小编搜集整理了SAT2生物考试专业词汇中以字母E打头的词汇，希望能够帮助大家更好地备考SAT2生物考试。

　　Ecology(生态学)

　　The study of the interactions and relationships of populations with each other and their abiotic environments.

　　Ecosystem(生态系统)

　　A community of organisms and its abiotic environment.

　　Ectotherm(变温动物)

　　See cold-blooded.

　　Egg(卵)

　　The female gamete in sexual reproduction; also called an ovum.

　　electron microscope(电子显微镜)

　　An instrument that uses an electron beam to form clear and highly magnified images of microscopic structures. Electron microscopes cannot take pictures of living organisms.

　　electron transport chain(电子传递链)

　　The final stage of aerobic respiration. The electron transport chain establishes an electrochemical gradient across the inner mitochondrial membrane that powers the synthesis of ATP in oxidative phosphorylation.

　　Embryo(胚胎)

　　Before birth, the maturing cells that will grow into a fully formed organism.

　　endocrine system(内分泌系统)

　　Control system of the body that functions by releasing hormones into the bloodstream.

　　Endocytosis(内吞作用)

　　Process by which liquids or small solid particles are taken into a cell in the form of small vesicles that are produced through the invagination of the cell membrane.

　　Ear(耳)

　　Sensory organ capable of detecting sound.

　　ecological succession(生态序列)

　　The progression of plant life and attendant animal life in a given geographic location, from pioneer plant to climax community.

　　endoplasmic reticulum(ER/内质网)

　　A network of membrane-bound tubes and sacs in the cytoplasm. The endoplasmic reticulum is a major site of protein and lipid synthesis.

　　Endoskeleton(内骨)

　　An interior skeleton found in vertebrates made of bone and cartilage.

　　Endotherm(恒温动物)

　　See warm-blooded.

　　energy pyramid(能级图)

　　Energy in a community can be depicted as a pyramid of food or biomass. The availability of food, biomass, and energy from the trophic level of producers up through each subsequent level on the food web is approximately 10 percent of that available in the previous trophic level.

　　Exocytosis(外排作用)

　　Process by which molecules are secreted from the cell. Exocytosis occurs when a vesicle fuses with the cell membrane and releases its contents to the outside.

　　exoskeleton (外骨)

　　A rigid, chitinous protective structure that surrounds the bodies of arthropods and provides support.

　　Eye(眼睛)

　　Sensory organ capable of detecting light.

　　Enzymes(酶)

　　Biological catalysts made from proteins. Enzymes have attachment locations for substrates called active sites.

　　Estrogen(雌激素)

　　Hormone that stimulates the growth of the uterine lining during pregnancy and that develops and maintains the female secondary sex characteristics, such as the development of mammary glands, a narrower waist and wider hips, axillary and pubic hair, and a higher-pitched voice.

　　Eukaryote(真核生物)

　　An organism whose cells have membrane-bound intracellular organelles, including a nucleus containing multiple chromosomes. Eukaryotes, unlike prokaryotes, can undergo sexual reproduction via meiosis. Compared to prokaryotes, eukaryotes are more complex and arose later in evolutionary history. Protists, fungi, plants, and animals are all eukaryotic organisms.

　　excretory system(排泄系统)

　　The organ system that filters blood and removes nitrogenous wastes from the body in the form of urea or uric acid. In humans, the two kidneys are the vital organs of blood filtration. In annelids, nephridia fill the filtering role; Malpighian tubules do the same in arthropods. In humans, other important structures of the system are the ureters, the urinary bladder, and the urethra.