5.4 Plant Responses Flashcards

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1
Q

Plants respond to what changes in their environment?

A

Lack of water
Light
Gravity

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2
Q

What are some limitations of plants?

A

Don’t have a nervous system

Rely on hormones which are much slower

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3
Q

(Hormones) what role do auxins play in plants?

A
Control cell elongation
Prevent abscission
Maintain apical dominance
Tropisms
Stimulate ethene release
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4
Q

(Hormones) what is the role of gibberellins in plants?

A

Cause stem elongation
Pollen tube growth
Mobilisation of food stores in germination

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5
Q

(Hormones) what is the role of ethene in plants?

A

Causes ripening

Promoted abscission

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6
Q

(Hormones) what is the role of ABA in the plant?

A

Maintains dormancy of deeds and buds

Stimulates protective responses such as antifreeze and stomatal closing

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7
Q

(Gibberellins in germination) for a plant to start growing it must do what?

A

Germinate

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8
Q

(Gibberellins in germination) 1. How is the embryo activated?

A

Seed absorbs water

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9
Q

(Gibberellins in germination) 2. The seed begins producing what?

A

Gibberellins

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10
Q

(Gibberellins in germination) 3. Gibberellins stimulate production of enzymes that do what?

A

Breakdown food stores

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11
Q

(Gibberellins in germination) 4. The embryo uses the food stores to make what?

A

Building materials to break through the seed coat

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12
Q

(Gibberellins in germination) 5. Gibberellins switch in genes coding for what?

A

Amylase and protease

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13
Q

(Gibberellins in germination) 6. ABA acts with gibberellins to determine what?

A

When the seed will terminate

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14
Q

What are auxins and where are they made?

A

Growth stimulants in plants

Made at tips of roots and shoots

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15
Q

(Auxins) what do auxins do in plants?

A

Stimulate growth of social shoot
Suppress lateral shoot growth
Promote root growth

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16
Q

(Auxins - apical shoot growth) 1. Auxin is synthesised where?

A

Meristems

17
Q

(Auxins - apical shoot growth) 2. Auxins diffuse away from where?

A

Tip

18
Q

(Auxins - apical shoot growth) 3. Auxins bind to what?

A

Receptor sites on cells

19
Q

(Auxins - apical shoot growth) 4. vacuoles form web what develops?

A

Low ph

20
Q

(Auxins - apical shoot growth) 5. Low pH does what to cell walls?

A

Keeps them flexible allowing cells to expand as they absorb water
Vacuoles get bigger

21
Q

(Auxins - apical shoot growth) 6. A large central vacuole forms, cell walls become rigid and no more what is possible?

A

Cell elongation as auxins are destroyed

22
Q

(Auxins - apical dominance) growth in the main apical shoot is stimulated by what?

A

Auxin produced at tip

23
Q

(Auxins - apical shoot growth) as the auxin moves down the stem what happens?

A

Lateral shoots are inhibited

24
Q

(Auxins - apical shoot growth) further down the stem auxin concentration is lower making what?

A

Lateral shoots grow more strongly

25
Q

(Auxins - apical shoot growth) what happens to the lateral shoots if the main apical shoot is removed?

A

They grow as they are no longer inhibited

26
Q

(Auxins - root growth) up to a certain concentration the more auxin that reached the roots the more they what?

A

Grow

27
Q

(Auxins - root growth) high concentrations of auxins do what to the roots?

A

Inhibit their growth

28
Q

(Auxins - root growth) if the apical shoot is removed the auxin reaching roots is what?

A

Reduced

Slowing and stopping root growth

29
Q

(Gibberellins) what are gibberellins important in?

A

Stem elongation

Germination of seeds

30
Q

(Gibberellins) gibberellins affect the length of what?

A

Internodes

31
Q

(Gibberellins) how were they discovered?

A

Fungus infecting rice plants producing gibberellins making them grow long and thin

32
Q

(Gibberellins) modified plants have been produced to produce little gibberellins and remain short, this is beneficial as..

A

They are less damaged by weather

33
Q

What is synergism?

A

Different hormones working together complimenting each other

34
Q

What is antagonism?

A

Hormones having opposite effects e.g. One promoting growth one preventing it