Terms in this set (123)
the scientific study of interactions among organisms & between organisms & the environment
What is ecology?
the combined portions of the planet in which all of life exists, including land, water, & the air/atmosphere
What does the biosphere contain?
to understand relationships within the biosphere
Why do ecologists ask questions about events and organisms that range in complexity from an individual to the biosphere?
a group of organisms so similar that they can breed & produce fertile offspring
a group of individuals that belong to the same species and live in the same area
assemblages of different populations that live together in a defined area
a collection of all the organisms that live in a particular place, together with their physical/nonliving environment
a group of ecosystems that have the same climate and the same dominant communities
the entire biosphere itself
What is the highest level of organization that ecologists study?
observing, experimenting, modeling
What are the three basic approaches that scientists use to conduct modern ecological research?
to imitate & manipulate conditions that organisms would encounter in the natural world
Why might an ecologist set up an artificial environment in a laboratory?
because they occur over long periods of time or on large spatial scales
Why are many ecological phenomena difficult to study?
to gain insight into complex phenomena (example: effects of global warming on ecosystems)
Why do ecologists make models?
True or False? An ecological model may consist of a mathematical formula.
its need for energy to power life's processes
What is at the core of every organism's interaction with the environment?
energy stored in inorganic chemical compounds
What source of energy do organisms use that don't use the sun's energy?
organisms that use energy from the environment to fuel the assembly of simple inorganic molecules into complex organic molecules
What are autotrophs?
they make their own food
Why are autotrophs also called producers?
use light energy to power chemical reactions that convert CO2 and H2O into O2 and energy rich carbohydrates, such as sugars and starches
What do autotrophs do during photosynthesis?
What kind of autotroph is the main producer on land?
What kind of autotroph is the main producer in the upper layers of the ocean?
photosynthetic bacteria (cyanobacteria)
What kind of autotroph is the main producer in tidal flats and salt marshes?
organisms use chemical energy to produce carbohydrates
What is chemosynthesis?
very remote places: volcanic vents on the deep-ocean floor, hot springs in Yellowstone park, or common places: tidal marshes along the coast
Where do bacteria that carry out chemosynthesis live?
Heterotrophs are also called ____.
Plant and animal remains and other dead matter are collectively called _____.
Heterotrophs that obtain energy by eating only plants
cows, rabbits, caterpillars, deer
Give examples of herbivores.
Heterotrophs that eat animals
Give examples of Carnivores.
Heterotrophs that eat both plants and animals
Humans, bears, crow
Give examples of Omnivores.
Heterotrophs that feed on plant and animal remains and other dead animals
mites, earthworms, snails, crabs
Give examples of Detritivores.
Heterotrophs that break down organic matter.
Give examples of decomposers.
in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)
How does energy flow through an ecosystem?
series of steps in which organisms transfer energy by eating and being eaten
links all the food chains in an ecosystem together
all the food chains in an ecosystem
What does a food web link together?
In a food web, what organisms make up the first trophic level?
the trophic level below it
What does a consumer in a food chain depend on for energy?
a diagram that shows the relative amounts of energy or matter contained in each trophic level in a food chain or web
What is an ecological pyramid?
organisms use much of the energy they consume for life processes: respiration, movement, and reproduction
Why is it that only part of the energy stored in one trophic level is passed on to the next level?
the total amount of living tissue within a given trophic level
What is biomass?
the amount of potential food available for each trophic level
What does a biomass pyramid represent?
the relative number of individual organisms at each trophic level
What does a pyramid of numbers show?
because each trophic level harvests only about 1/10 of energy from the level below it
Why can each trophic level support only about one tenth the amount of living tissue as the level below it?
oxygen, carbon, hydrogen, and nitrogen
What are the four elements that make up over 95 percent of the body in most organisms?
matter is recycled within and between organisms
How is the movement of matter through the biosphere different from the flow of energy?
Matter moves through an ecosystem in _____ ______.
biological, geological and chemical aspects of the atmosphere
What do biogeochemical cycles connect?
Water can enter the atmosphere by evaporating from the leaves of plants in the process of _______.
Is precipitation involved in the water cycle?
Is evaporation involved in the water cycle?
Is runoff involved in the water cycle?
Is fertilization involved in the water cycle?
all the chemical substances that an organism needs to sustain life
What are nutrients?
carbon, nitrogen, phosphorus
What are the three nutrient cycles that play especially prominent roles in the biosphere?
it is a key ingredient in living tissue
Why is carbon especially important to living systems?
As carbon dioxide gas in the atmosphere, as dissolved carbon dioxide in the ocean, as coal/petroleum/calcium carbonate rock found on land and in organisms.
What are three large reservoirs where carbon is found in the atmosphere?
In what process do plants use carbon dioxide?
to make amino acids, which are the building blocks for protein
Why do all organisms require nitrogen?
What kind of processes in the carbon cycle are photosynthesis, respiration, and decomposition?
