final focus

Question 1

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.

Answer 1

Most monocots exhibit considerable secondary growth.

Question 2

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.

Answer 2

are annuals.

Question 3

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.

Answer 3

Some flower before they become adult plants.

Question 4

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

Answer 4

vascular rays; fusiform initials

Question 5

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.

Answer 5

They serve as barriers to the movement of food substances and water.

Question 6

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.

Answer 6

the fusiform initials, the ray initials, and their immediate derivatives only.

Question 7

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.

Answer 7

are displaced outward.

Question 8

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.

Answer 8

in the pith rays.

Question 9

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.

Answer 9

Most plants produce more secondary phloem than secondary xylem.

Question 10

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.

Answer 10

dilated phloem rays are formed.

Question 11

The periderm consists of:

a. phellem only.
b. phellogen only.
c. phelloderm only.
d. phellem and phellogen only.
e. phellem and phellogen, and phelloderm.

Answer 11

phellem and phellogen, and phelloderm.

Question 12

In most woody plants, the first periderm usually arises in the:

a. cortex.
b. epidermis.
c. primary phloem.
d. primary xylem.
e. pith.

Answer 12

cortex.

Question 13

Which of the following is/are dead at maturity?

a. phellogen
b. fusiform initials
c. ray initials
d. phellem
e. vascular rays

Answer 13

phellem

Question 14

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.

Answer 14

vascular cambium.

Question 15

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.

Answer 15

secondary xylem.

Question 16

Lenticels function primarily in:

a. water transport.
b. gas exchange.
c. mineral uptake.
d. protection.
e. hormone production.

Answer 16

gas exchange.

Question 17

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.

Answer 17

They are found only on roots and stems.

Question 18

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.

Answer 18

all tissues outside the vascular cambium.

Question 19

Which of the following could never be part of the bark?

a. cortex
b. secondary xylem
c. primary phloem
d. secondary phloem
e. phelloderm

Answer 19

secondary xylem

Question 20

After the first periderm is formed, additional periderms originate from ______ cells.

a. epidermal
b. pith
c. cortical
d. phloem parenchyma
e. xylem parenchyma

Answer 20

phloem parenchyma

Question 21

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

Answer 21

cork

Question 22

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.

Answer 22

contains discontinuous layers of periderms.

Question 23

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.

Answer 23

is part of the inner bark.

Question 24

Wood contains mostly:

a. primary phloem
b. secondary phloem.
c. primary xylem.
d. secondary xylem.
e. periderm.

Answer 24

secondary xylem.

Question 25

“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.

Answer 25

found in conifers.

Question 26

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.

Answer 26

They are intercellular spaces lined with collenchyma cells.

Question 27

______ 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

Answer 27

A torus

Question 28

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.

Answer 28

vessels.

Question 29

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.

Answer 29

A false annual ring represents growth in an unusually short growing season.

Question 30

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

Answer 30

1

Question 31

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

Answer 31

may have much larger pores

Question 32

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.

Answer 32

the pores of early wood are larger than those of late wood.

Question 33

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.

Answer 33

is nonconducting.

Question 34

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.

Answer 34

They are balloon-like outgrowths from pit membranes.

Question 35

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.

Answer 35

is produced by increased cambial activity on the lower side of a leaning stem.

Question 36

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

Answer 36

xylem and phloem; ray

Question 37

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

Answer 37

phloem; xylem

Question 38

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

Answer 38

thick; narrow

Question 39

All plant hormones:

a. are equally effective in free and bound forms.
b. act in the tissues where they are produced.
c. are stimulatory.
d. are active in large quantities.
e. communicate information.

Answer 39

communicate information.

Question 40

_________ have recently been ranked along with the “classic five” as a major class of plant hormone.

a. Systemins
b. Florigens
c. Brassinosteroids
d. Salicylic acids

Answer 40

Brassinosteroids

Question 41

Which of the following is a phenolic compound with a structure similar to aspirin?

a. systemin
b. florigen
c. brassinosteroids
d. salicylic acids
e. jasmonic acid

Answer 41

salicylic acids

Question 42

______ activates the biosynthesis of ________, which then activates the genes that encode protease inhibitors.

a. Systemin; jasmonic acid
b. Jasmonic acid; auxin
c. Brassinosteroid; systemin
d. Salicylic acid; jasmonic acid
e. Systemin brassinosteroids

Answer 42

Systemin; jasmonic acid

Question 43

If a coleoptile tip is covered with a blackened glass tube then illuminated from the side, the coleoptile will:

a. die.
b. not bend.
c. bend toward the light.
d. bend away from the light.
e. bend at right angles to the light.

