f5 chap 5: response in plants Flashcards

1
Q

whats the definition of tropism responses?

A

(i)responses of certain parts of a plants
(ii) such as roots and shoots
(iii) that respond towards or away from a stimulus

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2
Q

characteristics of tropism

A

(i) slow response, not apparent
(ii) positive tropism: growth towards direction of stimulus
(iii) negative tropism: growth away from stimulus

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3
Q

which plant response is permanent and influenced by plant hormones

A

tropism

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4
Q

what are the types of tropism?

A

thigmotropism, geotropism, chemotropism, hydrotropism, phototropism

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5
Q

explain chemotropism

A

chemotropism is the response of plants towards chemicals. for example, roots show positive chemotropism when they grow towards mineral salts and negqative chemotropism when the grow away from poison

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6
Q

what response is it when a plant grows towards light?

A

phototropism

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7
Q

what are the types of nastic responses?

A

photonasty, seismonasty, nyctinasty, thermonasty, thigmonasty

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8
Q

characteristics of nastic responses

A

(i) response is quicker, more apparent than tropism
(ii) not all nastic responses are growth responses
(iii) some nastic responses are intended for survival

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9
Q

whats hydrotropism

A

plant response to water

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10
Q

whats phototropism

A

plant response to light

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11
Q

whats thigmotropism

A

plant response to touch

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12
Q

whats geotropism

A

plant response to gravity

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13
Q

whats nyctinasty

A

circadian rhythm that responds to onset of darkness

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14
Q

whats thermonasty

A

plant response to change in temperature

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15
Q

whats thigmonasty

A

plant response towards vibration

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16
Q

whats seismonasty

A

plant response that occur due to mechanical stimulus like shock, wind, touch and raindrops

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17
Q

in which plant can photonasty be observed?

A

japanese roses. it opens when it receives maximum sunlight and closes at night

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17
Q

whats photonasty

A

plant response to light

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18
Q

in which plant can seismonasty be observed?

A

mimosa plant

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19
Q

which part of the plant can seismonasty response be seen?

A

leaves, stigma and stamens

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20
Q

in which plant can nyctinasty be observed? explain.

A

river tamarind. it closes its leaves at night and unfurls them during daytime

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21
Q

in which plant can thermonasty be observed?. explain

A

tulips. it opens when theres an increase in temperature, closes when temperature drops

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22
Q

what response can be seen in venus flytrap?

A

thigmonasty

23
Q

what response can be seen in tulip?

A

thermonasty

24
Q

what response can be seen in river tamarind?

A

nyctinasty

25
Q

what are phytohormones?

A

chemical substances that stimulate and coordinate responses in plants, at low concentration

26
Q

state 5 types of phytohormones

A

auxin, ethylene, abscisic acid, gibberellin and cytokinin

27
Q

state 2 functions of auxin

A

(i)stimulates growth and elongation in root and shoot cells
(ii) inhibits growth of lateral buds

28
Q

state 2 functions of gibberellin

A

(i) stimulates growth of flowers in dwarf plants
(ii) inhibits development of roots

29
Q

state 2 functions of cytokinin

A

(i) stimulates seed germination
(ii) delays leaf senescence

30
Q

state 2 functions of abscisic acid

A

(i) induces seed dormancy
(ii) inhibits growth of plants

31
Q

state 2 functions of ethylene

A

(i) stimulates ripening in fruits
(ii) stimulates abscission of leaves and fruits

32
Q

which phytohormone inhibits abscission of fruits and young leaves?

A

auxin

33
Q

which phytohormone stimulates cell division in cambium during secondary growth?

A

auxin

34
Q

in which tropisms is auxin functional in?

A

phototropism and geotropism

35
Q

which phytohormone stimulates development of apical dominance in shoots and roots?

A

auxin

36
Q

which phytohormone stimulates development of adventitious roots at the end of stem cuttings?

A

auxin

37
Q

which phytohormone stimulates growth and elongation in the stem cell?

A

gibberellin

38
Q

which phytohormone stimulates development of leaves, flowers and fruits?

A

gibberellin

39
Q

which phytohormone stimulates development and germination of seeds?

A

gibberellin

40
Q

which phytohormone stimulates division and elongation of root and stem cells when auxin is present?

A

cytokinin

41
Q

which phytohormone stimulates seed germination?

A

cytokinin

42
Q

which phytohormone inhibits development of apical dominance?

A

cytokinin

43
Q

which phytohormone delays leaf senescence?

A

cytokinin

44
Q

which phytohormone stimulates growth of lateral buds?

A

cytokinin

45
Q

which phytohormone inhibits growth of plant?

A

abscisic acid

46
Q

which phytohormone induces seed dormancy?

A

abscisic acid

47
Q

which phytohormone stimulates abscission of mature fruits, leaves and flowers?

A

abscisic acid

48
Q

which phytohormone induces stomatal closing during drought season?

A

abscisic acid

49
Q

which phytohormone inhibits growth of buds and seed germination?

A

abscisic acid

50
Q

which phytohormone stimulates ripening in fruits?

A

ethylene

51
Q

which phytohormone stimulates senescence process in plants?

A

ethylene

52
Q

which phytohormone stimulates abscission of leaves and fruits?

A

ethylene

53
Q

what phytohormone controls growth response in plants?

A

auxin

54
Q

explain the effect of auxin on growth response

A
  1. auxin synthesised at coleptile tips stimulate ** cell elongation**
  2. auxin distribution influences direction of shoot growth
    3.uniform distribution auxin cause coleptile to grow upwards
  3. area which receives more auxin will grow faster and cause coleptile to curve to side that receives less or none auxin
54
Q

explain the role of auxin in phototropism

A
  1. distribution of auxin in shoots is uniform if shoots are exposed to light from all direction
  2. causes shoots to grow up
  3. shoots are exposed to light from one direction, auxin will move away from light
  4. auxin concentration is higher on shaded side 5. cells in shaded side elongate more than cells in bright side
    6 so, shoot bends towards light
54
Q

role of auxin in geotropism

A
  1. seeds germinate horizontally, gravity cause auxin pool at bottom side of tip and roots
  2. high auxin concentration cause cells at bottom to grow faster and also allow shoot to bend up)
  3. high auxin concentration at bottom of roots prevent root elongation and cause root to go down