4.1

Def: Species

A species is a group of living organisms that share common characteristics and can interbreed to produce fertile offspring.

Def: population

A population is a group of organisms of the same species that are living in the same area at the same time.

Def: Community

A group of populations living together and interacting with each other within a given area

Def: Habitat

A habitat is the natural environment where a particular plant or animal species lives and grows.

Def: Ecosystem

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A community of living and non-living things that interact with each other

Includes plants, animals, microorganisms, soil, air, and water

Def: Autotrophs

synthesizes organic molecules from simple inorganic molecules

commonly referred to as producers

Def: Heterotrophs

obtains organic molecules from other organisms (either living/dead)

referred to as consumers

Def: Mixotrophs

certain unicellular organisms may on occasion use both forms of nutrition, depending on resource availability

Def: Consumers

ingest organic molecules from living/recently killed organisms

Def: Detritivores

ingest organic molecules found in the non-living remnants of organisms (e.g humus)

Def: Saprotrophs

release digestive enzymes and then absorb the external products of digestion

Def: Scavengers

type of consumer that principally feed on dead, decaying carcasses rather than hunting live prey

Why is the supply of inorganic nutrients on Earth finite?

nutrients are composed of elements (e.g carbon and oxygen)

the supply of such elements on earth is finite- new elements cannot be created

Explain nutrient recycling

autotrophs obtain inorganic nutrients from the air, water and soil, convert them into organic compounds

heterotrophs ingest these organic compounds, use them for growth and respiration, releasing inorganic byproducts

when organisms die, saprotrophs decompose the remains and free inorganic materials into the soil

the return of inorganic materials to the soil ensures the continual supply of raw materials for the autotrophs

What are the three main components required for a sustainable ecosystem?

energy availability → light from the sun provides the initial energy source for most communities

nutrient availability → saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment

recycling of wastes → certain bacteria can detoxify harmful waste byproducts

Def: Mesocosm

enclosed environments that allow a small part of a natural environment to be observed under controlled conditions