Chapter 26: Secondary Growth in Stems
Multiple-Choice Questions
1.Introduction; p. 614; easy; ans: d
Which of the following statements about secondary growth is FALSE?
a.It results from the activity of the vascular cambium and the cork cambium.
b.It is responsible for the increase in girth of a plant.
c.It can occur simultaneously with primary growth.
d.Most monocots exhibit considerable secondary growth.
e.Herbaceous plants undergo little or no secondary growth.
2.Annuals, Biennials, and Perennials; p. 615; difficult; ans: b
In the southern hemisphere, biennials:
a.are represented by weeds.
b.are annuals.
c.form seeds and flowers in the same growing season.
d.usually become woody.
e.complete their life cycle in two calendar years.
3.Annuals, Biennials, and Perennials; p. 615; moderate; ans: c
Which of the following statements about woody perennials is FALSE?
a.Some form dormant rhizomes or bulbs during unfavorable seasons.
b.They include trees and shrubs.
c.Some flower before they become adult plants.
d.Some are deciduous.
e.Some live for many years.
4.The Vascular Cambium; p. 615; easy; ans: d
The cells that comprise the vascular cambium are the ______and the ______.
a.axial rays; vascular rays
b.axial rays; fusiform initials
c.vascular rays; fusiform initials
d.fusiform initials; ray initials
e.vascular rays; ray initials
5.The Vascular Cambium; p. 615; moderate; ans: e
Cambial initials produce ______cells toward the outside and ______cells toward the inside.
a.ray; phloem
b.phloem; phloem
c.xylem; xylem
d.xylem; ray
e.phloem; xylem
6.The Vascular Cambium; p. 615; moderate; ans: d
In secondary tissues, the axial system consists of ______cells and the radial system consists of ______cells.
a.parenchyma; phloem
b.parenchyma; xylem
c.xylem; phloem
d.xylem and phloem; ray
e.ray; xylem and phloem
7.The Vascular Cambium; p. 615; moderate; ans: b
Which of the following statements about vascular rays is FALSE?
a.They are composed largely of parenchyma cells.
b.They serve as barriers to the movement of food substances and water.
c.They store starch, proteins, and lipids.
d.They synthesize secondary products.
e.They are variable in length.
8.The Vascular Cambium; p. 615; moderate; ans: d
The cambial zone consists of:
a.the fusiform initials only.
b.the ray initials only.
c.the fusiform initials and ray initials only.
d.the fusiform initials, the ray initials, and their immediate derivatives only.
e.the fusiform initials, the ray initials, their immediate derivatives, and the vascular rays.
9.The Vascular Cambium; p. 615; moderate; ans: b
As the vascular cambium continues to divide, the cambial cells:
a.are displaced inward.
b.are displaced outward.
c.remain in their original location.
d.cease to divide periclinally.
e.cease to divide anticlinally.
10.Effect of Secondary Growth on the Primary Body of the Stem; p. 617; easy; ans: a
Interfascicular cambium arises:
a.in the pith rays.
b.between the primary xylem and primary phloem.
c.in the cortex.
d.between the primary xylem and secondary xylem.
e.between the primary phloem and secondary phloem.
11.Effect of Secondary Growth on the Primary Body of the Stem; p. 617; moderate; ans: e
Which of the following statements about secondary growth is FALSE?
a.The secondary vascular tissues form a cylindrical shape.
b.Vascular rays extend radially through the secondary xylem and secondary phloem.
c.Primary phloem fibers remain intact longer than other primary phloem cells.
d.The primary phloem is pushed outward.
e.Most plants produce more secondary phloem than secondary xylem.
12.Effect of Secondary Growth on the Primary Body of the Stem; pp. 617–619; moderate; ans: d
Secondary growth in the Tilia stem is different from that in the Sambucus stem because in the Tilia stem:
a.more secondary xylem than secondary phloem is formed.
b.more secondary phloem than secondary xylem is formed.
c.only a small amount of secondary tissue is produced.
d.dilated phloem rays are formed.
e.phloem fibers are formed.
13.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: e
The periderm consists of:
a.phellem only.
b.phellogen only.
c.phelloderm only.
d.phellem and phellogen only.
e.phellem and phellogen, and phelloderm.
14.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: a
In most woody plants, the first periderm usually arises in the:
a.cortex.
b.epidermis.
c.primary phloem.
d.primary xylem.
e.pith.
