Deck 38: Plant Developmental Responses to External and Internal Signals

Question 1

If you placed a coleoptile in unidirectional light and then immediately covered the tip, which of the following would happen?

A) The coleoptile would bend toward the light.
B) The coleoptile would not bend.
C) The coleoptile would bend away from the light.
D) The coleoptile would die.
E) The coleoptile would grow in a spiral pattern.

Answer 1

B

Question 2

Which of the following would be the most likely consequence of removing the apical meristem from a plant?

A) The plant dies.
B) The plant remains alive but will not grow again.
C) The growth of axillary buds is inhibited.
D) The axillary buds die.
E) Some axillary buds grow into branches.

Answer 2

E

Question 3

The most common and physiologically important auxin is:

A) indoleacetic acid.
B) indolebutyric acid.
C) naphthaleneacetic acid.
D) 2,4-D.
E) 2,4,5-T.

Answer 3

A

Question 4

The movement of auxin downward from its site of production is referred to as:

A) gravitropism.
B) apical dominance.
C) nonpolar transport.
D) polar transport.
E) turgor movement.

Question 5

What hormone promotes apical dominance in plants?

A) abscisic acid
B) auxin
C) cytokinin
D) ethylene
E) gibberellin

Question 6

If you expose a plant to a light that shines on the right side of a plant, which of the following best describes why the plant grows toward the light?

A) Light destroys auxin, and thus the shaded side grows faster.
B) Auxin moves from the shaded side to the lighted side where it stimulates growth.
C) Auxin moves from the lighted side to the shaded side where it stimulates growth.
D) Light destroys auxin and thus the lighted side grows faster.
E) Auxin moves from the shaded side to the lighted side where it inhibits growth.

Question 7

In the mechanism of action for auxin, after auxin binds with its receptor, which of the following happens next?

A) Proteins are targeted for destruction.
B) Genes are activated.
C) Ubiquitin attaches to repressor proteins.
D) Transcription occurs.
E) The cell wall loosens.

Question 8

What is the hormone that promotes cell elongation by changing plant cell walls so they can expand due to the force of turgor pressure?

A) abscisic acid
B) auxin
C) cytokinin
D) ethylene
E) gibberellin

Question 9

Which of the following statements concerning the auxin F-box protein is FALSE?

A) It is located in the nucleus.
B) It is a type of receptor.
C) It is involved in catalyzing the addition of ubiquitin tags.
D) Plants have about 700 of them.
E) An example is the transport inhibitor response 1 protein.

Question 10

If you wished to obtain the strongest phototropic response from a shoot, which wavelength of light would you use?

A) less than 500 nm
B) 660 nm
C) 730 nm
D) 800 nm
E) more than 800 nm

Question 11

The site of gravity reception in roots is the:

A) root apical meristem.
B) periderm.
C) root epidermis.
D) root cap.
E) root hair.

Question 12

A seedling growing toward the source of light is an example of:

A) shade avoidance.
B) a positive hypersensitive response.
C) a negative hypersensitive response.
D) a positive phototropic response.
E) a negative phototropic response.

Question 13

The photoreceptor that absorbs blue light and triggers a phototropic response is:

A) phototropin.
B) phytochrome.
C) jasmonate.
D) systemin.
E) zeatin.

Question 14

If you removed a coleoptile tip, placed it on an agar block for a period of time, and then placed the agar block to the side of the tip of a decapitated coleoptile, which of the following would happen next?

A) The coleoptile would grow in a spiral pattern.
B) The coleoptile would die.
C) The coleoptile would not bend.
D) The coleoptile would bend away from the side having the agar block.
E) The coleoptile would bend toward the side having the agar block.

Question 15

Changing day length, as well as variations in precipitation and temperature, are environmental cues that exert an important influence on:

A) the kinds of genes a plant has.
B) the number of mutations that genes undergo.
C) whether a plant is an annual, biennial, or perennial.
D) which genes will be expressed in a plant.
E) whether a plant reproduces sexually or asexually.

Question 16

__________ is growth in response to a mechanical stimulus, such as contact with a solid object.

A) Heliotropism
B) Phototropism
C) Gravitropism
D) Thigmotropism
E) Geotropic bending

Question 17

Which of the following statements about plant hormones is false?

A) They are organic compounds that act as a highly specific chemical signal.
B) They are effective in extremely small amounts.
C) They elicit many different responses.
D) They stimulate a response at one concentration and inhibit that same response at a different concentration.
E) They can be categorized into seven major classes.

