front 1 a set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena. | back 1 theory |
front 2 A theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations | back 2 evolution |
front 3 describes a species of animals that once lived on Earth but which no longer exists | back 3 extinct |
front 4 a group of organisms that share similar characteristics and can mate with each other to produce offspring | back 4 species |
front 5 the information about Earth's history that can be gathered from fossils | back 5 fossil record |
front 6 the average weather conditions in an area | back 6 climate |
front 7 all the living and nonliving things that surround an organism | back 7 environment |
front 8 layers of gas that surround a planet | back 8 atmosphere |
front 9 a layer or line of rock above or below another body of rock | back 9 rock layer |
front 10 measurement of the amount of radioactive material (usually carbon 14) that an object contains; can be used to estimate the age of the object | back 10 radioactive dating |
front 11 the age given in years, of a fossil, a rock, a feature, or an event; usually determined through radiometric dating | back 11 absolute age |
front 12 extremely old | back 12 ancient |
front 13 evidence that an organism once existed in an area | back 13 fossil |
front 14 an organism that is made of many cells, cannot make its own food, and can move during at least part of its life | back 14 animal |
front 15 an organism that is made up of many cells, makes its own food through photosynthesis, and cannot move | back 15 plant |
front 16 the third planet from the Sun; the planet on which we live | back 16 earth |
front 17 any individual living thing | back 17 organism |
front 18 fossilized evidence of plant existence or animal movements such as root channels, footprints, and burrows | back 18 trace fossil |
front 19 to break down into simple nutrients | back 19 decompose |
front 20 an element that makes up about 21% of Earth's atmosphere; a gas in Earth's atmosphere and in water that living organisms breathe | back 20 oxygen |
front 21 to break down or wear away | back 21 decay |
front 22 an extinct organism with reptile and birdlike features | back 22 dinosaur |
front 23 the physical or chemical breakdown of rocks and minerals into smaller pieces or aqueous solutions on Earth's surface | back 23 weathering |
front 24 When soil is moved from one location to another by wind or water. After rocks have been broken down, the small particles are transported to other locations by wind, water, ice, and gravity. | back 24 erosion |
front 25 the process during which rocks are formed, change, wear down, and are formed again over long periods of time | back 25 rock cycle |
front 26 a fossil resin from tree sap, usually a translucent, yellow-brown color, which may contain insects or other organisms | back 26 amber |
front 27 an element that is found in almost all compounds that make up living things | back 27 carbon |
front 28 a natural, solid substance found in rocks; each mineral has a specific chemical makeup | back 28 mineral |
front 29 solid material, moved by wind and water, that settles on the surface of land or the bottom of a body of water | back 29 sediment |
front 30 a fossil that forms when the remains of an organism leave an imprint in the sediment after the organic material has been completely replaced | back 30 mold |
front 31 a type of fossil formed when sediment fills a mold of an organic object such as a fossil shell, creating a replica of that object made of sediment | back 31 cast |
front 32 the process of comparing objects or events to determine which are younger or older, without knowing their specific ages | back 32 relative dating |