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Biology > Plant responses (chpt. 32) > Flashcards

Plant responses (chpt. 32) Flashcards

1
Q

Stimulus

A

Something that causes a reaction in an organism

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2
Q

Response

A

The activity of an organism in response to a stimulus
↳ animals modify behaviour
↳ plants modify growth

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3
Q

Tropism

A

Change in the growth of a plant in response to a stimulus
↳ ensure a plant is positioned most favourably for its growth

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4
Q

Positive tropism

A

Towards stimulus

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5
Q

Negative tropism

A

Away from stimulus

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6
Q

Phototropism

A

Response to light

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7
Q

Geotropism

A

Response to gravity

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8
Q

Thigmotropism

A

Response to touch

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9
Q

Hydrotropism

A

Response to water

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10
Q

Chemotropism

A

Response to chemicals

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11
Q

Growth regulator

A

Chemical that controls the growth of a plant

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12
Q

Where are growth regulators produced?

A

Meristematic regions (root/shoot tips)

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13
Q

How are growth regulators transported around the plant?

A

Mostly in xylem and phloem

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14
Q

Example of a growth regulator and its effect

A

auxin
↳ small amounts → root promoter & shoot inhibitor
↳ large amounts → root inhibitor & shoot promoter

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15
Q

Mechanism of phototropism

A

• IAA produced in meristem
• auxin diffuses down shaded side
• higher concentration of auxin on shaded side causes cells on this side to elongate
• as a result of uneven elongation, cell bends towards the light

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16
Q

Commercial uses of plant regulators

A

Fruit harvesting: spray with auxins to prevent fruit drop, allows fruit to grow larger
Rooting powders: auxins used to stimulate plant cuttings to grow quicker

17
Q

Adaptations of plants for protection (x4)

A

PHYSICAL:
• thorns - cactus
• epidermis/bark - prevent entry of pathogens, reduce water loss
CHEMICAL:
• tannins - make bark bitter tasting to prevent being eaten by caterpillars
• heat shock proteins - surround plant enzymes during high temperatures to prevent denaturing

18
Q

What is a benefit to the plant that the shoot is positively phototropic?

A

Absorbs more light for photosynthesis

19
Q

State why the action of an auxin is considered to be similar to the action of a hormone in the human body

A

Chemical action
Prolonged effect
Produced in one place and act in another

20
Q

State an inhibitory function of auxin

A

Slows mitosis

21
Q

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

A

IAA
Ethene

22
Q

Give two examples of auxins which inhibit growth

A

IAA
Ethene

23
Q

What is the role of the vascular system in tropic response?

A

Transport growth regulators

24
Q

Advantage of tropisms

A

Plants can achieve more favourable conditions for growth

25
Q

What are growth regulators transported in?

A

Vascular tissue

Biology (34 decks)

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