Populations and the Environment KEY WORDS

Question 0

Abundance

Answer 0

Counting the number of organisms in the sample. Usually the abundance of each species is recorded. If we divide the abundance by size of the sampling area we get the density (number/m²).

Question 1

Abiotic Factors

Answer 1

The non-living/physical components of the environment (temperature, light, soil pH).

Question 2

Autotroph

Answer 2

An organism that can trap an inorganic carbon source using energy from light or chemicals.

Question 3

Biomes

Answer 3

Parts of the atmosphere that have very different environmental conditions to each other.

Question 4

Biosphere

Answer 4

The parts of the earth that support life.

Question 5

Biotic Factors

Answer 5

A living factor that affects a population or a process (predation, competition, parasitism, disease).

Question 6

Carrying Capacity

Answer 6

The highest population that can be maintained for an indefinite period of time by a particular environment.

Question 7

Climax Community

Answer 7

The final community in succession.

Question 8

Competitive Exclusion Principal

Answer 8

When two species are competing for the limited resources the one using the resources most effectively will eliminate the other. Two species can’t occupy the same niche indefinitely when resources are limiting.

Question 9

Consumers

Answer 9

An organism that obtains energy by eating other living things.

Question 10

Decomposers

Answer 10

Live in the soil (generally) and feed on detritus, dead, decaying organic matter. There are two groups, the detritivores and the saprophytes.

Question 11

Detritivores

Answer 11

Organisms that on dead or decaying organic matter.

Question 12

Ecosystems

Answer 12

An area within which the organisms interact with each other and their physical environment.

Question 13

Detritus

Answer 13

Dead or decaying matter.

Question 14

Ecology

Answer 14

The study of interrelationships between organisms and their environment. The environment includes both biotic and abiotic factors.

Question 15

Ecosystems

Answer 15

An ecosystem is a self-supporting system made up of all the interacting biotic and abiotic features in a specific area.

Question 16

Ecological Niche

Answer 16

The position an organism fills in its environment, comprising its habitat, the resources it uses and the time at which it occurs there.

Question 17

Environmental Resistance

Answer 17

Conditions that reduce the growth rate of a population.

Question 18

Food Webs

Answer 18

A diagram showing all the feeding relationships in a single ecosystem or community.

Question 19

Gross Primary Production

Answer 19

The rate at which chemical energy is stored in plants.

Question 20

Habitat

Answer 20

The place where an organism is found.

Question 21

Inorganic Fertilisers

Answer 21

A fertiliser containing inorganic ions such as nitrate, ammonium, potassium and phosphate ions.

Question 22

Intraspecific Competition

Answer 22

Between members of the same species.

Question 23

Interspecific Competition

Answer 23

Between members of different species.

Question 24

Limiting Factor

Answer 24

The one factor of many that affect a process, that is nearest its lowest value and hence is rate-limiting.

Question 25

Microhabitats

Answer 25

An area within a habitat that has specific conditions.

Question 26

Net Primary Production

Answer 26

The energy that remains after the energy used in respiration has been subtracted from the gross primary production.

Question 27

Organic Fertiliser

Answer 27

A fertiliser containing organic substances such as, urea.

Question 28

Omnivore

Answer 28

Animals that regularly feed at both primary and higher tropic levels.

Question 29

Pioneer Species

Answer 29

Species which are first to colonise cleared or disturbed ground.

Question 30

Primary Succession

Answer 30

Succession that occurs on previously uninhabited ground.

Question 31

Population

Answer 31

A group of organisms of the same species that live together in the same area at the same time.

Question 32

Producers

Answer 32

An organism that uses solar energy in photosynthesis to produce carbohydrates.

Question 33

Pyramid of Numbers

Answer 33

A diagram that shows the number of organisms at each tropic level in an ecosystem/food chain, at a given moment irrespective of size.

Question 34

Pyramid of Biomass

Answer 34

A diagram that shows the total biomass at each tropic level of an ecosystem/food chain, at a given moment, irrespective of the numbers.

Question 35

Pyramid of Energy

Answer 35

A diagram that shows the energy transferred to each tropic level in an ecosystem/food chain in a period of time irrespective of the numbers and biomass.

Question 36

Richness

Answer 36

Number of different species found in the sample.

Question 37

Saprophytes

Answer 37

Microorganisms (fungi and bacteria) that feed through extracellular digestion, secreting enzymes onto organic matter and absorbing the soluble products into their body to use in respiration (releases carbon dioxide to the environment again for use in photosynthesis) or to use in assimilation building new cells (biomass).

Question 38

Secondary Succession

Answer 38

Succession that occurs in a place where there was some vegetation already present and the area has been disturbed by natural disaster or by deforestation etc.

Question 39

Succession

Answer 39

The process by which a community changes over time, a directional process where organisms affect the environment making it less suitable for themselves and more suitable for the next dominating species.

Question 40

Food Chains

Answer 40

A very simple diagram showing how energy flows through an ecosystem.

Question 41

Trophic Level

Answer 41

The position in a food chain at which an organism feeds.

Question 42

Niche

Answer 42

Describes how an organism fits into the environment. A niche refers to where an organism lives and what it does there. It includes all the biotic and abiotic conditions required for an organism to survive, reproduce and maintain a viable population. No two organisms occupy the same niche.