What kind of processes in the carbon cycle release co2 to the atmosphere by volcanoes, including erosion and volcanic activity?
Mixed biogeochemical cycles
What kind of processes in the carbon cycle are burial and decomposition of dead organisms and their conversion under pressure into fossil fuels?
What kind of processes in the carbon cycle are mining, cutting and burning forests, and burning fossil fuels?
What is the main reservoir of nitrogen in the biosphere?
bacteria convert nitrogen gas into ammonia
What is nitrogen fixation?
bacteria convert nitrates into nitrogen gas
What is dentirification?
releases nitrogen gas back into the atmosphere
What role does dentrification play in the nitrogen cycle?
True or false? In the phosphorus cycle, phosphate is released as rocks and sediments wear down.
True or false? In the phosphorus cycle, plants absorb phosphate from the soil or from water.
True or false? In the phosphorus cycle, phosphorus is abundant in the atmosphere.
True or false? In the phosphorus cycle, organic phosphate cannot move through food webs.
it forms part of important, life-sustaining molecules, like RNA and DNA
Why is phosphorus essential to living things?
the rate at which organic matter is created by producers
What is the primary productivity of an ecosystem?
it will limit an organisms growth
If a nutrient is in short supply in an ecosystem, how will it affect an organism?
when an ecosystem is limited by a nutrient that is scarce or cycles very slowly
When is a substance called a limiting nutrient?
In the ocean and other saltwater environments, what is often the limiting factor?
What is the typical limiting factor in streams, lakes, and freshwater environments?
"algal bloom" - an immediate increase in algae and other producers
When an aquatic ecosystem receives a large input of a limiting nutrient, what is often the result, and what is this result called?
there are more nutrients, so the producers grow and produce more quickly. If there are not enough consumers, conditions become favorable for growth so algae covers the surface of the water.
Why do blooms occur?
organisms that rely on other organisms for their energy and food supply
each step in a food chain or food web
the process by which water changes from a liquid form to an atmospheric gas
the process by which water enters the atmosphere by evaporating from the leaves of plants
1866, Ernest Haeckel (a German biologist)
When was the term "ecology" coined, and by whom?
8 kilometers above earth's surface to 11 kilometers below the ocean
From where does the biosphere extend?
species, population, community, ecosystem, biome, biosphere
List the six different levels of organization that ecologists study, in order from smallest to greatest.
What is often the first step in asking ecological questions?
True or false? Experiments can be conducted within natural ecosystems.
less than 1 percent
How much of the sun's energy that reaches the surface is used by living things?
uses energy from the sun to produce living tissue
What type of autotroph is Kelp?
in both, energy-rich carbohydrates are produced
What is similar about photosynthesis and chemosynthesis?
adding oxygen to and removing carbon dioxide from the atmosphere
What is photosynthesis responsible for?
True or false? No autotroph can produce food in the absence of light.
photosynthesis uses light energy, chemosynthesis uses energy stored in chemical bonds
What is the difference between photosynthesis and chemosynthesis?
lost as heat
What happens to the remaining light or chemical energy organisms don't use?
grams of organic matter per unit area
In what terms is biomass usually expressed?
photosynthesis and chemosynthesis
What are the two main forms of energy that power living systems?
because biological systems do not use up matter, they transform it. the matter is assembled into living tissue or passed out of the body as waste products
Why can matter cycle through the biosphere?
to build tissues and carry out essential life functions
Why do organisms need nutrients?
volcanic activity, respiration, human activities (burning of fossil fuels and vegetation), decomposition of organic matter
How is carbon dioxide released into the atmosphere?
to make amino acids which are used to make proteins
Why do all organisms need nitrogen?
What percent of Earth's atmosphere does nitrogen gas make up?
What is a major component of plant fertilizers?
What is the most abundant form of nitrogen on Earth?
decomposers return nitrogen to the soil as ammonia
What happens when organisms die?
it forms part of life sustaining molecules like DNA and RNA
Why is phosphorus essential to living organisms?
True or false? Phosphorus does not enter the atmosphere.
nitrogen, phosphorus, potassium
What three important nutrients do fertilizers contain?
0.00005%, or 1/10000
How much nitrogen does the sea contain compared to the amount found in soil?
matter is recycled within and between organisms and different ecosystems, while energy is a one way flow
How does the way that matter flows through an ecosystem differ from the way energy flows?
In what form does human activity add nitrogen to the atmosphere?
All life on Earth exists in a region known as the _______.
Groups of different species that live together in a defined area make up a _____.
use energy they take in from the environment to convert inorganic molecules into complex organic molecules
Autotrophs are organisms that:
The series of steps in which a large fish eats a small fish that has eaten algae is a ____ ______.
The total mass of living tissue at each trophic can be shown in a _____ pyramid.
Nutrients move through an ecosystem in processes known as _______ ________.
change nitrogen gas into ammonia
In the nitrogen cycle, bacteria that live on the roots of plants:
Which biogeochemical cycle does not involve a stage where the chemical enters the atmosphere?