Chapter.29 Plant Nutrition And Soils Exam Questions nan

Chapter 29: Plant Nutrition and Soils

Multiple-Choice Questions

Which of the following is NOT an essential element?

a. molybdenum

b. copper

c. iron

d. aluminum

e. chlorine

A micronutrient is a plant nutrient required in concentrations equal to or less than ______ mg per kg of dry matter.

a. 1

b. 10

c. 100

d. 1000

e. 10,000

Which of the following is NOT a micronutrient?

a. zinc

b. copper

c. manganese

d. calcium

e. nickel

Which of the following statements concerning beneficial elements is FALSE?

a. Silicon is a beneficial element only for horsetails.

b. Sodium is a beneficial element for certain halophytes.

c. They are essential for most plants.

d. Aluminum is a beneficial element for the tea plant.

e. They are essential for plants grown only under specific environmental conditions.

Legumes grown in culture benefit from the addition of cobalt because the cobalt:

a. inhibits the growth of pathogenic bacteria.

b. stimulates cell division of the apical meristem.

c. stimulates the growth of root cells.

d. is required by mycorrhizae.

e. is required by symbiotic nitrogen-fixing bacteria.

Chlorosis refers to the:

a. localized death of tissues.

b. yellowing of leaves.

c. stunted growth of stems and leaves.

d. development of tumors.

e. healing of wounds.

In magnesium-deficient plants, older leaves become more severely chlorotic than younger leaves because:

a. magnesium is less phloem-mobile than chlorophyll.

b. magnesium is more phloem-mobile than chlorophyll.

c. younger leaves withdraw magnesium from older leaves.

d. older leaves withdraw magnesium from younger leaves.

e. magnesium is more mobile in younger leaves than in older leaves.

Which of the following is NOT a phloem-mobile element?

a. nitrogen

b. magnesium

c. phosphorus

d. potassium

e. iron

Humus consists mostly of:

a. living organic matter.

b. dead organic matter.

c. sand.

d. silt.

e. clay.

Which of the following statements about soil is FALSE?

a. The A horizon has the greatest physical, chemical, and biological activity.

b. The A horizon is the topsoil.

c. The B horizon is a region of deposition.

d. The B horizon is the subsoil.

e. The C horizon is part of the true soil.

Which of the following soils can hold the greatest amount of water against the action of gravity?

a. silt

b. loam

c. coarse sand

d. fine sand

e. clay

Field capacity is the:

a. total amount of water present in a one-hectare field after a soaking rain.

b. percentage of water that a soil can hold against the action of gravity.

c. percentage of water remaining in a soil when plants undergo irreversible wilting.

d. total amount of fertilizer required for maximal plant growth in a one-hectare field.

e. total amount of mineral nutrients present in a one-hectare field after a soaking rain.

The permanent wilting percentage is the percentage of:

a. colloidal particles remaining in the soil after a heavy rain.

b. colloidal particles that would cause irreversible wilting.

c. colloidal particles that would cause reversible wilting.

d. water remaining in a soil when irreversible wilting occurs.

e. water remaining in a soil when reversible wilting occurs.

An example of cation exchange is ______ replacing ______ on a clay particle.

a. H⁺; K⁺

b. H⁺; NO₃⁻

c. NO₃⁻; SO₄²⁻

d. OH⁻; SO₄²⁻

e. HCO₃⁻; Mg²⁺

Which of the following statements concerning iron is FALSE?

a. Iron in the soil is usually insoluble and thus unavailable to plants.

b. Iron ranks fourth in abundance among all elements on the surface of the Earth.

c. All plants use Strategy I for iron mobilization and uptake.

d. Phytosiderophores are iron-chelating compounds.

e. Iron in the soil is normally present in the oxidized (Fe³⁺) form.

Plants using Strategy II will utilize which of the following for iron mobilization and uptake?

a. a Fe²⁺ transporter

b. pores in the plasma membrane

c. the reduction of Fe³⁺ to Fe²⁺

d. proton pumps that acidify the rhizosphere

e. Fe³⁺-phytosiderophores

Which of the following ions is MOST likely to be precipitated in alkaline soils?

a. hydroxide

b. bicarbonate

c. sulfate

d. iron

e. potassium

Which of the following statements about nutrient cycles is FALSE?

a. They are also called biogeochemical cycles.

b. All nutrients recycled to the soil are available for plant use.

c. Some cycles involve the atmosphere.

d. Each element has a different cycle.

e. Macronutrients and micronutrients are recycled.

The chief reservoir of nitrogen is:

a. the soil.

b. the ocean.

c. living organisms.

d. dead organic material.

e. the atmosphere.

