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/jəʊk/ Noun, plural yolks 1. Material stored in an ovum that supplies food to the developing embryo and consists chiefly of proteins, lecithin, and cholesterol. ( 2. The yellow internal part of a bird’s egg, which is surrounded by the white, is rich in protein and fat, and nourishes the developing embryo (Google Dictionary); The yellow, spherical part of an egg that is surrounded by the white albumen, and serves as nutriment for the growing young. ( 3. Also called Deutoplasm, the nutritive material of an egg, used as food by a developing, embryonic animal. ( 4. A corresponding portion of the egg of other animals, consisting of protein and fat that serve as the primary source of nourishment for the early embryo and protoplasmic substances from which the embryo develops. ( 5. The grease in a sheep’s fleece. ( Word origin: Old English geolca, geoloca “yolk,” literally “the yellow part,” from geolu...

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Noun, plural zonas or zonae or zonæ 1. A zone or band; a layer (; A band or a layer surrounding a structure, for example, zona pellucida refers to the layer surrounding a mammalian ovum. ( 2. Any encircling or belt-like structure....

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/ˈzəʊnjuːl/ Noun 1. A little zone, or girdle; a zonula. ( 2. A small zone, as of a ligament. ( Word origin: From zonula, probably influenced by diminutive suffix –ule (“diminutive...

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Noun, pl. zooflagellates 1. Any of the animal-like flagellates characterized by their lack of chlorophyll and heterotrophic mode of nutrition. ( 2. (Microbiology) Any of the heterotrophic flagellates of the phylum Zoomastigophora. ( Word origin: Greek: zôion, animal + flagellate » Latin flagellātus, ptp. of flagellāre to...

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/zo-ol´o-je/ Noun 1. Deals the study of animals, including classification, physiology, development, and behavior (branches include: Entomology, Ethology, Herpetology, Ichthyology, Mammalogy, and Ornithology). 2. A branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct.   Word origin: From Ancient Greek ζῷον (zōon, “animal”) + λόγος (logos,...

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