15.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; easy; ans: d
Which of the following is/are dead at maturity?
a.phellogen
b.fusiform initials
c.ray initials
d.phellem
e.vascular rays
16.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: c
At the end of the first year’s secondary growth, immediately inside the secondary phloem is the:
a.primary phloem.
b.periderm.
c.vascular cambium.
d.cortex.
e.secondary xylem.
17.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: e
At the end of the first year’s secondary growth, immediately outside the primary xylem is the:
a.primary phloem.
b.secondary phloem.
c.vascular cambium.
d.pith.
e.secondary xylem.
18.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; easy; ans: b
Lenticels function primarily in:
a.water transport.
b.gas exchange.
c.mineral uptake.
d.protection.
e.hormone production.
19.Effect of Secondary Growth on the Primary Body of the Stem; pp. 619–620; moderate; ans: a
Which of the following statements about lenticels is FALSE?
a.They are found only on roots and stems.
b.They are portions of the periderm.
c.They contain numerous intercellular spaces.
d.In stems they generally arise below stomata.
e.On the surface of stems they appear as raised areas.
20.Effect of Secondary Growth on the Primary Body of the Stem; p. 620; easy; ans: c
At the end of the first year’s growth, bark is composed of:
a.periderm.
b.cork.
c.all tissues outside the vascular cambium.
d.only secondary tissues.
e.only primary tissues.
21.Effect of Secondary Growth on the Primary Body of the Stem; p. 620; moderate; ans: b
Which of the following could never be part of the bark?
a.cortex
b.secondary xylem
c.primary phloem
d.secondary phloem
e.phelloderm
22.Effect of Secondary Growth on the Primary Body of the Stem; p. 621; moderate; ans: d
After the first periderm is formed, additional periderms originate from ______cells.
a.epidermal
b.pith
c.cortical
d.phloem parenchyma
e.xylem parenchyma
23.Effect of Secondary Growth on the Primary Body of the Stem; p. 622; difficult; ans: c
Which of the following is found in the outer bark but not the inner bark?
a.xylem
b.pith
c.cork
d.phelloderm
e.phloem
24.Effect of Secondary Growth on the Primary Body of the Stem; p. 622; moderate; ans: e
Unlike ring bark, scale bark:
a.is found in honeysuckle (Lonicera).
b.is found in grape (Vitis).
c.contains cork.
d.contains concentric rings of periderms.
e.contains discontinuous layers of periderms.
25.Effect of Secondary Growth on the Primary Body of the Stem; p. 625; moderate; ans: b
Conducting phloem:
a.is composed of primary tissue.
b.is part of the inner bark.
c.functions primarily to store foods.
d.consists of living or dead sieve elements.
e.makes up the majority of secondary phloem in older plants.
26.Wood: Secondary Xylem; p. 626; easy; ans: d
Wood contains mostly:
a.primary phloem
b.secondary phloem.
c.primary xylem.
d.secondary xylem.
e.periderm.
27.Wood: Secondary Xylem; p. 626; moderate; ans: a
“Softwood” is the name given to wood:
a.found in conifers.
b.found in eudicots.
c.composed of functional phloem.
d.composed of primary xylem.
e.having no commercial value.
28.Wood: Secondary Xylem; p. 626; moderate; ans: c
Which of the following statements about resin ducts is FALSE?
a.They may result from trauma.
b.They secrete resin that may protect against fungi and beetles.
c.They are intercellular spaces lined with collenchyma cells.
d.Their formulation may be stimulated by wounding.
e.In Pinus they occur in both the axial system and the rays.
29.Wood: Secondary Xylem; p. 628; moderate; ans: d
______is thought to block the movement of water or gases through a pit-pair in conifer tracheids.
a.Resin
b.The pit membrane
c.The middle lamella
d.A torus
e.A resin duct
30.Wood: Secondary Xylem; p. 628; moderate; ans: b
Angiosperm wood differs from conifer wood in that angiosperm wood has:
a.tracheids.
b.vessels.
c.orderly radial files of cells.
d.smaller rays.
e.fewer cell types in the axial system.