As dead organic materials are broken down by bacteria and fungi, the nitrogen not used by these organisms is released as ______ in a process called ______.

a. NH₄⁺; ammonification

b. NO₃⁻; nitrification

c. NO₂⁻; nitrification

d. N₂; denitrification

e. N₂O; denitrification

Nitrite is oxidized to nitrate by:

a. Nitrosomonas.

b. Nitrobacter.

c. ammonifying bacteria and fungi.

d. denitrifying bacteria.

e. plant roots.

Which of the following is(are) a product of denitrification?

a. NH₄⁺

b. NO₃⁻

c. NO₂⁻

d. N₂

e. Amino acids

Which of the following is NOT a way in which nitrogen is lost from an ecosystem?

a. harvesting of plants

b. soil erosion

c. burning of plants

d. leaching

e. nitrification

In the process of nitrogen fixation, ______ is converted to ______.

a. NH₄⁺; NO₃⁻

b. NO₃⁻; NO₂⁻

c. N₂; NO₂⁻

d. N₂; NO₃⁻

e. N₂; NH₄⁺

Which of the following statements about nitrogenase is FALSE?

a. It is an enzyme involved in nitrogen fixation.

b. It requires O₂ as a cofactor.

c. It appears to be similar in all organisms.

d. It contains molybdenum as one of its prosthetic groups.

e. It uses ATP as an energy source.

Rhizobia enter legumes by invading the:

a. seeds.

b. root hairs.

c. stems.

d. leaves.

e. flowers.

The direct role of flavonoids in nodule formation is to:

a. stimulate formation of infection threads.

b. stimulate cell wall degradation.

c. stimulate root-hair curling.

d. attract rhizobia.

e. activate the plant Nod genes.

The role of Nod factors is to:

a. stimulate the formation of infection threads.

b. stimulate root-hair curling.

c. activate the plant Nod genes.

d. activate the bacterial Nod genes.

e. activate the plant genes for nodule formation.

A symbiosome consists of:

a. bacterioids only.

b. bacterioids and the surrounding host membrane only.

c. bacteriods, host membrane, and curled root hair only.

d. bacteriods, host membrane, and nodule primordium only.

e. bacteriods, host membrane, cortical cells, and vascular tissues only.

A determinate nodule is different from an indeterminate nodule in that a determinate nodule:

a. is elongated.

b. is cylindrical.

c. is spherical

d. has a persistent meristem.

e. consists of several zones.

Which of the following statements about leghemoglobin is FALSE?

a. It acts as an O₂ carrier.

b. It buffers the O₂ concentration in nodules.

c. It is found in the cytosol of the bacteroid.

d. Its heme portion is produced by the bacteroid.

e. Its globin portion is produced by the plant.

The ______ symbiosis is an example of a nitrogen-fixing symbiosis that continues throughout the life cycle of the host.

a. legume-Rhizobium

b. legume-Bradyrhizobium

c. Azolla-Anabaena

d. Alnus-actinomycete

e. Ceanothus-actinomycete

Which of the following groups contains species that are nonsymbiotic, photosynthetic, nitrogen-fixing bacteria?

a. genus Azotobacter

b. genus Azotococcus

c. genus Beijerinckia

d. genus Clostridium

e. cyanobacteria

______ is the principal source of nitrogen available to crop plants.

a. Organic nitrogen

b. Nitrate

c. Ammonium

d. Glutamine

e. Glutamate

In soils where nitrogen is limiting, _____ is a major and direct source of nitrogen.

a. nitrate

b. ammonia

c. organic nitrogen

d. nitrite

e. N₂

In most herbaceous plants grown in nitrate-rich soil, the glutamine synthetase–glutamate synthase pathway occurs in:

a. leaf vacuoles.

b. leaf mitochondria.

c. leaf chloroplasts.

d. root mitochondria.

e. root plastids.

Which of the following is NOT a way in which the phosphorus cycle differs from the nitrogen cycle?

a. The phosphorus cycle has more steps.

b. The phosphorus cycle is not dependent on specific groups of microorganisms.

c. In the phosphorus cycle, the Earth’s crust is the primary reservoir of the element.

d. The phosphorus cycle does not involve a gaseous stage.

e. The phosphorus cycle involves the long-term weathering of rocks.

______ is one of the ways in which phosphorus is lost from terrestrial ecosystems.

a. Leaching

b. Evaporation

c. Burning

d. Recycling

e. The action of microorganisms

Which of the following is NOT a strategy utilized by plants for the uptake of phosphate from the soil?

a. rapid root growth

b. rapid lateral root growth

c. proliferation of root hairs

d. inhibition of extraradical hyphae

e. symbioses with arbuscular mycorrhizal fungi

Which of the following statements concerning cluster roots is FALSE?

a. They are portions of lateral roots.

b. They are bottlebrush-like.

c. They release phosphatases and protons.

d. They release large amounts of malate and citrate.

e. They are long-lasting.

