Plant Responses to Stimuli

Question 1

Etiolation

Answer 1

the process a plant undergoes to grow in absence of light characterized by long weak stems, small/no leaves, and a pale yellow color

Question 2

De-etiolation

Answer 2

the process a plant undergoes to grow when exposed to light characterized, by thick strong stems, leaves, and a green color

Question 3

Three steps of signal transduction pathways (STP)

Answer 3

reception, transduction, and response

Question 4

Reception

Answer 4

First step of STP; phytochrome receptors are activated by photons from a light source

Question 5

Transduction

Answer 5

Second step of STP; the signal is transmitted to the effector the protein kinase

Question 6

What molecules do phytochrome receptors activate to trigger the protein kinase

Answer 6

they produce cGMP and open calcium channels on the plasma membrane; both activate the protein

Question 7

Protein Kinase

Answer 7

the effector/transcription factor that receives the Ca2+ and cGMP

Question 8

Response

Answer 8

Final step of STP; the transcription factor triggers gene expression and enzyme activation which facilitate pigment synthesis

Question 9

Auxin hormone

Answer 9

increases flexibility of cell walls

Question 10

Cytokinin hormone

Answer 10

transported up through xylem sap to actively growing tissues to control cell division and assert apical bug dominance

Question 11

Auxin vs. Cytokinin

Answer 11

Auxin inhibits lateral growth from axillary buds, cytokinin stimulates it

Question 12

Gibberellin hormone

Answer 12

stimulates cell elongation and division in stem and leaf cells, increases fruit size and yield, and mobilizes nutrients needed for germination

Question 13

Abscisic acid hormone

Answer 13

closes stomata and prevents seeds from germinating (maintains seed dormancy)

Question 14

Abscisic acid and Gibberellin

Answer 14

abscisic acid counteracts the effects of gibberellin

Question 15

Ethylene hormone

Answer 15

the stress hormone of plants

Question 16

Ethylene triple response

Answer 16

a stress response triggered by ethylene to overcome a mechanical stresses
1. stem elongation slows
2. stem thickens
3. stem grows horizontally

Question 17

Leaf Abscission

Answer 17

occurs during low levels of auxin and high levels of ethylene; ethylene seals off a leaf and triggers digestive enzymes to digest it.
Leaf changes color because plant removes necessary pigments

Question 18

Fruit Ripening

Answer 18

ethylene stimulates digestive enzymes and ripens fruit

Question 19

Brassinosteroids

Answer 19

mimic the effects of auxin; promotes elongation and slows leaf abcission

Question 20

Jasmonates

Answer 20

involved in plant defense and immune response

Question 21

Strigolactones

Answer 21

produced in roots and attracts mycorrhizae to affiliate with the plant

Question 22

Photomorphogensis

Answer 22

light triggers important processes in plants

Question 23

What do blue-Light photoreceptors do?

Answer 23

mediate phototropism and induce stomata to open

Question 24

Phytochrome receptor purpose

Answer 24

mediate de-etiolation and light-induced germination

Question 25

Phytochrome response in red light

Answer 25

induce germination

Question 26

Phytochrome response in far red light

Answer 26

inhibit germination

Question 27

Phenology

Answer 27

the changing of the length of the day/night cycle of a plant over the course of a year

Question 28

Plant circadian rhythm

Answer 28

lift leaves/open flowers during day b/c of transpiration

Question 29

Gravitropism

Answer 29

growth orientation in response to gravity

Question 30

What kind of gravitropism do germinating roots (radicle) exhibit?

Answer 30

positive gravitropism (downward)

Question 31

What kind of gravitropism do germinating shoots (epicotyl) exhibit?

Answer 31

negative gravitropism (upward)

Question 32

What “pulls” the radicle downward?

Answer 32

starch statoliths located at the tip of the radicle

Question 33

Thigmotropism

Answer 33

directional growth in response to touch

Question 34

Thigmotropism cause

Answer 34

auxin causes cell growth in the non-contacted cells

Question 35

Thigmonasty

Answer 35

movement in response to touch

Question 36

Thigmonasty cause

Answer 36

touch triggers loss of water and pressure in support “hinge” cells

Question 37

How is the signal of touch distributed throughout the plant during thigmonasty?

Answer 37

action potentials

Question 38

Drought tolerance

Answer 38

enhanced production of abscisic acid closes stomata and leaves curl to minimize area for gas exchange

Question 39

Flood tolerance

Answer 39

plant roots unable to release ethylene which digests and creates snorkel like air tubes throughout the plant

Question 40

Heat tolerance

Answer 40

production of heat shock proteins that prevents denaturation of proteins

Question 41

Cold tolerance

Answer 41

reduces cell dehydration by increasing solute concentration and producing antifreeze proteins

Question 42

PAMP-triggered immunity

Answer 42

plants detect PAMPs (unfamiliar objects connected to pathogen) and produces antimicrobial compounds

Question 43

Effecter-triggered immunity

Answer 43

plants detect PAMP effectors and up regulate disease-resistant genes

Question 44

PAMP effectors

Answer 44

block the cell signal that alerts the immune response of the PAMP

Question 45

Hypersensitive immune response

Answer 45

local response; infected cells die and lesions are formed around the infected areas of the plant

Question 46

Methysalicylic acid

Answer 46

produces salicylic acid to trigger gene expression of acids to protect against the pathogen

Question 47

Systemic Acquired Resistance

Answer 47

Methylsalicylic travels throughout the plant and becomes salicylic acid as a resistant to the pathogen