Answer 43

not bend.

Question 44

______ is very similar to the amino acid tryptophan.

a. Gibberellin
b. Cytokinin
c. Indoleacetic acid
d. Abscisic acid
e. Ethylene

Answer 44

Indoleacetic acid

Question 45

Polar transport is ______ in stems, _______in leaves, and ______ in roots.

a. acropetal; acropetal; acropetal
b. basipetal; basipetal; basipetal
c. acropetal; acropetal; basipetal
d. basipetal; acropetal; acropetal
e. basipetal; basipetal; acropetal

Answer 45

basipetal; basipetal; acropetal

Question 46

In stems, polar auxin transport occurs mainly in the:

a. vessels only.
b. sieve tubes only.
c. vascular parenchyma cells only.
d. vessels and sieve tubes.
e. vessels and parenchyma cells.

Answer 46

vascular parenchyma cells only.

Question 47

A PIN protein:

a. is an auxin influx carrier.
b. is an auxin efflux carrier.
c. catalyzes the conversion of auxin to tryptophan.
d. catalyzes the conversion of auxin to indole.
e. is a synthetic auxin.

Answer 47

is an auxin efflux carrier.

Question 48

Which of the following statements concerning the role of auxin in developing leaves of Arabidopsis is FALSE?

a. Auxin is produced first at the leaf base and later at the tip.
b. Auxin stimulates the differentiation of vascular tissue.
c. Auxin induces the formation of lateral veins.
d. Auxin is produced by cells that will differentiate into hydathodes.
e. Auxin induces the formation of the midvein.

Answer 48

Auxin is produced first at the leaf base and later at the tip.

Question 49

If wounding causes the destruction of vascular tissues in an herbaceous eudicot stem:

a. replacement vascular tissues will not form under any conditions.
b. replacement vascular tissues will form if IAA is added to the stem just below the wound.
c. replacement vascular tissues will form if the leaves and buds above the wound are intact.
d. water will be transported in pith cells instead of in xylem.
e. food will be transported in pith cells instead of in phloem.

Answer 49

replacement vascular tissues will form if the leaves and buds above the wound are intact.

Question 50

In apical dominance, the apical bud:

a. inhibits the growth of lateral buds.
b. stimulates the growth of lateral buds.
c. stimulates the upward growth of the stem.
d. stimulates the growth of leaves.
e. inhibits the downward growth of the root.

Answer 50

inhibits the growth of lateral buds.

Question 51

Which of the following statements concerning strigolactone is FALSE?

a. It is a terpenoid derived from carotenoids.
b. It stimulates bud growth.
c. It is present in root exudates.
d. It promotes the formation of mycorrhizae.
e. It stimulates seed germination of root-parasitic plants.

Answer 51

It is present in root exudates.

Question 52

Which of the following statements about fruit development is FALSE?

a. A parthenocarpic fruit lacks seeds.
b. A parthenocarpic fruit lacks ovules.
c. Applications of auxin can stimulate carpels to develop into a fruit.
d. Removal of seeds from a developing fruit results in reduced fruit growth.
e. Application of auxin to a deseeded receptacle stimulates fruit growth.

Answer 52

A parthenocarpic fruit lacks ovules.

Question 53

Which of the following statements about 2,4-D is FALSE?

a. It is a synthetic auxin.
b. It is used as an herbicide.
c. It is not broken down in plants as readily as IAA.
d. It is absorbed more readily than IAA	
e. It kills grasses more readily than broad-leaf weeds.

Answer 53

It kills grasses more readily than broad-leaf weeds.

