Question 1
What is the source of the acidic pH of some mine runoff?
◦ Pyrite is oxidized by exposure to the atmosphere and microbes.
◦ Iron ores are reduced by exposure to the atmosphere.
◦ Iron ores contain sulfuric acid (H
2SO
4).
◦ Hydrogen gas trapped in ore reacts with the atmosphere to produce hydrochloric acid (HCl).
◦ Sulfur-containing ores are reduced by exposure to oxygen.
Question 2
Which of the following statements concerning the phosphorus cycle in bacteria is TRUE?
◦ It is the most important process for synthesizing proteins and nucleic acids.
◦ The element alternates among several oxidative states.
◦ The element cycles between different organic molecules.
◦ The element is converted to a gaseous state and is lost to the environment.
◦ The element changes from insoluble to soluble forms.
The sulphur cycle.
Menstrual cycle
Ovulation Process The two ovaries alternate ovulation in each monthly cycle.
Example of a cycle billing schedule.
Reactions of the Krebs cycle.
Citric acid cycle intermediates