chapter 21

Question 1

moves many elements through ecosystems.

Answer 1

The hydrologic cycle

Question 2

closely tied to the movement of energy.

Answer 2

The carbon cycle

Question 3

cycles through ecosystems in many different forms.

Answer 3

Nitrogen

Question 4

cycle that moves between land and water

Answer 4

The phosphorus cycle

Question 5

nutrients regenerate in the soil in what ecosystems

Answer 5

terrestrial ecosystems

Question 6

The movement of water from the oceans to continents is driven by

Answer 6

the Sun’s energy.

Question 7

the movement of water through ecosystems and atmosphere; includes evaporation, transpiration, and precipitation.

Answer 7

Hydrologic cycle

Question 8

97% of water is found in the oceans where is the reamaining water found

Answer 8

the remaining water is in lakes, streams, rivers, wetlands, underground aquifers, and soil

Question 9

what happens if evaporation doesnt balance the amount of precipitation

Answer 9

all water would accumulate in one part of the cycle

Question 10

on a global scale where is precipitation greater than evaporation

Answer 10

in terrestrial ecosystems

Question 11

where is evaporation greater than precipitation

Answer 11

aquatic systems

Question 12

what happens to excess water that falls on land

Answer 12

it is transported in runoff and groundwater into aquatic systems.

Question 13

reduces the water that enters the soil and increases runoff.

Answer 13

Creation of impervious surfaces (e.g., roofing, pavement)

Question 14

roofing, pavement are examples of

Answer 14

impervious surfaces

Question 15

decreases evapotranspiration and also increases runoff.

Answer 15

Removing plant biomass

Question 16

examples of removing plant biomass

Answer 16

cutting down a forest

Question 17

a way humans use water from the ground before it can be replenished

Answer 17

irrigation

Question 18

may increase temperatures and evaporation rates, leading to an intensity of rain and snowstorms.

Answer 18

Climate change

Question 19

How might the ocean reduce the effects of fossil fuel combustion on CO2 concentrations in the atmosphere

Answer 19

by absorbing atmospheric CO2

Question 20

in what habitats is carbon is used for respiration instead of oxygen.

Answer 20

In some O2 -poor habitats (e.g., swamps

Question 21

has increased to meet energy demands Over the past two centuries

Answer 21

extraction and combustion of fossil fuels (e.g., coal, oil, natural gas)

Question 22

Combustion of what releases CO2 into the atmosphere?

Answer 22

fossil fuels

Question 23

greenhouse gas that absorbs infrared radiation.

Answer 23

CO2

Question 24

exacerbates the problems of excessive greenhouse gases and global warming

Answer 24

Decomposing peat releases methane gas

Question 25

How might N-fixing bacteria living in symbiosis w/ a plant affect the types of EVRs in which the plant could live

Answer 25

It would allow the plant to live in areas without much nitrogen (i.e. low nitrogen).

Question 26

the process of converting atmospheric nitrogen (N2) into forms producers can use, including ammonia (NH3) which is rapidly converted into ammonium (NH4+), and nitrate (NO3–).

Answer 26

Nitrogen fixation

Question 27

occurs in some species of cyanobacteria, free-living species of bacteria (e.g., Azotobacter) and in bacteria that form mutualisms with plants (e.g., Rhizobium).

Answer 27

Nitrogen fixation

Question 28

requires high amounts of energy, which can be obtained by metabolizing organic matter or from mutualistic partners.

Answer 28

Fixation

Question 29

occurs when lightning, wildfires, or combustion of fossil fuels provide energy to convert N2 into NO3–.

Answer 29

Abiotic nitrogen fixation

Question 30

uses high amounts of energy to convert N2 gas into ammonia or nitrates.

Answer 30

Industrial production of N-rich fertilizers

Question 31

the final process in the nitrogen cycle, which converts ammonium to nitrite, and then from nitrite to nitrate

Answer 31

Nitrification

Question 32

occurs when primary producers take up NH4+ or NO3– and incorporate it into their tissues; consumers assimilate nitrogen from primary producers or excrete it as waste.

Answer 32

Assimilation

Question 33

the process of breaking down organic compounds into inorganic compounds.

Answer 33

Mineralization

Question 34

the process of converting nitrates into nitrogen gas:

Answer 34

Denitrification

Question 35

under what conditions do bacteria under go denitrification

Answer 35

anaerobic conditions

Question 36

necessary for breaking down organic matter in oxygen-depleted soils and sediments.

Answer 36

Denitrification

Question 37

causes nitrogen to leave ecosystems as a gas.

Answer 37

Denitrification

Question 38

reacts with water to form nitrates, which fall to the ground during precipitation.

Answer 38

Nitric oxide

Question 39

what effect does precipitation of nitrates have on ecosystems

Answer 39

precipitation of nitrates fertilizes ecosystems, increases productivity, and decreases species richness

Question 40

what does phosphorous not have in its cycle

Answer 40

a gas phase

Question 41

what is the only form phophorous can enter the atmosphere

Answer 41

dust

Question 42

how do animals eliminate excess phosphourous

Answer 42

by excreting urine with PO4^3- or other compiunds that are converted by phosphatizing bacteria

Question 43

iron binds with sulfur instead of phosphorus, making phosphorus more available under what conditions?

Answer 43

Under low-oxygen conditions

Question 44

what kind of nutrient is phosphorous in terrestrial and aquatic systems

Answer 44

limiting nutrient

Question 45

can contribute to algal blooms in aquatic ecosystems.

Answer 45

Phosphorus, in combination with excess nitrates,

Question 46

an increase in productivity of aquatic ecosystems

Answer 46

Eutrophication

Question 47

an increase in the productivity of aquatic ecosystems caused by human activities.

Answer 47

Cultural eutrophication

Question 48

example of humans impact on phosphorous cycling

Answer 48

phosphates from household detergents travelled to natual systems and contributed to eutrophication and dead zones

Question 49

Why is the weathering of bedrock responsible for such a small fraction of nutrients available to plants?

Answer 49

There is a large distance between bedrock and plant roots.

Question 50

Nutrient loss from leaching and water transport is balanced by

Answer 50

inputs of nutrients from the air (e.g., nitrogen) and from weathering of bedrock beneath the soil (e.g., phosphorus).

Question 51

Acids from rainwater and decomposition react with minerals in bedrock to

Answer 51

release elements essential to plant growth.

Question 52

Weathering rates can be determined by measuring

Answer 52

nutrients entering a system from rainfall and leaving a system by leaching.

Question 53

an area of land draining into a single stream or river.

Answer 53

watershed

Question 54

Ecologists often measure rates of nutrient regeneration in a

Answer 54

watershed

Question 55

primary production relies on regeneration of nutrients from

Answer 55

the break down of detritus.

Question 56

process that breaks down organic matter into smaller and simpler chemical compounds.

Answer 56

Decomposition

Question 57

90% of all plant matter produced in a year is not consumed by herbivores, but is ultimately decomposed in what ecosystem

Answer 57

terrestrial ecosystems

Question 58

removes 10–30% of soluble substances from organic matter; larger organic compounds are left behind

Answer 58

Leaching

Question 59

plant growth and decomposition in terrestrial systems is influenced by

Answer 59

temperature, pH, and moisture