Question 54

Folke Skoog and his colleagues found that ______ stimulated cells of tobacco to divide in culture.

a. coconut milk
b. a sugar
c. a salt
d. a vitamin
e. auxin

Answer 54

coconut milk

Question 55

Which of the following statements about cytokinins is FALSE?

a. They stimulate cell division.
b. They are present in bleeding sap.
c. Kinetin is a naturally occurring cytokinin.
d. They are found primarily in actively dividing tissues and in root tips.
e. The most active naturally occurring cytokinin is zeatin.

Answer 55

Kinetin is a naturally occurring cytokinin.

Question 56

When tobacco pith callus is treated with higher concentrations of auxin than kinetin, ______ is(are) formed.

a. more callus
b. roots
c. buds
d. leaves
e. vascular tissue

Answer 56

roots

Question 57

In roots of Arabidopsis, cytokinin ______ the initiation of lateral roots by preventing the establishment of a(n) ______ gradient.

a. inhibits; auxin
b. inhibits; gibberellin
c. stimulates; auxin
d. stimulates; gibberellin
e. stimulates; ethylene

Answer 57

inhibits; auxin

Question 58

In studies of leaf senescence, when an excised leaf containing radioactive amino acids is spotted with a kinetin-containing solution, the spot:

a. turns yellow and becomes nonradioactive.
b. turns yellow and becomes more radioactive.
c. remains green and becomes nonradioactive.
d. remains green and becomes more radioactive.
e. turns brown and becomes nonradioactive.

Answer 58

remains green and becomes more radioactive.

Question 59

Cytokinins are synthesized in ____ and transported from there to all other parts of the plant.

a. stems
b. shoot apical meristems
c. leaves
d. roots
e. fruits

Answer 59

roots

Question 60

Which of the following statements about ethylene is FALSE?

a. The final step in its synthesis in plants is catalyzed by enzymes on the tonoplast.
b. Its synthesis in plants begins with the amino acid tryptophan.
c. It exerts an influence on many aspects of plant growth and development.
d. It is the active component of illuminating gas that affects plant development.
e. It has the formula H2C=CH2.

Answer 60

Its synthesis in plants begins with the amino acid tryptophan.

Question 61

In etiolated pea seedlings, ethylene causes ______ longitudinal growth, ______ radial expansion of epicotyls, and ______ growth of epicotyls.

a. increased; increased; horizontal
b. increased; decreased; horizontal
c. decreased; increased; horizontal
d. decreased; increased; angular
e. increased; decreased; angular

Answer 61

decreased; increased; horizontal

Question 62

The climacteric is the phase in which fruits undergo a(n):

a. decrease in photosynthesis.
b. decrease in respiration.
c. increase in photosynthesis.
d. increase in respiration.
e. increase in pectin synthesis.

Answer 62

increase in respiration.

Question 63

Which of the following statements about abscisic acid is FALSE?

a. It has no direct role in abscission.
b. It induces the closing of stomata.
c. It prevents premature seed germination.
d. It inhibits the production of seed storage proteins.
e. It is produced during water stress.

Answer 63

It inhibits the production of seed storage proteins.

Question 64

Dwarf mutant plants are short because they:

a. synthesize too much gibberellin.
b. synthesize too much abscisic acid.
c. cannot synthesize ethylene.
d. cannot synthesize auxin.
e. cannot synthesize gibberellin.

Answer 64

cannot synthesize gibberellin.

Question 65

In germinating barley seeds, the ______ releases gibberellins, which then diffuse to the ______ where they stimulate the synthesis of hydrolytic enzymes.

a. endosperm; aleurone layer
b. embryo; aleurone layer
c. aleurone layer; embryo
d. aleurone layer; endosperm
e. embryo; seed coat

Answer 65

embryo; aleurone layer

Question 66

Which of the following statements about gibberellins is FALSE?

a. They induce bolting in long-day plants.
b. They induce early flowering in biennials.
c. They cause rosette formation in cabbages and carrots.
d. They cause development of parthenocarpic apples and currants.
e. They are used in the commercial production of seedless grapes.

Answer 66

They cause rosette formation in cabbages and carrots.

Question 67

The most widespread and active brassinosteroid is:

a. brassinolide.
b. 24-epibrassinolide.
c. S-adenosylmethionine.
d. strigolactone.
e. castasterone.

