Ch 39 Plant Behavior Flashcards Preview

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Flashcards in Ch 39 Plant Behavior Deck (60):
1

Plant horomones

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

2

Plant hormones control what?

A plant's dynamic response to its environment

3

Are plant hormones produced in high or low concentrations?

Very low concentrations

4

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

Very small amounts of plant hormones

5

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

By affecting the division, elongation, and differentiation of cells

6

Tropism

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

7

Phototropism

The growth towards light

8

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

Phototropism

9

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

Auxin

10

Auxin

Refers to any chemical that promotes elongation of coleoptiles

11

Coleoptiles

Grass shoots

12

Where is auxin produced?

In shoot tips

13

Where is auxin transported?

Down the stem

14

According to the acid growth hypothesis, auxin stimulates what?

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

15

Major responses to auxin

Stimlulates cell elongation

Regulates branching and organ bending

16

Major responses to cytokinins

Stimulate plant cells division

Promotes later bud growth and slow organ death

17

Major response to gibberellins

Promote stem elongation

Helps seeds break dormancy and use stored reserves

18

Major responses to brassinosteroids

Induce cell elongation and division

19

Brassinosteroids are chemically similar to what?

Sex hormones of animals

20

Major responses to abscisic acid

Protomotes stomatal closure in response to drought

Promotes seed dormancy

21

Major responses to strigolactones

Regulate apical dominance, seed germination, and mycorrhizal associations

22

Major responses to ethylene

Mediates fruit ripening

23

Cytokinins are produced by in what?

Actively growing tissues (roots, embryos, and fruits)

24

What three plant hormones interact in the control of apical dominance

1) Cytokinins
2) Auxins
3) Strigolactone

25

Apical dominance

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

26

What happens if a terminal bud is removed?

Plants become bushier

27

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

1) Auxin
2) Gibberelins

28

Gibberelins control what?

Bolting

29

Bolting

The rapid growth of a plant's flowering stalk

30

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

1) Auxins
2) Gibberelins

31

Gibberelins initiate secretions of what?

Digestive enzymes that make nutrients available to the plant embryo

32

In some seeds, germination is stimulated by what?

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

33

What can cause precocious (early) germination of seeds?

Inactive or low levels of ABA

34

How is the plant hormone ethylene distributed?

As a gas

35

When is ethylene produced?

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

36

Ethylene induces what kind of response?

A triple response

37

Triple response

Allows a growing shoot to avoid obstacles

38

Three steps of triple response

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

39

What usually initiates hormonal responses leading to flowering and fruiting?

A photoperiod

40

Photoperiod

The relative lengths of night and day

41

Short-day plants

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

42

Long-day plants

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

43

Thigmotropism

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

44

Thigmomorphogenesis

Refers to changes in form that result from mechanical disturbances

45

Touching young plants can result in what?

Slowed apical growth

46

Gravitropism

Response to gravity

47

Roots show what kind of gravitropism?

Positive gravitropism

48

Shoots show what kind of gravitropism?

Negative gravitropism

49

Statoliths

Dense cytoplasmic components

50

How doe plants detect gravity?

By the settling of statoliths

51

Secondary compounds

Compounds produced for defense

52

Toxins

Secondary compounds produced in small amounts

53

Inhibitors of digestion

Secondary compounds produced in large amounts

54

Alkaloids

A major group of bitter-tasting plant toxin

55

What are alkaloids derived from?

Amino acids

56

Four known alkaloids

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

57

Phenolics

Have antiseptic properties or inhibit digestion

58

How do phenolics inhibit digestion?

By binding proteins and interfering with enzymes

59

Three known phenolics

1) Tannins
2) Lignin
3) Cannibinoids

60

Plants damaged by insects release chemicals to:

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