Test Bank nan Chapter.24 The Root Structure And Development

Chapter 24: The Root: Structure and Development

Multiple-Choice Questions

1. Introduction; p. 558; easy; ans; b

When a seed germinates, the __________ is the first structure to emerge.

a. plumule

b. root

c. hypocotyl

d. epicotyl

e. cotyledon

The two primary functions of roots are:

a. conduction and protection.

b. storage and conduction.

c. anchorage and storage.

d. anchorage and absorption.

e. anchorage and conduction.

Which of the following statements concerning roots is FALSE?

a. Some roots produce buds.

b. Some roots store food.

c. Some roots synthesize nicotine.

d. Some roots synthesize cytokinins.

e. Some roots contain an internal rhizosphere.

The rhizosphere is the volume of:

a. nitrogen-fixing bacteria surrounding the root.

b. soil around the root.

c. mucilage secreted by the root.

d. root hairs plus mucilage.

e. rootcap cells released from the root.

In gymnosperms and eudicots, the primary root is called the:

a. fibrous root.

b. prop root.

c. lateral root.

d. taproot.

e. branch root.

Which of the following statements about monocot roots is FALSE?

a. The root system is generally shallower than in eudicots.

b. The main root system has one prominent root.

c. The roots form a fibrous root system.

d. The main root system develops from roots arising from the stem.

e. The primary root is short-lived.

Which of the following statements about feeder roots is FALSE?

a. They are usually found in the lower 15 centimeters of soil.

b. They are actively engaged in water uptake.

c. They are actively engaged in nutrient uptake.

d. They can be heavily infected with mycorrhizal fungi.

e. They are also called fine roots.

After you transplant a shrub, which of the following is the more effective next step you should do to increase the chances that the shrub will survive?

a. Add fertilizer.

b. Add weed killers.

c. Cut back the fine roots.

d. Cut back the lateral roots.

e. Cut back the shoot.

Which of the following statements about the rootcap is FALSE?

a. It secretes mucilage.

b. Its peripheral cells are released as it grows through the soil.

c. Its peripheral cells are not replaced.

d. It helps the root penetrate the soil.

e. It protects the root apical meristem.

Which of the following statements about border cells is FALSE?

a. They are the peripheral cells of the root cap.

b. They are programmed to separate from the root cap and from each other.

c. They remain alive in the soil as individual cells.

d. They protect the apical meristem from infection.

e. They produce a similar array of proteins during their lifetime.

Gravity- and water-potential gradients are perceived by the:

a. root apical meristem.

b. root hairs.

c. columella.

d. lateral rootcap.

e. border cells.

The promeristem of the root:

a. is composed of initials but not derivatives.

b. is the most distal part of the apical meristem.

c. is the most determined part of the apical meristem.

d. is characterized by few-sided cells with nondense cytoplasm.

e. is composed of relatively large cells with small nuclei.

In a “closed type” of root apical organization, the:

a. apical meristem lacks derivatives.

b. cortex and vascular cylinder each have their own initials, but the rootcap and epidermis do not.

c. cortex and rootcap each have their own initials, but the vascular cylinder and epidermis do not.

d. rootcap, vascular cylinder, and cortex each have their own initials.

e. rootcap, vascular cylinder, and cortex have common initials.

Which of the following statements about the quiescent center is FALSE?

a. It is located a short distance behind the apical meristem.

b. It may play an important role in the organization and development of the root.

c. It is a region that was mitotically active early in root development.

d. It is a relatively inactive region of the mature root apical meristem.

e. Quiescent centers isolated from maize can form whole roots in culture without first forming callus.

The sequence of regions in a growing root, beginning immediately behind the rootcap, is:

a. elongation, maturation, cell division.

b. cell division, maturation, elongation.

c. cell division, elongation, maturation.

d. elongation, cell division, maturation.

e. maturation, elongation, cell division.

Root hairs are produced in the:

a. region of cell division.

b. region of elongation.

c. region of maturation.

d. quiescent center.

e. area between the regions of cell division and elongation.

Protophloem and protoxylem mature in the:

a. region of cell division.

b. region of elongation.

c. region of maturation.

d. quiescent center.

e. area between the regions of cell division and elongation.

