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Home >>Biology Dictionary >> Amylases - Angiospermae
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Amphivasal bundle
A vascular bundle in which a central phloem is surrouned by xylem as in monocot stems of Dracena, Agave, Yucca, etc. A type of concentric vascular bundle.
Amylases (Diastases)
A group of enzymes which split starch or glycogen vario0usly to dextrin, maltose, glucose, Widely distributed in plants and animals, e.g. in malt, pancreatic juice and in micro-organisms.
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Anabolism. Synthesis by living thinks of complex molecules from simpler ones.
Anaerobic. Living in absence of free oxygen (gaseous or dissolved).
Analogous. An organ of one species is said to be analogous to an organ of another when both organs have the same function (q.v.) and when they are not homologous e.g. tendrils of pea and vine. or eyes of squid and vertebrates, are analogous.
Analogy
Refers to structurally different but functionally alike organs.
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Anamniota
Grouping of vertebrate classes sometimes used in classification in contrast to Amniota. Consists of Agnatha, fishes and Amphibia.
Anandrous
(Of flowers), lacking stamens.
Anaphase
Stages of mitosis or meiosis when daughter chromosomes are separating towards poles of spindle.
Anatomy
The science of the structure of living organisms.
Androecium
Collective name for the stamens of a flower.
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Androgens are produced principally by the testes when stimulated with Luteinizing hormone but they are also secreted in smaller amounts by the adrenal glands and the ovaries. Injections of natural or synthetic androgens are used to treat hormonal disorders of the testes and breast cancer and to build up body tissue (see anabolic steroid).
Andromonoecious
Having male and hermaphrodite flowers on the same plant.
Anemophily
Pollination by wind.
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Androgen
General name for any substance with male sex hormone activity in vertebrates, i.e. responsible for development and maintenance of many male sexual characteristics.
Aneuploid
(Heteroploid). Having more or less than an integral multiple of the haploid number of chromosomes; therefore genetically unbalanced.
Aneurism
Dilation of an artery wall, a sac formed by abnormal dilation of the weakened wall of a blood vessel.
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Animal Pole
Point on surface of egg nearest to its nucleus, making one end of the graded distribution of substances which occurs in most eggs. The other end, at opposite side of egg, is the vegetal pole. The animal-vegetal axis between the two poles passes through the nucleus. When yolk is present, its quantity is usually graded along the axis, and is least at animal, most at vegetal pole.
Anisogamy
Condition in which gametes that differ in size may be (1) restricted to condition in which they differ in size, but are similar in form (excluding therefore oogamy), or may (2) include oogamy, and all other grades of difference.
Amylin
It is insoluble cellulose covering starch grains.
Amyloplast
It is a colourless plastid storing starch.
Amylopsin
An enzyme that brings about the conversion of starch or glycogen into maltose.
Angiospermae
Flowering plants; a sub-division of Spermatophyta. Distinguished from other sub-division, Gymnospermae, by having the ovules borne within a closed cavity, the ovary, formed by the megasporophyll: after fertilization the ovary becomes a fruit, enclosing one or more seeds. Micro-and mega sporophylls (stamens and carpels) borne in flowers. Gametophyte generations are reduced.
Anesthetic
Refers to a substance that produces loss of sensation.
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