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115 Cards in this Set

  • Front
  • Back
organized way of using evidence to learn about the natural world; also, the body of knowledge that scientists have built up after yearsof using this process
possible explanation for a set of observatioins or possible answer to a scientific question
logical interpretation based on prior knowledge and experience
evidence; information gathered from observations
use of one or more of the senses--sight, hearing, touch, smell, and sometimes taste--to gather information
well-tested explanation that unifies a broad range of observations
Responding Variable
factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also known as a dependent variable
Manipulated Variable
factor in an experiment that a scientist purposely changes; also known as independent variable
Controlled Experiment
a test of the effect of a single variable by changing it while keeping all other variablse the same
Spontaneous Generation
hypothesis (disproven) stating that life could arise from nonliving matter
science that seeks to understand the living world
collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life
Sexual Reproduction
process by which cells from two different parents unite to produce the first cell of a new life form
Asexual Reproduction
Process by which a single parent reproduces by itself
set of chemical reactions through which an organism build up or breaks down materials as it carries out its life processes
a signal to which an organism responds
process by which organisms maintain a relatively stable internal environment
change in a kind of organism over time; process by which modern organisms have descended from ancient organisms
Metric System
decimal system of measurement based on certain physical standards and scaled on multiples of 10
device that produces magnified images of structures that are too small to see with the unaided eye
Compound Light Microscope
microscope that allows light to pass through a specimen and uses two lenses to form an image
Electron Microscope
microscope that forms an image by focusing beams of electrons onto a specimen
Cell Culture
group of cells grown in a nutrient solution from a single origional cell
Cell Fractionation
technique in which cells are broken into pieces and the different cell parts are separated
scientific study of interactions among organisms and between organisms and their environment
part of Earth in which life exists including land, water, and air or atmosphere
group of similar organisms that can breed and produce fertile offspring
group of individuals of the same species that live in the same area
assemblage of different populations that live together in a defined area
collection of all organisms that live in a particular place, together with their nonliving environment
group of ecosystems that have the same climate and dominant communities
organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer
organism that can capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotroph
process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches
process by which some organisms, such as bacteria, use chemical energy to produce carbohydrates
organism that obtains energy from the foods it consumes; also called a consumer
organism that relies on other organisms for its energy and food supply; also called a heterothroph
organism that obtains energy by eating only plants
organism that obtains energy by eating animals
organism that obtains energy by eating both plants and animals
organism that feeds on plant and animal remains and other dead matter
organism that breaks down and obtains energy from dead organic matter
Food Chain
series of steps in an ecosystem in which organisms transfer energy by eating and being eaten
Food Web
newtork of complex interactions formed by the feeding relationships among the carious organisms in an ecosystem
Trophic Level
step in a food chain or food web
Ecological Pyramid
diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web
total amount of living tissue within a given trophic level
Biogeochemical Cycle
process in which elements, chemical compunds, and other forms of matter are passed from one organism to another and from one part of the poisphere to another
process by which water changes from a liquid into an atmospheric gas
loss of water from a plant through its leaves
chemical substance that an organism requires to live
Nitrogen Fixation
process of converting nitrogen into ammonia
conversion of nitrates into nitrogen gas
Primary Productivity
rate at which organic matter is created by producers in an ecosystem
Limitin Nutrient
single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem
Algal Bloom
an immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient
condition of Earth's atmosphere at a particular time and place
average, yearr-after-year conditions of temperature and precipitation in a particular region
Greenhouse Effect
natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases
Polar Zone
cold climate zone where the sun's rays strike Earth at a very low angle
Temperate Zone
moderate climate zone between the polar zones and the tropics
Tropical Zone
warm climate zone that receives direct or nearly direct sunlight year round
Biotic Factor
biological influence on organisms within an ecosystem
Abiotic Factor
physical, or nonliving, factor that shapes an ecosystem
the area where an organism lives, including the biotic and abiotic factors that affect it
full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
any necessity of life, such as water, nutrients, light, food, or space
Competitive Exclusion Principle
ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time
interaction in which one organism captures and feeds on another organism
relatioinship in which two species live closely together
symbiotic relationship in which both species benefit from the relationship (+, +)
symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed (+, =)
sybiotic relationship in which one organism lives in or on another organism (the host) and consequently harms it (+, -)
Ecological Succession
gradual change in living communities that follows a disturbance
Primary Succession
succession that occurs on surfaces where no soil exists
Pioneer Species
first species to population an area during primary succession
Secondary Succession
succession following a disturbance that destroys a community without destroying the soil
group of ecosystem that have the same climate and dominant communities
oranism's capacity to grow or thrive when subjected to an unfavorable environmental factor
climate with a small area that differs significantly from the climate of the surrounding area
dense covering formed by the leafy tops of tall rain forest trees
layer in a rain forest formed by shorter trees and vines
term used to refer to a tree that sheds its leaves during a particular season each year
term used to refer to trees that produce seed-bearing cones and have thin leaves shaped like needles
material formed from decauing leaves and other organic matter
biome in which the winters are cold but summers are mild enough to allow the ground to thaw
layer of permanently frozen subsoil in the tundra
tiny, free-floating organisms that occur in aquatic eenvironments
population of algae and other small, photosynthetic organisms found near the surface of the ocean and forming part of plankton
tiny animals that form part of the plankton
ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year
wetlands formed where rivers meet the ocean
particles of organic material that provide food for organisms at the base of an estuary's food web
Salt Marsh
temperate-zone estuary dominated by salt-tolerant grasses above the low-tide line by seagrasses underwater
Mangrove Swamp
coastal wetland dominated by mangroves, salt-tolerant woody plants
Photic Zone
well-lit upper layer of the oceans
Aphotic Zone
permanently dark layer of the oceans below the photic zone
prominent horizontal bonding of organisms that live in a particular habitat
Coastal Zone
marine zone that extends from the low-tide mark to the end of the continental shelf
Kelp Forest
coastal ocean community named for its dominant organism--kelp, a giant brown algae
Coral Reef
diverse and productive environtment named for the coral animals that make up its primary structure
organisms that live attached to or near the ocean floor
Population Density
number of individuals per unit of area
movement of individuals into an area occupied by an existing population
movement of individuals out of an area
Exponential Growth
growth pattern in which the individuals in a population reproduce at a constant rate
Logistic Growth
growth pattern in which a population's growth rate slows or stops following a period of exponential growth
Carrying Capacity
largest number of individuals of a population that a given environment can support
Limiting Factor
factor that causes the growth of a population to decrease
Density-Dependent Limiting Factor
limiting factor that depends on population size
Predator-Prey Relationship
mechanism of population control in which a population is regulated by predation
Density-Independent Limiting Factor
limiting factor that affects all populations in similar ways, regardless of population size
scientific study of human populations
Demographic transition
change in a population from high birth and death rates to low birth and death rates
Age-Structure Diagram
graph of the numbers of males and females within different age groups of a population