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Noun (Order Passeriformes) Any member of the largest order of birds and the dominant avian group on Earth today. The passeriform birds are true perching birds, with four toes, three directed forward and one backward. Considered the most highly evolved of all birds, passerines have undergone an explosive evolutionary radiation in relatively recent geological time and now occur in abundance on all continents except Antarctica and on most oceanic islands. ( Syn: passerine or perching...

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Noun 1. Of or relating to the largest order (Passeriformes) of birds which includes over half of all living birds and consists chiefly of altricial songbirds of perching habits. ( 2. Perching birds mostly small and living near the ground with feet having 4 toes arranged to allow for gripping the perch; most are songbirds; hatchlings are helpless ( 3. A bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders; with over 5,000 identified species,[1] it has roughly twice as many species as the largest of the mammal orders, the Rodentia. It contains more than 110 families, the second most of any order of vertebrates (after the Perciformes) ( 4. Any bird of the order Passeriformes, which comprises more than half of all bird species. ( Syn: passeriform bird, perching bird Word origin: Derived from Passer domesticus, the scientific name of the eponymous species (the House Sparrow) and ultimately from the Latin term passer for Passer sparrows and similar small...

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Passive Immunity

1. The transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and can also be induced artificially, when high levels of human (or horse) antibodies specific for a pathogen or toxin are transferred to non-immune individuals. ( 2. A type of immunity acquired by the transfer of antibody from one individual to another, such as from mother to offspring. ( 3. The translocation of active humoral immunity from one individual to another in the form of custom-made antibodies. ( 4. The short-term immunity that results from the introduction of antibodies from another person or animal. (Google Dictionary) 5. An impermanent form of acquired immunity in which antibodies against a disease are acquired naturally (as through the placenta to an unborn child) or artificially (as by injection of antiserum))....

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Passive transport

1. A movement of biochemicals and other atomic or molecular substances across membranes. Unlike active transport, it does not require an input of chemical energy, being driven by the growth of entropy of the system. The rate of passive transport depends on the (semi-)permeability of the cell membrane, which, in turn, depends on the organization and characteristics of the membrane lipids and proteins. The four main kinds of passive transport are diffusion, facilitated diffusion, filtration and osmosis. ( 2. Transport of a substance across a cell membrane by diffusion; expenditure of energy is not required. ( 3. A kind of transport by which ions or molecules move along a concentration gradient, which means movement from an area of higher concentration to an area of lower concentration....

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