Answer 67

brassinolide.

Question 68

Which of the following statements concerning endogenous brassinosteroids is FALSE?

a. They are found in virtually every part of the plant.
b. They are synthesized from castasterone.
c. They are essential for tracheary element differentiation.
d. They are required for normal plant growth.
e. They are transported from root to shoot in the xylem.

Answer 68

They are transported from root to shoot in the xylem.

Question 69

In isolated barley aleurone cells, treatment with GA causes the levels of α-amylase to ______, and treatment with ABA causes the levels to ______.

a. increase; remain unchanged
b. decrease; remain unchanged
c. increase; decrease
d. decrease; increase
e. increase; increase

Answer 69

increase; decrease

Question 70

Cell wall extensibility, and thus cell expansion, is increased by ______ but decreased by ______.

a. auxin and ethylene; GA and ABA
b. auxin and GA; ABA and ethylene
c. auxin and ABA; GA and ethylene
d. ABA and ethylene; auxin and GA
e. ABA and GA; auxin and ethylene

Answer 70

auxin and GA; ABA and ethylene

Question 71

In the acid-growth hypothesis of cell wall extensibility, which of the following events occurs FIRST?

a. Expansins disrupt hydrogen bonds.
b. Protons are pumped into the cell wall.
c. Specific genes are activated.
d. A proton-pumping enzyme is activated.
e. Cross-links between noncellulosic polysaccharides are broken.

Answer 71

Protons are pumped into the cell wall.

Question 72

If cell wall microfibrils are oriented transversely, the cell normally expands:

a. in all directions.
b. at an oblique angle.
c. first laterally and then longitudinally.
d. laterally.
e. longitudinally.

Answer 72

longitudinally.

Question 73

Gibberellins promote a ______ orientation of the microtubules underlying the plasma membrane, and ethylene promotes a ______ orientation.

a. random; longitudinal
b. transverse; random
c. transverse; longitudinal
d. longitudinal; transverse
e. longitudinal; random

Answer 73

transverse; longitudinal

Question 74

In Arabidopsis, the ethylene receptor is located in the:

a. endoplasmic reticulum.
b. plasma membrane.
c. Golgi apparatus.
d. chloroplast.
e. nucleus.

Answer 74

endoplasmic reticulum.

Question 75

In the ethylene signaling pathway in Arabidopsis, when ethylene is absent, then ____ is active.

a. EIN2
b. CTR1
c. EIN3
d. ERF1
e. Cu

Answer 75

CTR1

Question 76

In the ethylene signaling pathway in Arabidopsis, when the EIN2 protein is activated which of the following happens next?

a. ETR1 undergoes a conformational change.
b. CTR1 is activated.
c. the ethylene signal is transmitted into the nucleus.
d. a transcription factor is activated.
e. genes are activated.

Answer 76

the ethylene signal is transmitted into the nucleus.

Question 77

The receptors for both auxin and gibberellin are located in the:

a. endoplasmic reticulum.
b. plasma membrane.
c. Golgi apparatus.
d. chloroplast.
e. nucleus.

Answer 77

nucleus.

Question 78

The brassinosteroid receptor differs from the receptors for auxin, gibberellin, ethylene and cytokinins in that the brassinosteroid receptor:

a. is located entirely in the endoplasmic reticulum.
b. has an extracellular region, a transmembrane region, and a cytoplasmic region.
c. is located entirely in the cytoplasm.
d. does not initiate a signaling cascade.
e. binds directly with genes in the nucleus.

Answer 78

has an extracellular region, a transmembrane region, and a cytoplasmic region.

Question 79

Which of the following statements about second messengers is FALSE?

a. They amplify the signal produced by a hormone.
b. They contribute to the diversity of responses to a hormone.
c. They transfer information from the hormone-receptor complex to the target protein.
d. An example is protein kinase.
e. An example is calcium ion.

Answer 79

An example is protein kinase.

