Deck 21: Ecosystem Energetics

Question 1

In the surface waters of oceans,the two most limiting nutrients for primary productivity are

A)sulfur and phosphorus.
B)sulfur and nitrogen.
C)nitrogen and iron.
D)nitrogen and phosphorus.

Answer 1

C

Question 2

Low-moisture conditions favor allocation by a plant to

A)leaves.
B)stems.
C)roots.
D)flowers.

Answer 2

C

Question 3

An ecosystem with inputs of matter and energy is a(n)________ ecosystem.

Answer 3

open

Question 4

The heterotrophic component of the ecosystem is often subdivided into two subsystems: consumers and ________.

Question 5

________ efficiency is the ratio of production to assimilation,which measures how efficiently the consumer incorporates assimilated energy into secondary production.

Question 6

Net primary ________ is the energy available to the heterotrophic component of the ecosystem.

Question 7

Net primary productivity in an ecosystem increases as mean annual temperature

A)and mean annual rainfall decrease.
B)decreases and mean annual rainfall increases.
C)increases and mean annual rainfall decreases.
D)and mean annual rainfall increase.

Question 8

Organic carbon produced within an ecosystem is termed ________.

Question 9

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

Question 10

________ primary production is the total rate of photosynthesis or energy assimilated by plants.

Question 11

Net primary productivity is generally greatest at

A)tropical latitudes near the equator.
B)subtropical latitudes (e.g.,25° of latitude).
C)temperate latitudes (e.g.,50° of latitude).
D)polar latitudes (e.g.,80° of latitude).

Question 12

In a body of water,the depth at which the availability of light is such that the rate of photosynthesis equals the rate of respiration is called the ________ depth.

Question 13

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

Question 14

Plants assimilate energy through the process of

A)decomposition.
B)respiration.
C)photosynthesis.
D)regeneration.

Question 15

Relative net primary productivity is the ratio of net primary productivity to standing ________.

Question 16

An ecologist studying productivity in a sample of grasses measures gross primary productivity as 1000 kcal / m2 / yr and autotrophic respiration as 100 kcal / m2 / yr.Based on these calculations,the net primary productivity would be

A)10 kcal / m2 / yr.
B)900 kcal / m2 / yr.
C)1100 kcal / m2 / yr.
D)10,000 kcal / m2 / yr.

Question 17

According to the first law of thermodynamics,

A)chemical reactions are exothermic.
B)entropy tends to increase.
C)potential energy tends to degrade into an unavailable form.
D)energy is neither created nor destroyed.

Question 18

A(n)________ chemical reaction must absorb energy in order to proceed.

Question 19

Within any ecosystem,the two major food chains are the ________ food chain and the grazing food chain.

Question 20

For photosynthesis and productivity to occur,a plant must open its ________ to take in carbon dioxide.

Question 21

Net primary productivity cannot be measured in aquatic ecosystems.

Question 22

Primary productivity in forests often increases during the early stages of stand development and then decreases again as the forest ages and standing biomass increases.

Question 23

Secondary production in an ecosystem is always less than primary production.

Question 24

Rates of herbivory are highest in

A)aquatic ecosystems dominated by phytoplankton.
B)aquatic ecosystems dominated by vascular plants.
C)terrestrial ecosystems dominated by herbaceous plants.
D)terrestrial ecosystems dominated by woody plants.

Question 25

Primary producers form the base of all food chains.

Question 26

In endotherms,an increase in mass-specific metabolic rate lowers production efficiency.

Question 27

Net primary productivity is greater in temperate grasslands than in tropical rain forest.

Question 28

If herbivores eat 1000 kcal of plant energy,approximately how much energy will be converted into the tissues of herbivores?

A)1 kcal
B)10 kcal
C)100 kcal
D)1000 kcal

Question 29

The base of the detrital food chain is formed by

A)primary producers.
B)decomposers.
C)herbivores.
D)dead organic matter.

Question 30

In most marine ecosystems,autochthonous inputs of organic carbon are greater than allochthonous inputs of carbon.

Question 31

Secondary production is limited primarily by

A)water availability.
B)nutrient availability.
C)primary production.
D)light availability.

Question 32

In a temperate rain forest,primary productivity remains relatively constant.

Question 33

Net primary productivity is greater in the open ocean than along the coast.

Question 34

Net primary productivity is greater in areas with a long photosynthetic period than in areas with a short photosynthetic period.

Question 35

When a chemical reaction results in the loss of energy from the system,the reaction is exothermic.

Question 36

Productivity may be expressed in units of energy per unit area per unit time or in units of dry organic matter per unit area per unit time.

Question 37

In plants,low water availability favors the allocation of energy to the roots.

Question 38

The second law of thermodynamics is valid only in a closed system,such as a living organism.

Question 39

In most terrestrial and many aquatic ecosystems,the ________ food chain is the dominant pathway of energy flow.

A)detrital
B)grazing
C)consumer
D)heterotroph

Question 40

Which organism is most likely to have the highest assimilation efficiency?

A)endothermic carnivore,such as a lion
B)ectothermic carnivore,such as a snake
C)endothermic herbivore,such as a deer
D)ectothermic herbivore,such as a grasshopper

Question 41

In stream and river ecosystems,the grazing food chain is of minor importance compared with the detrital food chain.

Question 42

In all food chains,the flow of energy is unidirectional from the bottom to the top.

Question 43

Consumption efficiency is the ratio of ingestion to production.

Question 44

In most ecosystems,the biomass of carnivores is greater than the biomass of producers.

Question 45

Wealthy nations typically have lower rates of human appropriation of net primary productivity (HANPP)than developing nations.

Question 46

Brian Silliman's research demonstrated that productivity in highly productive coastal salt marshes is controlled by bottom-up forces,such as physical conditions and nutrient availability.

Question 47

In all ecosystems,the biomass of primary producers is greater than the biomass of herbivores.

Question 48

In terrestrial and shallow-water ecosystems,the grazing food chain is dominant over the detrital food chain.