more nuts

Question 1

photosynthesis limited by what nutrients

Answer 1

mostly N or P
but sometimes S, Si or Fe

Question 2

most common form of nitrogen in atmosphere

Answer 2

N2

Question 3

inorganic forms of nitrogen

Answer 3

nitrate NO3-
ammonium NO4+
nitrite NO2-
nitrous oxide N2O

Question 4

organic forms of nitrogen

Answer 4

amino acids, nucleic acids, proteins, urea
dissolved and particulate forms

Question 5

fish, insects and mammals can only consume ____ nitrogen

Answer 5

organic

Question 6

aquatic plants get most of their nitrogen through roots or leaves?

Answer 6

roots

Question 7

primary producers love ______ (form of inorganic nitrogen), why?

Answer 7

ammonium because it’s less energy to process

Question 8

cyanobacteria fix nitrogen in certain situations. why

Answer 8

to fix nitrogen, use enzyme nitrogenase which is very energetically exhausting to use so they prefer not to use it unless absolutely necessary

Question 9

nitrogenase is inactivated by _____. what do bacteria have to get around this neucence?

Answer 9

oxygen
use special heterocyst cells to protect enzyme from oxygen

Question 10

nitrification in one senteance

Answer 10

oxidize ammonium to nitrate
NH4+ -> NO3-

Question 11

nitrification requirements

Answer 11

specific bacteria for ammonium and nitrate oxidation
oxygen must be present

Question 12

denitrification in one sentence

Answer 12

reduce nitrate to N2

Question 13

______ removes inorganic nitrogen from water

Answer 13

denitrification

Question 14

phosphorus dominant form

Answer 14

phosphate (PO4)-3

Question 15

how does phosphorus appear in water

Answer 15

breaking down rocks

Question 16

organic phosphorus forms

Answer 16

lipids, nucleic acids

Question 17

in oxic environment, phosphate is typically

Answer 17

bound to iron and not bioavailable

Question 18

in anoxic conditions, phosphate is typically

Answer 18

freely floating (not bound to iron) and available

Question 19

sulfur cycle is driven by

Answer 19

redox states that sulfur can exist as

Question 20

abundance of silicon in water depends on ________. give an example of an environment with high si and low si

Answer 20

geology/weathering

high silicon near volcano
low silicon near limestone area

Question 21

diatoms love silicon because

Answer 21

use it to make frustules (specialized cell wall)

Question 22

what is the dominant form of iron in oxic and anoxic conditions

Answer 22

oxic = Fe3+
anoxic = Fe2+

Question 23

trace metals important to life but toxic if…

Answer 23

present in ridiculously high amounts

Question 24

lots of Si movement into water during which season. why?

Answer 24

spring and fall because lots of runoff at this time

Question 25

describe how sulfur influences phosphate bioavailability

Answer 25

competition between S and P for Fe. but S has stronger binding affinity to Fe, so it outcompetes P.

only occurs in anoxic conditions because when oxygen present, Fe is always bound to oxygen. so when no oxygen around, Fe is free to bind to either ((S)) or P