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Biology > Chapter 39 > Flashcards

Chapter 39 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Etiolation

A

Physical adaptations for growing in darkness

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2
Q

De-etiolation

A

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

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3
Q

Different ways that plants can detect light

A

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

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4
Q

Photomorphogenesis

A

Effects of light on plant morphology

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5
Q

Two different classes of light receptors

A

Blue-light photoreceptors, phytochromes

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6
Q

Blue-light photoreceptors

A

Absorb blue light

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7
Q

What plant responses does blue light initiate?

A

Hypocotyl elongation, stomata opening, phototropism

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8
Q

Cryptochromes

A

Blue-light receptors involved in inhibition of stem elongation

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9
Q

Phototropin

A

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

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10
Q

Phytochromes

A

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

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11
Q

Responses to Pfr

A

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

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12
Q

What does red light trigger verse far-red light

A

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

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13
Q

Shade avoidance response

A

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

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14
Q

Photoperiodism

A

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

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15
Q

Gravity

A

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

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16
Q

Gravitropism

A

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

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17
Q

How can plants detect gravity?

A

By the settling of statoliths, which are dense cytoplasmic components

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18
Q

Thigmomorphogenesis

A

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

19
Q

Action potentials

A

Transmission of electrical impulses

20
Q

Phytotoxins

A

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

21
Q

Eavesdropping

A

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

22
Q

Plant hormones

A

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

23
Q

Ubiguitin

A

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

24
Q

What are some example of things Auxin does?

A

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

25
Q

What does Auxin do?

A

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

26
Q

Charles Darwin and his son Francis

A

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

27
Q

Auxin protein pumps

A

Can set up concentration gradients of auxin in plant tissue

28
Q

Case study of Auxin

A

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

29
Q

Loosening of the cell wall and enabling elongation

A

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

30
Q

Some of the effects of gibberellins

A

Stem elongation, fruit growth, seed germination

31
Q

What does Abscisic acid (ABA) do?

A

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”

32
Q

When is Ethylene produced?

A

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

33
Q

Senescence

A

Programmed cell death of certain cells or organs or entire plants

34
Q

What is a burst of ethylene associated with?

A

Apoptosis

35
Q

Abscission

A

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

36
Q

Burst of ethylene production in fruit

A

Triggers ripening, and reopening tiggers release of more ethylene

37
Q

What do brassinosteroids do?

A

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

38
Q

What does physical wounding of plants do?

A

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

39
Q

What are jasmonates?

A

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

40
Q

What is systemin and what does it do?

A

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

41
Q

Pheromones

A

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

42
Q

Some other things that Jasmonates does?

A

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

43
Q

Abiotic stress

A

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

44
Q

Biotic stresses

A

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

Biology (19 decks)

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