Chapter 20

Question 1

Most energy that moves through ecosystems originates as…

Answer 1

solar energy that powers photosynthesis.

Question 2

chemosynthesis

Answer 2

Where sunlight is not available (e.g., deep ocean thermal vents), producers rely on chemosynthesis as their source of energy.

Question 3

Primary productivity

Answer 3

the rate at which solar or chemical energy is captured and converted into chemical bonds by photosynthesis or chemosynthesis.

Question 4

Standing crop

Answer 4

the biomass of producers present in a given area of an ecosystem at a particular moment in time.

Question 5

Ecosystems with high primary productivity…

Answer 5

may not have a high standing crop; consumers may eat it as quickly as it grows.

Question 6

Gross primary produc-vity (GPP)

Answer 6

the rate at which energy is captured and assimilated by producers in an area.

Question 7

Net primary produc-vity (NPP)

Answer 7

the rate of energy that is assimilated by producers and converted into producer biomass in an area; includes all energy that is not respired

Question 8

NPP =

Answer 8

GPP - Respiration

Question 9

GPP =

Answer 9

NPP + Respiration

Question 10

In aquatic systems, measuring CO2 does not provide a good estimate of NPP because…

Answer 10

CO2 is rapidly converted into bicarbonate ions.

Question 11

Remote sensing

Answer 11

a technique that allows measurement of conditions on Earth from a distant location, typically using satellites or airplanes that take photographs of large areas of the globe.

Chlorophyll pigments absorb wavelengths in the red and blue range but reflect wavelengths in the green range.
Satellite images that show a pattern of high absorption of blue and red light, and high reflectance of green light indicate ecosystems with high standing crops.

Question 12

Egested energy

Answer 12

the portion of consumed energy that is excreted or regurgitated.

Question 13

Assimilated energy

Answer 13

the portion of energy that a consumer digests and absorbs; analogous to GPP for producers.

Question 14

Respired energy

Answer 14

the portion of assimilated energy a consumer uses for respiration; remaining energy can be used for growth and reproduction (i.e., net secondary productivity).

Question 15

Net secondary productivity

Answer 15

the rate of consumer biomass accumulation in a given area; analogous to NPP for producers.

Question 16

Trophic pyramid

Answer 16

a chart composed of stacked rectangles represen=ng the amount of energy (i.e., pyramid of energy) or biomass (i.e., pyramid of biomass) in each trophic group.

Question 17

Consumption efficiency

Answer 17

the percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level.

consumption coefficient=consumed energy (J)/net production energy of the next lower trophic level (J)

Question 18

Assimilation efficiency

Answer 18

the percentage of consumed energy that is assimilated (i.e., material that is not egested, such as bones).

assimilation efficiency=assimilated energy (J)/consumed energy (J)

Question 19

primary consumers tend to have ___________ efficiencies than secondary consumers because prey tissues are more digestible than plant tissues.

Answer 19

lower

Question 20

Net production efficiency

Answer 20

the percentage of assimilated energy that is used for growth and reproduction; the percentage of assimilated energy that remains ager respiration.

net production efficiency= net production energy (J)/assimilated energy (J)

Question 21

Ecological efficiency (food chain efficiency)

Answer 21

the percentage of net production from one trophic level compared to the next lower trophic level.

ecological efficiency= net production energy on a trophic level (J)/net production energy of the next lower trophic level (J)

Question 22

Because energy is lost at each of these steps, ecological efficiency is usually low, ranging from 5% to 20%; ___ is used as a rule of thumb.

Answer 22

10%

Question 23

Energy residence time

Answer 23

the length of time that energy spends in a given trophic level; the longer the residence time, the greater the accumulation of energy in that trophic level.

Question 24

Biomass residence time

Answer 24

the length of time that biomass spends in a given trophic level.

Question 25

Ecological stoichiometry

Answer 25

the study of the balance of nutrients in ecological interactions, such as between an herbivore and a plant.

The nutrients that a species requires depends on its biology.

Question 26

If the ratio of ingested nutrients to required nutrients is low, consumers must…

Answer 26

eat more food