Control of Flowering and Photoperiodism

Question 1

season with cooler nights/shorter days

Answer 1

autumn

Question 2

True or False: During autumn, there is a decreased growth in plants (dormancy and colorful leaves)

Answer 2

True

Question 3

True or False: During spring, growth stops because of inactive photosynthesis

Answer 3

False

growth resumes, active photosynthesis

Question 4

True or False: Responses to light are critical for plant success

Answer 4

True

Question 5

effects of light on plant morphology is called _

Answer 5

Photomorphogenesis

Question 6

True or false: Plants can only detect the presence of light

Answer 6

False, it detects:
Presence of light
direction
intensity
wavelength (color)

Question 7

It is a graph that depicts the relative response of a process to different wavelengths of light

Answer 7

Action spectrum

Question 8

It is useful in the study of any process that depends on light

Answer 8

action spectra

Question 9

True or False: Zea mays has a photoreceptor sensitive to red light

Answer 9

False; blue light causes it to bend in action spectra

Question 10

What led to the identification of two major classes of light receptors?

Answer 10

action spectra
absorption spectra of pigments

Question 11

What are the 2 major classes of light receptors?

Answer 11

blue light photoreceptors
phytochromes

Question 12

control hypocotyl elongation, stomatal opening, and phototropism

Answer 12

blue-light photoreceptors

Question 13

hidden pigment in blue light photoreceptors

Answer 13

Cryptochrome

Question 14

blue light photoreceptor that is responsible for inhibition of stem elongation

Answer 14

Cryptochrome

Question 15

blue light photoreceptor that is responsible for phototropism

Answer 15

Phototropin

Question 16

blue light photoreceptor that is responsible for stomatal opening

Answer 16

zeaxanthin

Question 17

regulate many of a plant’s responses to light throughout its life

Answer 17

phytochromes

Question 18

family of pigments with different forms

Answer 18

phytochrome

Question 19

known for their groundbreaking work on photoperiodism in plants, a phenomenon where plants’ flowering, growth, and reproduction are influenced by the length of the day and night.

Answer 19

Garner and Allard

Question 20

In Garner and Allard’s study, flowering is inhibited most effectively by _

Answer 20

Interrupting dark period with red light

Question 21

An interruption of the dark period with red light can be
reversed if it is followed immediately by _

Answer 21

exposure to far red light

Question 22

What led to the discovery of phytochromes?

Answer 22

studies of seed germination

Question 23

germination in the dark

Answer 23

Etiolation

Question 24

True or False: Etiolation is controlled by red light

Answer 24

True

Question 25

Pr to Pfr

Answer 25

Normal growth

Question 26

Pfr to Pr

Answer 26

Etiolation continues

Question 27

determined the action spectrum for light induced germination of lettuce seeds

Answer 27

US Department of Agriculture

Question 28

What is the result for the USDA experiment with lettuce seeds germination?

Answer 28

Germination increased with seeds exposed to red light. Germination is inhibited with seeds exposed to far-red light.

Question 29

photoreceptor responsible for the opposing effects of red and far-red light

Answer 29

phytochrome

Question 30

What are the functions of the two domain of phytochrome?

Answer 30

Photoreceptor Kinase activity

Question 31

covalently bonded to a nonprotein pigment, or chromatopore

Answer 31

Photoreceptor (phytochrome domain)

Question 32

The photoreceptor interact with this domain to link light reception to cellular responses triggered by the kinase.

Answer 32

Kinase activity

Question 33

What are the two photoreversible states of Phytochromes?

Answer 33

Pr and Pfr

Question 34

If Pr Absorbs red light

Answer 34

becomes Pfr

Question 35

If Pfr absorbs far red light, it becomes

Answer 35

Pr

Question 36

What is the inactive state of phytochrome

Answer 36

Pr

Question 37

What is the active state of Phytochrome

Answer 37

Pfr

Question 39

Pr → Pfr happens when there’s _ (especially red light), and it takes around 3–4 hours.

Answer 39

light

Question 40

Pfr → Pr happens in _

Answer 40

darkness (or when exposed to far-red light).

Question 41

What is the significance of the interconvertibility of Pr to Pfr by red and far red light?

Answer 41

measure the length of darkness relative to length of night

Question 42

True or False: if the plant is in Pr state, it won't flower

Answer 42

False; Pr state (inactive) urges flowering

Question 43

it also provides the plant information about the quality of light

Answer 43

Phytochrome system

Question 44

the phytochrome ratio shifts in favor of Pr when a tree is shaded

Answer 44

shade avoidance

Question 45

much of the red light of sunlight is absorbed by _ in a plant canopy

Answer 45

chlorophyll

Question 46

True or False: forest floor receives less red light

Answer 46

True, it promotes stem elongation (less conversion of Pr to Pfr)

Question 47

What directs shoot phototropism

Answer 47

Phytochrome

Question 48

state in shaded side, promotes stem elongation

Answer 48

Pr

Question 49

illuminated side, inhibits stem elongation, stimulates branching

Answer 49

Pfr

Question 50

What are the other effects of phytochrome

Answer 50

Shoot gravitroprism Stomatal formation Leaf abscission Flower formation nyctinasty

