Chapter 3: The Biosphere and Ecology - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the biosphere, ecology, energy flow, and cycles of matter.

Biosphere

The global sum of all ecosystems; the zone of life on Earth that includes land, water, and air and extends from about 8 km above Earth’s surface to about 11 km below the ocean.

Ecology

The scientific study of interactions among organisms and their physical environment.

Biotic factor

Living parts of the environment with which an organism might interact (plants, animals, bacteria, etc.).

Abiotic factor

Nonliving components of the environment (sunlight, temperature, water, soil, etc.).

Organism

A single living individual that carries out life processes.

Population

A group of individuals of the same species living in the same area.

Community

An assemblage of different populations that live together in a defined area.

Species

A group of similar organisms that can breed and produce fertile offspring.

Ecosystem

A system consisting of all living organisms in an area plus the physical environment with which they interact.

Biome

A large region that has similar climate and typical organisms; a group of ecosystems.

Autotroph

An organism that captures energy (sunlight or chemicals) to produce organic molecules; also called a primary producer.

Primary producer

The first producers of energy-rich compounds in a food web, typically autotrophs.

Photosynthesis

Process by which light energy is used to convert carbon dioxide and water into oxygen and carbohydrates.

Chemosynthesis

Process by which some organisms use chemical energy (often from inorganic compounds) to synthesize organic molecules.

Heterotroph

An organism that cannot make its own food and must obtain energy from other organisms; also called a consumer.

Consumer

An organism that obtains energy and nutrients by feeding on others.

Herbivore

A consumer that eats plants.

Carnivore

A consumer that eats other animals.

Omnivore

A consumer that eats both plants and animals.

Scavenger

An animal that feeds on the carcasses of dead animals.

Decomposer

An organism (bacteria or fungi) that breaks down dead organic matter, recycling nutrients.

Detritivore

An organism that feeds on detritus (dead organic matter) and breaks it into smaller pieces.

Food chain

A sequence showing how energy and nutrients move from producers to consumers through feeding relationships.

Food web

A network of interconnected food chains illustrating energy flow in an ecosystem.

Trophic level

A position in a food chain or web; starting with the primary producers as the first level.

Ecological pyramid

A diagram showing the relative amount of energy, biomass, or numbers at each trophic level; includes pyramids of energy, biomass, and numbers.

Pyramid of Energy

An ecological pyramid that shows the amount of energy available at each trophic level, with about 10% typically transferred to the next level.

Pyramid of Biomass

A pyramid illustrating the total mass of living matter at each trophic level.

Pyramid of Numbers

A pyramid showing the relative number of individual organisms at each trophic level.

Biogeochemical cycle

Closed loops in which nutrients move through biological, geological, chemical, and sometimes human processes.

Nutrient

A chemical substance that organisms need to build tissues and carry out life functions.

Limiting nutrient

The nutrient whose supply limits the rate of primary production in an ecosystem.

Nitrogen fixation

Process by which bacteria convert nitrogen gas (N2) into ammonia (NH3) usable by living things.

Denitrification

Process by which bacteria convert nitrates (NO3-) into nitrogen gas (N2), returning nitrogen to the atmosphere.

Nitrates and nitrites

Forms of nitrogen usable by plants; NO3- (nitrate) and NO2- (nitrite) are intermediate forms in the nitrogen cycle.

Carbon cycle

Movement of carbon among the atmosphere, oceans, biosphere, and geologic reservoirs, involving photosynthesis, respiration, decomposition, and fossil fuels.

Oxygen cycle

Oxygen moves through the biosphere primarily via photosynthesis and respiration and participates in several nutrient cycles.

Phosphorus cycle

Movement of phosphorus through rocks, soils, water, and organisms; does not involve a significant atmospheric phase.

Water cycle

The continuous movement of water through evaporation, transpiration, condensation, precipitation, runoff, and groundwater.

Nutrient limitation

When the supply of a particular nutrient limits the rate of primary production in an ecosystem.

Observation

A basic method of ecological research involving careful watching and recording of natural phenomena.

Experimentation

A method of ecological research that tests hypotheses under controlled conditions.

Modeling

Creating abstract representations (often mathematical) of ecological processes to understand and predict outcomes.

Krill

Small shrimp-like crustaceans that are a key food source for many Antarctic predators and a central part of marine food webs.

Zooplankton

Tiny free-floating animals that feed on phytoplankton and form an essential link in marine food webs.

Phytoplankton

Microscopic photosynthetic organisms that float in aquatic environments and form the base of many aquatic food webs.

Algae

Photosynthetic organisms, including microalgae, that are primary producers in aquatic ecosystems.