Chapter 39

Question 1

Etiolation

Answer 1

Physical adaptations for growing in darkness

Question 2

De-etiolation

Answer 2

After exposure to light, plant greens meaning the shoots and roots grow normally again

Question 3

Different ways that plants can detect light

Answer 3

Intensity, spectral composition, direction it’s coming from, spatial gradient of intensity, amount of time it’s available

Question 4

Photomorphogenesis

Answer 4

Effects of light on plant morphology

Question 5

Two different classes of light receptors

Answer 5

Blue-light photoreceptors, phytochromes

Question 6

Blue-light photoreceptors

Answer 6

Absorb blue light

Question 7

What plant responses does blue light initiate?

Answer 7

Hypocotyl elongation, stomata opening, phototropism

Question 8

Cryptochromes

Answer 8

Blue-light receptors involved in inhibition of stem elongation

Question 9

Phototropin

Answer 9

Protein kinase involved in mediating blue-light-mediated stomatal opening, chloroplast movements, and phototropic curvatures

Question 10

Phytochromes

Answer 10

Pigments that absorb mostly red and far-red light ; red light increases germination, far-red light inhibits germination

Question 11

Responses to Pfr

Answer 11

Seed germination ; inhibition of vertical growth and stimulation of branching ; setting internal clocks ; control of flowering

Question 12

What does red light trigger verse far-red light

Answer 12

Red light converts Pr to Pfr ; far-red light converts Pfr to Pr

Question 13

Shade avoidance response

Answer 13

When a tree is shaded, the phytochrome ratio shifts in favor of Pr inducing vertical growth

Question 14

Photoperiodism

Answer 14

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

Question 15

Gravity

Answer 15

A constant force and critical environmental cue for plants to determine the growth pattern

Question 16

Gravitropism

Answer 16

Response to gravity ; roots show positive gravitropism (grow down) ; shoots show negative gravitropism (grow up)

Question 17

How can plants detect gravity?

Answer 17

By the settling of statoliths, which are dense cytoplasmic components

Question 18

Thigmomorphogenesis

Answer 18

Refers to changed in form that result from mechanical disturbance ; growth in response to touch

Question 19

Action potentials

Answer 19

Transmission of electrical impulses

Question 20

Phytotoxins

Answer 20

Metabolites (bioproducts) produced by plant pathogens to damage the cell plants ; affect photosynthesis, germination, and root and shoot growth

Question 21

Eavesdropping

Answer 21

Chemical defense signals can be detected by eavesdropping neighbors and used to prime their own defenses ; targeted to other branches of the same plant or to insect bodyguards

Question 22

Plant hormones

Answer 22

May act via signaling by removing a repress or from a transcription factor that stimulates the expression of growth-promoting genes

Question 23

Ubiguitin

Answer 23

Protein that binds covalently to another protein and targets it for breakdown

Question 24

What are some example of things Auxin does?

Answer 24

(Indole-3 acetic acid) root initiation ; leaf and fruit abscission ; apical dominance ; fruit development ; cell expansion

Question 25

What does Auxin do?

Answer 25

Inhibits growth of the axillary buds further down on the stem to promote apical dominance

Question 26

Charles Darwin and his son Francis

Answer 26

Observed positive phototropism in grass seedlings only if the tip of coleoptile was present and exposed to light ; postulated that a signal was transmitted from the tip to the elongating region

Question 27

Auxin protein pumps

Answer 27

Can set up concentration gradients of auxin in plant tissue

Question 28

Case study of Auxin

Answer 28

Cells at coleoptile tip sense light, hormone travels from tip down the coleoptile, cells lower in coleoptile respond to hormone ; bending results

Question 29

Loosening of the cell wall and enabling elongation

Answer 29

Actin increases activity of proton pumps, low pH activated expansions, polysaccharides are cleaved by cell wall-loosening enzymes, losening the microfibrils

Question 30

Some of the effects of gibberellins

Answer 30

Stem elongation, fruit growth, seed germination

Question 31

What does Abscisic acid (ABA) do?

Answer 31

Slows growth, often by antagonizing the actions of growth hormones ; Has many effects on plants including seed dormancy, drought tolerance, causes stomata to rapidly close, and it can act as an “early warning system”

Question 32

When is Ethylene produced?

Answer 32

When a seedling tip pushes against an obstacle ; it induces a triple response in which stem elongation is slowed, the stem thickens and then begins to grow horizontally ; vertical growth resumes when ethylene wears off

Question 33

Senescence

Answer 33

Programmed cell death of certain cells or organs or entire plants

Question 34

What is a burst of ethylene associated with?

Answer 34

Apoptosis

Question 35

Abscission

Answer 35

Process that occurs in autumn when a leaf falls ; change in the balance of auxin and ethylene controls this

Question 36

Burst of ethylene production in fruit

Answer 36

Triggers ripening, and reopening tiggers release of more ethylene

Question 37

What do brassinosteroids do?

Answer 37

They induce cell elongation and division in stem segments and seedlings at low concentration ; slow leaf abscission and promote xylem differentiation

Question 38

What does physical wounding of plants do?

Answer 38

Causes a rapid loss of hydrostatic pressure and generated electrical perturbation called variation potential to travel a short distance beyond the wound through the xylem

Question 39

What are jasmonates?

Answer 39

Produced in response to wounding and are involved in controlling plant defenses ; activate the wound response genes that code for the production of a second round off wound-induced chemical defenses

Question 40

What is systemin and what does it do?

Answer 40

It is a wound-response hormone produced by herbivore-damaged cells initiatives a protective response ; synthesis of jasmonic acid in undamaged cells activated the production of proteinase inhibitors

Question 41

Pheromones

Answer 41

Chemical messengers synthesized by an individual and released into he environment that elicit a response from a different individual ; plants produce wasp attractant pheromones in response to attack by caterpillars

Question 42

Some other things that Jasmonates does?

Answer 42

Nectar secretion, fruit ripening, pollen production, flowering time, seed germination, root growth, tuber formation, mycorrhizal symbiosis, tendril coiling

Question 43

Abiotic stress

Answer 43

Drought, flooding, salt stress, heat stress, and cold stress ; during drought plants reduce transpiration by closing stomata, reducing exposed surface area and in some species, shedding leaves

Question 44

Biotic stresses

Answer 44

Herbivores and pathogens ; plants use defense systems to deter herbivory, prevent infection, and combat pathogens