Question 18

When a plant responds to external stimuli, such as light, gravity, or touch by directional growth, these responses are referred to as:

A) turgor movements.
B) sleep movements.
C) nastic movements.
D) circadian rhythms.
E) tropisms.

Question 19

When a root is placed on its side, what happens to the amyloplasts in the root cap cells?

A) They move to the top.
B) They settle on the bottom.
C) They are digested by amylase.
D) They move into the root apical meristem.
E) They move into a root hair.

Question 20

The purification and elucidation of the primary auxin's chemical structure were accomplished by:

A) Charles Darwin.
B) Francis Darwin.
C) Frits Went.
D) Kenneth Thimann.
E) F.Skoog.

Question 21

If you wanted to develop an herbicide that was structurally most similar to cytokinin, which of the following molecules would you use as starting material?

A) adenine
B) glucose
C) naphthaleneacetic acid
D) $\alpha$ -amylase
E) a steroid

Question 22

The herbicides (weed killers) 2,4-D and 2,4,5-T are examples of synthetic:

A) abscisic acid.
B) auxins.
C) cytokinins.
D) ethylene.
E) gibberellins.

Question 23

In barley seed germination, the __________ releases gibberellin which triggers the synthesis of __________ in the __________.

A) seed coat; $\alpha$ -amylase; embryo
B) endosperm; cellulase; embryo
C) embryo; $\alpha$ -amylase; endosperm
D) embryo; cellulase; seed coat
E) endosperm; $\beta$ -amylase; embryo

Question 24

What am I? I am present in reduced amounts in dwarf plants, and I stimulate bolting in many species.

A) abscisic acid
B) gibberellin
C) cytokinin
D) ethylene
E) auxin

Question 25

Figure 38-1
Use the figure to answer the corresponding question(s).
Unripe green fruits ripen quickly in supermarkets or commercial storage facilities after exposure to:

A) abscisic acid.
B) auxin.
C) cytokinin.
D) ethylene.
E) gibberellin.

Question 26

A plant growth response to mechanical stress, such as rain and contact with passing animals, is known as:

A) phototropism.
B) gravitropism.
C) thigmomorphogensis.
D) a circadian rhythm.
E) thigmotropism.

Question 27

__________ is a synthetic auxin that stimulates root development on stem cuttings and is used extensively in asexual propagation.

A) Indoleacetic acid
B) Indolebutyric acid
C) Naphthalene acetic acid
D) 2,4-D
E) 2,4,5-T

Question 28

Which hormone promotes cell division and delays senescence in plants?

A) abscisic acid
B) auxin
C) cytokinin
D) ethylene
E) gibberellin

Question 29

The "stress hormone" involved in stomatal closure during water stress is:

A) abscisic acid.
B) auxin.
C) cytokinin.
D) ethylene.
E) gibberellin.

Question 30

Any response of a plant to the relative lengths of light and darkness is referred to as:

A) gravitropism.
B) photoperiodism.
C) phototropism.
D) thigmotropism.
E) thigmomorphogenesis.

Question 31

What is the hormone that promotes stem elongation and was first discovered while studying the growth of extremely tall and spindly rice plants?

A) abscisic acid
B) auxin
C) cytokinin
D) ethylene
E) gibberellin

Question 32

Figure 38-1
Use the figure to answer the corresponding question(s).
Based on the data in Figure 38-1, the condition that results in root development is:

A) a high ratio of auxin to cytokinin.
B) a low ratio of auxin to cytokinin.
C) a relatively equal proportion of auxin to cytokinin.
D) cytokinin levels of at least 0.2 mg/L.
E) auxin concentrations of 0.5 mg/L.

Question 33

Examples of long-day plants are:

A) poinsettia.
B) florist's chrysanthemum.
C) spinach.
D) black-eyed Susan.
E) both spinach and black-eyed Susans.

Question 34

Brassinosteroids differ from other plant hormones in that they are _______.

A) peptides
B) steroids
C) derivatives of adenine
D) derivatives of aspirin
E) derivatives of prostaglandins

Question 35

Figure 38-1
Use the figure to answer the corresponding question(s).
Which hormone stimulates both leaf abscission and fruit ripening?

A) abscisic acid
B) auxin
C) cytokinin
D) ethylene
E) gibberellin

Question 36

What hypothetical hormone promotes flowering but has never been successfully isolated?

A) florigen
B) ubiquitin
C) jasmonic acid
D) brassinosteroids
E) methyl salicylate

Question 37

Examples of short-day plants are:

A) poinsettia.
B) florist's chrysanthemum.
C) spinach.
D) black-eyed Susan.
E) both poinsettias and chrysanthemums.

