Species are grouped in populations, which make up communities
Which of the following descriptions about the organization of an ecosystem is correct?
The simplest grouping of more than one kind of organism in the biosphere is a(n)
Which ecological inquiry method is an ecologist using when he or she enters an area periodically to count the population of a certain species?
The algae at the beginning of the food chain are
An organism that uses energy to produce its own food supply from inorganic compounds is called a(n)
Which of the following organisms does NOT require sunlight to live?
The total amount of living tissue within a given trophic level is called the
What animals eat both producers and consumers?
A snake that eats a frog that has eaten an insect that fed on a plant is a
the relative number of individual organisms
The trophic levels illustrate
eliminated as heat
Only 10 percent of the energy stored in an organism can be passed on to the next trophic level. Of the remaining energy, some is used for the organism’s life processes, and the rest is
What is the process by which bacteria convert nitrogen gas in the air to ammonia?
Carbon cycles through the biosphere in all of the following processes EXCEPT
energy flows in one direction and nutrients recycle
The movements of energy and nutrients through living systems are different because
Which is most likely to be a limiting nutrient in a freshwater pond?
Autotrophs capture energy from sunlight or ________ to produce food.
Organisms that break down organic matter and return it to the environment are called ________.
sharks (top level)
Of the organisms, the organisms in the ocean with the smallest total biomass are most likely the ________.
Water can enter the atmosphere through the processes of evaporation and ________.
Living organisms require nitrogen to make ________, which are used to build proteins.
The algae are autotrophs, the producers at the base of the food chain.
Describe the role of algae in ocean food chains
Energy flows from the sun to the autotrophs, and from the autotrophs to the heterotrophs. Energy also flows from the autotrophs and the heterotrophs to the decomposers
Describe the flow of energy among the following members of an ecosystem: decomposers, autotrophs, heterotrophs, and the sun
The insects would provide 10 percent (one tenth) of 1500 calories, or 150 calories, of energy to the shrews. The shrews would provide one tenth of 150 calories, or 15 calories, to the owl.
Describe the flow of energy from a tree to an insect to a shrew to an owl if the tree begins with 1500 calories.
The tree at the base has much more available energy than all the insects that live in it. An energy diagram would be broad at the base like a typical pyramid.
What is the most likely explanation of a pyramid having only one organism at its base? In what way would an energy diagram be different?
Water seeps through soil and into the ground water. Roots of trees and plants take the water up through their roots. Plants release the water trough the process of transpiration. Both seepage and transpiration are parts of the water cycle.
Explain how seepage and transpiration are related.
Sunlight is the main energy source for all life on Earth. Less than 3 percent of all the sun’s energy that reaches Earth is used by living things. Inorganic chemical compounds also provide energy for life on Earth. Plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food.
Describe the two sources of energy that fuel life on Earth.
A food chain is a series of steps in which organisms transfer energy by eating and being eaten. A food web is a feeding relationship among the various organisms in an ecosystem that forms a network of complex interactions. A food web links together all the food chains in an ecosystem.
How does a food web differ from a food chain?
An energy pyramid is a diagram that shows the relative amounts of energy contained within each trophic level in a food chain or web. A biomass pyramid represents the amount of living tissue within each trophic level. A pyramid of numbers shows the relative number of organisms in each trophic level.
Describe the three types of ecological pyramids.
Certain types of bacteria are able to use nitrogen gas directly. These bacteria, which live in the soil and on the roots of legumes, convert nitrogen gas to ammonia during the process of nitrogen fixation. Other bacteria in the soil convert ammonia into nitrates and nitrites, which are also taken up directly by producers. Still other soil bacteria convert nitrates into nitrogen gas during the process of denitrification, returning the nitrogen to the atmosphere.
Describe the roles of bacteria in the nitrogen cycle.
The growth of producers in a water environment like a lake is slowed by lack of a limiting nutrient. Phosphorus is a limiting nutrient in most freshwater environments. If phosphorus is added in large amounts, such as from runoff from heavily fertilized fields, an immediate rise in the amount of algae and other producers can occur. This result is called an algal bloom. If an algal bloom in a lake gets too extensive, it may cover the surface of the water.
How might a large input of phosphorus affect a freshwater lake over time?
A large omnivore would consumer energy at every trophic level, reducing the amount of energy available to each level above the producers.
How might a large omnivore change the flow of energy in a pyramid?
Adding a limiting nutrient would increase the amount of primary productivity, which causes an increase in biomass and available energy at each successful level. The number of birds could increase, because there would be more for them to eat.
If a limiting nutrient is supplied to the producers, what effect could it have on the top level consumer?
The bass will use part of the energy received for its life processes, lose some as heat, and be able to store only about 10 percent, or 10 kcal.
How many kcal fourth-level consumer store if the base has 10,000 kcal?
observing, experimenting, and modeling
What three scientific approaches do ecologists use to explain complex relationships?
Certain bacteria are chemosynthetic autotrophs and live in tidal marshes along the coast. They are producers that use inorganic molecules to produce food. The energy they produce would add to the total amount produced by plants to supply energy to the ecosystem.
Describe how chemosynthesis could contribute to the energy transfer.
combined parts of the planet in which all life exists
collection of different populations that live together in an area
organism that can capture energy and use it to produce food
process in which organisms use chemical energy to produce carbohydrates
consumer that feeds on plant and animal remains and other dead matter
total amount of living tissue within a trophic level
process in which water evaporates from the leaves of plants
process in which bacteria convert nitrates into nitrogen gas
group of ecosystems that have the same climate and similar dominant communities
each step in a food chain or food web
False – ecosystem
True or False: A(n) species is a collection of all the organisms that live in a particular place, together with their physical environment.
False – photosynthesis
True or False: The process in which autotrophs use light energy to make carbohydrates is called nitrogen fixation.
False – omnivores
True or False: Heterotrophs that eat both plants and animals are referred to as carnivores.
True or False: A(n) food web links together all the food chains in an ecosystem.
False – primary productivity
True or False: The rate at which organic matter is created by producers is called the limiting nutrient of an ecosystem.
True or False: Ecology is the scientific study of interactions among organisms and between organisms and their environment.
False – population
True or False: A(n) community is a group of individuals that belong to the same species and live in the same area.
False – producers
True or False: Autotrophs are also called consumers.
False – decomposers
True or False: Organisms that break down organic matter are called herbivores.
True or False: The process in which water changes from a liquid to a gas is called evaporation.