Chapter 13 Study Questions
- What is the source of NH4+ in plant cells? Explain how NH4+ can be toxic to cells. How is this toxicity avoided?
- Nitrogen is taken up as NO3– by roots and converted first into NO2–, and then to NH4+, and the amide nitrogen of glutamine. What are the main enzymatic steps of this assimilatory process? How much ATP is consumed, and in which steps?
- Explain the symbiotic association between higher plants and nitrogen-fixing bacteria, and provide an example of this type of association.
- What are the Nod factors? Describe the genes involved in their production.
- What are the main enzymatic steps mediating the assimilation of sulfate? What is sulfate activation? Why is it necessary for the assimilation of sulfate into organic compounds?
Textbook Reference: Nitrogen in the Environment, pp. 355–356; Ammonium Assimilation, p. 358
Textbook Reference: Nitrate Assimilation, pp. 356–360
Textbook Reference: Biological Nitrogen Fixation, pp. 360–367
Textbook Reference: Biological Nitrogen Fixation, pp. 364–365
Textbook Reference: Sulfur Assimilation, pp. 367–369