18

Question 1

Biggest source of nitrogen in the nitrogen cycle?

Answer 1

From the atmosphere (3,900,000,000) g (Tg)/year.

Question 2

Ways to break N2 gas? 3•

Answer 2

•Lightning
•Biological N fixation
•Industrial N fixation (fossil fuels)

Question 3

Are humans faster/slower at fixing nitrogen compared to natural nitrogen fixation?

Answer 3

Faster

Question 4

Hager-Bosch process?

Answer 4

Fixes ammonia from atmospheric nitrogen to use as fertilizer.

Question 5

What is one important way N-fixation is increased by humans?

Answer 5

By planting a lot of N-fixing crops that carry nodules that contain N-fixing bacterial.

Question 6

Biogeochemical sink?

Answer 6

Large input -> pool increases -> small output

Question 7

Biogeographical source?

Answer 7

Small input -> pool decreases -> large output

Question 8

As nutrients leave from outputs, where does it go?

Answer 8

To inputs in another pool since finite # of elements.

Question 9

How does human agriculture and land conversion increase/decrease the amount of biologically reactive N entering the atmosphere?

Answer 9

Increasing

Question 10

!!!!Nitrogen deposition?

Answer 10

When nitrogen enters a pool.

Question 11

Nitrification?

Answer 11

When ammonium enters an organism (bacteria) that converts it into nitrate.

Question 12

!!!!Denitrification?

Question 13

Process of eutrophication? 5•

Answer 13

•Excessive nutrients from fertilizer are washed or leached into lakes and rivers.
•Algae, Cyanobacteria, or plants overgrow (sometimes toxic)
•Surface algae block out light, killing macrophages/submerged plants
•Decoomposers consume dead plants and algae, using lots of oxygen (creates hypoxia)
•Fish and other animals run out of oxygen and die.

Question 14

In some ecosystems, species richness increase/decline with increasing N pollution?

Answer 14

Decline

Question 15

Most of the nitrogen comes from?

Answer 15

Decomposed remains of other organisms

Question 16

Which plays a greater role in nitrogen and phosphorus cycles: internal or external cycling?

Answer 16

Internal cycling

Question 17

What factors speeds up decomposition? 2•

Answer 17

•Moist environments (but not too wet)
•warmer temperatures.

Both increase NPP, and decomposition rate is a parameter of NPP.

Question 18

Decomposition rate gradient goes?

Answer 18

Highest in tropics to lower in temperate zones.

Question 19

What determines the relative amounts of nutrients in organisms? The two hypothesis 2•

Answer 19

H1: determined by concentrations in the environment
H2: Determined by the relative ratios of cellular components

Question 20

Primary producers can change their cellular and body composition of nutrients based on?

Answer 20

Ratios from the environment.