Describing species that leave the nest soon after hatching, such as many bird species.

The study of birds’ nests, including their construction, function, and the behavior of birds that build them.

Referring to species, organisms, or characteristics that are black or dark in color, often used in biological classifications.

A compound containing the ion NO2-, often produced by bacteria in the nitrogen cycle and associated with pollution in water.

A genus of bacteria involved in the oxidation of nitrite to nitrate as part of the nitrogen cycle.

A chemical element (atomic number 7) that makes up about 78% of Earth’s atmosphere and is essential for life, especially in amino acids and proteins.

The process by which certain bacteria and archaea convert atmospheric nitrogen (N2) into a form usable by plants, such as ammonia (NH3).

Containing nitrogen, especially in compounds such as proteins, nucleic acids, and ammonia.

The network of neurons and other cells that transmit signals throughout the body, controlling various functions including movement, sensation, and cognition.

Tissue composed of neurons and supporting glial cells that transmit electrical impulses throughout the body.