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BIOL 350 - Plants and Fungi > CH27: Hormones > Flashcards

CH27: Hormones Flashcards

1
Q

What are the 5 major categories of major hormone classes in plants?

A
  1. auxins
  2. Cytokinins
  3. Ethylene
  4. Abscisic acid
  5. Gibberellins
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2
Q

What are the minor hormones?

A
  • salysilic acid
  • jasmonic acid
  • systemin
  • florigen
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3
Q

What is a hormone?

A

A compound produced in one part of the organims that has significant impact of the reactions and processes in other parts of the organism (signaling molecule)

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4
Q

What is the first and most impartant hormone category?

A

Auxin

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5
Q

How to plants bend towards the light?

A

Differential cell elongation due to auxins
-as sun moves, the auxins will accumilate on the opposite side of the location of the sun (causes more growth on shade size, causing the overal plant to lean to the sun)

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6
Q

What does IAA stand for?

A

Indoleacetic acid
- smells like vinegar

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7
Q

What hormone category does IAA fall under?

A

Auxin

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8
Q

What does NAA stand for?

A

Naphthaleneacetic acid
- smells like mothballs

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9
Q

What hormone category does NAA fall under?

A

Auxin

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10
Q

Where are auxins produced?

A

The edges/margins of leaves or the stem tip

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11
Q

What direction does auxin transport?

A

Flows from top to bottom (down)
- does not come from the ground up, only top down

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12
Q

How to auxins flow between cells?

A
  1. By passive transport in IAAH (protonated) form
  2. By active transport via influx carrier (AUX1 protein) in IAA- (anion) form
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13
Q

What are the effects of auxin?

A
  • Induces regeneration of xylem cells to reconnect the water conducting tubes when a plant is wounded
  • Helps with fleshy fruit development
  • plant bending towards light
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14
Q

What do cytokinins focus on?

A

Cytokinesis

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15
Q

How were cytokinins discovered?

A

First discovered in coconut milk (liquid endosperm)

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16
Q

How do you tell the difference between natural vs synthetic cytokinins?

A

Naturally occuring: Zeatin and i6 Ade (no additional rings)

Synthetic: an additional ring

Base rings are adenine

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17
Q

What does ABA stand for?

A

Abscisic Acid

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18
Q

What is ABA synthesized from?

A

Carotenoids

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19
Q

What are the functions of ABA?

A
  • stomatal closing
  • root to shoot signaling
  • prevents seed gernimation and bud break (dormancy)
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20
Q

Where is ABA synthesized?

A

Mature leaves in roots, also in seeds (water stress stimulates production)

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21
Q

How does ABA move in leaves vs roots?

A

Leaves: via phloem

Roots: via xylem upwards

22
Q

How do chloroplats (and other plastids) synthesize ABA?

A

Use terpenoid pathway

23
Q

When the stoma is open, the guard cells are _____.

A

Turgid

24
Q

When the stoma is closed, the guard cells are _____.

A

Flaccid

25
Q

Why would the plant want to close stomata quickly?

A

To protect plant from water loss and pathogen entry.

26
Q

What is the “shooting” hormone?

A

Cytokinins

27
Q

What is the “rooting” hormone?

A

Auxins

28
Q

What color are carotenoids?

A

Orange

29
Q

What color are xanthophylls?

A

Yellow

30
Q

What hormone helps with root to stem balance (not more than the other)?

A

Abscisic Acid (ABA)

31
Q

Where is IAA NOT synthesized?

A

Roots

32
Q

If the apical meristem of Phaseolus vulgaris is removed and auxin is applied to the cut surface, the growth of _____ is _____.

A

lateral buds; inhibited

33
Q

When cultured tobacco stem tissues are treated with a combination of kinetin and IAA:

A

The cells divide rapidly

34
Q

Where are high % of Gibberellins found?

A

In immature seeds

35
Q

What do Gibberellins stimulate?

A

Cell division and cell elongation

36
Q

What is the role of Giberellins?

A
  • Breaking seed sormancy and germination
  • cause flower bolting and affect fruit development
37
Q

How do gibberellins cause dwarf “bush” beans to revert to their vining wild type?

A

Epigenetics - the giberellins “override” the swarf genetics

38
Q

How do GA break dormancy in seeds?

A

Migrates from embryo to aleurone, stimulates enzymes, break down endosperm to start germination.

39
Q

What hormone is involved with stomatal movement?

A

ABA

40
Q

Studies on cucurbits have shown that, in this family:

A

Plants grown under short-day conditions evolve more ethylene than those grown under long day conditions.

41
Q

Gibberellins overcome seed dormancy by:

A

stimulating cell elongation

42
Q

Totipotency feres to the potential of:

A

A plant cell to give rise to an entire plant

43
Q

Once a hormone binds to its receptor protein, THE NEXT event is that the receptor:

A

undergoes a conformational change

43
Q
A
44
Q

Patch clamp studies suggest that the IMMEDIATE effect of ABA in regulating stomatal movement is activation of _____in guard cells.

A

calcium channels

45
Q

What are the effects of hormone ethylene?

A
  • Fruit ripening (bananas, avo, apples)
  • leaf and flower senescence
  • leaf and fruit abscission
46
Q

Define senescence.

A

The loss of a cell’s power to divide and grow.

47
Q

Define abscission.

A

Detatchment of parts (falling off)

48
Q

Ethylene transports by

A

Diffusion from site of synthesis due to being a gas

49
Q

Where are cytokinins synthesized?

A

Root tips

50
Q

Where is ethylene synthesized?

A
  • most tissues in response to stress
  • tissues undergoing senescence or ripening
51
Q
A

BIOL 350 - Plants and Fungi (13 decks)

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