Chapter 35

Which statement best applies to plant micronutrients? a. They typically are not available in loams. b. They cannot be replaced by the use of fertilizers. c. They appear early on the periodic chart compared with macronutrients. d. They are required in large amounts for normal metabolism. e. They are essential for normal growth and development.

Nutrient runoff from fertilizing lush lawns often causes "algal blooms" in nearby lakes, making swimming impossible. The fertilizer components most likely to have caused the blooms are: a. iron, magnesium, and nitrogen. b. nitrogen, phosphorus, and sulfur. c. nitrogen, potassium, and phosphorus. d. selenium, magnesium, and potassium. e. nitrogen, magnesium, and nickel.

Which of the following processes contributes to the uptake of mineral ions by plant roots? a. chlorosis b. osmosis c. cation exchange d. anion leaching e. growth of root hairs

Which of the following does not influence soil pH? a. rainfall b. the outward expansion of root systems c. release of sulfur and nitrogen oxides into the air d. decomposition of organisms e. weathering of rock

Which of the following is a common process that makes usable nitrogen available to plants? a. nitrogen-fixing bacteria synthesizing nitrate b. ammonifying bacteria using ammonium to produce nitrate c. nitrifying bacteria converting \(\mathrm{NH}_{4}^{+}\) to \(\mathrm{NO}_{3}^{-}\) d. the direct absorption of \(\mathrm{NH}_{4}^{+}\) by root hairs e. the absorption of atmospheric \(\mathrm{N}_{2}\) into the xylem

The nod genes in the bacteria in soybean nodules allow the bacteria to fix nitrogen. Which of the following, if any, is not a step in this process? a. The products of nod genes cause cells of the root cortex to divide and become the root nodule in which bacteroids fix nitrogen for the plant. b. In the cortex cells bacteria enlarge and become immobile, forming bacteroids. c. Bacteria enter the root hair cell and multiply, causing the cell plasma membrane to form an infection thread that extends into the root cortex. d. Roots release flavonoid, which turns on the expression of bacterial nod genes. Products of nod genes cause the tip of the root hair to curl toward the bacteria. e. Root hairs trigger release of bacterial enzymes that break down root hair cell walls.

Being "carnivorous" is a plant adaptation mainly to obtain: a. oxygen. b. phosphorus. c. potassium. d. nitrogen. e. carbon.

Haustorial roots are characteristic of plants that are: a. parasites. b. epiphytes. c. nitrate fixers. d. leghemoglobin users. e. carnivorous.

Identify the correct match of a nutrient with its function. a. chlorine: component of several enzymes b. potassium: component of nucleic acids c. phosphorus: component of most proteins d. manganese: role in shoot and root growth e. calcium: maintenance of cell walls and membrane permeability

One effect of acid rain is to dissolve rock, liberating minerals into soil. Accordingly, can a case be made that acid rain confers environmental benefits, as well as doing harm? What are some other factors, especially with regard to plant adaptations for gaining nutrients, that bear on this question?

This chapter's Focus on Research: Applied Research discusses phytoremediation, the use of plants to remove environmental pollutants such as heavy metals. As noted, some plant species are hyperaccumulators that take up arsenic and other metallic contaminants and sequester such toxins in shoot parts. How might this activity confer a selective advantage?