Question 38

Auxin sprayed on tomato flowers stimulates the __________ to develop without the formation of __________.

A) roots; root hairs
B) fruit; ovaries
C) seeds; ovaries
D) ovary; seeds
E) seeds; fruits

Question 39

Figure 38-1
Use the figure to answer the corresponding question(s).
One conclusion that can be drawn from Figure 38-1 is that:

A) a low ratio of auxin to cytokinin stimulates root development.
B) a low ratio of auxin to cytokinin stimulates shoot development.
C) a low ratio of auxin to cytokinin results in undifferentiated growth.
D) a low ratio of auxin to cytokinin stimulates the formation of an entire plant.
E) a low ratio of auxin to cytokinin results in no growth.

Question 40

The application of __________ substitutes for low temperature or light requirements for biennial germination.

A) indoleacetic acid
B) indolebutyric acid
C) naphthaleneacetic acid
D) gibberellins
E) ethephon

Question 41

Who am I? I am a lipid-derived hormone produced in response to the presence of insect pests.

A) cytokinin
B) abscisic acid
C) jasmonic acid
D) gibberellin
E) auxin

Question 42

If you planted two gardens, one in the sun and one in the shade, the plants grown in the shade would most likely be __________ because chlorophyll absorbs more __________.

A) shorter; far-red light than red light
B) shorter; red light than far-red light
C) taller; red light than far-red light
D) taller; far-red light than red light
E) shorter; cryptochrome than phytochrome

Question 43

Which statement about the internal biological clock is not true:

A) is known as a circadian rhythm.
B) is related to the opening and closing of stomata.
C) includes the sleep movements observed in some plants, such as beans.
D) may involve both phytochrome and cryptochrome.
E) disappears abruptly if it is not reset by the rising and setting sun.

Question 44

Which of the following would not be characteristic of a plant exhibiting shade avoidance?

A) stem elongation
B) fewer leaves
C) lower quantity of storage products
D) less reproductive tissue
E) more branches

Question 45

When you shine light having a wavelength of 660 nm on a plant, which of the following will most likely happen next?

A) Pfr is stored for later use.
B) Pr is synthesized.
C) Pr is converted to Pfr.
D) Pfr is converted to Pr.
E) Pr is degraded.

Question 46

Which of the following statements concerning cryptochrome is FALSE?

A) It is implicated in resetting the biological clock.
B) It is a "clock protein."
C) It absorbs green light.
D) Its counterparts are found in fruit flies and mice.
E) It sometimes interacts with phytochrome.

Question 47

In not more than three sentences, explain why a plant placed in a window grows toward the light.

Question 48

What am I? I am structurally related to aspirin, and I help defend plants against insect attack.

A) systemin
B) jasmonates
C) brassinosteroids
D) methyl salicylate
E) oligosaccharins

Question 49

Which of the following sequences correctly represents the phytochrome signal transduction pathway?

A) red light $\rightarrow$ PIF3 activation $\rightarrow$ PIF3 into nucleus $\rightarrow$ light-responsive gene switched off
B) red light $\rightarrow$ Pfr to Pr $\rightarrow$ Pr into nucleus $\rightarrow$ Pr-PIF3 complex $\rightarrow$ light-responsive gene regulation
C) UV light $\rightarrow$ PIF3 into nucleus $\rightarrow$ light responsive gene produces phytochrome $\rightarrow$ Pr to Pfr
D) blue light $\rightarrow$ Pfr into nucleus $\rightarrow$ Pfr-PIF3 complex $\rightarrow$ light-responsive gene regulation
E) red light $\rightarrow$ Pr to Pfr $\rightarrow$ Pfr into nucleus $\rightarrow$ Pfr-PIF3 complex $\rightarrow$ light-responsive gene regulation

Question 50

The effect of red light on plants is to:

A) inactivate phytochrome.
B) convert Pfr to Pr.
C) inhibit germination in some seeds.
D) initiate shade avoidance responses.
E) impact processes in plants that use phytochrome to detect day length.

Question 51

Which of the following statements concerning phytochrome-induced responses is FALSE?

A) All responses are very rapid and short-term.
B) Red light causes potassium channels to open.
C) The absorption of light by one part of the phytochrome molecule triggers a conformational change in another part.
D) Phytochrome activates transcription of the gene for a subunit of rubisco.
E) Far-red light causes potassium channels to close.