31.Wood: Secondary Xylem; p. 628; difficult; ans: e
Which of the following statements about growth rings is FALSE?
a.They may be absent in trees growing in the tropics.
b.They are caused by variations in the activity of the vascular cambium in each growing season.
c.They may occur in secondary phloem as well as in secondary xylem.
d.An annual ring represents one season’s growth.
e.A false annual ring represents growth in an unusually short growing season.
32.Wood: Secondary Xylem; p. 628; moderate; ans: b
How many rings of vascular cambium would be found in a tree that is 6 years old?
a.0
b.1
c.2
d.3
e.6
33.Wood: Secondary Xylem; p. 631; difficult; ans: e
In angiosperms, early wood ______than late wood.
a.has narrower cells
b.has thicker cell walls
c.is denser
d.is produced later in the growing season
e.may have much larger pores
34.Wood: Secondary Xylem; p. 632; moderate; ans: b
Ring-porous woods are different from diffuse-porous woods because in ring-porous woods:
a.the pores of late wood are larger than those of early wood.
b.the pores of early wood are larger than those of late wood.
c.the pores are fairly uniform in size throughout the growth layer.
d.almost all the water is conducted in the innermost growth layer.
e.vessels are lacking.
35.Wood: Secondary Xylem; p. 632; moderate; ans: b
Heartwood is different from sapwood in that heartwood:
a.has a lighter color.
b.is nonconducting.
c.contains living cells.
d.is older.
e.is found closer to the vascular cambium.
36.Wood: Secondary Xylem; p. 632; moderate; ans: d
Which of the following statements about tyloses is FALSE?
a.They may inhibit the spread of pathogens through the xylem.
b.Their formation may be induced by plant pathogens.
c.They may completely block a vessel.
d.They are balloon-like outgrowths from pit membranes.
e.They are formed when vessels become nonfunctional.
37.Wood: Secondary Xylem; p. 632; difficult; ans: b
Compression wood:
a.develops on the upper side of a leaning stem.
b.is produced by increased cambial activity on the lower side of a leaning stem.
c.is the reaction wood found in angiosperms.
d.is characterized by wider portions of growth rings on the upper side of the stem.
e.has less lignin and more cellulose than normal wood.
38.Wood: Secondary Xylem; p. 634; moderate; ans: d
In wood having a high specific gravity, the fibers have ______walls and ______lumens.
a.thin; variable
b.thin; narrow
c.thin; wide
d.thick; narrow
e.thick; wide
True-False Questions
1.Annuals, Biennials, and Perennials; p. 615; easy; ans: F
Biennials form roots, stems, leaves and flowers in the first growing season and seeds in the second season.
2.Annuals, Biennials, and Perennials; p. 615; moderate; ans: T
In the southern hemisphere, a biennial can correctly be called a winter annual.
3.Annuals, Biennials, and Perennials; p. 615; easy; ans: F
Woody perennials usually keep growing during unfavorable seasons.
4.The Vascular Cambium; p. 615; easy; ans: F
The meristematic cells of the vascular cambium are the fusiform initials and the interfascicular initials.
5.The Vascular Cambium; p. 615; difficult; ans: T
New ray initials are produced by the fusiform initials.
6.The Vascular Cambium; p. 615; moderate; ans: T
In secondary tissues, the cells of the axial system are oriented vertically and those of the radial system are oriented horizontally.
7.The Vascular Cambium; p. 615; moderate; ans: F
The cambial zone consists of the fusiform initials and their immediate derivatives.
8.The Vascular Cambium; p. 616; easy; ans: T
Reactivation of the vascular cambium in the spring is triggered by the expansion of the buds.
9.The Vascular Cambium; p. 617; moderate; ans: F
The genes that regulate secondary growth are entirely different from those that regulate primary growth.
10.Effect of Secondary Growth on the Primary Body of the Stem; p. 617; easy; ans: F
Fascicular cambium arises from procambium immediately outside the vascular bundles.
11.Effect of Secondary Growth on the Primary Body of the Stem; p. 618; moderate; ans: F
In the elderberry stem during its first year of secondary growth, all primary phloem cells are destroyed.
12.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: F
The order of tissues in the periderm, from the center of the plant toward the outside, is cork, cork cambium and phelloderm.
13.Effect of Secondary Growth on the Primary Body of the Stem; p. 619; moderate; ans: F
The cortex of the stem is usually sloughed during the first year of growth.
14.Effect of Secondary Growth on the Primary Body of the Stem; p. 620; moderate; ans: T
Bark may contain primary tissues as well as secondary tissues.
