a· b· c· d· e· f· g· h· i· j· k· l· m· n· o· p· q· r· s· t· u· v· w· x· y· z   adaptation A structure or behavior that helps a plant or animal live in its surroundings. algae A marine or freshwater plant or plant-like organism that usually contains chlorophyll. analyze To study or determine the nature and relationship of the parts, suggest separating or breaking down the parts of something to understand its true nature. annuals Plants that complete their life cycles in one growing season. arid Lacking in rainfall, very dry. atmosphere The layer of gases, like air, that surrounds the Earth. basin A low, bowl-shaped area of land surrounded by higher lands. biome A community of plants and animals living together in a particular climate. broadleaf A type of tree with wide, flat leaves. carbon dioxide A gas in air that is taken in by plants, exhaled by animals, and given off when fuel is burned. A carbon dioxide molecule is formed when two oxygen atoms combine with a single carbon atom. Celsius scale (C) The metric temperature scale where 0 degrees is assigned to the temperature where water freezes, and 100 to the temperature where water boils. centimeter (cm) A unit of length in the metric system. There are 100 centimeters in a meter. chlorophyll A green pigment found in plants, necessary for conducting photosynthesis. classify To arrange in groups according to specified similarities. climate The average weather conditions of an area over many years, as measured by temperature, wind speed, and precipitation. community The whole group of plants and animals that interact in a common location. competition The active demand by two or more organisms, such as plants, for some environmental resource in short supply. conserve To preserve, or to avoid wasteful use. correlate To show a relationship between things. deciduous tree One of a group of trees that lose their leaves in the fall. dormant Inactive or asleep, but capable of waking up; not actively growing, but protected from the environment. drought A period of dryness, that when prolonged, causes damage to crops; a shortage of water. elevation The height of a place above sea level. environment The surroundings in which a person, plant or animal lives, including the air, water, and land. epiphyte An organism that grows on another organism. The two organisms do not take nutrients from or give nutrients to each other. equator An imaginary circle around the Earth that lies halfway between the North Pole and the South Pole. evaporate To change from a liquid to a gas. evergreen A plant that stays green all year, including firs and pines. fluctuate To change back and forth uncertainly. fungus An organism that grows from spores, not seeds, usually classified as a plant without chlorophyll, such as mold, mildew, mushrooms, and yeast. growing season The time of the year when crops grow. humid Containing moisture. hypothesis An educated guess; a likely explanation for a problem. insulate To separate to prevent transfer of electricity, heat, or sound. investigate To observe or study closely. landforms Shapes, like mountains or hills, that make up the Earth's surface. latitude Imaginary lines on a map or globe that measure distance in degrees north or south of the equator. Latitude lines extend horizontally, from east to west on a globe. longitude Imaginary lines on a map or globe that measure distance in degrees east or west of the prime meridian. Longitude lines extend vertically, from pole to pole on a globe. mean The average. millimeter (mm) A unit for measuring length in the metric system. There are 10 mm in 1 cm, and 1,000 mm in a meter. needleleaf A type of tree with long, thin leaves. nutrient A material that plants and animals need to live and grow. organism A living being. oxygen A gas that is given off by plants and used by animals. perennials Plants that complete a growing cycle each year for several years. photosynthesis The process by which plants use light, carbon dioxide, and water to make food. plain A large area of flat or nearly flat land. prairie Flat land covered with tall grass and wildflowers. precipitation Moisture that falls to the ground from clouds; includes rain, snow, sleet, and hail. predominant Most frequent or most common. property Something about an organism or object that can be observed, such as size or shape; characteristics common to all members of a group. reflect To bend or fold back, to change direction. region A large area with common features that set it apart from other areas. resource Something that is useful. sod A thick layer of soil. species A group of organisms having common attributes and given a common name. steppe A flat, dry plain covered with short grass. symbiosis Living together in a way that benefits both individuals. temperature The degree of hotness or coldness of a substance as measured by a thermometer. thrive To flourish or grow vigorously. tolerate To put up with, endure, or withstand. vegetation Plant life of an area.