a moderate level of fertility.

Mineralization (Ammonification)

The process by which fungal and bacterial decomposers break down the organic matter found in dead bodies and waste products and convert it into inorganic compounds, such as inorganic ammonium (NH4+).

Mutualism

An interaction between two species that increases the chances of survival or reproduction for both species.

Native species

A species that lives in its historical range, typically where it has lived for thousands or millions of years.

Net primary productivity (NPP)

The energy captured by producers in an ecosystem minus the energy producers respire.

Nitrification

The conversion of ammonia (NH4+) into nitrite (NO2−) and then into nitrate (NO3−).

Nitrogen cycle

The movement of nitrogen around the biosphere among reservoir sources and sinks.

Nitrogen fixation

The process that converts nitrogen gas in the atmosphere (N2) into forms of nitrogen that plants and algae can use.

Oligotrophic

Describes a lake with a low level of phytoplankton due to low amounts of nutrients in the water.

Open ocean

Deep-ocean water, located away from the shoreline where sunlight can no longer reach the ocean bottom.

Parasitism

An interaction in which one organism lives on or in another organism, referred to as the host.

Parasitoid

A specialized type of predator that lays eggs inside other organisms—referred to as its host.

Pathogen

A parasite that causes disease in its host.

Permafrost

An impermeable, permanently frozen layer of soil.

Phosphorus cycle

The movement of phosphorus around the biosphere among reservoir sources and sinks.

Photic zone

The upper layer of ocean water in the ocean that receives enough sunlight for photosynthesis.

Photosynthesis

The process by which plants and algae use solar energy to convert carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2).

Phytoplankton

Floating algae.

Predation

An interaction in which one animal typically kills and consumes another animal.

Primary productivity

The rate of converting solar energy into organic compounds over a period of time.