The ______ occupies the greatest area of the primary root.

a. epidermis

b. xylem

c. phloem

d. pericycle

e. cortex

Aerenchyma is found in the:

a. cortex.

b. pericycle.

c. phloem.

d. xylem.

e. epidermis.

Substances moving through the root cortex:

a. follow a symplastic pathway only.

b. follow an apoplastic pathway only.

c. follow both symplastic and apoplastic pathways.

d. are unable to travel via cell walls.

e. are unable to pass through plasmodesmata.

The innermost layer of the cortex is the:

a. pericycle.

b. xylem.

c. epidermis.

d. endodermis.

e. pith.

Which of the following statements about Casparian strips is FALSE?

a. They are found in the anticlinal walls of endodermal cells.

b. They are permeable to water but not to ions.

c. They are band-like portions of the cell wall and middle lamella.

d. They contain suberin.

e. The do not contain plasmodesmata.

The presence of Casparian strips forces substances entering and leaving the vascular cylinder to pass through the protoplasts of ______ cells.

a. endodermal

b. epidermal

c. pericycle

d. xylem

e. phloem

Suberin lamellae, such as those found in some older roots, are alternating layers of:

a. lignin and cellulose.

b. cellulose and wax.

c. suberin and wax.

d. suberin and lignin.

e. suberin and cellulose.

Endodermal cells that do not become suberized in older roots are called ______ cells.

a. epidermal

b. exodermal

c. Casparian

d. transfer

e. passage

Which of the following statements about the exodermis is FALSE?

a. It apparently reduces water loss from the root.

b. It may contain cellulose.

c. It contains suberin lamellae.

d. It contains Casparian strips.

e. It is part of the epidermis.

The outermost layer of a root’s vascular cylinder is the:

a. pericycle.

b. protoxylem.

c. metaxylem.

d. phloem.

e. endodermis.

At the center of most eudicot roots is:

a. pith.

b. protoxylem.

c. metaxylem.

d. pericycle.

e. air.

The protoxylem poles are located next to the:

a. pith.

b. cortex.

c. pericycle.

d. exodermis.

e. endodermis.

Primary phloem is located between the:

a. epidermis and cortex.

b. endodermis and pericycle.

c. xylem and pith.

d. xylem ridges.

e. exodermis and endodermis.

In the center of maize roots is:

a. xylem.

b. a pith.

c. an endodermis.

d. a pericycle.

e. aerenchyma.

The vascular cambium is initiated by cells:

a. of the pericycle.

b. of the endodermis.

c. in the center of the vascular cylinder.

d. opposite the protoxylem poles.

e. between the primary xylem and primary phloem.

In roots, the vascular cambium arises from the:

a. procambium only.

b. endodermis only.

c. pericycle only.

d. procambium and pericycle only.

e. procambium, endodermis, and pericycle.

As the vascular cambium continues to divide during secondary growth of the root, most of the primary phloem:

a. is crushed.

b. is pushed inward.

c. remains where it was produced.

d. differentiates into pericycle.

e. differentiates into xylem.

In roots, cork cambium arises in the:

a. procambium.

b. phloem.

c. xylem.

d. endodermis.

e. pericycle.

Immediately inside the cells of the cork cambium is:

a. cork.

b. cortex.

c. phelloderm.

d. endodermis.

e. pericycle.

If you placed your hand on the outer surface of a root that is one meter in diameter, you would be touching:

a. epidermis.

b. cork.

c. phelloderm.

d. proliferated pericycle.

e. cortex.

In a woody root one meter in diameter, which tissue would NOT be present?

a. primary xylem

b. secondary xylem

c. secondary phloem

d. epidermis

e. cork

In angiosperms, cells of the ______ and the ______ contribute to lateral root formation.

a. endodermis; pericycle

b. epidermis; pericycle

c. epidermis; endodermis

d. pith; cortex

e. primary phloem; secondary phloem

A stilt root is an example of a(n):

a. aerial root.

b. air root.

c. pneumatophore.

d. storage root.

e. valamen.

A pneumatophore is:

a. produced by below-ground structures.

b. negatively gravitropic.

c. produced by trees growing in dry habitats.

d. produced by trees growing in well-drained soil.

e. also called an aerial root.

