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Plant Responses Flashcards

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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
What is a stimulus?
Anything that causes a reaction in an organism or in any of its parts
26
Give an example of plant stimuli
Light, Gravity and temperature
27
Give an example of animal stimuli?
Hearing a loud noise
28
What is a response?
It's the activity of an organism as a result of a stimulus
29
Give examples of plant responses
Growth, Flowering
30
Give examples of animal responses
Movement
31
What structures are required for response?
Method of movement | A defence or immune system
32
What are external factors that control growth of flowering plants?
Light - provides energy for photosynthesis | Temperature - affecting rate of enzyme activity
33
What are internal factors that control growth of flowering plants?
Chemicals called growth regulators
34
What is a tropism?
Growth response of a plant as a result of an external stimulus
35
What is a positive tropism?
Growth towards stimulus
36
What is a negative tropism?
Growth away from stimulus
37
What is the main advantage of tropisms
Allow plants to obtain more favourable growing conditions
38
Why do plants grow towards gravity? Benefit of geotropism
They can penetrate deeper into the soil for better anchorage and absorbtion
39
Give an example of a thigmotropic plant
Ivy, Vines, Peas
40
What grows towards water?
Roots and pollen tubes grow towards water
41
What grows towards chemicals?
Fertilisers such as nitrogen and potassium
42
What's the name of specialised parts in thigmotropism?
Tendrils
43
Why is it difficult to establish the exact role of growth regulators
- active in small amounts - effects depend on concentration - effects depend on location in plant
44
What are the functions of an auxin?
Stimulate stem elongation Cause phototropism Developing fruit
45
Identify the hormone that regulates a plant’s growth response to light
Auxin
46
What is an auxin?
It’s a growth regulator in plants produced in the meristematic regions
47
Graph that shows effect of varying auxin concentration on root and shoot of plant How do you know when it reaches max stimulation?
Highest part of the graph
48
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
i) Inhibition | ii) Stimulation
49
Give two examples of uses of synthetic [man-made] auxins
Rooting powder Ripening of fruit with ethene Tissue culture Weed killer
50
Describe three methods used to be plants to protect themselves from adverse external environments
``` Structural - Thick cuticle Thorns Deep roots Chemical - Production of heat shock proteins Production of toxic chemicals ```
51
What is a growth regulator?
It’s a chemical that controls the growth of a plant at a very low concentration
51
Give one commercial use of a plant growth regulator
Ethene - to ripen fruit
52
Give an example of a growth regulator that i) promotes growth ii) inhibits growth
i) IAA | ii) Ethene
53
How would you find the percentage increase in the IAA experiment?
average length /average length of control and x 100/1
54
Explain how a hormone [auxin] can bring about apical dominance in plants
- 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
Through which part of a stem are growth promoters transported?
Vascular tissue
56
What are meristems?
Regions of active cell division by mitosis to allow for growth
57
What are growth promoters
These increase the rate of growth of a plant
58
Give two places where auxins are produced?
Meristematic tissue in tips of root and shoot | Developing seeds
59
What are growth inhibitors
These slow down or stop the growth of a plant
60
What is thigmotropism
Growth response to touch
61
What is geotropsim
It’s the growth response to gravity
62
What adverse conditions must plants protect themselves from?
Against loss of H2O, overheating, being infected by micro organisms
63
How did you vary concentration in the IAA experiment?
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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