Question 51

These are long night plants that has light proof shades that manipulate photoperiodism

Answer 51

Mums (Chrysanthemums)

Question 52

internal timing mechanism that do not speed up as temperature increases

Answer 52

biological clock

Question 53

allows plant to synchronize their activities (flowering); sense and anticipate change in seasons

Answer 53

biological clocks

Question 54

resynchronization of the biological clock by the environment

Answer 54

entrainment

Question 55

circa means

Answer 55

about

Question 56

dies means

Answer 56

day

Question 57

plant that lower their leaves in the evening and raise them in the morning

Answer 57

legumes

Question 57

common 4 o'clock plant opens flower in late afternoon

Answer 57

Mirabilis jalapa

Question 58

Scientists took the luciferase gene (this is the gene from fireflies that makes them glow) and attached it to the promoter (a control switch) of a plant gene called

Answer 58

CAB2 gene

Question 58

cyclical responses to environmental stimuli

Answer 58

circadian rhythms

Question 58

evening primrose opens flower in evening

Answer 58

Oenethera biennis

Question 59

Why does scientist choose CAB2 gene

Answer 59

regulated by light and circadian clock gene expression is great in cotyledons, not roots

Question 60

What is the result of CAB2 gene experiment

Answer 60

Phytochrome and blue light receptors reset the circadian rhythm

Question 61

marks sunrise and sunset by providing the biological clock with environmental cues

Answer 61

Phytochrome conversion

Question 62

relative lengths of night and day

Answer 62

Photoperiod

Question 63

environmental stimulus plants use most often to detect the time of year

Answer 63

photoperiod

Question 64

physiological response to photoperiod

Answer 64

photoperiodism

Question 65

accompanying aging that lead to the death of a plant or plant part

Answer 65

Senescence

Question 66

Rapid senescence (few hours flower examples)

Answer 66

Oxalis europaea (wood sorrel) Erodium cicutarium (heron's bill)

Question 67

not a gradual cessation of growth

Answer 67

senescence

Question 68

energy requiring process brought about by metabolic changes

Answer 68

senescence

Question 69

period of decreased metabolism

Answer 69

dormancy

Question 70

These scientists studied how day length affects flowering in tobacco plants.

Answer 70

Wightman Garner and Henry Allard

Question 71

Normal tobacco plants flower in _, when days are _

Answer 71

late summer (august), long

Question 72

But a special kind of mutant plant tobacco called _ only flowers in December, when days are shorter.

Answer 72

Maryland Mammoth

Question 73

When does Maryland Mammoth flower?

Answer 73

December, days are short

Question 74

ratio of the length of day to the length of night

Answer 74

Photoperiodism

Question 75

# Kinds of Flowering Responses in Plants without regard to photoperiod

Answer 75

Day Neutral plants

Question 76

examples of day neutral plants

Answer 76

roses, cotton, sunflowers, tomatoes, cucumbers, weeds, **snapdragons, and carnation**

Question 77

# Kinds of Flowering Responses in Plants light periods are shorter than some critical length

Answer 77

short-day plants

Question 78

example of short day plant

Answer 78

asters, strawberries, poinsettias, potatoes, soybeans, chrysanthemums, **ragweed, dahlia, christmas cactus**

Question 79

# Kinds of Flowering Responses in Plants flower in spring or early summer light periods are longer than critical length (9-16 hours)

Answer 79

long day plants

Question 80

examples of long day plants

Answer 80

lettuce, spinach, radish, beet, clover, corn, gladiolus, iris

Question 81

Flower only when exposed to days of intermediate length

Answer 81

intermediate-day plants

Question 82

either days of too long or too short

Answer 82

intermediate day plants

Question 83

example of intermediate day plant

Answer 83

purple nutsedge, sugar cane

Question 84

Who concluded that flowering requires a specific period of uninterrupted dark rathen than uninterrupted light

Answer 84

Karl Hammer and James Bonner

Question 85

True or False: Flowering and other responses to photoperiod is controlled by night length, not day length

Answer 85

True, critical night length

Question 86

10 hours of dark or more

Answer 86

Ragweed (long night)

Question 87

will not flower unless exposes to long nights

Answer 87

obligate photoperiodism (Glycine max - soybean)

Question 87

less than 10 hours of dark

Answer 87

spinach short night plant

Question 88

flower without inductive photoperiod

Answer 88

facultative periodism (Cannabis sativa - marijuana) (Schlumbergera bridgesii - Christmas cactus)

Question 89

long night plant at high temp short night plant at low temp

Answer 89

Euphorbia pulcherrima (poinsettia)

Question 90

flower when exposed to 13.7 hours of dark but not in 14 hours

Answer 90

Hyocyamus niger (henbane)

Question 91

flowering signal, may be a hormone or a change in relative concentrations of multiple hormones

Answer 91

florigen

Question 91

combination of environmental cues and internal signals necessary for flowering to occur results to

Answer 91

Meristem transition (vegetative to flowering state)