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Plant Responses Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What name is given to the regions of plants which secrete growth regulators?

A

Meristems [apical]

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2
Q

Give an example of a growth regulator which has a negative effect on plant growth and how

A

Ethene

Stimulates leaf fall in autumn

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3
Q

State two ways in which growth regulators in plants are similar to hormones in animals

A

Made at one site and function at another
Slow transport
In vascular tissue

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4
Q

Name a plant growth regulator that promotes growth and give a precise location for site of action

A

IAA

meristem / zone of elongation

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5
Q

Through which part of the stem are growth promoters transported?

A

Vascular bundles

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6
Q

Outline two uses of growth promoters in horticulture

A

Tissue culture

Promote ripening

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7
Q

What do you understand by the term adverse external environment?

A

Surroundings that are harmful to organisms

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8
Q

Name the group of substances in plants which control responses to external stimuli

A

Auxins

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9
Q

What name is given to the regions in plans in which auxins are produced?

A

Meristems

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10
Q

Give two locations of meristems

A

Root tip

Shoot tip

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11
Q

How does a plant benefit from phototropism?

A

Increased photosynthesis

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12
Q

Explain the mechanism of response by a plant to a named external stimulus

A

PHOTOTROPISM - IAA

  • iaa produced meristems of stem
  • when stem is exposed to light at one side, IAA diffuses to shaded side
  • concentration of IAA in shaded cells - elongate more than cells on bright side
  • uneven elongation causes the stem to bend towards light
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13
Q

In the IAA expediment, what plant tissue did you use?

A

Radish seeds

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14
Q

Describe how you carried out the IAA experiment

A
  • label eight petri dishes
  • stock solution to first [dish a]
  • distilled water into each of dishes B-H [none in dish a]
  • pipette, transfer 1ml of IAA from B-C and then continue, C-D, D-E, E-F, F-G and then throw in the sink. This is to create diff concentrations of IAA. don’t transfer any to H [control]
  • Petri dishes as follows - acetate grid in lid and put radish seeds on grid line.
  • put filter paper and cotton wool and tape shut with solutions
  • put in incubator for 2-3 days
  • compare growth of radish seeds
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15
Q

Describe control that was used in IAA experiment?

A

One dish [DISH H] is filled with distilled water and no stock solution

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16
Q

Compare the results that you obtained in experiment and in the control for IAA / what were the results

A

IAA - cell elongation/inhibition in roots or shoots
Dishes with high concentration - IAA promotes shoot growth
Dishes with low concentration - IAA promotes root growth
Control - normal growth

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17
Q

Why is IAA dissolved in ethanol first in IAA experiment?

A

It does not dissolve easily in water

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18
Q

What’s the name of the first step of IAA experiment?

A

Serial dilation

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19
Q

What is the reason to use acetate for experiment of IAA

A

Measure length of roots or shoots

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20
Q

Why must you make sure that the Petri dishes are standing on their edge?

A

Ensures the roots grow down and shoots grow up

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21
Q

What does IAA stand for?

A

Indole Acetic Acid

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22
Q

What biomolecules would you equate IAA to in an animal?

A

Protein [hormone]

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23
Q

From which structure in the seed did the root develop?

A

Radicle

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24
Q

Give a safety precaution you took while carrying out IAA experiment?

A

Wear glasses

Wear lab coat

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25
Q

What is a stimulus?

A

Anything that causes a reaction in an organism or in any of its parts

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26
Q

Give an example of plant stimuli

A

Light, Gravity and temperature

27
Q

Give an example of animal stimuli?

A

Hearing a loud noise

28
Q

What is a response?

A

It’s the activity of an organism as a result of a stimulus

29
Q

Give examples of plant responses

A

Growth, Flowering

30
Q

Give examples of animal responses

A

Movement

31
Q

What structures are required for response?

A

Method of movement

A defence or immune system

32
Q

What are external factors that control growth of flowering plants?

A

Light - provides energy for photosynthesis

Temperature - affecting rate of enzyme activity

33
Q

What are internal factors that control growth of flowering plants?

A

Chemicals called growth regulators

34
Q

What is a tropism?

A

Growth response of a plant as a result of an external stimulus

35
Q

What is a positive tropism?

A

Growth towards stimulus

36
Q

What is a negative tropism?

A

Growth away from stimulus

37
Q

What is the main advantage of tropisms

A

Allow plants to obtain more favourable growing conditions

38
Q

Why do plants grow towards gravity? Benefit of geotropism

A

They can penetrate deeper into the soil for better anchorage and absorbtion

39
Q

Give an example of a thigmotropic plant

A

Ivy, Vines, Peas

40
Q

What grows towards water?

A

Roots and pollen tubes grow towards water

41
Q

What grows towards chemicals?

A

Fertilisers such as nitrogen and potassium

42
Q

What’s the name of specialised parts in thigmotropism?

A

Tendrils

43
Q

Why is it difficult to establish the exact role of growth regulators

A
  • active in small amounts
  • effects depend on concentration
  • effects depend on location in plant
44
Q

What are the functions of an auxin?

A

Stimulate stem elongation
Cause phototropism
Developing fruit

45
Q

Identify the hormone that regulates a plant’s growth response to light

A

Auxin

46
Q

What is an auxin?

A

It’s a growth regulator in plants produced in the meristematic regions

47
Q

Graph that shows effect of varying auxin concentration on root and shoot of plant
How do you know when it reaches max stimulation?

A

Highest part of the graph

48
Q

Graph that shows effect of varying auxin concentration on root and shoot of plant
What is the effect when the graph is going
i) down
ii) up

A

i) Inhibition

ii) Stimulation

49
Q

Give two examples of uses of synthetic [man-made] auxins

A

Rooting powder
Ripening of fruit with ethene
Tissue culture
Weed killer

50
Q

Describe three methods used to be plants to protect themselves from adverse external environments

A 
Structural - 
Thick cuticle
Thorns
Deep roots
Chemical -
Production of heat shock proteins
Production of toxic chemicals
51
Q

What is a growth regulator?

A

It’s a chemical that controls the growth of a plant at a very low concentration

51
Q

Give one commercial use of a plant growth regulator

A

Ethene - to ripen fruit

52
Q

Give an example of a growth regulator that

i) promotes growth
ii) inhibits growth

A

i) IAA

ii) Ethene

53
Q

How would you find the percentage increase in the IAA experiment?

A

average length /average length of control and x 100/1

54
Q

Explain how a hormone [auxin] can bring about apical dominance in plants

A
  • Auxin produced in the meristematic tissue in the tips of the shoots diffuses down the stem and inhibits lateral buds
  • Apical dominance is seen in cacti
  • If the apex (apical tip) is removes, side branches are allowed to develop
55
Q

Through which part of a stem are growth promoters transported?

A

Vascular tissue

56
Q

What are meristems?

A

Regions of active cell division by mitosis to allow for growth

57
Q

What are growth promoters

A

These increase the rate of growth of a plant

58
Q

Give two places where auxins are produced?

A

Meristematic tissue in tips of root and shoot

Developing seeds

59
Q

What are growth inhibitors

A

These slow down or stop the growth of a plant

60
Q

What is thigmotropism

A

Growth response to touch

61
Q

What is geotropsim

A

It’s the growth response to gravity

62
Q

What adverse conditions must plants protect themselves from?

A

Against loss of H2O, overheating, being infected by micro organisms

63
Q

How did you vary concentration in the IAA experiment?

A

Using a pipette, transfer 1ml of IAA from B-C and then continue, C-D, D-E, E-F, F-G and then throw in the sink.

Biology (36 decks)

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