The destruction of marshes and wetlands most notably affects the ______ stage of the nitrogen cycle.

a. ammonification

b. denitrification

c. nitrogen fixation

d. nitrification

e. assimilation

If a bag of fertilizer is labeled 5-10-6, then you know that the fertilizer contains:

a. 5% potassium.

b. 10% nitrogen.

c. 6% phosphorus.

d. 5% nitrogen.

e. 10% potassium.

Lime is added to soils in order to:

a. provide nutrients.

b. raise the pH.

c. remove excess salts.

d. provide ions for cation exchange.

e. kill insect pests.

Which of the following statements about hyperaccumulators is FALSE?

a. They are plants that are harmed by high concentrations of potentially toxic materials.

b. They may concentrate trace elements, radionucleides, and/or heavy metals.

c. They are being used in phytoremediation.

d. They may concentrate toxins to produce toxic foliage.

e. They include alpine penny cress and Arabidopsis halleri.

______ is the most common metal in soils and causes problems where the soil is acidic.

a. Lead

b. Cadmium

c. Zinc

d. Cobalt

e. Aluminum

True-False Questions

Plants can synthesize all their required amino acids and vitamins.

Nickel is an essential element for plant growth.

A beneficial element is one that is essential for limited groups of plants.

Deficiency symptoms of phloem-immobile elements such as potassium and nitrogen appear first in older leaves.

The C horizon of soil is also called the subsoil.

Loam soils, the best agricultural soils, contain sand, silt, and clay particles.

Wilted plants in a soil at its permanent wilting percentage will not recover even when placed in a humid chamber.

Clay particles have an excess of surface negative charges, and humus has an excess of positive charges.

Strategy I for iron mobilization and uptake involves the acidification of the rhizosphere by proton pumps.

In the process of ammonification, ammonium ions are used to form amino acids.

Nitrosomonas is the bacterium that is primarily responsible for oxidizing ammonia to nitrite.

The most common nitrogen-fixing bacteria are Rhizobium and Bradyrhizobium.

Bacteria that induce nodule formation in clover will also induce nodule formation in soybeans.

A single root hair may contain several infection threads.

A determinate nodule has a persistent meristem.

Leghemoglobin acts as an oxygen carrier.

Parasitic angiosperms such as mistletoe directly break down proteins in organic matter found in the soil.

Some nitrogen-fixing symbioses involve plants other than legumes.

Once present in the cell, ammonia is then incorporated into organic compounds via the glutamine synthetase–glutamate synthetase pathway.

Extraradical hyphae extend beyond the phosphorus-depletion zone of the root.

Cluster roots are usually found in plants that usually form mycorrhizae.

Exudative bursts are characteristic of cluster roots.

In desert ecosystems, nitrogen loss from the soil by leaching is negligible.

In most soils, most of the phosphorus is present in forms that are not available to the plant.

A bag of fertilizer labeled 20:10:5 contains 20% phosphorus.

Some plants accumulate toxins to such levels that their foliage becomes toxic.

Essay Questions

1. Essential Elements; p. 684; moderate

What three criteria are used to determine whether an element is essential to a plant?

2. Essential Elements; pp. 684–685; moderate

What is the difference between a micronutrient and a macronutrient? Name the macronutrients and micronutrients required by plants. What is the difference between an essential element and a beneficial element?

3. Functions of Essential Elements; p. 686; difficult

What is the relationship between the mobility of a nutrient in the phloem and the age of leaves in which deficiency symptoms first appear?

4. The Soil; pp. 689; moderate

Describe the differences between the A, B, and C horizons of soil.

5. The Soil; p. 691; moderate

Why is iron a problem in soils, and what are the two strategies by which plants solve this problem?

6. Nutrient Cycles; p. 692; moderate

Why are nutrient cycles also called biogeochemical cycles? In what way are such cycles “leaky”?

7. Nitrogen and the Nitrogen Cycle; pp. 692–693; difficult

Trace the pathway by which nitrogen is released from dead organic matter and converted to the form in which it is assimilated by plants. Name all the organisms involved.

8. Nitrogen and the Nitrogen Cycle; pp. 695–696; difficult

Describe the sequence of events in which a nitrogen-fixing root nodule is formed.

9. Nitrogen and the Nitrogen Cycle; pp. 697-698; moderate

Why is it important to regulate the O₂ concentration in a root nodule? How is this regulation achieved?

10. Phosphorus and the Phosphorus Cycle; pp. 700–701; moderate

Describe the steps in the phosphorus cycle. What are the major differences between the phosphorus cycle and the nitrogen cycle?

11. Human Impact on Nutrient Cycles and Effects of Pollution; pp. 701–702; moderate

In what ways have humans upset the recycling of both nitrogen and phosphorus in ecosystems?

12. Plant Nutrition Research; pp. 705-706; difficult

What is hyperaccumulation? Discuss the advantages and disadvantages associated with this process.