Biology - Chapter 3 Facts & Vocab

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Section 1

Question Answer
What is ecology?The scientific study of interactions among organisms and between organisms and their environment, or surroundings.
What does the biosphere contain?Necessary things, such as land, water, and air, or atmosphere.
Why do ecologists ask questions about events and organisms that range in complexity from an individual to the biosphere?To understand the relationships within biosphere.
Species (Lowest level of organization)Group of organisms
Populations (Second lowest level of organization)A group of individuals; belong to the same species
Community (Third lowest level of organization)Groups of different populations
Ecosystem (Second highest level of organization)A collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment.
Biome (Highest level of organization)Group of ecosystems
What are the three basic approaches scientists use to conduct modern ecological research?Observing, Experimenting, and Modeling
Why might an ecologist set up an artificial environment in a laboratory?To imitate and manipulate conditions that organisms would encounter.
Why are many ecological phenomena difficult to study?They occur over long periods of time or on such large spatial scales that they are difficult to study.
Why do ecologists make models?To gain insight into complex phenomena such as the effects of global warming on ecosystems.
True or False? An ecological model may consist of a mathematical formula.True

Section 2

Question Answer
What is at the core of every organism's interaction with the environment?The organism's need for energy to power life's processes.
What source of energy to organisms use if they don't use the sun's energy?Energy stored in inorganic chemical compounds.
What are autotrophs?Plants, some algae, and certain bacteria that capture energy from the sunlight or chemicals and use that energy to produce food.
Why are autotrophs also called producers?They make their own food.
What do autotrophs do during photosynthesis?They harness solar energy.
The Main producer autotroph on land is...Plants
The Main producer autotroph on Upper layers of ocean is...Algae
The Main producer autotroph on Tidal flats and salt marshes is...Photosynthetic bacteria (cyanobacteria)
What is chemosynthesis?When organisms use chemical energy to produce carbohydrates.
Where do bacteria that carry out chemosynthesis live?Very remote places on Earth such as volcanic vents on the deep-ocean floor and hot springs in Yellowstone Park.
What are heterotrophs also called?Consumers.
What is the name for plant and animal remains and other dead matter?Detritus
What are herbivores? And give some examples.Herbivores obtain energy by eating only plants, such as cows and rabbits.
What are carnivores? And give some examples.Heterotroph that eats animals, such as snakes, dogs, and owls.
What are omnivores? And give some examples.They eat both plants and animals, such as humans, bears, and crows.
What are detritivores? And give some examples.They feed on plants and animal remains and other dead matter, such as mites, earth worms, snails, and crabs.
What are decomposers? And give some examples.They break down organic matter, such as bacteria and fungi.
How does energy flow through an ecosystem?In one direction: from the sun, or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).
What is a food chain?A series of steps in which organisms transfer energy by eating and being eaten.
What is a food web?When the feeding relationships among the various organisms in an ecosystem form a network of complex interactions.
What does a food web link together?All the food chains in an ecosystem.
What is a trophic level?Each step in a food chain or food web.
In a food web, what organisms make up the first trophic level?Producers
What does a consumer in a food chain depend on for energy?They depend on the trophic level below it for energy.
What is an ecological pyramid?A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.
Why is it that the only part of the energy stored in one trophic level is passed on to the next level?Organisms use much of the energy that they consume for life processes, such as respiration, movement, and reproduction.
What is biomass?The total amount of living tissue within a given trophic level.
What does a biomass pyramid represent?Represents amount of living organic matter at each trophic level. Greatest biomass = base of pyramid.
What does a pyramid of numbers show?The relative number of individual organisms at each trophic level.
Why can each trophic level support only about one tenth the amount of living tissue of the level below it?It can support only about one tenth the amount of living tissue.

Section 3

Question Answer
What are the four elements that make up over 95 percent of the body in most organisms?Oxygen, carbon, hydrogen, and nitrogen.
How is the movement of matter through the biosphere different from the flow of energy?Matter is recycled within and between ecosystems.
Matter moves through an ecosystem in...Cycles.
What do biogeochemical cycles connect?biological, geological, and chemical aspects of the biosphere.
Water can enter the atmosphere by evaporating from the leaves of plants in the process of...Evaporation.
What are nutrients?All the chemical substances that an organism needs to sustain life.
What are the three nutrient cycles that play especially prominent roles in the biosphere?The Carbon Cycle, the nitrogen cycle, and the phosphorus cycle.
What are the three large reservoirs where carbon is found in the biosphere?As carbon dioxide gas in the atmosphere, as dissolved carbon dioxide in the ocean, and as coal, petroleum, and calcium carbonate rock found carbonate rocks.
In what process do plants use carbon dioxide?Photosynthesis.
Why do all organisms require nitrogen?To make amino acids, which in turn are used to build proteins.
What is nitrogen fixation?Bacteria that live in soil and roots on plants that convert nitrogen gas to ammonia
What is denitrification?Bacteria converts nitrates into nitrogen gas.
What role does denitrification play in the nitrogen cycle?It releases nitrogen into the atmosphere.
Why is phosphorus essential to living things?It forms part of important life-sustaining molecules such as DNA and RNA.
What is the primary productivity of an ecosystem?The rate at which organic matter is created by producers.
If a nutrient is in short supply in an ecosystem, how will it affect an organism?It will limit an organism's growth.
When is a substance called a limiting nutrient?When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly.
Why do algal blooms occur?There are more nutrients available, so the producers can grow and reproduce more quickly.