Inhalation, 967
Inheritance, 308, 310, 318, 456, 461. See also Genetics; Human heredity
Inorganic chemistry, 45
Insects, 755
Insight learning, 843
Integrated pest management (IPM), 162
Interdependence, 21
Interferons, 1015
Intergovernmental Panel on Climate Change (IPCC), 177–178
International HapMap Project, 407
International System of Units (SI), 24
Intertidal zone, 120
Intestinal diseases, 615
Intestine
Intracellular digestion, 784
Introduced species, 169
Introns, 365
Invasive species, 136
Invertebrate biologist, 736
Invertebrates, 730. See also Chordates; Vertebrates
Iodine, 985
Ionic bonds, 37
Iris (of eye), 912
Islets of Langerhans, 984
Isolation, reproductive, 494–495
Isotonic solutions, 210–211
Isotopes, 35
Ivanovski, Dmitri, 574
Iwata, So, 229
Laboratory technician, 195
Lac repressor, 378
Lactobacillus, 585
Land plants, 637
Langerhans, Paul, 984
Language, 851
Large intestine, 881
Lartet, Edouard, 773
Larynx, 964
Lateral gene transfer, 485
Leaf loss, 714
Leakey, Maeve, 773
Leakey, Mary, 773
Learning, 842–845. See also Animal behavior
Lens, 912
Leucine, 367
Leukocytes, 955
Levels of organization
Lewis, Edward B., 382
Life cycle of plants, 637
Life span of plants, 654
Light. See also Sunlight
Light microscopes, 191–192
Limb girdles, 815
Limbic system, 902
Limiting nutrient, 85
Linnaean classification system, 512–514
Lipid bilayer, 204–205
Lipoproteins, 959
Liverworts, 641
Living things, 17–19
Lobes, 902
Local hormones, 980
Logistic growth, 134–135
Lohest, Max, 773
Long-day plants, 713
Loop of Henle, 884
Loudness, 910