Lecture 11

Question 1

All nutrient cycles are linked to the _______ cycle, but nitrogen is very closely linked because nitrogen and _____ are ________.

Answer 1

Carbon, Carbon, macronutirents

Question 2

While the ______ and rocks in the Earth’s crust are the
largest carbon reservoir, CO2 in the atmosphere is the _____
_____ _____ carbon reservoir.

Answer 2

sediments, most rapidly transferred

Question 3

CO2 is removed from the atmosphere by ________ land
plants and marine microbes, so a large amount of carbon is
found there.

Answer 3

photosynthetic

Question 4

More carbon is found in humus, or _____ organic material, than is found in the living organisms in a region.

Answer 4

dead

Question 5

CO2 is returned to the atmosphere by _______ and ________ as well as by human-related (anthropogenic) activities.

Answer 5

respiration, decomposition

Question 6

Photosynthesis

Answer 6

CO2 + H2O (CH2O) + O2

Question 7

Respiration

Answer 7

(CH2O) + O2 CO2 + H2O

Question 8

The two major end products of decomposition are ____ and _____.

Answer 8

methane (CH4) and carbon dioxide (CO2 ).

Question 9

form when high levels of methane are under high pressure and low temperature

Answer 9

Methane hydrates

Question 10

Methane hydrates fuel deep-sea ecosystems called

Answer 10

cold seeps

Question 11

_______ is central to carbon cycling in anoxic environments.

Answer 11

Methanogenesis

Question 12

Most ______ use carbon dioxide as a terminal electron acceptor, reducing CO2 to CH4 with H2 as an electron donor; some can reduce other substrates (e.g., acetate) to form CH4.

Answer 12

methanogens

Question 13

Methanogens team up with partners (______) that supply them with necessary substrates.

Answer 13

syntrophs

Question 14

Nitrogen exists in a number of ____ states.

Answer 14

oxidation

Question 15

Four major nitrogen transformations

Answer 15

• nitrification
• denitrificatoin
• anammox
• nitrogen fixation

Question 16

N2 is abundant but not _____ ______

Answer 16

biologically available

Question 17

Nitrogen fixatoin is only done by_____

Answer 17

bacteria

Question 18

_____ is the anaerobic oxidation of ammonia to N2 gas.

Answer 18

Anammox

Question 19

________ and ______ result in losses of organic nitrogen from the biosphere.

Answer 19

Denitrification and anammox

Question 20

The _____ process is dependent on natural gas

Answer 20

Haber process

Question 21

slide 15, 16,

Question 22

Nitrogen fixaton has ___ round of reduction per N2.

Answer 22

4

Question 23

____ _____ consumed for each N2 fixed

Answer 23

40 ATPs

Question 24

Anaerobic ______ make NH3

Answer 24

heterocysts

Question 25

Glutamine donates NH3 to make other amino acids

Answer 25

Transamination

Question 26

The steps of nitrogen fixation

Answer 26

1. slide 17
   2.
   3.
   4.

Question 27

Incorporation of NH4+ into amino acids

Answer 27

Nitrogen assimilation

Question 28

2nd species oxidizes NO2- to NO3-

Answer 28

Nitrobacter

Question 29

species oxidizes NH4+ to NO2-

Answer 29

Nitrosomas

Question 30

_____ of streams comes from excess nutrients and growth

Answer 30

Eutrophication

Question 31

NO3- -> NO2- -> NO -> N2O -> N2

Answer 31

Dissimilatory nitrate reduction

Question 32

The bulk of sulfur on Earth occurs in sediments and rocks as ___ and ____ minerals (e.g., gypsum, pyrite).

Answer 32

sulfate and sulfide

Question 33

The ___ represent the most significant reservoir of sulfur (as sulfate) in the biosphere.

Answer 33

oceans

Question 34

slide 23 pic, memorize

Question 35

flide 12 pic memorize

Question 36

is a major volatile sulfur gas that is produced by bacteria via sulfate reduction or emitted from geochemical sources.

Answer 36

Hydrogen sulfide

Question 37

is toxic to many plants and animals and reacts with numerous metals.

Answer 37

Sulfide

Question 38

The most abundant organic sulfur compound in nature is ____ _____.

Answer 38

dimethyl sulfide (DMS).

Question 39

On Earth’s surface, iron exists naturally in two oxidation states.

Answer 39

ferrous (Fe2+) and ferric (Fe3+).

Question 40

____ is soluble but tends to rust (______) and become _____, which is not soluble.

Answer 40

Ferrous (2+), oxidize, ferric (3+)

Question 41

Memorize slide 27 pic cycle

Question 42

Phosphorus is a typical ____ ____ that limits the growth of aquatic photosynthetic autotrophs.

Answer 42

limiting nutrient

Question 43

Calcium cycle _____ are rocks and oceans

Answer 43

reservoirs

Question 44

The marine silica cycle is controlled by unicellular eukaryotes that build cell skeletons called ______.

Answer 44

frustules

Question 45

Examples of frustules

Answer 45

• diatoms
• silicoflagellates
• radiolarians

Question 46

Mercury is not harmful, but ____ ___ is. It is dangerous because it can _________.

Answer 46

mythyl mercury, bioaccumulate