11. A major plant macronutrient found in nucleic acids and proteins is

A. calcium
B. nitrogen
C. sulfur
D. iron

12. What is the metal-ligand in chlorophylls?

A. Copper (Cu)
B. Iron (Fe)
C. Magnesium (Mg)
D. Manganese (Mn)

13. Nitrosomonas and Nitrobacter obtain their carbon for growth from

A. organic compounds
B. carbon dioxide
C. elementary carbon
D. none of these

14. Chlorophyll is associated with

A. thylakoids
B. stroma
C. cristae
D. matrix

15. Organisms capable of converting N₂ to NO₃ are

A. yeasts
B. bacteria
C. roundworms
D. molds