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Biology 9. Plants > Plants 9.3 Growth in plants > Flashcards

Plants 9.3 Growth in plants Flashcards

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1
Q

What is determinate growth?

A

animals and some plant organs are either a defined juvenile or embryonic period or growth stops when a certain size is reached or a structure is fully formed

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2
Q

How can growth be indeterminate?

A

when cells continue to divide indefinitely

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3
Q

Do most plants have determinate or indeterminate growth?

A

indeterminate

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4
Q

What phenomenon sets plant cells apart from most animal cells?

A

plants cells (including fully differentiated types) have capacity to generate whole plant called TOTIPOTENT

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5
Q

What does it mean when cells are totipotent

A

plants cells (including fully differentiated types) have capacity to generate whole plant

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6
Q

What are meristems?

A

regions where growth in plants occurs as it is composed of undifferentiated cells undergoing active cell division

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7
Q

What are apical meristems?

A

primary meristems found at tips of stems and roots

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8
Q

Where are shoot apical meristems found?

A

top of the stem

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9
Q

What kinda of meristems do many dicotyledonous plants also develop?

A

Lateral meristems

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10
Q

What do undifferentiated cells in the meristem allow?

A

indeterminate growth

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11
Q

How do cells in meristems produce more cells?

A

by dividing by mitosis and cytokineses

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12
Q

What is the root apical meristem responsible for?

A

growth of the root

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13
Q

What do shoot apical meristems produce?

A

throws off the cells that are needed for growth and produces cells that grow leaves and flowers

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14
Q

What type of meristems can be found in plants?

A

apical and lateral

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15
Q

How does the differentiation of meristem cells cause the growth of the plant?

A

For each division, one cell remains in the meristem while the other one grows in size and is pushed away from th region

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16
Q

What kinda of meristems can apical meristems produce?

A

protoderm, procambium and ground meristem

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17
Q

what tissue does protoderm produce?

A

epidermis

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18
Q

What tissue does procambium produce?

A

vascular tissues

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19
Q

What tissus does ground meristem produce?

A

pith

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20
Q

What is leaf primordia?

A

Small bumps at the side of shoot apical meristem that will develop into leaves

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21
Q

What is this called?

A

leaf primordia

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22
Q

What controls the growth in shoot appex?

A

Plant hormones

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23
Q

What is hormone?

A

chemical message produced and released in one part of an organism to affect another part

24
Q

What are auxins?

A

hormones that can initiate growth of roots, influence development of fruits and regulating leaf development

25
Q

What is the most abundant auxin?

A

IAA

26
Q

What role does IAA have?

A

controls growth in shoot apex; promotes elongation of cells in stems

27
Q

Where is IAA synthesized

A

in the apical meristem of the shoot and transported down the stem to stimulate growth

28
Q

What can high concentrations if IAA cause?

A

it can inhibit growth at nodes

29
Q

What are axillary buds?

A

shoots that form the junction/node of the stem and base of a leaf

30
Q

What is apical dominance?

A

As shoot apical meristem grows and forms leaves, regions of meristem are left behind at the nodes. Growth at nodes is inhibited by auxin

31
Q

What happens when the further distant a node is from the shoot apical meristem?

A

lower concentration of auxin and the less likely that growth in the axillary bud will be inhibited by auxin

32
Q

What is ahormone produced in the root of plants?

A

cytokinins

33
Q

What does cytokinin promote?

A

axillary bud growth

34
Q

What balance determines the axillary bud develops?

A

ratio of cytokinin and auxins

35
Q

What influences the direction in which a stem grows?

A

light and gravity

36
Q

How does light affect stem’s growth?

A

grows towards source of brightest light

37
Q

How do stems grow in absence of light?

A

upwards/opposite gravity

38
Q

What is tropisms?

A

directional growth responses to directional external stimuli

39
Q

What is growth towards the light called?

A

phototropism

40
Q

What is growth in response to gravitational force called?

A

gravitropism

41
Q

what is the first stage in phototropism?

A

absorption of light by photoreceptors using phototroponins

42
Q

What do phototroponins do?

A

absorption of light of an appropriate wavelength by photoreceptors that changes conformation; bind to receptors within cell that control transcription; that codes a group of glycoproteins

43
Q

How does auxin influence cell growth rates?

A

changing patterns of gene expression

44
Q

What protein transports auxin?

A

PIN3

45
Q

What happens if phototropins detects greater intensity of light on one side?

A

auxin is transported to the shaded side; higher concentration of auxin on the shadier side causes cell elongation (greater growth on oneside); stem grows in a curve towards source of light; leaves can recieve more light and photosynthesize at greater rate

46
Q

Is gravitropism auxin dependent?

A

yes

47
Q

What are cellular orgenelles called that accumulate on the lower side of cells in roots?

A

statoliths

48
Q

If a plant is tipped over, what happens?

A

statoliths accumulate on lower side of cells; PIN3 transporter proteins distribute and direct auxin transport to the bottom cells (closer to earth core); high concentration of auxin IN ROOTS inhibits growth, so top cells elongate; root bends downwards

49
Q

In shoot (stems) what does high concentration of auxin cause?

A

promotes elongation of cells

50
Q

In roots what does high concentration of auxin cause?

A

inhibits elongation of cells, top cells elongate

51
Q

Explain role of auxin in phototropism

A
  • auxin is plant hormone
  • produced by the tip the stem/shoot tip
  • causes transportation of hydrogen ions from cytoplasm to cell wall
  • decrease in pH/H+ pumping breaks bonds between cell wall fibres
  • makes cell walls flexible/extnsible/softens cell walls
  • auxin promotes cell elongation/growth
  • gene expression also altered by auxin to promote cell growth
  • positive phototropism is growth towards light
  • shoot tip senses direction of (brightest) light
  • auxin moved to side of stem with least light/dark side
  • causes cells on dark side to elongate/cells on dark side grow faster
52
Q

What is micropropagation?

A

in vitro procedure that produces large numbers of identical plants

53
Q

What does micropropagation depend on?

A

totipotentency of plant tissues (ability to differentiate into any functional plant part)

54
Q

Describe process of micropropagation of plants

A
  • stock plant is identified that often has desirable feature
  • tissue is chosen usually the least differentiated (meristem)
  • tissues from plant is sterilized and cut into pieces called explants
  • explant is placed into sterilized growth media that includes plant hormones
  • auxin and cytokinin is equally added
  • forms an undifferented mass called callus
  • if media contains a ratio of auxin 10 times greater than cytokinin roots develop
  • this is called rooting media
  • if media contains ratio of cytokinin 10times greater, then shoots develop
  • this is called shoot media
55
Q

Why are micropropagation techniques used?

A
  • international exchange of plants materials carries risk of pathogen transmission
  • micropropagation produces virus-free strains of plants
  • produces identical copies of desirable characteristics
  • process is fast and takes little space
  • can help preserve endangered varieties (eg. orchids)
    • commerical production
    • orchid seeds are difficult to germinate
56
Q

How are apical meristems virus-free?

A

Viruses are transported within a plant from cell to cell through vascular tissue and via plasmodesmata

57
Q

What is cryopreservation?

A

micropropagated plantlets can be stored in liquid nitrogen

Biology 9. Plants (6 decks)

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