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from article Migratory behavior
Northern pintail ducks (Anas acuta) in migratory flight. (Credit: Josh Kelly/U.S. Fish and Wildlife Service)
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from article Migratory behavior
Monarch butterflies (Danaus plexippus) migrate from Canada and the northern United States in early autumn on a 2500-km (1550-mi) flight to Mexican wintering sites that are used year after year by individuals that have never been there before and…
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from article Endodermis
Transection from part of Zea root illustrating endodermis in relation to contiguous tissues. (After K. Esau, Plant Anatomy, 2d ed., John Wiley and Sons, 1967)
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from article Endodermis
Details of endodermal structure. (a) Diagram of cell showing location of Casparian strip. (b) Cells of endodermis and of ordinary parenchyma before treatment with alcohol. (c) Cells after treatment. Casparian strip is seen only in sectional views in…
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from article Systems ecology
Decrease in system productivity with loss of species: (a) Under the assumption that most species are redundant. Initial losses do not matter because the remaining species are able to carry out the ecosystem function necessary for production. (b)…
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from article Biome
Terrestrial biomes of the world. (Copyright © McGraw-Hill Education)
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from article Aging
Rates of death in the United States showing an exponential increase in mortality risk with chronological age. (Copyright © McGraw-Hill Education)
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from article Aging
Hypothetical impact of reduced disability of the aging population in the twentieth, twenty-first, and twenty-second centuries. The goal is to keep the interval of disability prior to death as high (rectangular) as possible at the end of the life…
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from article Behavior genetics
DNA analysis can be used to determine the positions (loci) of genes on chromosomes. Each gene may come in several variations, called alleles, that may produce somewhat different phenotypic outcomes, influencing behavior. Molecular weight markers are…
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from article Behavior genetics
Alcoholism, a very complex behavioral disorder, results from the interplay of genetics, environment, and physiology in the context of development. (Credit: National Institute of Alcohol Abuse and Alcoholism)
