Karyotype

A picture of an individual’s chromosomes.


Keratin

A protein that forms hair, bird feathers, human fingernails, and the horny scales of reptiles.


Keystone species

A species whose loss from an ecosystem would cause a greater than average change in other species populations or ecosystem processes.


Kidney

An excretory organ in which wastes are filtered from the blood.


Kingdom

In taxonomy, a group of similar phyla or divisions.


Kyoto Protocol, Kyoto agreement

An international agreement signed in Japan in 1997, attached to the UN Framework Convention on Climate Change. Under the agreement, which has been in force in Ireland since 2005, industrialized countries promised to reduce their combined greenhouse gas emissions to at least 5 percent below 1990 levels over the period 2008-2012.  See also UN Framework Convention on Climate Change