Lewis/Life - Glossary

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echinoderm ee-KINE-o-derm Animal with a five-part body plan, radial symmetry, and a spiny outer covering. 513

ecology The study of relationships between organisms and their environments. 836

ecosystem A unit of interaction among organisms and their surroundings, including all life in a defined area. 9, 858

ectoderm EK-TOE-derm The outermost embryonic germ layer, whose cells become part of the nervous system, sense organs, outer skin layer, and its specializations. 220

ectomycorrhizae ek-toe-mi-kor-IZ-ee Parts of a fungus that ensheath a plant's roots but do not greatly penetrate the plant. 485

ectopic pregnancy ek-TOP-ik PREG-nan-see The implantation of a zygote in the wall of a fallopian tube rather than in the uterus. 239

ectoplasm EK-toe-PLAZ-m In an amoeba, an outer layer of thick, gel-like material. 692

ectotherm EK-toe-therm Animal that loses or gains heat to its surroundings by moving to where the temperature is suitable. 771

edema eh-DEEM-ah Swelling of a body part from fluid buildup. 727

effector e-FEK-ter A muscle or gland that receives input from a neuron. 611

efferent arteriole EF-fer-ent are-TEAR-ee-ol Branch of the renal artery that leaves the proximal portion of a nephron. 781

ejaculation e-JAK-u-LAY-shun Discharge of sperm through the penis. 197

elastin e-LAS-tin A type of connective tissue protein. 594

electrolyte e-LEK-tro-lite Solution containing ions. 40

electromagnetic spectrum e-LEK-tro-mag-NET-ik SPECK-trum A spectrum of naturally occurring radiation. 147

electron e-LEK-tron A negatively charged subatomic particle with negligible mass that orbits the atomic nucleus. 32

electronegativity e-LEK-tro-neg-a-TIV-it-ee The tendency of an atom to attract electrons. 38

electron orbital e-LEK-tron OR-bit-al The volume of space where a particular electron is 90% of the time. 35

element A pure substance consisting of atoms containing a characteristic number of protons. 32

El niño l NEEN-yo A periodic slack in the trade winds that prevents upwelling along Peru's coast and changes global weather patterns. 883

embryonic induction EM-bree-ON-ik in-DUK-shun In an embryo, the ability of a group of specialized cells to stimulate neighboring cells to specialize. 226

embryonic stage em-bree-ON-ik STAJE Stage of prenatal development when organs form from a three-layered structure. 216

emergent property A quality that appears as biological complexity increases. 8

empiric risk em-PEER-ik RISK Risk calculation based on prevalence. 277

endergonic reaction en-der-GONE-ik re-AK-shun An energy-requiring chemical reaction. 116

endocrine system EN-do-crin SIS-tum Glands and cells that secrete hormones. 660

endocytosis EN-doe-si-TOE-sis The cell membrane's engulfing extracellular material. 93

endoderm EN-doe-derm The innermost embryonic germ layer, whose cells become the organs and linings of the digestive, respiratory, and urinary systems. 220

endodermis en-do-DER-mis The innermost part of a root's cortex. 548

endometrium EN-doe-MEE-tree-um The inner uterine lining. 197

endomycorrhizae en-doe-mi-kor-IZ-ee Fungal threads that penetrate a plant through the roots. 485

endoplasm EN-doe-plaz-m In an amoeba, an inner layer of sol-like cytoplasm. 692

endoplasmic reticulum EN-doe-PLAZ-mik reh-TIK-u-lum Interconnected membranous tubules and sacs that wind from the nuclear envelope to the cell membrane, along which proteins are synthesized (in rough ER) and lipids synthesized (in smooth ER). 70

endoskeleton en-do-SKEL-eh-ten An internal scaffolding type of skeleton in vertebrates. 684

endosperm EN-do-sperm A triploid tissue that nourishes the embryo in a seed. 568

endospore EN-doe-spor A walled structure that forms around a bacterial cell's nucleus, enabling the organism to survive harsh environmental conditions. 447

endosymbiont theory EN-doe-SYM-bee-ont THER-ee The idea that eukaryotic cells evolved from large prokaryotic cells that engulfed once free-living bacteria. 79

endothelium end-o-THEEL-e-um Layer of single cells that forms a capillary wall. 722

endotherm EN-doe-THERM Animal that uses metabolic heat to regulate its temperature. 771

energy The ability to do work. 110

energy nutrients Fats, proteins, and carbohydrates. 755

energy of activation Energy required for a chemical reaction to begin. 121

energy pyramid A diagram depicting trophic levels of energy stored in living tissues per unit time. 863

energy shell Levels of energy in an atom formed by electron orbitals. 35

entrainment en-TRANE-ment The resynchronization of a biological clock by the environment. 588

