Chapter 3 - Life Sciences 11

Study flashcards for Chapter 3 of Life Sciences.

Biosphere

A part of the Earth in which life exists, including land, water and air or atmosphere.

Biomass

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

Biome

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

Autotroph

Organisms that can capture energy from sunlight or chemicals & use it to produce their own food from inorganic compounds; also called producers.

Community

An assemblage of different populations that live together in a defined area.

Population

A group of individuals of the same species that live together.

Chemosynthesis

The process by which some organisms, like bacteria, use chemical energy to produce carbohydrates.

Detritivore

Organism that feeds on plant and animal remains & other dead matter.

Transpiration

Loss of water from a plant through its leaves.

Denitrification

The conversion of nitrates into nitrogen gas.

Trophic level

Step in a food chain or food web.

Species

A group of similar organisms that can breed and produce fertile offspring.

Nitrogen fixation

Process of converting nitrogen gas into ammonia.

Carnivore

An organism that obtains its energy by eating other animals.

Ecosystem

A collection of all the organisms that live in a particular place, together with their non-living environment.

Ecology

The scientific study of interactions among organisms & their environment.

Herbivore

An organism that obtains energy solely by eating plants.

Evaporation

When water changes from a liquid to a gas.

Food web

A network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.

What are the levels of organization from smallest to largest?

Biosphere, biome, ecosystem, community, population, individual.

Where does all life exist?

In the biosphere.

What are groups of different species that live together in an area called?

A community.

What are autotrophs?

They are organisms that use energy they take from the environment to convert inorganic molecules into complex organic molecules.

Where can the total mass of living tissue at each trophic level be shown?

It can be shown in a biomass pyramid.

How do nutrients move through an ecosystem?

They move through biogeochemical cycles.

What do bacteria that live on the roots on plants do in the nitrogen cycle?

They change nitrogen gas into ammonia.

What biogeochemical cycle does not involve a stage where the chemical enters the atmosphere?

The phosphorus cycle.

What is the substance that limits an ecosystem due to being scarce or cycling very slowly called?

The limiting nutrient.

How is sunlight important to most ecosystems?

It is through sunlight that energy flows through most ecosystems via processes, like photosynthesis.

Distinguish between autotrophs and heterotrophs.

Autotrophs are organisms that turn sunlight or chemicals into food, like plants during photosynthesis. Heterotrophs are organisms that can’t get their energy directly and have to rely on other organisms for their energy and food, like a deer that eats grass.

What is a decomposer?

It is a type of heterotroph that obtains nutrients by breaking down dead or decaying plants and animals, like fungi or algae.

What is a biogeochemical cycle?

It is a system through which elements and chemical compounds are passed from one organism to another and from one part of the biosphere to another.

Two ways through which water enters the atmosphere in the water cycle.

Evaporation, water changing to an atmospheric gas, or transpiration, water evaporating from the leaves of plants.

What is nitrogen fixation?

It is when bacteria that live in the soil and roots, called legumes, convert nitrogen into ammonia.

What does nutrient limitation mean?

It means that a nutrient in an ecosystem is very scarce or cycles very slowly, which results in limiting an organism’s growth.