Phytochrome and Photomorphogenesis

Question 1

is as protein pigment that absorbs red and far-red light most strongly, and also blue light

Answer 1

phytochrome

Question 2

each subunit of phytochrome consists of a light absorbing pigment molecule called

Answer 2

chromophore

Question 3

each subunit of phytochrome consists of a polypeptide chain

Answer 3

apoprotein

Question 4

T/F: Phytochrome is a soluble, light-regulated protein kinase, which first auto phosphorylates and then activates other proteins

Answer 4

true

Question 5

In dark-grown or – plants, phytochrome is present in a red light-absorbing form Pr

Answer 5

etiolated

Question 6

Pr is converted by – to a far-red light absorbing form, Pfr

Answer 6

red light

Question 7

switching of forms between Pr and Pfr

Answer 7

photoreversibility

Question 8

Pr = red light

Answer 8

650-680 nm

Question 9

Pfr = far red light

Answer 9

710-740 nm

Question 10

Which form is physiologically active?

Answer 10

Pfr

Question 11

– red:far red ratio → germination. Lets wild seeds respond when they arrive in a forest gap or clearing

Answer 11

high

Question 12

Low red:far red ratio → – in sun plants

Answer 12

elongation

Question 13

“Etiolation” response involves allocating strongly to –, to escape the shade

Answer 13

long, thin stems

Question 14

– plants show etiolation response more strongly

Answer 14

Sun-adapted

Question 15

phytochrome regulates - leaf movements (open day, close night)

Answer 15

nyctinastic

Question 16

in legumes nyctinastic movements are caused by rhythmic – changes in flexor and extensor motor cells int eh pulvinus at the base of the petiole

Answer 16

turgor

Question 17

because red:far red ratio is low under canopies, plants can sense –

Answer 17

green shade

Question 18

domestic plants lose etiolation response so they can be grown in – without etiolating

Answer 18

high densities

Question 19

floral meristems distinguished from vegetative meristems by their

Answer 19

larger size

Question 20

transition from vegetative to reproductive dev is marked by an increase in – in central zone of shoot apical meristem

Answer 20

frequency of cell divisions

Question 21

when reproductive dev is initiated, vegetative meristem is transformed into the – which bears cauline leaves and flowers

Answer 21

primary inflorescence meristem

Question 22

axillary buds of cauline leaves dev into –

Answer 22

secondary inflorescence meristem

Question 23

inflorescence meristem has – growth

Answer 23

indeterminate

Question 24

flowers have – growth

Answer 24

determinate

Question 25

floral meristems initiate four organ types in concentric rings called

Answer 25

whorls

Question 26

initiation of -- consumes all of the meristematic cells in the apical dome

Answer 26

carpels

Question 27

specifies sepals

Answer 27

A

Question 28

specifies petals

Answer 28

A + B

Question 29

specifies stamens

Answer 29

B + C

Question 30

specifies carpels

Answer 30

C

Question 31

loss of A

Answer 31

carpels replace sepals, stamen replace petals

Question 32

loss of B

Answer 32

sepals replace petals, carpels replace stamen

Question 33

loss of C

Answer 33

petals replace stamen, new flower replace carpel

Question 34

-- may flower within a few weeks after germinating

Answer 34

annual plants

Question 35

perennial plants (forest trees) take up to -- to flower

Answer 35

20+ years

Question 36

-- and -- is an internal factor controlling the switch to reproductive dev

Answer 36

size or age

Question 37

internal cues

Answer 37

autonomous regulation

Question 38

environmental cues

Answer 38

obligate response

Question 39

promoted by environment but flower w/o

Answer 39

facultative response

Question 40

in many populations of a given species, flowering is -- favoring cross-breeding and allowing seeds to be produced in favorable environments

Answer 40

synchronized

Question 41

gradual change from juvenile to adult accompanied by changes in -- like leaf morphology and phyllotaxy, thorniness

Answer 41

vegetative characteristics

Question 42

shoot dev can be described as a series of independently regulated, overlapping programs which modulate the expression of a common set of processes

Answer 42

combinatorial model

Question 43

dev phase change tends to occur first at the -- of the shoot

Answer 43

base

Question 44

in rapidly flowering herbaceous species juvenile phase is very short

Answer 44

few days

Question 45

once meristem has switched to the adult phase, only adult vegetative structures are produced, culminating in --

Answer 45

floral evocation

Question 46

reversion of adult shoots to juvenile phase

Answer 46

rejuvenation

Question 47

-- cause phase change

Answer 47

gibberellins

Question 48

once adult phase has been attained it is relatively stable and tends to be maintained during vegetative propagation or --

Answer 48

grafting

Question 49

two stages of floral evocation

Answer 49

competence and determination

Question 50

a but is competent if it is able to -- when given the appropriate signal which leads to determination

Answer 50

flower

Question 51

vegetative shoot that is not determined is grafted onto a flowering stock it will

Answer 51

continue in vegetative phase until it achieves determination

Question 52

vegetative shoot that is determined is grafted onto a flowering stock

Answer 52

flower immediately

Question 53

organisms can sense and respond to tome of day by showing -- attuned to light/dark cycles

Answer 53

circadian rhythms

Question 54

internal pacemaker exists such that the cycles can continue in the absence of external cues, in continuous light or darkness

Answer 54

endogenous oscillator

Question 55

three parameters of circadian rhythms

Answer 55

period, phase, amplitude

Question 56

recognizable features, peaks, troughs

Answer 56

phase

Question 57

time between comparable points in cycle, peaks

Answer 57

period

Question 58

in constant light or dark rhythms become

Answer 58

free-running