Biology Ch. 3

What is an ecological pyramid?

A diagram that shows there relative amounts of energy or matter contained within each trophic level in a food chain or food web.

Biome

A group of ecosystems that have the same climate and dominant communities

Populations

A group of individuals that belong to the same species and live in the same area

What are three large reservoirs where carbon is found in the biosphere?

As carbon dioxide gas in the atmosphere As dissolved carbon dioxide in the oceans As coal, petroleum, and calcium carbonate rock found underground

What is at the core of every organism's interaction with the environment?

At the core of every organism's interaction with the environment is its need for energy to power life's processes.

What is nitrogen fixation?

Bacteria that live in the soil convert nitrogen gas into ammonia

Why is carbon especially important in living systems?

Carbon dioxide is taken in by plants during photosynthesis.

How is the movement of matter through the biosphere different from the flow of energy?

Matter is recycled within and between ecosystems.

biomass

The total amount of living tissue within a given trophic level.

What are nutrients?

all the chemical substances that an organism needs to sustain life

What does a food web link together?

all the food chains in an ecosystem together

Detritivore

feed on plant and animal remains and other dead matter

What are the four elements that make up over 95% of the body in most organisms?

oxygen, carbon, hydrogen, nitrogen

In what process do plants use carbon dioxide?

photosynthesis

For each of the following, write which kind of autotroph is the main producer. Land Upper layers of ocean Tidal flats and salt marshes

plants algae Photosynthetic bacteria (most common cyanbacteria)

What does a biomass pyramid represent?

the amount of potential energy food available for each trophic level in an ecosystem

What does a pyramid of numbers show?

the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels

food web

the feeding relationships among the various organisms in an ecosystem form a network of complex interactions.

What does the biosphere contain?

The biosphere contains the combined portions of the planet in which all of life exists, including land, water, and air, or atmosphere.

What is the highest level of organization that ecologists study?

The highest level of organization that ecologists study is the entire biosphere itself.

Herbivore

obtain energy by eating only plants

Why might an ecologist set up an artificial environment in a laboratory?

An ecologist may set up an artificial environment in a laboratory to imitate and manipulate conditions that organisms would encounter in the natural world.

Why can each trophic level support only about one tenth the amount of living tissue of the level below it?

Because each trophic level harvests only about one tenth of the energy from the level below

Why are autotrophs also called producers?

Because they make their own food

What does a consumer in a food chain depend on for energy?

Each consumer depends on the trophic level below it for energy

What is a trophic level?

Each step in a food chain or food web

What do ecologists ask questions about events and organisms that range in complexity from an individual to the biosphere?

Ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere.

Why do ecologists make models?

Ecologists make models to gain insight into complex phenomena such as the effects of global warming on ecosystems.

How does energy flow through an ecosystem?

Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs and then to various heterotrophs.

Carnivores

Heterotroph that eats animals

Why are many ecological phenomena difficult to study?

Many ecological phenomena occur over long periods of time or on such large spatial scales that they are difficult to study.

Why is it that only part of the energy stored in one trophic level is passed on to the next level?

Only about 10% of the energy available within one trophic level is transferred to organisms in the next trophic level.

denitrification

Other soil bacteria convert nitrates into nitrogen gas

In a food web, what organisms make up the first trophic level?

Producers

What source of energy do organisms use if they don't use the sun's energy?

Some types of organisms rely on the energy stored in inorganic chemical compounds.

Why do algal blooms occur?

There are more nutrients available, so the producers can grow and reproduce more quickly

What do autotrophs do during photosynthesis?

These autotrophs use light energy to power chemical reactions that convert carbon dioxide and water into oxygen and energy rich carbohydrates such as sugars and starches.

Where do bacteria that carry out chemosynthesis live?

These bacteria represent a large proportion of living autotrophs. Some chemosynthetic bacteria live in very remote places on Earth, volcanic events on the deep Ocean floor and hot springs in Yellowstone Park. Others more common places such as tidal marshes along the coast.

Is this true or false? An ecological model may consist of a mathematical formula.

True

When is a substance called a limiting nutrient?

When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly

Chemosynthesis

When organisms use chemical energy to produce carbohydrates

Ecosystem

a collection of all the organisms that live together in a particular place, together with their nonliving, or physical, environment

Species

a group of organisms so similar to one another that they can breed and produce fertile offspring

Food Chain

a serious of steps in which organisms transfer energy by eating and being eaten

Community

assemblages of different populations that live together in a defined area

Matter moves through an ecosystem in ______

biogeochemical cycles.

What do biogeochemical cycles connect?

biological, geological, and chemical aspects of the biosphere

decomposer

breaks down organic matter

what are the three nutrient cycles that play especially prominent roles in the biosphere?

carbon cycle, nitrogen cycle, phosphorus cycle

Heterotrophs are also called _______.

consumers

Plant and animal remains and other dead matter are collectively called ______.

detritus

Omnivore

eat both plants and animals

Why is phosphorus essential to living things?

it forms part of important life- sustaining molecules such as DNA and RNA

If a nutrient is in short supply in an ecosystem, how will it affect an organism?

it will limit an organism's growth

What are the three basic approaches scientists use to conduct modern ecological research?

observing, experimenting, modeling

What role does denitrification play in nitrogen cycle?

releases nitrogen into the atmosphere once again

transpiration

the process that water can enter the atmosphere by evaporating from the leaves of plants

Why is the primary productivity of an ecosystem?

the rate at which organic matter is created by producers

ecology

the scientific study of interactions among organisms and between organisms and their environment, or surroundings

Why do all organisms require nitrogen?

to make aminoacids, which in turn are used to build proteins

autotrophs

use energy from the environment to fuel the assembly of simple inorganic compounds into complex organic molecules.