Ch 39 Plant Behavior

Question 1

Plant horomones

Answer 1

Chemical signals that modify or control one or more specific physiological processes within a plant

Question 2

Plant hormones control what?

Answer 2

A plant’s dynamic response to its environment

Question 3

Are plant hormones produced in high or low concentrations?

Answer 3

Very low concentrations

Question 4

What can greatly affect growth and development of a plant organ?

Answer 4

Very small amounts of plant hormones

Question 5

In general, how do hormones control plant growth and development?

Answer 5

By affecting the division, elongation, and differentiation of cells

Question 6

Tropism

Answer 6

Any response resulting in curvature of organs toward or away from a stimulus

Question 7

Phototropism

Answer 7

The growth towards light

Question 8

What was the first plant tropism and its hormonal basis to be investigated?

Answer 8

Phototropism

Question 9

What was the first plant hormone discovered in association with phototropism?

Answer 9

Auxin

Question 10

Auxin

Answer 10

Refers to any chemical that promotes elongation of coleoptiles

Question 11

Coleoptiles

Answer 11

Grass shoots

Question 12

Where is auxin produced?

Answer 12

In shoot tips

Question 13

Where is auxin transported?

Answer 13

Down the stem

Question 14

According to the acid growth hypothesis, auxin stimulates what?

Answer 14

Proton pumps that lower pH and activate expansins and enzymes that loosen the cell wall

Question 15

Major responses to auxin

Answer 15

Stimlulates cell elongation

Regulates branching and organ bending

Question 16

Major responses to cytokinins

Answer 16

Stimulate plant cells division

Promotes later bud growth and slow organ death

Question 17

Major response to gibberellins

Answer 17

Promote stem elongation

Helps seeds break dormancy and use stored reserves

Question 18

Major responses to brassinosteroids

Answer 18

Induce cell elongation and division

Question 19

Brassinosteroids are chemically similar to what?

Answer 19

Sex hormones of animals

Question 20

Major responses to abscisic acid

Answer 20

Protomotes stomatal closure in response to drought

Promotes seed dormancy

Question 21

Major responses to strigolactones

Answer 21

Regulate apical dominance, seed germination, and mycorrhizal associations

Question 22

Major responses to ethylene

Answer 22

Mediates fruit ripening

Question 23

Cytokinins are produced by in what?

Answer 23

Actively growing tissues (roots, embryos, and fruits)

Question 24

What three plant hormones interact in the control of apical dominance

Answer 24

1) Cytokinins
2) Auxins
3) Strigolactone

Question 25

Apical dominance

Answer 25

A terminal bud's ability to suppress development of axillary buds

Question 26

What happens if a terminal bud is removed?

Answer 26

Plants become bushier

Question 27

What two plants hormones interact to loosen cell walls and facilitate entrance into the cells by expansins?

Answer 27

1) Auxin | 2) Gibberelins

Question 28

Gibberelins control what?

Answer 28

Bolting

Question 29

Bolting

Answer 29

The rapid growth of a plant's flowering stalk

Question 30

What two plant hormones that are necessary for flowers to yield fully-developed fruits?

Answer 30

1) Auxins | 2) Gibberelins

Question 31

Gibberelins initiate secretions of what?

Answer 31

Digestive enzymes that make nutrients available to the plant embryo

Question 32

In some seeds, germination is stimulated by what?

Answer 32

When the hormone abscisic acid (ABA) is removed by heavy rain, light, or prolonged cold

Question 33

What can cause precocious (early) germination of seeds?

Answer 33

Inactive or low levels of ABA

Question 34

How is the plant hormone ethylene distributed?

Answer 34

As a gas

Question 35

When is ethylene produced?

Answer 35

1) During fruit ripening | 2) In response to stress (drought, flooding, injury, infection)

Question 36

Ethylene induces what kind of response?

Answer 36

A triple response

Question 37

Triple response

Answer 37

Allows a growing shoot to avoid obstacles

Question 38

Three steps of triple response

Answer 38

1) Slowing of stem elongation 2) Thickening 3) Horizontal growth

Question 39

What usually initiates hormonal responses leading to flowering and fruiting?

Answer 39

A photoperiod

Question 40

Photoperiod

Answer 40

The relative lengths of night and day

Question 41

Short-day plants

Answer 41

Plants that flower when a light period is shorter than a critical legnth

Question 42

Long-day plants

Answer 42

Plants that flower when a light period is longer than a critical length

Question 43

Thigmotropism

Answer 43

Growth in response to touch that occurs in vines and other climbing paltns

Question 44

Thigmomorphogenesis

Answer 44

Refers to changes in form that result from mechanical disturbances

Question 45

Touching young plants can result in what?

Answer 45

Slowed apical growth

Question 46

Gravitropism

Answer 46

Response to gravity

Question 47

Roots show what kind of gravitropism?

Answer 47

Positive gravitropism

Question 48

Shoots show what kind of gravitropism?

Answer 48

Negative gravitropism

Question 49

Statoliths

Answer 49

Dense cytoplasmic components

Question 50

How doe plants detect gravity?

Answer 50

By the settling of statoliths

Question 51

Secondary compounds

Answer 51

Compounds produced for defense

Question 52

Toxins

Answer 52

Secondary compounds produced in small amounts

Question 53

Inhibitors of digestion

Answer 53

Secondary compounds produced in large amounts

Question 54

Alkaloids

Answer 54

A major group of bitter-tasting plant toxin

Question 55

What are alkaloids derived from?

Answer 55

Amino acids

Question 56

Four known alkaloids

Answer 56

1) Caffeine 2) Nicotine 3) Morphine 4) Strychnine

Question 57

Phenolics

Answer 57

Have antiseptic properties or inhibit digestion

Question 58

How do phenolics inhibit digestion?

Answer 58

By binding proteins and interfering with enzymes

Question 59

Three known phenolics

Answer 59

1) Tannins 2) Lignin 3) Cannibinoids

Question 60

Plants damaged by insects release chemicals to:

Answer 60

1) Warn other plants of the same species | 2) "Recruit" predators that help defend against predators