The Nitrogen Cycle: ‘Out of Thin Air’
Natural History magazine, September 2001
Use the marginal numbers to help you read and answer these questions.
1
What is the most common gas in our atmosphere?
What is its chemical formula?
How did the earliest forms of life (early bacteria) get their nitrogen?
What is the chemical form of this nitrogen?
What does it say drove (caused) the evolution of ‘nitrogen-fixing microbes’?
2
What two nutrients can cyanobacteria capture for the rest of living things to use?
List three environments in which nitrogen-fixing bacteria are known to live.
What is ‘nitrogenase’? (please don’t write ‘a large molecule’!)
3
What bond is nitrogenase trying to separate?
4
What enables some plants (beans, peas, alfalfa) to live in soil where most plants would not survive?
(4, cont)
What is the genus of the type of bacteria that live inside the roots of these plants?
5.
What are ‘flavinoids’?
Describe the relationship between the bacteria and the plant as described in this section:
6
What was the Nobel Prize in Chemistry awarded for in 1918?
7
What is the importance of ‘leghemoglobin’ made by a plant?
8
In what way are bacteria in the genus Frankia similar to those in the Rhizobium genus?
9
How could global warming benefit farmers re-nitrogen levels in their fields?
10
How do decomposers get their nitrogen?
11
Why do you think rising fuel prices (oil, e.g.) are driving up the cost of fertilizers?
(It cost Laurie over $400 in fertilizer to produce about $750 worth of hay last year)
How is this related to promoting people choosing to eat less meat?
12
List some of the problems of nitrogen runoff:
What are some of the solutions to applying excess nitrogen? (A farmer, e.g. Laurie, would never chose to buy and spread more than is needed)