Deck 24: The Root: Structure and Development

Question 1

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

A) fibrous root.
B) prop root.
C) lateral root.
D) taproot.
E) branch root.

Answer 1

D

Question 2

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

A) root apical meristem.
B) root hairs.
C) columella.
D) lateral rootcap.
E) border cells.

Answer 2

D

Question 3

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.

Answer 3

E

Question 4

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.

Question 5

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.

Question 6

The innermost layer of the cortex is the:

A) pericycle.
B) xylem.
C) epidermis.
D) endodermis.
E) pith.

Question 7

Aerenchyma is found in the:

A) cortex.
B) pericycle.
C) phloem.
D) xylem.
E) epidermis.

Question 8

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.

Question 9

The ______ occupies the greatest area of the primary root.

A) epidermis
B) xylem
C) phloem
D) pericycle
E) cortex

Question 10

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.

Question 11

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.

Question 12

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.

Question 13

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.

Question 14

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.

Question 15

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.

Question 16

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.

Question 17

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.

Question 18

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.

Question 19

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.

Question 20

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.

Question 21

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.

Question 22

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

Question 23

The protoxylem poles are located next to the:

A) pith.
B) cortex.
C) pericycle.
D) exodermis.
E) endodermis.

Question 24

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.

Question 25

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.

Question 26

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

Question 27

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.

Question 28

In roots, cork cambium arises in the:

A) procambium.
B) phloem.
C) xylem.
D) endodermis.
E) pericycle.

Question 29

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.

Question 30

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.

Question 31

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

Question 32

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

A) aerial root.
B) air root.
C) pneumatophore.
D) storage root.
E) valamen.

Question 33

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.

Question 34

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

A) pericycle.
B) protoxylem.
C) metaxylem.
D) phloem.
E) endodermis.

Question 35

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.

Question 36

In the center of maize roots is:

A) xylem.
B) a pith.
C) an endodermis.
D) a pericycle.
E) aerenchyma.

Question 37

At the center of most eudicot roots is:

A) pith.
B) protoxylem.
C) metaxylem.
D) pericycle.
E) air.

Question 38

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

A) epidermal
B) exodermal
C) Casparian
D) transfer
E) passage

Question 39

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.

Question 40

Immediately inside the cells of the cork cambium is:

A) cork.
B) cortex.
C) phelloderm.
D) endodermis.
E) pericycle.

Question 41

The terms "diarch" and "triarch" refer to the number of xylem ridges in a root's vascular cylinder.

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

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

Question 47

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.

Question 48

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

Question 49

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

Question 50

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

Question 51

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

Question 52

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

Question 53

Velamen is a(n):

A) multiple epidermis.
B) multiple cortex.
C) epiphyte.
D) pneumatophore.
E) enzyme produced by lateral roots.

Question 54

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

Question 55

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

Question 56

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

Question 57

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

Question 58

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

Question 59

Most monocot roots lack secondary growth.

Question 60

The lateral rootcap receives gravity.

Question 61

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

Question 62

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

Question 63

Lateral roots originate from cells of the vascular cambium.

Question 64

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

Question 65

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