Biology V
What is vaccination ?
Injection of a killed or weakened infectious organism (virus, bacterium) in order to prevent the disease. Vaccinations are administered via needles, orally, or by aerosol spray.
What is vaccine ?
A preparation that stimulates an immune response in the body that can prevent an infection or create resistance to an infection or disease. Vaccines are administered via needles, orally, or by aerosol spray. There are several types of vaccines, ranging from monovalent types that contain only one antigen to combinational vaccines where several antigens are combined into one. Vaccines can be live or attenuated, i.e., a weakened strain, to induce the immune response while bypassing the severe effects of the disease. Common vaccines include measles, mumps, polio, and others. A live-vector vaccine uses a nondisease virus or bacterium to deliver a foreign substance to develop immunity. An inactive vaccine contains dead viruses or bacteria and cannot cause disease but will trigger a response.
There are acellular vaccines that contain only a partial amount of cellular material; DNA vaccines that inject genes with coding for a specific antigen protein; bacterial vaccines that use bacteria; intracellular vaccines within a cell; and conjugate vaccines that are made with polysaccharide (carbohydrate) antigens bound to proteins to improve the effect of immunity.
What is vacuole ?
A large membrane-bound, fluid-filled space within a cell. In plant cells, there usually is a single large vacuole filling most of the cell’s volume, which helps maintain the shape of the cells. Vacuoles can contain food, gas, ingested bacteria, and other debris. In species such as the paramecium, two vacuoles are important: the contractile vacuole is used in osmoregulation, which is the removal of excess water; the food vacuole contains recently ingested food, where it eventually combines or fuses with the cell’s lysosomes, which contain enzymes for digestion.
What is vagility ?
Free to move about, ability to move or migrate. A vagile species is one whose distribution can vary widely from year to year.
What is valence shell ?
Valence electrons are the electrons located in the outermost, highest energy orbits or “shell” of an atom. The “shell” is more of a field density and indicates the region where the electrons are located. The valence electrons determine the chemical properties of an element, since it is these valence electrons that are gained or lost during a chemical reaction.
What is van der Waals forces ?
Weak forces, such as seen in hydrogen bonding, that contribute to intermolecular bonding.
What is vascular cambium ?
A secondary meristem, i.e., a thin layer of undifferentiated plant cells that divide indefinitely, which gives rise to secondary xylem and phloem, leading to an increase in stem girth. Tissue external to the vascular cambium is bark.
What is vascular plants ?
The plant kingdom comprises algae, bryophytes, seedless vascular plants, and seed vascular plants (gymnosperms and angiosperms). Most of the familiar flora in the United States such as trees, shrubs, herbs, vines, grasses, ferns, and most other land plants belong to the Tracheophyta, or vascular plants.
These plants have systems for transporting water, sugars, and nutrients and are differentiated into stems, leaves, and roots. They have an elaborate system of conducting cells, consisting of xylem, where water and minerals are transported, and phloem, where carbohydrates are transported. This method of rigid internal support enables them to stand and grow erect and distribute nutrients against gravity.
There are about 17,000 species of vascular plants native to the United States, along with several thousand additional native subspecies, varieties, named natural hybrids, and about 5,000 exotic species known outside cultivation. More than 4,850 species (about 28 percent) of the native U.S. vascular plants are considered globally rare.
Vascular plants first appear in the fossil record during the mid-Silurian period, about 410 million years ago. Rhyniophyta is the earliest known division of these plants, represented by several genera. Vascular is from Latin vasculum, meaning a vessel or duct.
Nonvascular plants, like mosses and liverworts, have poorly developed fluid transportation systems.
What is vascular system ?
A network of specialized cells; the vascular tissue that transports water and nutrients from the roots throughout a plant’s body. In animals, it is a specialized network of vessels—arteries, veins, and capillaries—for the circulation of fluids throughout the body tissue of an animal.
What is vascular tissue ?
The collective name given to the xylem and phloem, both tissues that carry food, water, and minerals through the plant for the nourishment of the cells in vascular plants.
What is vas deferens (sperm duct) ?
The excretory duct or tube that carries sperm from the epididymis, a long coiled tube in which spermatozoa are stored, to the ejaculatory duct and urethra. The tube connects the testes with the urethra and has thick muscles to move the sperm down the tract.
What is vector ?
A vector can be a bacterium or virus that does not cause disease in humans. It is often used in genetically engineered vaccines to transport antigen-encoding genes into the body to initiate an immune response. Additionally, a vector can be an organism, usually an insect, that transmits an infectious agent to its alternate host. Examples are malaria, where the vector of the parasite is mosquitoes, and the hosts are humans.
What is vegetative reproduction ?
Asexual reproduction in plants from vegetative parts (stems, leaves, or roots) or from modified stems (bulbs, tubers, rhizomes, and stolons). There is no exchange of gametes, and unless mutations occur, each new generation of plants is genetically identical to the parent plant.
What is vein ?
