35. Soil

How might roots react when they encounter a region of the soil that is low in nitrates?

The American Dust Bowl of the 1930s resulted from __________.

Soil can easily become deficient in __________ because these ions are negatively charged and do not stick to negatively charged soil particles.

The particles in soil are important because they __________.

Fertilizers are usually enriched in __________.

Which of the following would be considered a sustainable agricultural practice?

What is the goal of phytoremediation?

Why do farmers need to be concerned with the pH level of soil?

At low soil pH levels (5 or less), what can happen?

Phytoremediation is showing promise as a sustainable, cost-effective way to decontaminate soil and water. In the case of a hyperaccumulater such as Thlaspi caerulescens, however, what might be a drawback of the technology?

The biological process that produces 96% of the dry mass of a plant is called __________.

Which of the following substances does a plant obtain from the air?

A botanist claims to have discovered a new macronutrient required for plant growth. Most of this scientist's colleagues are skeptical of her claim. Why might they consider it unlikely?

If a plant's leaves are yellowing, it may be that the plant is deficient in the elements needed to make chlorophyll, one of which is __________.

If a plant is deficient in __________, it will not be able to make DNA.

Soil could be deficient in any of the following nutrients. If you had to supply one of them, which would be needed in the smallest amount?

Which of the following is a true statement regarding mineral deficiency symptoms in plants?

When you add "plant food" to your potted geraniums, what are you actually providing the plant with?

How did the addition of a gene for citrate synthesis increase the tolerance of tobacco and papaya plants to high aluminum concentrations in the soil?

What supplies the energy for most of the microorganisms in the rhizosphere?

Plants require the smallest amount of which of the following nutrients? a. oxygen b. phosphorus c. carbon d. iron

. A problem with intensive irrigation is (A) overfertilization. (B) aquifer depletion. (C) the long-term depletion of soil oxygen. (D) the clogging of waterways by vegetation debris.

An advantage of using fertilizers derived from natural sources is that these fertilizers a. have different minerals than artificial fertilizers. b. are retained in soil longer. c. are more soluble in water. d. are more concentrated.

If the apples you buy are labeled 'organic,' does that tell you anything about how they were grown? About the nutritional content of the apples?

Acid rain contains an excess of hydrogen ions (H+). One effect of acid rain is to deplete the soil of plant nutrients such as calcium (Ca2+), potassium (K+), and magnesium (Mg2+). Offer a hypothesis to explain why acid rain washes these nutrients from the soil. How might you test your hypothesis?

SCIENTIFIC THINKING One of the most important properties of proper scientific investigations is their repeatability. Yet, as discussed in Module 32.11, studies that compare the nutritional content of conventional and organic produce sometimes produce contradictory results. Name some possible confounding factors that can account for such uneven results.