13. What is the main cause of iron deficiency?
(A) Not enough iron in the soil；
(B)High soil pH causing precipitation；
(C)Too much iron；
(D) Anaerobic edaphic conditions

9. What is the main form of sulfur taken up by plants through their roots? (A) Sulfur dioxide；(B)Sulfite；(C) Sulfate； (D) Glutathione

10. In which organic molecule is sulfur first assimilated? (A) Sulfite；(B)Sulfate；(C) Adenosine 5' phosphosulfate； (D) Cysteine

11 . Which strategy is employed by grass plants to take up iron from soil? (A)Transport of free ferrous ions (Fe2+, reduced form) (B)Transport of free ferric ions (Fe3+, oxidized form) (C) Secretion of chelators, called phytosiderophores, and uptake of ferric chelates (D)Secretion of chelators, called phytosiderophores, and uptake of ferrous chelates

複選題12. What is the main cause of magnesiun deficiency in plants? (A) Not enough magnesium in the soil (B) High soil pH causing precipitation (C) Competition with other ions, and protons at acidic pH (D) Low bioavailability

14. A plant that can survive with very high concentration of metals in its tissues is called: (A) A halophyte；(B)An byperaccumulator；(C) A chelator； (D) A calcicole plant

15. What is the main visual symptom of iron deficiency in plants? (A)Anemia；(B)Interveinal chlorosis；(C) Accumulation of anthocyanin； (D) Increased plant size

16. What happens to the major portion of phosphate fertilizers applied to rice crops? (A) Phosphate precipitates and becomes unavailable. (B)Rain provokes the leaching of phosphate into underground water, causing eutrophication. (C) Rice plants take up and store phosphate it in their grains. It is then removed from the field when the grains are harvesteD. (D) 85% of the phosphate is not taken up by plants and stays trapped in phytates in the soil.

17. What are the properties of the SPDT transporter characterized in this article? (A)SPDT is expressed in the roots and it mediates phosphate uptake from the soil. (B)SPDT is expressed in the seeds and controls phosphate storage in the husk. (C) SPDT is expressed in the nodes and control phosphate the whole-plant phosphate distribution. (D) SPDT transports phosphate into leaves, thereby decreasing transport to the seeds.

18. How does SPDT protein performs its function? (A) It is a vacuolar transporter that store the phosphorus inside cells. (B)It is a plasma-membrane transporter that load phosphorus into the xylem. (C) It is a plasma membrane transporter that transport the phosphorus out of the xylem. (D) It is a plasma membrane transporter that mediates phosphorus uptake into leaf cells.

19. Phosphorus is an important nutrient. Why is it not better to have more in the rice grains? (A) Too much phosphorus will become toxic for animals and humans who cat the grains. (B)Phosphorus is stored as phytate in rice grains, and phytate is not bioavailable to humans and animals. (C) Animals do not need phosphorus, only plants do. (D) More phosphorus in the grains means that less fertilizers are useD.