Biogeochemical Cycles

Question 1

Nutrients move through ecosystems in ______, also known as ______

Answer 1

nutrient cycles, biogeochemical cycles.

Elements or molecules travel through the atmosphere, hydrosphere, lithosphere, and biosphere in dynamic equilibrium.

Question 2

Nutrients move from one ____, or ____, to another for varying amounts of time, called the _____.

Answer 2

reservoir, pool, residence time

Question 3

When a reservoir releases more materials than it accepts, it is called a _____.

Answer 3

source

Question 4

When a reservoir accepts more materials than it releases, it is called a _____.

Answer 4

sink

Question 5

_____ is the rate at which materials move between reservoirs.

Answer 5

Flux

Question 6

The _____ describes the routes that carbon takes through the environment.

Answer 6

carbon cycle,

Carbon is found in all organic molecules—carbohydrates, fats, and proteins, which make up living organisms.

Question 7

_____ (plants, algae, and cyanobacteria) pull _____ out of the air and use it to produce sugars like _____

Answer 7

Producers, carbon dioxide, glucose (C6H12O6).

Question 8

____, _____ consume organic molecules and release some of the ____ as carbon dioxide.

Answer 8

Autotrophs, consumers, and decomposers, carbon

Question 9

As aquatic organisms ____, their remains may settle in _____ in ocean basins or______

Answer 9

die, sediments, freshwater wetlands.

Question 10

Converted over time to _____ into oil and skeletons into sedimentary rock like ____

Answer 10

soft tissue sediments, limestone

Question 11

The oceans are the _______ of carbon, dissolving carbon dioxide, _____ and _____.

Answer 11

second-largest reservoir, carbonate ions (C O3 2−), bicarbonate ions (H C O3−).

Question 12

_____ is the largest reservoir in the carbon cycle.

Answer 12

Sedimentary rock,

Released during uplift, erosion, volcanic eruptions, or the burning of fossil fuels

Question 13

Today’s _____ reservoir is estimated to be the largest in the past _____

Answer 13

atmospheric carbon dioxide, 800,000 years.

Combustion of fossil fuels (a carbon sink)

Decrease of surface vegetation

Question 14

Some of the excess ___ is being absorbed by the oceans, causing it to become more ____.

Answer 14

C O2, acidic

Question 15

About 2.3–2.6 billion metric tons of released fossil fuel C O2 is ____ for.

Answer 15

unaccounted

Question 16

Nitrogen is an essential ingredient in ____

Answer 16

D N A, R N A, and proteins.

Question 17

_____ makes up 78% of the atmosphere, but is chemically inert and cannot leave the atmosphere without assistance.

Answer 17

Nitrogen gas (N2)

Question 18

Under the right conditions, nitrogen can become biologically active and enter the biosphere and lithosphere, a process called _____

Answer 18

the nitrogen cycle.

Question 19

In _____, inert nitrogen gas becomes biologically available by combining with hydrogen to form _____, whose water-soluble ions of ______ can be taken up by plants.

Answer 19

nitrogen fixation, ammonia (N H3, ammonium (N H4+)

The intense energy of lightning strikes can also fix nitrogen.

Question 20

_____ convert nitrogen gas into ammonia.

Answer 20

Nitrogen-fixing bacteria

The bacteria form nodules on plant roots, absorbing sugars from the roots in exchange for nitrogen fixation.
Found in legumes, such as soybeans

Question 21

Other bacteria perform a process called _____, which converts ammonium ions into nitrite ions (N O2−), then into nitrate ions (N O3−), which plants can directly take up.

Answer 21

nitrification

These ions are also added to the soil through the use of fertilizer.

Question 22

Consumers obtain nitrogen by ingesting plants or other animals, while _____ obtain and release nitrogen from dead and decaying matter.

Answer 22

Consumers, decomposers

Question 23

______ will then convert nitrates back into nitrogen gas.

Answer 23

Denitrifying bacteria

Question 24

Nitrogen fixation has historically been a ______, a step that limited the flux of nitrogen out of the atmosphere.

Answer 24

bottleneck

Question 25

The _____ enabled people to artificially fix nitrogen, greatly enhancing agriculture.

Answer 25

Haber-Bosch process

Humans have effectively doubled the rate of nitrogen fixation on Earth.

Question 26

Runoff can cause excess nitrogen to enter waterways, causing ____.

Answer 26

eutrophication

Question 27

_____ releases additional nitrogen into the atmosphere.

Answer 27

Burning fossil fuels

Question 28

Phosphorus is a key element in many organic molecules, including _____

Answer 28

D N A, R N A, and A T P.

Question 29

The biggest phosphorus _____ are rocks, soil, sediments, and the oceans.

Answer 29

sinks

Very little is in the atmosphere.

Question 30

The processes that move phosphorus from these sinks to living matter are called the _____

Answer 30

phosphorus cycle.

Question 31

Weathering of rocks releases ____ into water.

Answer 31

phosphate ions (P O4−)

These phosphates precipitate into a solid form, sink to the bottom of bodies of water, and re-enter the lithosphere as sediments.

Question 32

Aquatic organisms take up ____ directly from surrounding waters.

Answer 32

phosphates

Question 33

Terrestrial organisms take up ____ from soil water through their roots.

Answer 33

phosphates

Phosphates are passed through the food chain and eventually returned to the soil by decomposers.

Question 34

Like nitrogen, the runoff of phosphorus ____ its concentration in surface waters.

Answer 34

increases

Question 35

Water is the medium for all _____, and it plays key roles in nearly every environmental system.

Answer 35

biochemical reactions

Carries nutrients, sediments, and pollution
Returns atmospheric pollutants to the surface through rain or snow

Question 36

The ____ summarizes how water flows as a solid, liquid, and gas through our environment.

Answer 36

hydrologic cycle

The oceans are the main reservoir (97%) for water.
Only about 3% is fresh water, and two-thirds of that is frozen in glaciers, ice caps, and snowfields.

Question 37

_____ converts water from a liquid to gaseous form, taking it to the atmosphere.

Answer 37

Evaporation

Increased by warmth, wind, and exposure

Question 38

____ is the release of water vapor by plants through their leaves.

Answer 38

Transpiration

Dissolved substances are left behind.

Question 39

Water returns to Earth’s surface as _____ when it condenses into rain or snow.

Answer 39

precipitation

Most of it flows as runoff into surface waters.

Question 40

Some precipitation and surface water soaks down through soil and rock, becoming _____.

Groundwater recharges underground ____.

Answer 40

groundwater

aquifers

Question 41

The upper limit of groundwater in an aquifer is called the _____

Answer 41

water table.