Biology, VIR-ZYG

How do plants feed themselves? How did dogs evolve from wolves? What good is the appendix in humans, anyway? Such questions fall within the domain of biology, which seeks to understand living organisms and their vital processes (although the jury’s still out on what our appendixes are for). Biology’s diverse fields include botany, ecology, evolution, genetics, medicine, physiology, and zoology.
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Biology Encyclopedia Articles By Title

virion
virion, an entire virus particle, consisting of an outer protein shell called a capsid and an inner core of nucleic......
virology
virology, branch of microbiology that deals with the study of viruses. Although diseases caused by viruses have......
vision
vision, physiological process of distinguishing, usually by means of an organ such as the eye, the shapes and colours......
visual field defect
visual field defect, a blind spot (scotoma) or blind area within the normal field of one or both eyes. In most......
visual pigment
visual pigment, any of a number of related substances that function in light reception by animals by transforming......
vitalism
vitalism, school of scientific thought—the germ of which dates from Aristotle—that attempts (in opposition to mechanism......
vitiligo
vitiligo, patchy loss of melanin pigment from the skin. Though the pigment-making cells of the skin, or melanocytes,......
viviparity
viviparity, retention and growth of the fertilized egg within the maternal body until the young animal, as a larva......
vivisection
What do you think? Explore the ProCon debate vivisection, operation on a living animal for experimental rather......
vocal cord
vocal cord, either of two folds of mucous membrane that extend across the interior cavity of the larynx and are......
vocal sac
vocal sac, the sound-resonating throat pouch of male frogs and toads (amphibians of the order Anura). Vocal sacs......
vocalization
vocalization, any sound produced through the action of an animal’s respiratory system and used in communication.......
Volkmann contracture
Volkmann contracture, disorder of the wrist and hand in which the hand and fingers become fixed in a characteristic......
volvocid
volvocid, any of a group of green algae (division Chlorophyta) that are common in fresh water. Colonies vary from......
Volvox
Volvox, genus of some 20 species of freshwater green algae (division Chlorophyta) found worldwide. Volvox form......
vomiting
vomiting, the forcible ejection of stomach contents from the mouth. Like nausea, vomiting may have a wide range......
von Willebrand disease
von Willebrand disease, inherited blood disorder characterized by a prolonged bleeding time and a deficiency of......
vulva
vulva, the external female genitalia that surround the opening to the vagina; collectively these consist of the......
vulvitis
vulvitis, inflammation and infection of the vulva—the external genitalia of the female. The external organs of......
warm-bloodedness
warm-bloodedness, in animals, the ability to maintain a relatively constant internal temperature (about 37° C [99°......
wart
wart, a well-defined growth of varying shape and size on the skin surface caused by a virus, most commonly one......
West Nile virus
West Nile virus, virus belonging to the family Flaviviridae, related to viruses that can cause yellow fever and......
white blood cell
white blood cell, a cellular component of the blood that lacks hemoglobin, has a nucleus, is capable of motility,......
white nose syndrome
white nose syndrome, disease affecting hibernating bats in North America that is caused by the growth of a white......
whooping cough
whooping cough, acute, highly communicable respiratory disease characterized in its typical form by paroxysms of......
Why Are Plants Green?
Plants are green because of a pigment found in the chloroplasts of plant cells called chlorophyll. It plays a crucial......
Why Are There Different Blood Types?
Different blood groups are the result of genetic variations that determine the presence or absence of specific......
Why Do Giraffes Have Long Necks?
The long neck of a giraffe (genus Giraffa) is a classic example of adaptation, which is the process by which a......
Why Do Snakes Shed Their Skin?
As snakes grow, their skin does not grow with them. Instead, they periodically shed their outer layer of skin to......
wilt
wilt, common symptom of plant disease resulting from water loss in leaves and stems. Affected parts lose their......
witches’-broom
witches’-broom, symptom of plant disease that occurs as an abnormal brushlike cluster of dwarfed weak shoots arising......
wound
wound, a break in the continuity of any bodily tissue due to violence, where violence is understood to encompass......
Xanthophyta
Xanthophyta, division or phylum of algae commonly known as yellow-green algae...
xeroderma pigmentosum
xeroderma pigmentosum, rare, recessively inherited skin condition in which resistance to sunlight and other radiation......
Xg blood group system
Xg blood group system, classification of human blood based on the presence of proteins called Xg antigens on the......
yaws
yaws, contagious disease occurring in moist tropical regions throughout the world. It is caused by a spirochete,......
yeast
yeast, any of about 1,500 species of single-celled fungi, most of which are in the phylum Ascomycota, only a few......
yellow-green algae
yellow-green algae, (class Xanthophyceae), class of approximately 600 species of algae in the division Chromophyta,......
Yersinia
Yersinia, (genus Yersinia), any of a group of ovoid- or rod-shaped bacteria of the family Enterobacteriaceae. Yersinia......
yersiniosis
yersiniosis, acute gastrointestinal infection caused by the bacterium Yersinia enterocolitica and characterized......
Yt blood group system
Yt blood group system, classification of human blood based on the presence of molecules known as Yt antigens on......
Zellweger syndrome
Zellweger syndrome, congenital disorder characterized by complete absence or reduction in the number of peroxisomes......
Zika virus
Zika virus, infectious agent of the genus Flavivirus in the family Flaviviridae. Zika virus was first isolated......
zoo
zoo, place where wild animals and, in some instances, domesticated animals are exhibited in captivity. In such......
zoochlorella
zoochlorella, small green alga (often Chlorella) or, sometimes, flagellate protozoan (e.g., Tetraselmis, Carteria)......
zooflagellate
zooflagellate, any flagellate protozoan that is traditionally of the protozoan class Zoomastigophorea (sometimes......
zoogeography
zoogeography, the branch of the science of biogeography (q.v.) that is concerned with the geographic distribution......
zoology
zoology, branch of biology that studies the members of the animal kingdom and animal life in general. It includes......
zoonotic disease
zoonotic disease, any of a group of diseases that can be transmitted to humans by nonhuman vertebrate animals,......
zooplankton
zooplankton, small floating or weakly swimming organisms that drift with water currents and, with phytoplankton,......
zooxanthella
zooxanthella, flagellate protozoan (or alga) with yellow or brown pigments contained in chromatophores that lives......
zygote
zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm).......

Biology Encyclopedia Articles By Title