Chapter 21: Ecosystem Energetics

Question 1

This law states that energy is neither created nor destroyed.

Answer 1

First law of thermodynamics

Question 2

This law states that when energy is transferred or transformed, part of the energy assumes a form that cannot pass on any further.

Answer 2

Second law of thermodynamics

Question 3

A chemical reaction that results in the loss of energy from the system is an ___ reaction.

Answer 3

exothermic

Question 4

A chemical reaction that must absorb energy to proceed is an ___ reaction.

Answer 4

endothermic

Question 5

A reduction in potential energy is called ___.

Answer 5

entropy

Question 6

True or false: The flow of energy through a terrestrial ecosystem starts with harnessing of sunlight by autotrophs.

Answer 6

True

Question 7

The rate at which radiant energy is converted by photosynthesis to organic compounds is referred to as ___.

Answer 7

primary productivity

Question 8

The total rate of photosynthesis, or energy assimilated by autotrophs, is the ___.

Answer 8

gross primary productivity

Question 9

The rate of energy storage as organic matter after respiration is called ___.

Answer 9

net primary productivity

Question 10

Net primary = gross primary - respiration by autotrophs

Answer 10

Yup

Question 11

What unit is productivity usually expressed as?

Answer 11

units of energy per unit area per unit time

Question 12

The amount of accumulated organic matter found in an area at a given time is the ___.

Answer 12

standing crop biomass

Question 13

Net primary productivity = NPP

Answer 13

Kay

Question 14

SCB = standing crop biomass

Answer 14

Kay

Question 15

NPP = ΔSCB + D + C

Answer 15

D is death of plants (loss of biomass) and C is loss of biomass due to consumption by organisms

Question 16

NPP ___ with increasing rainfall and temperature.

Answer 16

increases

Question 17

Temperature, water, and nutrients control primary production in ___ ecosystems.

Answer 17

terrestrial

Question 18

Temperature, light, and nutrients control primary production in ___ ecosystems.

Answer 18

aquatic

Question 19

Photosynthesis changes with water depth, but ___ does not.

Answer 19

Respiration

Question 20

The depth at which the availability of light is equal to the light compensation point is called the ___.

Answer 20

compensation depth

Question 21

At compensation depth, the rate of photosynthesis is ___ than rate of respiration, and NPP is ___.

Answer 21

equal to; zero

Question 22

Organic carbon produced within an ecosystem is called ___ carbon.

Answer 22

autochthonous

Question 23

Carbon that comes from outside an ecosystem is called ___ carbon.

Answer 23

allochthonous

Question 24

In small, shaded streams where not a lot of photosynthesis can happen, ___ carbon is very important.

Answer 24

allochthonous

Question 25

Net energy of production is called ___.

Answer 25

secondary production

Question 26

Secondary production per unit time is referred to as ___.

Answer 26

secondary productivity

Question 27

The ratio of assimilation to ingestion is called ___ and is a measure of the efficiency with which the consumer extracts energy from food.

Answer 27

assimilation efficiency

Question 28

The ratio of production to assimilation is called ___ and is a measure of how efficiently the consumer incorporates assimilated energy into secondary production.

Answer 28

production efficiency

Question 29

True or false: consumers vary in efficiency of production.

Answer 29

True

Question 30

True or false: Bigger, more complex organisms have higher production efficiency.

Answer 30

False. Invertebrates have the highest, actually.

Question 31

In this food chain, the source of energy is living plant biomass or net primary production.

Answer 31

Grazing food chain

Question 32

In this food chain, the source of energy is dead organic matter.

Answer 32

Detrital food chain

Question 33

In the grazing food chain, flow of energy between trophic levels is ___, while in the detrital food chain it is not.

Answer 33

unidirectional

Question 34

True or false: the energy available to a given trophic level is the production of the next lower level (n-1).

Answer 34

True

Question 35

The ratio of ingestion to production at the next lower trophic level is called the ___.

Answer 35

consumption efficiency

Question 36

Values of consumption efficiency for the various consumer trophic levels determine the pathway of energy flow through the food chain, providing a basis for comparison of energy flow through different ecosystems.

Answer 36

Ok.

Question 37

A measure of efficiency used to describe the transfer of energy between trophic levels is called the ___.

Answer 37

trophic efficiency

Question 38

This is the ratio of productivity in a given trophic level to the trophic level it feeds on.

Answer 38

trophic efficiency

Question 39

Decreasing energy transfers through the food web causes a ___ in the standing biomass of organisms within each successive trophic level.

Answer 39

decrease

Question 40

What are the two types of biogeochemical cycles?

Answer 40

gaseous and sedimentary

Question 41

Nutrients entering the ecosystem via rainfall is called ___.

Answer 41

wetfall

Question 42

Nutrients brought in by particles and aerosols are called ___.

Answer 42

dryfall

Question 43

Nutrients for ___ ecosystems enter via drainage water, detritus, and sediment.

Answer 43

aquatic

Question 44

Fires and harvesting are examples of ___ that result in loss of nutrients from the ecosystem.

Answer 44

outputs

Question 45

True or false: the output of one system can be the input of another.

Answer 45

True

Question 46

The difference between the rate of carbon uptake in photosynthesis and the rate of carbon loss due to autotrophic and heterotrophic respiration is the ___.

Answer 46

net ecosystem productivity

Question 47

Why do levels of atmospheric carbon dioxide drop in the spring?

Answer 47

Because the plants are using it all.

Question 48

True or false: atmospheric nitrogen can be taken up by plants.

Answer 48

False

Question 49

One method for nitrogen to enter ecosystems is ___.

Answer 49

nitrogen fixation

Question 50

Microbial decomposition of organic matter, in which NH3 is released as a waste product of microbial activity and NH4 occurs in the soil as a product of microbial decomposition of organic matter, occurs in a process called ___.

Answer 50

ammonification

Question 51

Oxidizing NO2 to NO3 is called ___.

Answer 51

nitrification

Question 52

This can occur under anaerobic conditions and is when NO3 is reduced to N2O or N2.

Answer 52

denitrification