plant responses Flashcards

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1
Q

define stimulus

A

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

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2
Q

whats an animal stimulus

A

includes feeling pain/hunger, hearing a noise

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3
Q

whats a plant stimulus

A

light, gravity, temperatures

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4
Q

define response

A

the action pf a cell/organism as a result of a stimulus

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5
Q

give an example of an animal response

A

movement, production of enzymes and feeding

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6
Q

give an example of a plant response

A

growth, flowering

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7
Q

what is needed structurally for response

A

chemical/hormonal system (plants and animals), nerve and sense organ system, method of movement, immune system

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8
Q

what do plants depend on for their response

A

chemical co-ordination

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9
Q

define tropsim

A

a chenge in the growth of a plant in response to an external stimulus

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10
Q

define positive tropism

A

when the growth is towards the stimulus

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11
Q

define negative tropism

A

when the growth is away from the stimulus

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12
Q

what is the advantage of tropisms in a plant

A

they allow plants to obtain favourable growing contidtions

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13
Q

what is phototropism

A

change in growth in a plant in response to light

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14
Q

are stems positively phototropic

A

yes… allows the plant to get more sunlight

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15
Q

are roots positively phototropic or negatively phototropic

A

most are neg… e.g ivyy

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16
Q

what is geotropism

A

the change in growth of a plant in response to gravity

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17
Q

are roots positively geotrophic

A

yes, they grow downwards

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18
Q

are stems positvely geotrophic

A

no they are negatively geotrophic… grow against gravity

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19
Q

whats the benefit of roots growing towards gravity

A

can anchor the plant better, absorb water + minerals better

20
Q

whats thigmotropism

A

the change in growth of a plant in response to touch

21
Q

give an example of a plant that uses thigmotropism

A

climbing plants e.g ivy, vines, peas

22
Q

what do positively thigmotropic plants grow to climb

A

tendrils which have positive thigmotropism

23
Q

what’s hydrotropism

A

the change in growth of a plant in response to water

24
Q

define chemotropism

A

the change in grwoth of a plant in response to chemicals

25
Q

give an example of positive chemotropism

A

roots grow towards minerals… pollen tubes grow towards chemicals from the ovule

26
Q

what might make a root negatively chemotropic

A

presence of harsh acids or heavy metals in soil e.g zinc/lead

27
Q

what is a growth regulator

A

chemicals that control the growth of a plant

28
Q

where are grwoth regulators mainly produced

A

meristem region

29
Q

how are growth regulators transported

A

vascular tissues

30
Q

give an example of a growth regulator which is a growth promoter?

A

auxins, e/g indoleactic acid (IAA)

31
Q

what is the name given to a regulator that slows down plant growth

A

growth inhibitor e.g abscisic acid

32
Q

where is IAA produced?

A

shoot tips, young leaves and seeds

33
Q

give 3 functions of auxins

A

stimulate stem elongation and root growth, develop fruit, inhibit side branching in stems, cause phototropism and geotropism, cause cells to grow into different structures

34
Q

what are some effects of auxins

A

tropism ( cell elongation and growth/bending), apical dominance, root growth (at low concentrations), fruit formation (IAA made in developing seeds… stimulates food to form in the fruit that surrounds the seed)

35
Q

explain apical dominance

A

if the apical bud is intact, auxins produced in the tip will travel down the stem and it will inhibit lateral buds from developing. if apex is removed, side branches develop

36
Q

explain the mechanism of a plant’s response to light

A

auxins loosen cell walls allowing them to expand. IAA is produced in the growth tips of the stem. if the stem is exposed to light from one side, IAA diffuses down the shaded side. concentration of IAA causes cells in shaded side to elongate more than bright side. as result of uneven elongation, stem bends towards light

37
Q

what is the only growth regulator that is a gas

A

ethene gas

38
Q

where is ethene gas used

A

to commercially ripen bananas

39
Q

what is the role of ethene in a plant

A

causes fruit colour to form, fruit flavour to develop and fruit tissues to soften

40
Q

name a growth inhibitor and state where it is produced

A

absisic acid… produced in leaves, stems and root caps

41
Q

what is a stress regulator and give an example

A

absisic acid… causes plants to respond to harmful conditions

42
Q

give an example as to how absisc acid helps regulate stress in plants

A

dry conditions it causes stomata to close in order to conserve water

43
Q

name some comercially prepeared growth regulators

A

rooting powders(naphtyacetic acid), tissue culturing, ethene

44
Q

list some structural adaptations in plants for protection

A

plants enclosed by a physical barrier e.g epidermis,bark,stingning hairs… guard cells close stomata when lack or water

45
Q

list 2 chemical adaptations of plants for protection

A

excessive heat causes heat-shock proteins to form in order to protect enzymes… when a plant is infected it can produce stress proteins called photoalexins which attack micro-organism cell wall and stimulate production of plant cell walla to reduce micro-organism spread