A thin-walled blood vessel that carries blood to the heart. Smaller veins called venules connect veins to capillaries.
In plants, they are the vascular bundles in leaves that consist of xylem and phloem. The veins are large along the leaf midvein and petiole and get smaller as they radiate out into the leaf, becoming known as veinlets.
What is ventilation ?
Ventilation is the passage of air into and out of the respiratory tract. Ventilation exchange (VE) is the exchange of oxygen and carbon dioxide and other gases during the passage of air into and out of the respiratory passages.
What is ventricle ?
The chamber of the heart that receives blood from the atrium (chamber that collects blood returning from the rest of the body) and contracts and pumps blood away from the heart. There are two ventricles in mammals and birds. The right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery; the left ventricle pumps oxygenated blood to the body via the aorta. The tricuspid valve separates the right atrium and the right ventricle and prevents backflow from the ventricle to the atrium. The mitral valve separates the left atrium and the left ventricle and prevents backflow from the ventricle to the atrium. The aortic valve prevents backflow of blood from the aorta into the left ventricle.
There are four brain ventricles. The right and left lateral ventricles lie within the cerebral cortex and connect with the very narrow third ventricle by way of openings called interventricular foramina. This third ventricle lies between the two halves of the thalamus and connects to the fourth ventricle via a long, thin tube called the cerebral aqueduct. The fourth ventricle lies in the hindbrain, under the cerebellum and dorsal to the pons and medulla.
What is vernalization ?
A required chilling period leading to the breaking of dormancy in plants. Flowering can be accelerated or induced by exposure to a long period of near-freezing temperatures.
What is vertebra ?
One of the segments of bone or cartilage composing the spinal column of vertebrates. In the spinal column of adult humans, there are 33 vertebrae: seven cervical vertebrae in the neck, 12 thoracic vertebrae that support the ribs, five lumbar vertebrae in the lower back, and other fused vertebrae forming the sacrum and the coccyx, beneath the sacrum.
What is vertebral bodies ?
The oval segments of bone on the spine that support most of the axial load of the spine and consist mostly of the thoracic and lumbar vertebrae. The lumbar part of the spine—consisting of five lumbar vertebral bodies that sit on top of the sacrum— is above the coccyx, the tailbone. The lumbar spine supports most of the weight of the body, and its vertebral bodies are larger than the rest. The thoracic part of the spine consists of 12 bodies. The thoracic region supports the cervical spine (neck), which has seven bodies and supports the head.
What is vertebrates ?
Chordate animals that have a spinal column or backbone (with the exception of hagfish and the rudimentary form of lampreys). The category includes fish, amphibians, reptiles, birds, and mammals; a member of the phylum Chordata.
There are approximately 50,000 living species of vertebrates, with slightly fewer total fish vertebrates (25,988), the oldest group, than all others combined (4,500 mammals, 9,100 birds, 7,082 reptiles, 4,880 amphibians). They range in size from 0.1 gram to 100,000 kilograms. The Cephalochordata have the fewest number of living species with 45, followed by the Urochordata with 2,000 species, and the Craniata with 43,000 species.
Vertebrates are chordates with a distinct head and contain sense organs and a brain. Other characteristics include a segmented vertebral rod of cartilage/bone, a closed circulatory system, true coelom, and a bilaterally symmetrical body.
Vertebrates first appeared on Earth some 500 million years ago when continents were fragmented. Then the continents combined into the supercontinent Pangaea, which included most of the Earth’s crust, some 300 million years ago, fragmenting again 100 million years ago into Laurasia (the northern continents) and Gondwanaland (the southern continents). Vertebrates live in almost every conceivable habitat on earth.
What is vesicle ?
A small, membrane-enclosed sac, cyst, or bubble found in the cytosol, the semifluid inside the cell membrane of eukaryotic cells. Vesicles are used to transport proteins and lipids to various destinations in the cell, including the sites of glycolysis (the first stage of energy production by the cell), and fatty acid synthesis. Vesicles can import particles in a process called endocytosis or export waste in a process called exocytosis.
In botanical terms, a vesicle is a small bladderlike body in the substance of a vegetable or on the surface of a leaf. In medical terms, a vesicle is a small and more-or-less circular elevation of the cuticle, skin lesion, or blister containing a clear watery fluid; a cavity or sac, especially one filled with fluid. Anatomy refers to the umbilical vesicle, while zoology defines a vesicle as a small, convex, hollow prominence on the surface of a shell or a coral. In geological terms, a vesicle is a small cavity, nearly spherical in form and the size of a pea or smaller, common in some volcanic rocks and produced by the liberation of watery vapor in the molten mass.
What is vessel element ?
Individual, short, wide, or fat cells arranged end to end, forming a system of tubes in the xylem. The cell walls are pitted and contain lignin, which gives them strength. They function to carry water and minerals upward in the stem and root.
What is vestigial organ ?
