IB Biology Topic C4.1: Populations and Communities Key Definitions

Adaptations are traits that increase an organism’s fitness in response to environmental factors.

Allelopathy occurs when plants release chemicals, called allelochemicals, into the soil to inhibit the growth of nearby plants.

Antibiotic secretion is a strategy used by microorganisms, like fungi and bacteria, to inhibit the growth of competing microbes.

Carrying capacity is the maximum population size that an ecosystem can sustain indefinitely without degrading the habitat.

The chi-squared test is a statistical method used to assess whether the occurrences of two species in a given area are due to chance or due to some form of association, possibly from ecological interactions like competition or mutualism.

A community includes all the populations of different species living together in the same area and interacting with each other.

The competitive exclusion principle states that two species cannot occupy the same ecological niche indefinitely.

Herbivores feed on plants or algae, which are producers in the ecosystem.

Interspecific competition occurs when two or more species vie for the same limited resources, such as food, space, or light.

Mutualism is a cooperative relationship where both species gain benefits.

Parasitism involves one species (the parasite) benefiting at the expense of another (the host).

A form of parasitism where the parasite causes disease in its host.

A population is a group of individuals of the same species living in a specific area. These individuals interact with each other and their environment, forming the building blocks of ecosystems.

Predators hunt, kill, and eat prey to obtain energy.

Standard deviation measures how much the data varies from the mean.