endocrine, 828
excretion, 734–735, 794–798
feeding and digestion, 734, 782–786
and homeostasis, 732, 827–830
muscular, 733, 816–818
nervous, 733, 808–811, 864, 951
reproductive, 277, 735, 819–826
respiration, 734–735, 787–790, 864
sensory, 812–813
skeletal, 733, 814–816
Annelids, 755–756, 792
Anterior cruciate ligament (ACL), 927
Antheridia, 642
Anthers, 697
Anthrax, 583, 589
Anthropoids, 766, 766–767
Antibiotics, 588, 591, 1021
Antibodies, 1016–1017
Anticodons, 369
Antidiuretic hormone (ADH), 886, 982, 986–987
Antigens, 394, 1016
Antihistamines, 1024
Antiparallel strands, 347
Anus, 739
Aorta, 952
Aphotic zone, 117, 121
Apical dominance, 710
Apical meristems, 668, 670, 714
Apoptosis, 288, 1019
Appendages, 755
Appendicular skeleton, 922
Appendix, 881
Aquaculture, 176
Aquaporins, 210
Aquatic animals
Aquatic ecosystems, 117–121
biotic and abiotic factors in, 66–67
changes in, 63
energy production in, 70
estuaries, 119
food chains and webs in, 73–76
freshwater, 118–119
marine, 120–121
nutrient limitation in, 86
underwater conditions in, 117–118
Aqueous humor, 912
Archaea, 524, 526, 580–581
Archaebacteria, 524, 526
Archaeopteryx, 763
Archean Eon, 542
Archegonia, 642
Arteries, 952
Arthropods, 755, 815, 817, 821
Artificial selection, 457–458, 461
Asexual reproduction, 19, 277–278
Aspirin, 980
Association of Zoos and Aquariums (AZA), 170
Asthma, 163, 1024
Atherosclerosis, 958–960
Athlete's foot, 623, 1010
Atmospheric resources, 163–165
Atomic number, 35
Atoms, 34–38
ATP. See Adenosine triphosphate (ATP)
ATP synthase, 237, 258
Atrioventricular (AV) node, 951, 958
Atrium, 792–793, 949–951
Aurelia, 820–821
Australopithecus afarensis, 768–769, 773
Autoimmune diseases, 1025
Autonomic nervous system, 908
Autosomes, 393
Autotrophic protists, 610–611
Autotrophs, 69, 117, 228, 250
Auxins, 709–712
Avery, Oswald, 340, 349
Avian influenza, 591, 1013, 1023
Axial skeleton, 922
Axon, 897
Axon terminal, 897, 900
B
Bacilli, 582
Backbones, 731
Background extinction, 548
Bacteria, 214
bacterial meningitis, 587
and cell organelles, 557
chemosynthetic, 70
classification of, 524–526
diseases caused by, 586–588, 1010–1011
early images of, 190
gene expression in, 377
growth of, 133, 146, 594
lateral gene transfer in, 485
and mutations, 375, 420
photosynthetic, 70, 545, 555
and recombinant DNA, 424–425
viral infections of, 340–341, 575–577
Bacteria, domain, 524–525, 580–581
Bacterial transformation, 339–340
Bacteriophages, 340–341, 575–577
Balance, 911
Balanced diet, 872–873
Bar coding, DNA, 529
Bark, 679
Barr body, 396
Basal cell carcinoma, 939
Base pairing, 348, 350
Bases, 44
Beagle, 450–451
Beak size, 473, 502
Beans, 706
Bears, 512, 848
Beekeeper, 736
Behavior, 767, 841, 844–845. See also Animal behavior
Behavioral isolation, 495, 497
Beijerinck, Martinus, 574
Benign tumors, 289
Benthic zone, 117, 121
Benthos, 117
Beta-carotene, 430
Beta cells, 984
Beta-globin, 398
Bias, 14
Biennial plants, 654
Bilateral symmetry, 738–739
Bile, 878
Binary fission, 281, 583
Binocular vision, 765
Binomial nomenclature, 511
Biodiversity, 166–171. See also Diversity
Biogeochemical cycles, 79, 163
Biogeography, 465
Bioinformatics, 407, 422
Biological magnification, 161
Biology, 17–25, 80
Biomass, 78
Biomes, 65, 110–116, 122