Velamen is a(n):

a. multiple epidermis.

b. multiple cortex.

c. epiphyte.

d. pneumatophore.

e. enzyme produced by lateral roots.

Which of the following statements about supernumerary cambia in sugarbeet roots is FALSE?

a. They are types of additional cambia.

b. They are arranged in concentric rings.

c. They produce storage parenchyma.

d. They produce phloem toward the inside and xylem toward the outside.

e. They are responsible for most of the increase in thickness.

True-False Questions

The root systems of eudicots are well suited to preventing soil erosion.

An example of the developmental plasticity of roots is the rapid development of lateral roots into nutrient-rich soil.

In most trees, 10 percent of their roots are located in the upper 2 feet of soil.

If “fine roots” are damaged or destroyed, they cannot be replaced.

In seedlings, the total water- and mineral-absorbing surface of the roots usually exceeds the photosynthesizing surface of the leaves and stem.

Cells of the root cap columella secrete a highly hydrated polysaccharide called mucilage.

Border cells undergo programmed cell death immediately after being separated from the root.

The lateral rootcap receives gravity.

In an “open type” of root apical meristem, all regions arise from one group of initials.

The quiescent center contains cells that cease to divide when bordering meristematic cells are injured.

Casparian strips are located in the anticlinal walls of endodermal cells.

All substances entering the vascular cylinder must pass through living cells of the endodermis.

The endodermis is found in the outermost layer of cells of the cortex.

The terms “diarch” and “triarch” refer to the number of xylem ridges in a root’s vascular cylinder.

Most monocot roots lack secondary growth.

In roots, cells of the pericycle contribute to the vascular cambium.

The vascular cambium of roots produces secondary xylem toward the outside and secondary phloem toward the inside.

In roots, cells of the pericycle contribute to the cork cambium.

The cork cambium produces phelloderm toward the outside and cork toward the inside.

Lenticels are found in the periderm and permit the passage of air.

Most likely epidermis would be present in a 10-year-old woody root.

Lateral roots originate from cells of the vascular cambium.

Prop roots are types of lateral roots common in tropical trees.

Sweet potato roots have a single vascular cambium that produces storage parenchyma.

Essay Questions

1. Introduction; pp. 558–559; easy

Discuss the various functions of roots.

2. Root Systems; p. 559; easy

Distinguish between the root systems of monocots and those of eudicots.

3. Origin and Growth of Primary Tissues; pp. 560-562; moderate

List the functions of the rootcap.

4. Origin and Growth of Primary Tissues; p. 562; moderate

Compare and contrast open and closed types of root apical organization.

5. Origin and Growth of Primary Tissues; pp. 562-563; difficult

What is a quiescent center? Explain how a quiescent center can be inactive under certain conditions but active under others.

6. Origin and Growth of Primary Tissues; pp. 563-564; moderate

List the three growth regions of the root, and describe the events that are characteristic of each. Give examples to show that the regions are not sharply delimited.

7. Primary Structure; pp. 564–569; moderate

Trace the movement of an ion from the soil to the center of a root, listing all tissues through which the ion must pass.

8. Primary Structure; p. 565; moderate

Describe the composition and precise location of Casparian strips.

9. Primary Structure; pp. 565–568; difficult

Explain the role of the endodermis in regulating the movement of substances into and out of the root’s vascular cylinder. How does the structure of the endodermis change over time?

10. Primary Structure; p. 569; moderate

What is the pericycle? What are some of its functions?

11. Effect of Secondary Growth on the Primary Body of the Root; pp. 569–570; difficult

Describe the process by which the activity of the vascular cambium results in an increase in root diameter.

12. Origin of Lateral Roots; p. 571; difficult

Describe the process by which lateral roots arise. What is the advantage for the plant of lateral roots arising endogenously rather than exogenously?

13. Aerial Roots and Air Roots; pp. 572, 573; moderate

What is the difference between an aerial root and an air root? Give some examples of each.

14. Adaptations for Food Storage: Fleshy Roots; pp. 573–575; moderate

Describe some of the adaptations for food storage in roots.