Nitrogen Cycle

Question 1

what is the nitrogen cycle?

Answer 1

the movement of atoms and molecules containing the element nitrogen between sources and sinks

Question 2

how long do reservoirs in which nitrogen compounds occur hold these compounds?

Answer 2

most of the reservoirs in which nitrogen compounds occur in the nitrogen cycle hold these compounds for relatively short periods of time (compared to the carbon cycle)

Question 3

what is nitrogen fixation?

Answer 3

nitrogen fixation is the process in which atmospheric nitrogen is converted into a form of nitrogen (primarily ammonia) that is available for uptake by plants and that can be synthesized into plant tissue

Question 4

what do nitrogen sources do?

Answer 4

sources release nitrogen into the atmosphere

Question 5

what is the major reservoir of nitrogen?

Answer 5

the atmosphere is the major reservoir of nitrogen

Question 6

what do nitrogen sinks do?

Answer 6

sinks take nitrogen out of the atmosphere in increasing amounts

Question 7

what are some examples of short term nitrogen reservoirs?

Answer 7

plants (only hold nitrogen as long as they’re alive, then it’s returned to the soil), soil (nitrogen removed from soil by plants for growth), the atmosphere

Question 8

what is nitrogen critical for?

Answer 8

nitrogen is a critical plant and animal nutrient

Question 9

what things need nitrogen and for what?

Answer 9

all living things need nitrogen for DNA and amino acids to create proteins

Question 10

what is the key difference between the carbon cycle and the nitrogen cycle?

Answer 10

nitrogen reservoirs hold nitrogen for shorter periods of time than carbon reservoirs; sedimentary rocks can hold carbon for millions of years

Question 11

what is the primary form of atmospheric nitrogen?

Answer 11

nitrogen in the atmosphere exists mostly as N2 gas, not useable by plants or animals

Question 12

what is nitrogen fixation?

Answer 12

the process of nitrogen gas being converted into biologically available (useable by plants) ammonia (NH3) or nitrate (NO3-)

Question 13

how do living things take in nitrogen if most exists as unusable nitrogen gas?

Answer 13

nitrogen fixation

Question 14

what is synthetic fixation?

Answer 14

humans combust fossil fuels to convert nitrogen gas into nitrate

Question 15

what is bacterial fixation?

Answer 15

certain bacteria that live in the soil, or in symbiotic relationship with plant root nodules convert N2 into ammonia

Question 16

what is an example of bacterial fixation?

Answer 16

rhizobacteria live in root nodules of legumes (peas/beans) and fix nitrogen for them in return for amino acids from the plant

Question 17

what is an example of synthetic fixation?

Answer 17

nitrates are added to synthetic fertilizers like miracle grow and used in agriculture

Question 18

what is the first step in the nitrogen cycle?

Answer 18

nitrogen fixation

Question 19

how can nitrogen fixation occur naturally?

Answer 19

through lightning storms (converts nitrogen to ammonia in the atmosphere) or bacteria

Question 20

what are the two types of bacteria in bacteria fixation?

Answer 20

bacteria in the soil and symbiotic bacteria

Question 21

what are the nitrogen cycle steps?

Answer 21

Nitrogen Fixation
Nitrification
Assimilation
Ammonification
Denitrification

Question 22

what is assimilation?

Answer 22

the process of plants and animals taking in nitrogen and incorporating it into their body (a similar back and forth like the process of photosynthesis and respiration with carbon)

Question 22

what is ammonification?

Answer 22

soil bacteria, microbes, and decomposers converting waste and dead biomass back into ammonia and returning it to soil

Question 23

what is nitrification?

Answer 23

conversion of ammonia into nitrite and then nitrate by soil bacteria

Question 24

how do animals assimilate nitrogen (absorbs and incorporate it?)

Answer 24

animals assimilate nitrogen by eating plants or other animals that have eaten plants (all starts with plants)

Question 24

what is critical to almost every step of the nitrogen cycle?

Answer 24

bacteria

Question 24

what is denitrification?

Answer 24

conversion of soil nitrogen (NO3) into nitrous oxide gas (N2O) which returns to the atmosphere, this nitrougs oxide gas can break down into nitrogen gas

Question 25

how do plants assimilate nitrogen (absorbs and incorporate it?)

Answer 25

plant roots take in ammonia or nitrates from soil

Question 25

how have humans had an impact on the nitrogen cycle?

Answer 25

through climate change by growing food (nitrous oxide), ammonia volatilization, leaching, and eutrophication

Question 26

how has the climate affected the nitrogen cycle?

Answer 26

nitrous oxide is a greenhouse gas that warms earth’s climate

Question 27

what is ammonia volatilization?

Answer 27

excess fertilizer use leading to ammonia gas entering the atmosphere

Question 28

what is leaching?

Answer 28

synthetic fertilizer use leads to nitrates leaching, or being carried out of soil by water because there are more nitrates in the soil than it can hold

Question 29

how is nitrous oxide produced?

Answer 29

it’s produced by agricultural soils when humans clear land and til the soil for crops; the bacteria in the soil, through the denitrification of nitrate in agricultural soils especially when waterlogged or over watered, will turn the nitrates in the soil into nitrous oxide

Question 30

what are the effects of ammonia volatilization?

Answer 30

ammonia gas in the atmosphere can lead to acid precipitation and respiratory irritation in humans and animals by combining with other pollutants

it also leads to lost profits while growing crops because less nitrogen stays in the soil for crops to use for growth

Question 31

what is eutrophication?

Answer 31

eutrophication occurs when bodies of water are enriched with nutrients, increasing the amount of plant and algae growth, leading to harmful algal blooms, dead zones, and fish kills

agricultural runoff (leaching) moves into local bodies of water, causing aggressive algae growth which covers the surface of the body of water, blocking light from aquatic plants, killing them