Question 52

Figure 38-2
Use the figure to answer the corresponding question(s).
Phy B may inhibit flowering in:

A) day-neutral plants.
B) vernalized plants.
C) long-day plants.
D) senescing plants.
E) short-day plants.

Question 53

After the sun goes down:

A) the level of Pfr increases.
B) the level of Pfr remains constant.
C) Pfr is converted to Pr.
D) Pfr is degraded.
E) Pr is converted to Pfr.

Question 54

Figure 38-2
Use the figure to answer the corresponding question(s).
The plant in row b of Figure 38-2 demonstrates a photoperiodic response characteristic of:

A) short-day plants.
B) day-neutral plants.
C) long-day plants.
D) long-night plants.
E) intermediate-day plants.

Question 55

In a hypersensitive response:

A) long-lasting resistance is built up throughout the plant.
B) the axillary buds break dormancy.
C) cryptochrome is synthesized.
D) jasmonic acid activates enzymes.
E) the infected area is sealed off by necrotic lesions.

Question 56

Figure 38-2
Use the figure to answer the corresponding question(s).
The photoreceptor for photoperiodism and some other light-initiated plant responses is a group of blue-green pigments named:

A) xanthophyll.
B) carotene.
C) chlorophyll.
D) phytochrome.
E) phycocyanin.

Question 57

Figure 38-2
Use the figure to answer the corresponding question(s).
Refer to Figure 38-2.The photoperiodic response of the plant in row a suggests:

A) a brief dark period is the light cue that induces flowering.
B) a brief daylight period is the light cue that induces flowering.
C) a long uninterrupted daylight period is the light cue that induces flowering.
D) a long uninterrupted dark period is the light cue that induces flowering.
E) Cannot be determined from the data provided.

Question 58

Pr is located in the __________, and after it absorbs red light, the resulting Pfr moves to the __________.

A) endoplasmic reticulum; plasma membrane
B) cytoplasm; nucleus
C) plasma membrane; cytoplasm
D) cytoplasm; plasma membrane
E) nucleus; cytoplasm

Question 59

Plants compete for light, a response known as __________, in which plants tend to grow taller when closely surrounded by other plants.

A) epinasty
B) phototropism
C) shade avoidance
D) shade tolerance
E) thigmotropism

Question 60

During the day the leaves of bean plants are __________, and at night they are __________.

A) horizontal; wilted
B) horizontal; vertical
C) horizontal; horizontal
D) vertical; vertical
E) vertical; horizontal

Question 61

A long day plant will flower when exposed to short nights.
____________________

Question 62

MATCHING
Match the plant hormone with its description.
a.abscisic acid
d.cytokinin
b.auxin
e.ethylene
c.brassinosteroid
f.gibberellin
stimulates fruit ripening

Question 63

Pr strongly absorbs light having a wavelength of 730 nm.

Question 64

Cryptochrome absorbs blue light.

Question 65

MATCHING
Match the plant hormone with its description.
a.abscisic acid
d.cytokinin
b.auxin
e.ethylene
c.brassinosteroid
f.gibberellin
stimulates division of cells growth in tissue culture

Question 66

Write a one-sentence explanation for the role of each of the following plant hormonelike signaling molecules: methyl salicylate and jasmonic acid.

Question 67

The site of gravity perception in roots is the root apical meristem.
____________________

Question 68

Auxin produced by the apical meristem inhibits the germination of lateral buds.
____________________

Question 69

Gibberellin-stimulated cell elongation occurs via cell wall acidification.
____________________

Question 70

MATCHING
Match the plant hormone with its description.
a.abscisic acid
d.cytokinin
b.auxin
e.ethylene
c.brassinosteroid
f.gibberellin
stimulates stem elongation in dwarf varieties

Question 71

When Pfr absorbs far-red light, the Pfr is converted to Pr.

Question 72

A circadian rhythm has a period that approximates a 12-hour cycle.

Question 73

Jasmonic acid is structurally similar to prostaglandins.

Question 74

Methyl salicylate triggers the genes that code for the systemic acquired resistance pathway.

Question 75

Phototropins are light-activated kinases.
____________________

Question 76

The twining of tendrils around a support is an example of thigmomorphogenesis.
____________________

Question 77

Abscisic acid stimulates the abscission of leaves.
____________________

Question 78

Describe the evidence for the existence of a flowering promoter and also for the existence of a flowering inhibitor.

Question 79

When cytokinins are sprayed on leaves of a cut stem, the leaves turn yellow.
____________________

Question 80

Ethylene stimulates the ripening of fruits.
____________________