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Biology > Chemical Coordination in Plants > Flashcards

Chemical Coordination in Plants Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define stimuli

A

changes either in the external or internal environment of an organism

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2
Q

define responses

A

the resulting actions caused by stimuli

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3
Q

define hormones

A

they are produced in one area of a plant, transported around the body of the plant and have their effects at a location far away from the site of their production. they work as messengers.

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4
Q

main areas of growth/cell division in plants

A

meristems (just behind the tip of a root or shoot)

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5
Q

hormones of plants are called

A

phytohormone

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6
Q

define auxin

A

powerful growth stimulants, effective at low concentrations. they are present in more actively growing regions.

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7
Q

main natural auxin found in plant

A

IAA (indole 3-acetic acid)

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8
Q

functions of auxins

A
  1. promote growth of stem, root, fruits by cell elongation. (hormone induces cell wall loosening)
  2. delay leaf senescence(falling)
  3. promote growth of apical buds, and inhibit lateral buds
  4. induce rooting in the cutting of plants like rose
  5. induce fruit formation without fertilization, like apples and tomatoes
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9
Q

define apical dominance

A

suppression of growth of lateral buds by apical buds

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10
Q

define parthenocarpy

A

development of fruits without fertilization, brought about by auxins

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11
Q

formula of Gibberellic acid

A

GA3

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12
Q

location of gibberellins

A

meristematic regions like stem apex, root apex, buds, seeds

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13
Q

functions of gibberellins

A
  1. promote growth of internodes by stem elongation
  2. break seed dormancy and initiate germination
  3. induce parthenocarpy
  4. delay senescence
  5. enhance longitudinal growth of internodes in dwarf plants
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14
Q

location of cytokinins

A

produced in root tips and transported through xylem.
found in germinating seeds, developing fruits, embryo.

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15
Q

functions of cytokinins

A
  1. stimulate plant growth by cell DIVISION (even in non-meristematic tissues)
  2. expansion of cotyledons in seeds
  3. break seed dormancy
  4. promote chlorophyll synthesis
  5. delay senescence
  6. INHIBIT apical dominance
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16
Q

only hormone which is a gas at ordinary temperature

A

ethylene

17
Q

site of synthesis and action of ethylene

A

produced in fruits, and stay in same fruit (more ethylene produced in meristematic tissues)

18
Q

functions of ethylene

A
  1. reduction in cell elongation!
  2. acceleration of senescence
  3. ripening of fruits
  4. promoting root growth
  5. initiate germination
  6. inducing flowering in mango
19
Q

most widely used plant growth hormone in agriculture

A

ethylene

20
Q

define abscisic acid (ABA)

A

growth retarding hormone found in angiosperms, gymnosperms, pteridophytes, mosses.

21
Q

location of ABA

A

chloroplasts of leaves

22
Q

functions of abscisic acid

A
  1. plant growth inhibitor by slowing down metabolism
  2. induces seed dormancy
  3. accelerates senescence (ageing) and abscission (falling) of leaves, flowers
  4. stimulates closure of stomata and increases tolerance
23
Q

difference between senescence and abscission

A

senescence: ageing
abscission: falling

24
Q

stress hormone

A

abscisic acid (increases tolerance to stress)

25
Q

define tropism

A

the direction of response is related to direction from which stimulus comes. such a response is called tropism

26
Q

define tropic movement

A

growth movements occurring in response to unidirectional external stimuli in a plant part

27
Q

define phototropism

A

movement towards light

28
Q

how do auxins play an important role in phototropism

A

help in bending a shoot towards source of light, by getting accumulated in the part of the shoot which is not facing the light. promotes cell elongation in this area, causing shoot to bend towards source of light

29
Q

define geotropism

A

growing towards the earth’s gravity (AKA gravitropism)

30
Q

how can geotropism be demonstrated in the lab

A

clinostat

31
Q

define hydrotropism

A

movement of plant parts in response to water or moisture

32
Q

define thigmotropism

A

growth movement of plant parts in response to touch stimulus

33
Q

how does thigmotropism work

A

stimulus is perceived by tendril tips and is then transmitted to basal parts. entire tendril becomes sensitive to stimulus.

34
Q

define chemotropism

A

growth of plant organs in response to chemicals

35
Q

sunflowers exhibit what kind of tropism

A

heliotropism

Biology (15 decks)

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