entropy EN-tro-pee Randomness or disorder. 8, 113

environmentalism The philosophy of living in harmony with the global ecosystem. 892

environmental resistance Mortality and emigration, which limit population growth. 842

enzyme EN-zime A protein that catalyzes a specific type of chemical reaction. 46

enzyme-substrate complex EN-zime SUB-strate COM-plex A transient structure that forms when a substrate binds an enzyme's active site. 50

epidemiology EP-eh-dee-mee-OL-o-gee The analysis of data derived from real-life, nonexperimental situations. 26, 384

epidermis ep-ee-DERM-is The outer integumentary layer in several types of organisms. 517, 536, 598

epididymis EP-eh-DID-eh-mis In the human male, a tightly coiled tube leading from each testis, where sperm mature and are stored. 197

epigenesis ep-ee-GEN-i-sis The idea that specialized tissue arises from unspecialized tissue in a fertilized ovum. 210

epiglottis ep-ee-GLOT-is Cartilage that covers the glottis, routing food to the digestive tract and air to the respiratory tract. 736

epinephrine ep-ee-NEF-rin (adrenaline) A hormone produced in the adrenal medulla that raises blood pressure and slows digestion. 670

epistasis eh-pis-tah-sis A gene masking another gene's expression. 274

epithelial tissue EP-eh-THEEL-e-al TISH-ew Tightly packed cells that form linings and coverings. 594

epoch Eh-poc Time within a period. 359

equational division ee-QUAY-shun-el deh-VISZ-un The second meiotic division, when four haploid cells form from two haploid cells that are the products of meiosis I. 198

eras Very long periods of time of biological or geological activity. 359

erythropoietin eh-rith-ro-po-EE-tin A hormone produced in the kidneys that stimulates red blood cell production when oxygen is lacking. 715

esker ES-kur Extensive ridge of gravel and sand deposited by a river that ran under a glacier. 878

esophagus ee-SOF-eh-gus A muscular tube that leads from the pharynx to the stomach. 757

essential nutrient Nutrient that must come from food because the body cannot synthesize it. 755

estuary ES-tu-air-ee An area where fresh water in a river meets salty water of an ocean. 881

ethology eth-OL-o-gee Study of how natural selection shapes adaptive behavior. 812

ethylene ETH-eh-leen A simple organic molecule that is a plant hormone that hastens fruit ripening. 569

etiolated seedling E-ti-o-LAY-tid SEED-ling Seedling that has abnormally elongated stems, small roots and leaves, and a pale color, because it was grown in the dark. 586

euchromatin u-KROME-a-tin Light-staining genetic material. 296

euglenoid YEW-glen-oyd A type of algae. 466

Eukarya yoo-KAR-ee-a One of the three domains of life, including organisms that have eukaryotic cells. 430

eukaryotic cell u-CARE-ee-OT-ik SEL A complex cell containing organelles. 14, 63

euphotic zone u-FOT-ik ZONE Part of the ocean where photosynthesis occurs. 883

euploid U-ployd A normal chromosome number. 298

eusocial yu-SO-shal A population of animals that communicate, cooperate in caring for young, have overlapping generations, and divide labor. 819

eutrophic yu-TRO-fik An aging lake, containing many nutrients and decaying organisms, often tinted green with algae. 880

evaporative cooling Loss of body heat by evaporation of fluid from the body's surface. 773

evolution Changing gene frequencies in a population over time. 8

excision repair ex-SIZ-jhun ree-PARE Cutting pyrimidine dimers out of DNA. 319

excurrent siphon ex-cur-ent SI-fon A structure that shoots water from a tunicate when it is disturbed. 526

exergonic reaction ex-er-GONE-ik re-AK-shun An energy-releasing chemical reaction. 116

exocrine glands EX-o-crine GLANDZ Structures that secrete substances through ducts. 660

exocytosis EX-o-si-TOE-sis Fusing of secretion-containing organelles with the cell membrane. 93

exon EX-on The bases of a gene that code for amino acids. 330

exoskeleton ex-o-SKEL-eh-ten A braced framework skeleton on the outside of an organism. 683

experiment A test to disprove a hypothesis. 21

experimental control An extra test that can rule out causes other than the one being investigated. 25

extinction ex-TINK-shun Disappearance of a type of organism. 815

extracellular digestion ex-tra-SEL-yu-lar di-JEST-shun Dismantling of food by hydrolytic enzymes in a cavity within an organism's body. 753

extraembryonic membranes EX-tra-EM-bree-on-ik MEM-branz Structures that support and nourish the mammalian embryo and fetus, including the yolk sac, allantois, and amnion. 216

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