ecology exam 4

Question 1

percent of carbon dioxide in the atmosphere

Answer 1

0.0410%

Question 2

industrial nitrogen cycle pathway

Answer 2

industrial N fixation in factories to plants utilizing from fertilizer to grow crops and fed to animals to us eating animal products to incorporating N to DNA

Question 3

natural nitrogen cycle pathway

Answer 3

nitrogen gas in air to N-fixing by lightning to non-N-fixing producers or nitrogen fixing producers like legumes or cyanobacteria to heterotrophs

Question 4

nitrogen gas back to air

Answer 4

from animals and n-fixing producers to ammonium compound in soil to nitrate compounds in soil bacterias through denitrification to n2 in the air

Question 5

biological nitrogen fixation

Answer 5

conversion of N2 to ammonium and nitrate by bacteria,

Question 6

nitrogen percentage in atmosphere

Answer 6

78.08%

Question 7

symbiotic N2 fixation

Answer 7

rhizobia, legume family, non-legumes (black alder, water fern), white clover - give plant nitrogen, grows a lot and has symbiotic relationship with n2 fixing bacteria

Question 8

non-symbiotic N2 fixation

Answer 8

free living bacteria in soil (azotobacter, clostridium), cyanobacteria in aquatic systems

Question 9

nitrogen transformation in soil

Answer 9

nitrification (aerobic), denitrification (anaerobic), ammonia volatilization (pH>7), nitrogen leaching (nitrate from soil to groundwater)

Question 10

human impacts on N cycling

Answer 10

too much N in agriculture, animal/food wastes improperly treated, cars, power plants all leads to high N in groundwater and increased atmospheric deposition

Question 11

oxygen percentage in atmosphere

Answer 11

20.95%

Question 12

major sources of O2 in atmosphere

Answer 12

photodissociation of H2O (photolysis) and photosynthesis

Question 13

ozone

Answer 13

pollutant - smog and damaging to life forms

sunscreen - prevent excessive UV rays from earth

Question 14

holes in ozone layer

Answer 14

caused by chemicals like CFCs increase rate of ozone depletion and lead to holes in stratospheric ozone layer

Question 15

bad ozone

Answer 15

occurs at ground level (troposphere), results from vehicles, industry emissions, also known as brown haze in and around large cities

Question 16

ozone production in stratosphere

Answer 16

UV breaks O2, free O molecules react with O2 to form O3

Question 17

natural ozone destruction

Answer 17

UV breaks ozone to O2 and O so free O bumps with O3 and forms two O2.

Question 18

chemicals that destroy ozone

Answer 18

CFCs (refrigerants, solvents, aerosols - anthropogenic), nitrous oxide (nitrogen fertilizers, sewage), methane (wetlands, landfills)

Question 19

CFCs depleting ozone

Answer 19

UV hits CFC, causes Cl to break away, Cl hits O3 and forms O2 and ClO, if a free O hits ClO, it will form O2 and free Cl, which goes on to destroy more O3

Question 20

nitrification

Answer 20

NH4+ -> NO2-

NO2- -> NO3-

Question 21

denitrification

Answer 21

NO3- -> N2

Question 22

ammonia volatilization

Answer 22

NH4+ + OH- -> NH3 + H2O

Question 23

how does N2O deplete ozone?

Answer 23

UV makes N2 and O, if O reacts with N2O, it forms N2 and O2 or 2 NO, and NO depletes O3 to make NO2 and O2

Question 24

ozone hole definition

Answer 24

where O3 concentration has decreased to <220 DU