K-strategist Species of organism that uses
a survival and reproductive "strategy" characterized
by low fecundity, low mortality, and longer life and with populations
approaching the carrying capacity of the environment, controlled
by density-dependent factors.
kala-azar Disease caused by Leishmania donovani.
Also called Dumdum fever or visceral leishmaniasis.
karyogamy In sexual reproduction, the fusion of
genetically distinct nuclei.
karyotyping The determination of the number and
structure of chromosomes in an individual.
kelp A group of large brown seaweeds.
kentrogon Larva in the crustacean order Rhizocephala
that is attached to its host crab; formed after the cypris larva
molts and its appendages and carapace are discarded.
keratin A tough, water-resistant protein found
in the epidermal layers of the skin. Found in hair, feathers,
hoofs, nails, claws, bills, etc.
keystone predator A predator that is very important
in the maintenance of the structure of a community.
keystone species A species upon which several other
species depend. Removal of the keystone species leads to the death
or disappearance of the dependent species.
kilocalorie A unit of heat equal to 1,000 calories.
kin selection The selection of genes due to individuals
assisting the survival and reproduction of nondescendant relatives
who possess the same genes by common descent.
kinesis Movements by an organism in random directions
in response to stimulus.
kinetic energy The energy resulting from the random
movement of molecules.
kinetid Axoneme of a cilium of flagellum together
with its basal fibrils and organelles. Also called a mastigont.
kinetochore A disc of proteins located on the
centromere, specialized to interact with the spindle fibers during
mitosis.
kinetodesma Fibril arising from the kinetosome
of a cilium in a ciliate protozoan, and passing along the kinetosomes
of cilia in that same row.
kinetodesmose Compound fiber joining cilia into
rows.
kinetoplast Conspicuous part of a mitochondrion
in a trypanosome; usually found near the kinetosome.
kinetosome Centriole from which an axoneme arises.
Also called a basal body or blepharoplast.
kinety All the kinetosomes and kinetodesmata of
a row of cilia.
kingdom The highest level of classification of life;
the most widely accepted classification system includes five kingdoms:
Monera, Protista, Fungi, Plantae, and Animalia.
kinin A type of local hormone that is released
near its site of origin; also called parahormone or tissue hormone.
kinocilium A long cilium at the apex of a hair cell.
Kinorhyncha The phylum of aschelminths that contains
members called kinorhynchs; small elongate worms found exclusively
in marine environments where they live in mud and sand.
knockout gene A genetically engineered mutant gene
that is introduced into an embryo to study the specific effects
of that gene.
knot Commonly seen as an irregular formation in
a longitudinal section of wood formed when a branch becomes surrounded
(buried) by formation of secondary xylem.
known resources Minerals or other useful environmental
materials or services that are identified and partially mapped;
may not be environmentally or socially acceptable or economically
feasible to exploit.
Koch's blue bodies Schizonts of Theileria parva
in circulating lymphocytes.
Kranz anatomy A specialized leaf anatomy found
in C4 plants in which the vascular bundle is surrounded by bundle
sheath cells.
Krebs Cycle The second stage of cellular respiration
that occurs in the mitochondria; completes the breakdown of glucose
into carbon dioxide. See citric acid cycle.
krill Any of the small, pelagic, shrimplike crustaceans.
Krill are an important source of energy in antarctic food webs.
Kupffer cells Phagocytic epithelial cells lining
the sinusoids of the liver.
kwashiorkor Malnutrition caused by
diet high in carbohydrate and extremely low in protein.