Biogeochemical Cycling - Chemical 14

Question 1

Describe the GAIA hypothesis

Answer 1

-J. Lovelock observed how earth is a closed system when it comes to matter –> earth is superorganism with limited resources

Question 2

from an evolutionary standpoint, what is the contribution of cyanobacteria to primary production today?

Answer 2

• initially produced the available oxygen in the atmosphere

- endosymbiotic theory ( clinical role)

Question 3

from an evolutionary standpoint, what is the contribution of cyanobacteria to primary production today?

Answer 3

• initially produced the available oxygen in the atmosphere

- endosymbiotic theory ( clinical role)

Question 4

are humans involved in biogeochemical cycling of nutirent ?

Answer 4

yes…

Question 5

give an example of the recycling of a nutrient by humans

Answer 5

• ## digestive system ( intake glucose and recycle into mineral CO2 and cell mass)

Question 6

give an example of the recycling of a nutrient by humans

Answer 6

• digestive system ( intake glucose and recycle into mineral CO2 and cell mass)
• mineralization of amino acids into urea

Question 7

What examples are there of loss of self-regulation and why ?

Answer 7

-global warming

Question 8

What examples are there of self-regulation of the superorganism?

Answer 8

-

Question 9

How has earth maintained conditions favorable for life?

Answer 9

-biogeochemical cycling helps maintain life

Question 10

what is an example of a unidirectional biogeochemical activity?

Answer 10

• evolution of the carbon cycle

- “ “ oxygen cyle

Question 11

what are stromatolites?

Answer 11

-microbial mats (layered cyanobacteria that are taken advantage by other evolved microorganisms;symtrophy) fosilized

Question 12

how did stromatolites form?

Answer 12

• the microbial mats are exposed to conditions that allow fossilisation ( symtrophic environment present)

Question 13

what might be a limiting factor to microbial growth rate with the evolution of oxygen production ?

Answer 13

-the development of a symtrophic cycles ( important cycles developed so that they can use resources)

Question 14

How is biomass in the oceans generated?

Answer 14

• accumulation of food chain

- -> phytoplankton< zooplankton< Predatory zooplankton< filter feeders < predatory fish < ect.

Question 15

what reaction drive biogeochemical cycling?

Answer 15

• physical transformations ( dissolution, precipitation, volatilization, fixation)
  ie. pH change, carbon dioxide reabsorption in ocean forming carbonates that are used to form coral, through fixation process the loss of material, nitrogen cycling
• chemical transformations ( biosynthesis and biodegradationi)
• sunlight and energy flow through the ecosystems is the driving forces

Question 16

Spirulina, what is it?

Answer 16

-blue green algae = cyanobacteria, filamentous

Question 17

what makes microbes good at geochemical reactions?

Answer 17

• they are super adaptable
• -> size and surface area
• ->ubiquity
• ->diversity (the ability to adapt metabolically)
• ->high rates of enzymatic activity (growth rate)

Question 18

what is the result of carbon fixation?

Answer 18

• net primary productivity of some natural and managed ecosystems

Question 19

consider evolution and the present day . what is the contribution of cyanobacteria to primary production today ?

Answer 19

-cyanobacterium theory

Question 20

how does carbon cycle within a habitat?

Answer 20

see slide

Question 21

what are the major carbon inputs into the environment?

Answer 21

lab 8

• plant materials (through photosynthesis)
• fungal cell walls/arthropods

Question 22

what role does the nitrogen cycle play in maintaining earths atmosphere?

Answer 22

• ## level of nitrogen is maintain based on the amount of other gases present in the atmosphere

Question 23

what are we doing in lab 5?

Answer 23

• amminia oxdiation( nitirification)
• nitrite oxidation (nitrification)
• nitrate reduction to ammnonium or nitrogen gas (denitrification)
• nitrate reduction to fixed N compounds like a.a ammonia annd amino groups (assimilation)
• ammonium mineralization (mineralization)

Question 24

what are we doing in lab 5?

Answer 24

• ammonia oxidation( nitrification)
• nitrite oxidation (nitrification)
• nitrate reduction to ammonium or nitrogen gas (denitrification)
• nitrate reduction to fixed N compounds like a.a ammonia and amino groups (assimilation)
• ammonium mineralization (mineralization)

Question 25

what kinds of results did we get in lab 5?

Answer 25

• growth is slow because little energy is produced in these reaction
• ## nitrate build up (nitrification)

Question 26

What does SNGDD indicate?

Answer 26

-nitrite presence
–>SNGDD reagent reactions with NO2-
if no reaction–> add zinc –> NO3–> no reaction indicates : been converted to N2

Question 27

negative stain and slime bacteria

Answer 27

• slime layer inhibits staining to bac

Question 28

what is the mienralization of urea important?

Answer 28

-produces forms of nitrogen that can be assimilated

Question 29

Other than high or low concentrations of ammonia, what other factor may be involved in whether Nitrogen is mineralized or assimilated?

Answer 29

• presence of [ nitrogen ]
• presence of other nutrients ( carbon, ) ie. C:N ratio greater then 20 = mineralization
  and less then 20 = assimilation

Question 30

why might bacteria need such a high c:n ratio to support biosynthetic reactions

Answer 30

you have a certain amount of carbon that does not end up as biomass ( only 40% of carbon is used to generate biomass)

Question 31

what is the fate of NO3-, following Nitrification ?

Answer 31

• it can accumulate if no leaching takes place
  -some will be retained
• some will assimilate
  and some will disassimilate