15.Effect of Secondary Growth on the Primary Body of the Stem; p. 620; moderate; ans: F
Primary phloem would not normally be part of the bark.
16.Effect of Secondary Growth on the Primary Body of the Stem; p. 621; moderate; ans: F
The stem and root of most woody plants usually contains only one periderm.
17.Effect of Secondary Growth on the Primary Body of the Stem; pp. 622-623; moderate; ans: T
In the cork oak, the cork produced by the first cork cambium has the least commercial value.
18.Effect of Secondary Growth on the Primary Body of the Stem; p. 623; easy; ans: T
In many woody roots and stems, only the secondary phloem in the current growth ring is active in long-distance food transport.
19.Effect of Secondary Growth on the Primary Body of the Stem; p. 622; easy; ans: T
All the periderms make up the outer bark.
20.Wood: Secondary Xylem; p. 626 easy; ans: T
Hardwood is another name for angiosperm wood.
21.Wood: Secondary Xylem; p. 628; moderate; ans: F
Conifer wood typically contains more parenchyma than angiosperm wood.
22.Wood: Secondary Xylem; p. 628; moderate; ans: T
A radial section and a tangential section are longitudinal sections.
23.Wood: Secondary Xylem; p. 630; easy; ans: F
Growing seasons with favorable environmental conditions produce narrower growth rings than seasons with unfavorable conditions.
24.Wood: Secondary Xylem; p. 631; easy; ans: F
Early wood is more dense than late wood.
25.Wood: Secondary Xylem; p. 632; difficult; ans: T
In diffuse-porous woods, the pores are fairly uniform in size and distribution throughout the growth layers.
26.Wood: Secondary Xylem; p. 632; moderate; ans: F
Compression wood is a type of reaction wood found in angiosperms.
27.Wood: Secondary Xylem; p. 634; moderate; ans: T
The differences in specific gravity of woods depends on the proportion of cell wall substance to cell lumen.
Essay Questions
1.Annuals, Biennials, and Perennials; pp. 614–615; easy
Explain the differences between annuals, biennials, and perennials.
2.The Vascular Cambium; p. 615; difficult
What two types of cells make up the vascular cambium? Explain why these cells must divide anticlinally and periclinally.
3.Effect of Secondary Growth on the Primary Body of the Stem; p. 617; moderate
What is the difference between fascicular and interfascicular cambium. Explain the process by which they develop.
4.Effect of Secondary Growth on the Primary Body of the Stem; pp. 617–619; moderate
Which tissues are produced by the vascular cambium and which by the cork cambium? Describe how the functioning of the cork cambium results from the activity of the vascular cambium.
5.Effect of Secondary Growth on the Primary Body of the Stem; pp. 619-620; easy
What is a lenticel? What function does it play in the plant?
6.Effect of Secondary Growth on the Primary Body of the Stem; pp. 620-622; moderate
What is bark? Explain how the composition of bark changes over time.
7.Effect of Secondary Growth on the Primary Body of the Stem; p. 620; moderate
Explain why less secondary phloem than secondary xylem accumulates in the stem.
8.Effect of Secondary Growth on the Primary Body of the Stem; pp. 620–623; moderate
Distinguish among periderm, cork, and bark. What is the difference between the inner bark and the outer bark?
9.Effect of Secondary Growth on the Primary Body of the Stem; pp. 620-622; difficult
Why is it advantageous for a plant to produce more than one periderm?
10.Wood: Secondary Xylem; pp. 626, 628; moderate
Compare and contrast angiosperm and conifer woods.
11.Wood: Secondary Xylem; pp. 626, 628; difficult
Describe the appearance of conifer wood in transverse, radial, and tangential sections.
12.Wood: Secondary Xylem; pp. 626, 631–632; moderate
Explain the difference between hardwood and softwood, between early wood and late wood, and between heartwood and sapwood.
13.Wood: Secondary Xylem; pp. 628, 630; moderate
What causes growth rings to form? How can growth rings be used to determine past climates?
14.Wood: Secondary Xylem; p. 632; moderate
What is reaction wood? What are the characteristics of the two types of reaction wood?
15.Wood: Secondary Xylem; p. 634; moderate
Distinguish between the specific gravity and the density of wood. What do these properties tell us about the strength of wood?