Question 80

In the ABA-induced closing of stomata, the following ion fluxes occur across guard cell plasma membranes: first calcium ions flow ______, then anions flow ______, and finally potassium ions flow ______.

a. in; out; out
b. in; in; in
c. out; in; out
d. out; out; in
e. out; out; out

Answer 80

a. in; out; out

Question 81

Which of the following is NOT a finding from experiments on the role of auxin in phototropism of coleoptile tips?

a. Light does not affect the total amount of auxin.
b. Light does not destroy auxin.
c. Auxin migrates from the lighted side to the shaded side.
d. More auxin can be isolated from the shaded side of an intact tip than from the lighted side.
e. If the tip is split and the two halves separated by a barrier, more auxin can be isolated from the shaded side than from the lighted side.

Answer 81

If the tip is split and the two halves separated by a barrier, more auxin can be isolated from the shaded side than from the lighted side.

Question 82

______ light is the most effective in producing a phototropic response.

a. Green
b. Yellow
c. Orange
d. Blue
e. Red

Answer 82

Blue

Question 83

According to the original hypothesis on negative gravitropism of shoots, auxin is redistributed to the ______ side where it ______ cell expansion.

a. lower; stimulates
b. lower; inhibits
c. upper; stimulates
d. upper; inhibits
e. upper; first inhibits then stimulates

Answer 83

lower; stimulates

Question 84

In roots and shoots, the statoliths are:

a. chloroplasts.
b. amyloplasts.
c. plasma membranes.
d. cell walls.
e. lignified cells.

Answer 84

amyloplasts.

Question 85

In roots, statoliths are localized in the:

a. endodermis.
b. vascular tissues.
c. starch sheath.
d. epidermis of the root cap.
e. root cap columella.

Answer 85

root cap columella.

Question 86

When a growing root is oriented horizontally, the amyloplasts in the central column of the rootcap:

a. slide downward.
b. float upward.
c. attach to the nuclear envelope.
d. attach to the mitochondria.
e. do not move.

Answer 86

slide downward.

Question 87

In the current model of root gravitropism, elongation is _____ in the upper side of the distal elongation zone and ______ along the lower side.

a. stimulated; stimulated
b. stimulated; suppressed
c. suppressed; stimulated
d. suppressed; is neither stimulated nor suppressed
e. is neither stimulated nor suppressed; suppressed

Answer 87

stimulated; suppressed

Question 88

Which of the following statements concerning hydrotropism is FALSE?

a. It is the directed growth of roots in response to moisture.
b. Decapped roots do not curve hydrotropically.
c. Under normal gravity, hydrotropism is suppressed by gravitropism.
d. Auxin apparently is required for hydrotropism.
e. Inhibitors of auxin influx and efflux also inhibit hydrotropism.

Answer 88

Inhibitors of auxin influx and efflux also inhibit hydrotropism.

Question 89

Which of the following statements about thigmotropism is FALSE?

a. It enables roots to navigate around rocks.
b. It is a response to contact with a solid object.
c. An example is the climbing of tendrils.
d. Cells touching the support lengthen more than cells on the other side.
e. The stems of peas can store the memory of tactile stimulation.

Answer 89

Cells touching the support lengthen more than cells on the other side.

Question 90

Which of the following statements about circadian clocks is FALSE?

a. Input pathways and output pathways are the parts of the clock that do not interact.
b. Conceptually they consist of three parts.
c. They cause the regular oscillation of 30-40 percent of Arabidopsis genes.
d. The central oscillator is the part of the clock that generates rhythmic behavior.
e. Input pathways are the part of the clock that carries information to the oscillator.

Answer 90

Input pathways and output pathways are the parts of the clock that do not interact.

Question 91

In terms of the circadian clock, gating refers to the observation that stimuli of _____ strength employed at different times of the day can result in ______ intensity of response.

a. different; a smaller
b. different; the same
c. different; different
d. equal; the same
e. equal; a different

Answer 91

equal; a different

Question 92

Long-day plants flower:

a. in the summer.
b. in early spring or fall.
c. when exposed to eight hours of daylight.
d. when the light period is shorter than a critical length.
e. without respect to day length.

Answer 92

in the summer.

Question 93

Which of the following statements concerning photoperiodism is FALSE?

a. Short-day plants in the early spring or fall.
b. Spinach and lettuce are examples of long-day plants.
c. Day-neutral plants flower without respect to photoperiod.
d. Photoperiodic behavior remains constant over a wide range of temperatures.
e. In some plants, only a single exposure to the critical day-length will produce a response.

