ACT科学真题必备词汇（上）

　　ACT考试是美国大学入学的一条道路，要想通过ACT考试并且取得一个好成绩不是一件容易的事，首先你就得掌握词汇这个能力，词汇是一切的基础，词汇都不知道的话，就不要谈什么ACT考试了。接下来小编就给大家讲一讲ACT科学考试的必备词汇！

　　acceleration—The rate that velocity changes per unit time and the direction itchanges in. Computed from the change in velocity divided by tire change in time. Common units are meters per second squared (m/s2)

　　acceleration due to gravity—The acceleration of an object that is onlyACTed on bythe force of the Earth's gravity. This value is given the symbol g and near the surface of the Earth it has a value of approximately 9.8 m/s2. The direction of the acceleration due to gravity is vertically downward.

　　accuracy—The closeness of an experimental measurement to the accepted ortheoretical value.

　　acid—A substance that is a proton donor. The pH of an acid is less than 7.

　　analysis— Astage in the scientific method where patterns of observations are made.

　　antioxidant—any substance that inhibits oxidation, including vitamin E, vitamin C,or beta carotene, and is thought to protect the body from the damaging effects of oxidation

　　aqueous solution—A solution in which the solvent is water.

　　arteries—The vascular tissue which carries blood away from the heart.

　　astronomy—The study of planets, stars, and space.

　　atom—The smallest structure that has tire properties of an element. Atoms containpositively charged protons and uncharged neutrons in the nucleus. Negatively charged electrons orbit around the nucleus.

　　ATP—(Adenosine Triphosphate.)—A chemical that is considered to be the "fuel" orenergy source for an organism.

　　atria—The chambers of the heart that receive blood.

　　base—A substance that is a proton acceptor. The pH of a base is greater than 7.

　　bacteria—one-celled organisms that are involved in fermentation, putrefaction, and infectiousdiseases

　　calibration—The examination of the performance of an instrument in an experimentwhose outcomes are known, for the purpose of accounting for the inaccuracies inherent in the instrument in future experiments whose outcomes are not known.

　　capillaries—Vascular tissue that receives blood from the arterioles and releases theblood to the venules.

　　catalyst—An agent that changes the rate of a reaction, without itself being altered bythe reaction.

　　celestial equator—The extension of the Earth's equator out onto the celestial sphere.

　　celestial poles—Tire extension of the Earth's north and south pole onto the celestialsphere.

　　celestial sphere—The imaginary sphere onto which all the stars are viewed as beingon for the purposes of locating them.

　　cell membrane—An organelle found in all cells that acts as the passageway throughwhich materials can pass in and out. This organelle is highly selectively permeable, only allowing materials to pass through that it "chooses" chemically.

　　cell wall—An organelle found primarily in plant cells and fungi cells, and also somebacteria. The cell wall is a strong structure that provides protection, support, and allows materials to pass in and out without being selectively permeable.

　　centripetalforce—The net force that acts to result in the centripetal acceleration. Itis not an individual force, but the sum of the forces in the radial direction. It is directed toward the center of the circular motion.

　　chemical change—A process that Involves the formation or breaking of chemicalbonds.

　　chromosome—An organelle that contains the entire DNA of the organism.

　　component—The part of a vector that lies in the horizontal or vertical direction.

　　compound—A substance composed of more than one element that has a definitecomposition and distinct physical and chemical properties.

　　concentration—A measure of the amount of solute that is present in a solution. Asolution that contains very little solute is called dilute. A solution that contains a relatively large amount of solute is said to be concentrated.

　　conclusion—The last stage of the scientific method where explanations are madeabout why the patterns identified in the analysis section occurred.

　　concentric model—Tire model of the solar system that places the Earth at the centerwith the planets and the Sun orbiting around it.

　　constellation—An apparent grouping of stars in the sky that is used for identificationpurposes. These stars are not necessarily near each other in space since they are not necessarily the same distance from the Earth.

　　continental rift—The region on a continent where new crust is being created, andthe plates on either side of the rift are moving apart.

　　convergent boundary—A boundary between two of the Earth's plates that aremoving toward each other.

　　cosmology—The study of the formation of the universe.

　　crystal—A solid in which atoms or molecules have a regular repeated arrangement.

　　current—The flow of charge past a point per unit time; it is measured in Amperes(A).

　　cuticle—The top layer on a leaf. It Is a non-living layer consisting primarily of waxthat is produced by the epithelium, a cell layer directly underneath.

　　cytoplasm—A jelly-like substance located in the cell where all of the internalorganelles can be found. The cytoplasm consists primarily of water and supports the cell and its organelles.

　　cytoskeleton—Organelles that are the internal "bones" of the cell. They exist in thickand thin tubules.

　　decibel—A unit of measure for the relative intensity of sounds.

　　decimation—The celestial coordinate similar to that of latitude on the Earth.Declination measures how many degrees, minutes, and seconds north or south of the celestial equator an object is.

　　delta— Afan shaped deposit of material at the mouth of a river.

　　density—The mass of a substance for a given unit volume. A common unit ofdensity is grams per milliliter (g/ml).

　　displacement—The change in position of an object. Computed from the finalposition minus the initial position. Common units of measure are meters (m).

　　divergent boundary—A boundary between two of the Earth's plates that are movingaway from each other.

　　DNA—Contains all genetic material for an organism. The smallest units of DNA arecallednucleotides.

　　ecliptic—The apparent path of the Sun across the sky over the course of a year.

　　electric potential energy—The energy due to an object's position within an electricfield.

　　electromagnetic wave—A light wave that has an electric field component and amagnetic field component. An electromagnetic wave does not require a medium to travel through.

　　electrostatic force—The force that exists between particles due to their charge.Particles of like charge repel, particles of unlike charge attract.

　　element—The smallest entity that has distinct chemical properties. It can not bedecomposed by ordinary chemical reactions.

　　好了，以上就是小编给大家准备的一些ACT科学考试的一些必备词汇，只有掌握了这些词汇，你才能看得懂题目，才能去解决问题，只有我们平时生活中多努力，多去积累，虽然临阵磨枪，也能光一光，但是毕竟不是长久之计，只有彻底掌握了知识才能取得一个好成绩。好了，如果大家想咨询更多ACT考试费多少钱等内容可以在线咨询我们！