unit 3

Population

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

Exponential population growth

Growth with no limits; population increases rapidly.

Logistic population growth

Growth that slows as population reaches carrying capacity.

Community

All the interacting species living in the same area.

Interspecific competition

Two species compete for the same resources (–/–).

Predation

One organism kills and eats another (+/–).

Herbivory

An animal eats plants (+/–).

Mutualism

Both species benefit (+/+).

Parasitism

One organism lives on/in another and steals nutrients (+/–).

Ecological niche

A species’ 'role' in its environment: habitat, diet, activity, and interactions.

Producers

Organisms that make their own food (plants, algae).

Primary consumers

Herbivores that eat producers.

Secondary consumers

Carnivores that eat herbivores.

Tertiary consumers

Top predators that eat carnivores.

Species diversity

The variety and relative abundance of species in a community.

Ecosystem

A community plus the nonliving environment.

Carbon sink

Anything that absorbs more carbon than it releases (forests, oceans, soil).

Animal

A multicellular heterotroph that ingests food.

Ingestion

Taking food into the body to digest internally.

Endoderm

Inner tissue layer; forms digestive system.

Mesoderm

Middle tissue layer; forms muscles and organs.

Ectoderm

Outer tissue layer; forms skin and nervous system.

Molting

Shedding an exoskeleton to grow.

Exoskeleton

Hard outer skeleton that protects and supports the body.

Radial symmetry

Body arranged around a central axis (like a jellyfish).

Bilateral symmetry

Left and right mirror halves (most animals).

Segmentation

Body divided into repeating units.

Metamorphosis

A developmental change from juvenile to adult form.

Carrying capacity

The maximum population size an environment can sustain.

Density-dependent factors

Factors that get stronger as population size increases.

Density-independent factors

Affect populations regardless of size.

Eutrophication

A nutrient overload that causes algal blooms.

Trophic level

Each step in a food chain or food web.

Biomass

The total mass of living matter in a given area.

Photosynthesis

The process by which producers convert sunlight into energy.

Cellular respiration

The process by which organisms convert glucose and oxygen into energy.

Predation (+/–)

A relationship where one organism kills another for food.

Herbivory (+/–)

A relationship where an animal eats plants.

Mutualism (+/+)

A relationship where both species benefit.

Parasitism (+/–)

A relationship where one organism benefits at the expense of another.

Competition (–/–)

A relationship where both species are harmed.

Protostome

An animal whose mouth develops from the blastopore.

Deuterostome

An animal whose anus develops from the blastopore.

Cnidarians

A phylum that includes jellyfish and sea anemones.

Annelids

A phylum characterized by segmented bodies.

Mollusks

A phylum that includes clams, snails, and octopus.

Arthropods

A phylum recognized for jointed legs and exoskeleton.

Tissues

Collections of specialized cells.

Sexual reproduction

Reproduction involving two parents and genetic diversity.

Asexual reproduction

Reproduction involving one parent and identical offspring.

Metamorphosis

A transformative development from juvenile to adult form.

Segmentation

Division of the body into repeated units.

Exoskeleton

A hard protective outer structure in arthropods.

Biodiversity

The variety of life in a particular habitat or ecosystem.

Habitat

The natural environment in which a species lives.

Niche

The role and position a species has in its environment.

Food web

A complex network of feeding interactions.

Ecological role

The function of a species within an ecosystem.

Algal blooms

Rapid increases in algal population, often due to nutrient overload.

Ecologists

Scientists who study interactions of organisms and their environment.

Biomagnification

The increase in concentration of substances in organisms higher up the food chain.