Answer 93

Photoperiodic behavior remains constant over a wide range of temperatures.

Question 94

Experiments on cocklebur have shown that the ______ perceives the photoperiod.

a. apical meristem
b. columella
c. leaf blade
d. petiole
e. stem

Answer 94

leaf blade

Question 95

If a short-day plant receives a one-minute exposure to light in the middle of the dark period rather than continuous darkness, it will:

a. produce more flowers.
b. produce smaller flowers.
c. produce larger flowers.
d. flower at a lower temperature.
e. not flower.

Answer 95

not flower.

Question 96

Light with a wavelength of about ______ nanometers is the most effective for interrupting the dark period of both short-day and long-day plants.

a. 220
b. 340
c. 440
d. 660
e. 730

Answer 96

660

Question 97

Suppose lettuce seeds are exposed to a series of alternating flashes of red light (abbreviated R) and far-red light (abbreviated FR). (E.g., a flash of red light followed by a flash of far-red light is denoted as R→RF.) Which of the following series of flashes would result in the germination of those seeds?

a. FR only
b. R→FR
c. R→FR →R→FR
d. R →FR→R→FR→R
e. R→FR→R→FR→R→FR

Answer 97

R →FR→R→FR→R

Question 98

Which of the following statements about Pr and Pfr is FALSE?

a. They are photoreceptors.
b. They participate in photoconversion reactions.
c. Pr is the biologically active form.
d. Pr absorbs 660-nanometer light.
e. Pfr absorbs 730-nanometer light.

Answer 98

Pr is the biologically active form.

Question 99

When lettuce seeds are exposed to red light:

a. Pfr is converted to Pr.
b. Pr is converted to Pfr.
c. 660-nanometer light is converted to 730-nanometer light.
d. 730-nanometer light is converted to 660-nanometer light.
e. they will not germinate.

Answer 99

Pr is converted to Pfr.

Question 100

Which of the following statements concerning the phytochrome molecule is FALSE?

a. The phytochromes in Arabidopsis are encoded by just 2 genes.
b. Most plants have several different phytochromes.
c. The chromophore portion is similar to the phycobilins in cyanobacteria.
d. One part is a protein.
e. The chromophore portion absorbs light.

Answer 100

The phytochromes in Arabidopsis are encoded by just 2 genes.

Question 101

When phytochromes interact with PIF proteins, what happens next?

a. The PIF proteins bind DNA.
b. The PIF proteins enter the endoplasmic reticulum.
c. The PIF proteins enter the nucleus.
d. The PIF proteins are degraded.
e. The PIF proteins are polymerized.

Answer 101

The PIF proteins are degraded.

Question 102

An etiolated eudicot seedling:

a. has a short stem.
b. has small leaves.
c. is green.
d. lacks plastids.
e. cannot undergo further growth.

Answer 102

has small leaves.

Question 103

Compared with similar plants growing in full sunlight, plants growing in the shade of other vegetation:

a. receive more red light and less far-red light.
b. are usually shorter.
c. receive more wavelengths below 700 nanometers than above.
d. have a reduced red/far-red ratio.
e. receive more reflected light and less transmitted light.

Answer 103

have a reduced red/far-red ratio.

Question 104

If a leaf is given an inductive cycle and then removed immediately the plant _____, but if the leaf is removed several hours after photoinduction, then the plant _______.

a. won’t flower; won’t flower
b. will flower; won’t flower
c. won’t flower; will flower
d. won’t be vernalized; will be vernalized
e. will be vernalized; won’t be vernalized

Answer 104

won’t flower; will flower

Question 105

In Arabidopsis, what is the correct order of action of the following flower-promoting genes?

a. FT then GI then CO
b. CO then FT then GI
c. CO then GI then FT
d. GI then CO then FT
e. FT then CO then GI

Answer 105

GI then CO then FT

Question 106

The florigen FT is produced in:

a. vessel elements.
b. companion cells.
c. tracheids.
d. sieve-tube elements.
e. guard cells.