Nonfunctional remains of organs that were previously functional and served a purpose in ancestral species, that no longer serve that purpose, but that remain part of the body and may still be functional in related species; e.g., the dewclaws of dogs, tails in human embryos, wisdom teeth in adults, wings of the ostrich, rudimentary legs in snakes, and whales with hip bones.
What is vetch (Vicia sativa) ?
An annual forage legume, 40 to 80 cm in height. Chiefly pollinated by bees because it produces much nectar. Also, the maximum surface of a lake exposed to prevailing winds.
What is vicariance ?
The separation of a group of organisms caused by a geographic barrier (e.g., mountain, lake, sea, etc.), resulting in the original group differentiating into new varieties or species.
What is viremia ?
The presence of virus in the bloodstream. Often associated with malaise, fever, and aching in the back and extremities.
What is viroid (satellite RNA) ?
Once thought to be a virus, a viroid is an infectious, pathogenic entity similar to a virus but having only one strand of nucleic acid without the protein coat that defines a virus; a naked unencapsulated strand of RNA. Viroids are known to cause plant diseases. For example, potato spindle tuber viroid (PSTV) can cause a destructive disease of potatoes.
What is virus ?
A small microorganism that contains RNA or DNA and is surrounded by a protein coat. Viruses infect cells and then replicate new viruses after invasion using the protein of the infected cells to reproduce. Viruses can cause many human diseases, including chicken pox, measles, mumps, rubella, pertussis, and hepatitis, and they are not affected by common drugs such as antibiotics, which are effective against bacteriabased disease. Instead, vaccines are used to prevent or fight off virus attacks.
What is visceral (visceral muscle) ?
Pertaining to the internal organs of the body, especially those within the abdominal cavity such as the digestive tract, bladder, and the heart; smooth muscle, as opposed to the two other muscle types, skeletal and cardiac.
What is visible light ?
The portion of the electromagnetic spectrum that humans perceive. This excludes radio waves, microwaves, infrared light, ultraviolet light, X rays, and gamma rays. The human eye perceives the visiblelight spectrum as a continuum of colors (red, orange, yellow, green, blue, indigo, and violet, along with various combinations and shades of these colors), with the perceived color depending on the wavelength. The spectrum of visible light ranges in wavelength from about 400 nm to about 700 nm. Visible light travels at the same speed as all other radiation, i.e., at 186,000 miles per second, and its wavelength is longer than ultraviolet light but shorter than X rays. Violet has the shortest wavelength, while red has the longest.
What is vitalism ?
Attributed to the teachings of Aristotle, the concept of vitalism, in its many forms, is the belief that life forms and natural phenomena cannot be explained by simple explanations of matter and processes. Vitalism posits that there must be another force, perhaps a soul or spirit, that must be added to the equation that brings us life as we know it. This was one of the central interests of scientists and scholars during the latter part of the 19th century, and many spent time investigating the relationship between human beings and nature by studying the physiology of perception, as opposed to the mechanistic theory that all living organisms are inanimate and mechanical. Most of the biologists of that era believed in the existence of a life force of some kind. It was opposed in the 19th century by meteorologist/scientist Hermann von Helmholtz (1821–94), who spent many years trying to prove it wrong.
What is vitamin ?
An essential organic nutrient that is needed in small amounts by an organism for metabolism and other processes. Organisms either synthesize them or obtain them in other ways. Examples of vitamins are vitamin C and vitamin E, both antioxidants. A vitamin usually functions as a coenzyme or a component of a coenzyme and is soluble in either water or organic solvent. The lack of certain vitamins can lead to disease such as in rickets (vitamin D), tooth decay (vitamin K), bone softening (vitamin D), or night blindness (vitamin A). Other vitamins include vitamin B1 (thiamin), vitamin B2 (riboflavin), niacinamide (niacin-vitamin B3), vitamin B6 (pyridoxine), vitamin B12 (cobalamin), pantothenic acid (vitamin B5), pyridoxal (vitamin B6), phylloquinone (vitamin K), biotin, folic acid, inositol, choline, and PABA (para amino benzoic acid). Vitamin supplements are a billion dollar per year industry.
What is vitiligo ?
A skin condition of unpigmented spots determined by a dominant gene that destroys special skin cells (melanocytes). These skin cells produce the pigment melanin in the skin along with tissues (mucus membranes) that line the inside of the mouth, nose, genital and rectal areas, and the retina of the eyes. About 40 to 50 million people worldwide have vitiligo, and in the United States alone, 2 to 5 million people have it.
What is viviparous ?
Animals that are viviparous are born live after being nourished by blood from the placenta while in the uterus, and do not hatch from eggs.
What is voltage-gated channel ?
Ion channels are pores in cell membranes that allow the passage of ions in and out of cells. There are two types, voltage-gated and chemically gated channels. The opening and closing of the voltage-dependent ion channels is regulated by voltage, the electrical charge or potential difference between the inside and outside of the membrane, while chemical stimuli are responsible for opening and closing the chemically gated channels. Neurons use these channels to pass sodium and potassium ions through them.
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