Chapter 20: Ecosystem Energetics

Question 1

A system that neither receives inputs from nor contributes output to the external environment

Answer 1

Closed system

Question 2

A system with exchanges of materials and energy to the surrounding environment

Answer 2

Open system

Question 3

Energy fixed per unit area by photosynthetic activity of plants before respiration;

Total energy flow at the secondary level is not gross production, but rather assimilation, because consumers use material already produced with respiratory losses

Answer 3

gross primary productivity

Question 4

The rate of energy storage as organic matter after respiration

Answer 4

net primary productivity (NPP)

Question 5

Total amount of biomass per unit area at a given time

Answer 5

standing crop biomass

Question 6

Production by consumer organisms over time

Answer 6

Secondary production

Question 7

Rate at which heterotrophs produce biomass per unit area per unit time;

It is greatest when the birthrate of the population and the growth rate of individuals are highest

Answer 7

Secondary productivity

Question 8

In aquatic ecosystems, the depth of the water column at which light intensity reaching plants is just sufficient for the rate of photosynthesis to balance the rate of respiration

Answer 8

Compensation depth

Question 9

compensation point

Answer 9

check the book just in case compensation depth is not the same

Question 10

Organic matter former od originating from the place where it is found (produced within the ecosystem)

Answer 10

autochthonous

Question 11

Organic matter originating in a place other than where it is found (produced outside the ecosystem)

Answer 11

allochtonous

Question 12

Ratio of assimilation to ingestion;

A measure of efficiency with which a consumer extracts energy from food

Answer 12

assimilation efficiency

Question 13

The ratio of production to assimilation

A measure of the efficiency of a consumer to incorporate assimilated energy into secondary production

Answer 13

production efficiency

Question 14

Food chain in which primary producers (green plants) are eaten by grazing herbivores, with subsequent energy transfers to other trophic levels

Answer 14

grazing food chain

Question 15

Food chain in which detritivores consume detritus or litter, mostly from plants, with subsequent transfer of energy to various trophic levels;

Ties into the grazing food chain

Answer 15

detrital food chain

Question 16

Ratio of ingestion to production or energy available;

Defines the amount of available energy being consumed

Answer 16

consumption efficiency

Question 17

Ratio of productivity in a given trophic level with the trophic level on which it feeds

Answer 17

trophic efficiency

Question 18

range of estimates for human use of global NPP

Answer 18

Although humans represent only approximately 0.5% of the total heterotrophic biomass on Earth, our species accounts for the appropriation of approximately 20% of the planet’s net primary productivity