Answer 106

companion cells.

Question 107

Winter rye is usually planted in the ______, and it flowers in the ______.

a. early spring; summer
b. early spring; autumn
c. early spring; winter
d. summer; following spring
e. autumn; following summer

Answer 107

autumn; following summer

Question 108

In the process of vernalization, early ______ is stimulated by exposing the germinating seeds to ______ temperatures.

a. dormancy; low
b. flowering; low
c. germination; low
d. dormancy; high
e. germination; high

Answer 108

flowering; low

Question 109

Vernalization takes place directly in the cells of the:

a. shoot apical meristem.
b. leaf blade.
c. petiole.
d. stem.
e. hypocotyl.

Answer 109

shoot apical meristem.

Question 110

Stratification is the process used by horticulturalists in which seeds are:

a. moistened and exposed to low temperature.
b. moistened and exposed to high temperature.
c. mechanically abraded.
d. soaked in alcohol.
e. dried.

Answer 110

moistened and exposed to low temperature.

Question 111

Which of the following statements about bud scales is FALSE?

a. They may contain growth inhibitors.
b. They protect the bud against desiccation.
c. They restrict the movement of oxygen into the bud.
d. They insulate the bud from heat loss.
e. They have leaf primordia in their axils.

Answer 111

They have leaf primordia in their axils.

Question 112

In temperate regions, the acclimation of buds is initiated primarily by decreasing ______, and it produces ______.

a. daylength; cold hardiness
b. temperature; cold hardiness
c. moisture; moisture resistance
d. levels of growth inhibitors; early flowering
e. numbers of bud scales; early flowering
produces ______.

Answer 112

daylength; cold hardiness

Question 113

The direction of a nastic movement is always ______ the direction of the stimulus.

a. away from
b. toward
c. at right angles to
d. at an oblique angle to
e. independent of

Answer 113

independent of

Question 114

In nyctinastic movements, leaves:

a. twine around a support such as a fence post.
b. have their stomata open during the night and closed during the day.
c. are rolled during the day and unrolled at night.
d. are oriented vertically in darkness and horizontally in light.
e. are oriented horizontally in darkness and vertically in light.

Answer 114

are oriented vertically in darkness and horizontally in light.

Question 115

Which of the following statements about a pulvinus is FALSE?

a. It is a joint-like thickening at the base of a leaf or a leaflet.
b. It is responsible for most nyctinastic leaf movements.
c. It lacks vascular tissue.
d. It contains parenchyma cells.
e. Some of its cells undergo changes in turgor.

Answer 115

It lacks vascular tissue.

Question 116

In Mimosa pudica, movement of leaflets involves all of the following changes in cells of the pulvinus EXCEPT:

a. accumulation of sucrose unloaded from the phloem.
b. an influx of potassium ions from the apoplast.
c. a change in turgor pressure.
d. an efflux of water.
e. a decrease in water potential.

Answer 116

an influx of potassium ions from the apoplast.

Question 117

The rapid closure of leaves of the Venus flytrap is now thought to be due to:

a. changes in turgor pressure in the cells beneath the epidermis.
b. changes in turgor pressure in the upper epidermis.
c. changes in turgor pressure in cells of the pulvinus.
d. acid-induced wall loosening of motor cells.
e. unloading of sucrose from the phloem.

Answer 117

changes in turgor pressure in the cells beneath the epidermis.

Question 118

In contrast to thigmonastic movements, thigmomorphogenesis:

a. is a response to touch.
b. is a response to a mechanical stimulus.
c. is independent of the direction of the stimulus.
d. involves cells of the pulvinus.
e. involves an altered growth pattern.

Answer 118

involves an altered growth pattern.

Question 119

In Arabidopsis thaliana, touch induces the expression of genes that encode proteins related to ______, suggesting a role for ______ in thigmomorphogenesis.

a. an endogenous inhibitor; the biological clock
b. amylase; starch
c. the cytoskeleton; microtubules
d. calmodulin; calcium
e. chlorophyll; magnesium

Answer 119

calmodulin; calcium

Question 120

Which of the following statements about heliotropism is FALSE?

a. It is a diurnal movement involving pulvini.
b. It is a process involving an orientation to the sun.
c. It involves the leaves and flowers of many plants.
d. It is also called solar tracking.
e. It involves a mechanism similar to that of stem phototropism.

