Chapter 24 Part 2

Question 1

What are the 6 essential elements?

Answer 1

1) carbon
2) hydrogen
3) nitrogen
4) phosphorus
5) oxygen
6) sulfur

Question 2

Why is recycling of elements essential to life on earth?

Answer 2

Recycling of elements is needed for new life forms to continuously emerge

Question 3

What are the 5 general qualities of biogeochemical cycles?

Answer 3

1) elements originate from non-living reservoirs
2) elements cycle between the abiotic and biotic environments
3) recycling is necessary to maintain balance of nutrients
4) cycles depend on a variety of organisms, including producers, consumers, and decomposers
5) although all organisms participate in recycling, only microorganisms are capable of converting organic compounds into inorganic compounds

Question 4

Which element accounts for over half of the dry weight of living organisms?

Answer 4

Carbon

Question 5

What are the primary chemical reactions that cycle carbon?

Answer 5

Photosynthesis, respiration, and fermentation

Question 6

In reference to carbon, how are photosynthesis, respiration, and fermentation related to one another?

Answer 6

CO2 is the primary reactant for photosynthesis (input) and the product (output) for respiration and fermentation.

Question 7

What types of organisms are the primary photosynthesizers on earth?

Answer 7

Plants, algae, and Cyanobacteria

Question 8

By how much has the concentration of CO2 (in ppm) increased in the atmosphere since the industrial revolution?

Answer 8

280ppm to over 409 ppm or 40%

Question 9

What other atmospheric gas contributes to the greenhouse effect?

Answer 9

Methane (CH4)

Question 10

How much more effective at trapping heat is methane?

Answer 10

20x more effective

Question 11

What types of animals contribute 20% to this greenhouse gas?

Answer 11

Cows, goats, sheep

Question 12

What is the largest reservoir of nitrogen on earth?

Answer 12

The air

Question 13

What percent of the atmosphere is made up of oxygen?

Answer 13

20%

Question 14

Why is nitrogen essential for living organisms?

Answer 14

Essential for living organisms to synthesize nucleotides and amino acids

Question 15

Why is it that the majority of nitrogen on earth cannot be utilized by most organisms?

Answer 15

Most of it is in the form of N2 and it cannot be absorbed and incorporated into amino acids and nucleotides

Question 16

What is unique about “nitrogen-fixing bacteria”?

Answer 16

They convert “unusable” nitrogen into “usable” nitrogen

Question 17

What is the association between Rhizobia and legumes?

Answer 17

Symbiotic

Question 18

What benefit do Rhizobia and legumes have have on each other?

Answer 18

The bacteria converts nitrogen and provides it to the plants. Thus, fertilizing the plants. The plants give carbon-based nutrients to the bacteria and an isolated location for growth.

Question 19

What is the primary abiotic reservoir for phosphorus?

Answer 19

Rocks

Question 20

How is phosphorus removed from its reservoir?

Answer 20

Natural weathering of rocks and acids cause the release of phosphorus

Question 21

What is the primary limiting nutrient in the soil?

Answer 21

Phosphorus

Question 22

What is eutrophication?

Answer 22

The excessive richness of nutrients in a body of water