kaempferol n. A common flavonol with a single hydroxyl group attathed to the B ring; occurs as a copigment in flowers and fruits.
karyoevolution (Gr. karyon: nut, nucleus; L. evolutio: unfolding, unrolling) n. Evolutionary change in the chromosome set, expressed as changes in number andgross structure of the chromosomes; (more broadly), evolutionary relationshipsbetween taxa as indicated by karyotype differences.
karyogamy n. Th fusion of genotypically different nuclei.
karyology n. A branch of cytology that deals with the nature and structure of chromosomes.
karyolymph (Gr. karyon: nut, nucleus; L. lympha: water) n. The transparent or translucent fluid in a nucleus.
karyotype (Gr. karyon: nut, nucleus; typos: mark, image) n. The gross morphology of the chromosome set, described in terms of number, length, centromere position, etc. The karyotype is identical in all the diploid cells of an organism.
karyotypic adj. Related to a karyotype.
katabolism See catabolism.
kathodic adj. Away from the direction of apical cell segmentation; applied to the rectangular merophyte surface oriented away from the segmentation spiral. Cf. anodic.
Kazanian n. 1. An age in the Late Permian, which is preceded by the Ufimian, followed bythe Tatarian, and has its upper boundary dated at 253 million years ago. Someauthors extend the Kazanian to incorporate the Ufimian Age, referring tothis longer time-span as the Kazanian (or Kama) Age. 2.The name of the corresponding eastern European stage, which is roughly contemporaneouswith the upper Zechstein (western Europe), upper Guadalupianand lower Ochoan (N. America), and the upper Basleoan and lower Amarassian(New Zealand).
keel n. The folded edge or ridge of any structure; a ridge like the keel of a boat; in particular, a boat-shaped structure formed by fusion of the two anteriorpetals of a flower in Fabaceae.
keeled adj. Of leaves or bracts, folded and ridged along the midrib; v-shaped in cross-section; e.g. the leaves of Grimmia affinis, Fontinalis antipyretica. Cf. carinate.
kernel n. The essential part of a seed; all that is within the seed walls; the edible substance contained in the shell of a nut; hence, anything included in a shell, husk, or integument; as, the kernel of a nut. A single seed or grain; as, a kernel of corn. A small mass around which other matter is concreted; a nucleus; a concretion or hard lump in the flesh.
ketone n. A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. Ketones are often used in perfumes and paints to stabilize the other ingredients so that they don't degrade as quickly over time. Other uses are as solvents and intermediates in chemical industry. Examples of ketones are acetophenone, butanone (methyl ethyl ketone) and propanone (acetone).
kettle pond A pond formed in a depression on the land surface left by an ice block after glacial retreat. Kettle ponds have rounded bottoms like the cooking vessels of the same name. Some ice-block depressions are dry, simply because they are not deep enough to reach the water table.
kestose n. A frutosyl sucrose oligosaccharide, may serve as intermediates in the biosynthesis of fructans.
key n. An indehiscent, one-seeded fruit furnished with a wing, as the fruit of the ash and maple; a samara. Also key fruit.
kieselguhr n. A sedimentary mineral deposit formed from the skeletons of diatoms. It hasseveral industrial uses, for example in the manufacture of toothpaste andpolishes, and in filters for purifying liquids. Syn. diatomaceous earth, diatomite.
Kinderhookian n. The basal series in the Mississippian of N. America, underlain by the Bradfordian(Devonian) and overlain by the Osagean, and roughly contemporaneouswith the Hastarian Stage of the Tournaisian Series of Europe.
kinetochore A Spindle attachment. A localized region in each chromosome to which the `spindle fiber' appears to be attached and which seems to determine movement of the chromosomes during mitosis and meiosis.
kingdom n. One of the primary taxonomic categories into which natural objects are commonlyclassified, i.e. the largest, highest of the categories used in theclassification of organisms. Traditionally two kingdoms were recognized, thePlantae and the Animalia. There are currently five kindoms used: Plantae,Animalia, Fungi, Protoctista [(single-celled eukaryotic organisms) (Protista)(protozooans, some types of algae, etc.)], Prokaryota (Monera) (Bacteria).
kinin See cytokinin.
knee n. A joint or articulation, as in a grass stem; a bent outgrowth of a root whichrises above water, as in the bald cypress.
krummholz n. Literally crooked forest; the low wind-contorted forest at timberline.
Kungurian n. 1. The final age in the Early Permian Epoch, preceded by the Artinskian, followedby the Ufimian (Late Permian), and dated at 259.7 to 256.1 million yearsago. 2.The name of the corresponding eastern European stage, which is roughly contemporaneouswith the Weissliegende (western Europe), upper Leonardian (N.America), and Tae Weian (New Zealand). Boundary and correlation uncertaintieshave led to some rocks being assigned to either the Artinskianor Ufimian Stages.