Answer 120

It involves a mechanism similar to that of stem phototropism.

Question 121

Which of the following is NOT an essential element?

a. molybdenum
b. copper
c. iron
d. aluminum
e. chlorine

Answer 121

aluminum

Question 122

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

Answer 122

100

Question 123

Which of the following is NOT a micronutrient?

a. zinc
b. copper
c. manganese
d. calcium
e. nickel

Answer 123

calcium

Question 124

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.

Answer 124

They are essential for most plants.

Question 125

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.

Answer 125

is required by symbiotic nitrogen-fixing bacteria.

Question 126

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.

Answer 126

yellowing of leaves.

Question 127

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.

Answer 127

younger leaves withdraw magnesium from older leaves.

Question 128

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

a. nitrogen
b. magnesium
c. phosphorus
d. potassium
e. iron

Answer 128

iron

Question 129

Humus consists mostly of:

a. living organic matter.
b. dead organic matter.
c. sand.
d. silt.
e. clay.

Answer 129

dead organic matter.

Question 130

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.

Answer 130

The C horizon is part of the true soil.

Question 131

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

Answer 131

clay

Question 132

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.

Answer 132

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

Question 133

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.

Answer 133

water remaining in a soil when irreversible wilting occurs.

Question 134

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+

Answer 134

H+; K+

Question 135

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.

Answer 135

All plants use Strategy I for iron mobilization and uptake.

Question 136

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

Answer 136

Fe3+-phytosiderophores

Question 137

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

a. hydroxide
b. bicarbonate
c. sulfate
d. iron
e. potassium

Answer 137

iron

Question 138

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.

Answer 138

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

Question 139

The chief reservoir of nitrogen is:

a. the soil.
b. the ocean.
c. living organisms.
d. dead organic material.
e. the atmosphere.

Answer 139

the atmosphere.

Question 140

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

Answer 140

NH4+; ammonification

Question 141

Nitrite is oxidized to nitrate by:

a. Nitrosomonas.
b. Nitrobacter.
c. ammonifying bacteria and fungi.
d. denitrifying bacteria.
e. plant roots.

Answer 141

Nitrobacter.

Question 142

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

a. NH4+
b. NO3−
c. NO2−
d. N2
e. Amino acids

Answer 142

N2

Question 143

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

Answer 143

nitrification

Question 144

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

a. NH4+; NO3−
b. NO3−; NO2−
c. N2; NO2−
d. N2; NO3−
e. N2; NH4+

Answer 144

N2; NH4+

Question 145

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.

Answer 145

It requires O2 as a cofactor.

Question 146

Rhizobia enter legumes by invading the:

a. seeds.
b. root hairs.
c. stems.
d. leaves.
e. flowers.

Answer 146

root hairs.

Question 147

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.

Answer 147

attract rhizobia.

Question 148

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.

Answer 148

activate the plant genes for nodule formation.

Question 149

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.

Answer 149

bacterioids and the surrounding host membrane only.

Question 150

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.

Answer 150

is spherical

Question 151

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.

Answer 151

It is found in the cytosol of the bacteroid.

Question 152

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

Answer 152

Azolla-Anabaena

Question 153

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

Answer 153

cyanobacteria

Question 154

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

a. Organic nitrogen
b. Nitrate
c. Ammonium
d. Glutamine
e. Glutamate

Answer 154

Nitrate

Question 155

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

Answer 155

organic nitrogen

Question 156

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.

Answer 156

leaf chloroplasts.

Question 157

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.

Answer 157

The phosphorus cycle has more steps.

Question 158

______ 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

Answer 158

Leaching

Question 159

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

Answer 159

inhibition of extraradical hyphae

Question 160

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.

Answer 160

They are long-lasting.

Question 161

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

Answer 161

denitrification

Question 162

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.

Answer 162

5% nitrogen.

Question 163

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.

Answer 163

remove excess salts.

Question 164

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.

Answer 164

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

Question 165

______ 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

Answer 165

Aluminum