Abiotic factors, 66–67, 100, 111
Abscisic acid, 711
Absorption, 875
Acetylcholine, 931
Acetyl-CoA, 256
Acid rain, 164, 180
Acids, 44
Acne, 938
Acoelomates, 738
Acquired characteristics, 456
Acquired immune deficiency syndrome (AIDS), 578, 588, 994, 1001, 1023, 1025–1027
Acquired immunity, 1020
Actin, 199, 606, 930
Action potential, 898–899
Activation energy, 51–52
Active immunity, 1020
Active site, 53
Active transport, 212–213, 227
Adaptations, 461
to biomes, 112–115
in chordates, 758–759, 761–762, 825
evolutionary, 487
excretory, 798
to high altitude, 831
of leaves, 684
of mouthparts, 785–786
and natural selection, 461–464
in pathogens, 1012
seasonal, 714
of seed plants, 646
Adaptive radiation, 550–551
Addiction, 904–905
Adenine, 344–345, 348, 366
Adenosine diphosphate (ADP), 227, 235
Adenosine triphosphate (ATP), 48, 226–227
Adhesion, 41, 686
Adrenal glands, 979, 983
Adreno-corticotropic hormone (ACTH), 983
Adult stem cells, 295, 297
Aerobic respiration, 252
African sleeping sickness, 615
Age of Fishes, 759
Age structure of populations, 131, 144
Aggression, 848
Agriculture, 155, 715–717, 719
AIDS, 578, 588, 994, 1001, 1023, 1025–1027
Air pollution, 163–165
Albumin, 954
Alcohol, 904
Alcoholic fermentation, 263
Aldosterone, 983
Alemseged, Zeresenay, 773
Algae, 610
brown, 527, 602, 604, 611
in food chains and webs, 73–74
green, 528, 610, 623, 634, 636–640
and photosynthesis, 70
phytoplankton, 73, 117
red, 528, 611
symbiotic, 783
unicellular, 214
Algal bloom, 611
Alkaline solution, 44
Allantois, 825
Alleles, 310, 482. See also Genetics
allele frequencies, 483, 490–492
dominant and recessive, 310–312, 318, 394
and gene linkage, 328–329
multiple and codominant, 320, 394
and phenotypes, 488
segregation of, 312, 314, 318
and traits, 397, 485–486
Allergies, 1024
Alternation of generations, 608, 637
Alveoli, 790, 964–966
Amebic dysentery, 615
Amenorrhea, 1005
Amino acids, 48–49, 870
and genetic code, 366
in nitrogen cycle, 84
Ammonia, 585, 794–795, 867, 882
Amnion, 825, 998
Amniota, 518–519
Amniotic egg, 825
Amoebas, 213, 606, 608, 612
Amoeboid movement, 606
Amphibians, 761, 790, 793, 796
Amygdala, 902
Amylase, 876
Anaerobic respiration, 252, 262
Angina, 958
Angiosperms, 646, 647, 650–654
Animal behavior, 840–851
Animalia, 514, 523–524, 528, 730
Animals, 730–743. See also Chordates;
Invertebrates; Vertebrates
animal society, 848–849
asexual reproduction in, 277, 735, 819
body plans of, 737–741
cell differentiation in, 293
cells of, 203, 206–207, 211, 215
characteristics of, 730
cladogram of, 742–743
cloned, 427, 429
cytokinesis, 284
development of young, 823–824
differentiation stages in, 740
embryo development in, 738–739, 822
and emerging diseases, 1022
genetically modified, 429–430
homeostasis in, 732, 827–830
hormones of, 708
and language, 851
parental care in, 824
and pollination, 700
response to stimuli, 733, 808–809
and seed dispersal, 651, 705
sexual reproduction in, 735, 820–822
transgenic, 426, 429–430
Animal systems