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BOT*2100 > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

what property do plastids confer on plants

A

make them autotrophic

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2
Q

in plant cells are plastids motile or non-motile

A

motile

- they display amoebic motility

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3
Q

stromules

A

dynamic extensions displayed by plastids

- names stromules because they are filled with stroma (think of the liquid in chloroplasts)

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4
Q

how many membranes do plastids have

A
  • two (inner and outer)

- secondary endosymbiotic plastids have three or more

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5
Q

describe the DNA in plastids

A
  • circular
  • prokaryotic
  • supports endosymbiogenesis
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6
Q

what is the purpose of plastids

A
  • synthesize proteins

- factories for sugars, starches, fatty acids (lipids)

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7
Q

describe the structure of plastids

A
  • stroma is the fluid on the very inside
  • inner membrane encases the stroma
  • outer membrane covers the inner membrane
  • different plastids have different components within the stroma (ex. chloroplasts have thylakoids, elaioplasts have oil within them)
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8
Q

what is the importance of proplastids

A

they are both autotrophic and heterotrophic and can differentiate into other types of plastids (etioplasts and leucoplasts and chloroplasts)

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9
Q

what is the important thing to note about plastids

A

we typically tend to think of chloroplasts which are autotrophic, however of all the plastids in a plant, 80% are not able to use photosynthesis and only 20% may be chloroplasts

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10
Q

what plastid are internal cells not likely to have

A

chloroplasts (they have no means for capturing light energy in internal cells) and will more likely have heterotrophic plastids

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11
Q

why do photoautotrophic organisms occupy diverse habitats

A

niche

- you will have a wide variety of life forms which are all suited best for wherever they are located

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12
Q

describe how cells go from single celled to multicellular forms

A

A. Cell divides and the new cell adhere to the parental one after division
B. The cells can then divide into either one plane, in all three planes, in mostly one plane with occasionally in others, and in two planes regularly (know how this looks for each)
- gelatinous substances secreted by the cells help them stick together

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13
Q

what is required for multicellular forms to form

A
  • tolerance to high temperature, dehydration (desiccation), and radiation
  • ability to undergo mitosis
  • ability to undergo meiosis to conserve the size of the genome (reductive mechanism)
  • exchange of genetic material (development of sex) for differentiation between individual cells
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14
Q

what is the difference between oogonium/ antheridia and antheridia

A

oogonium/ antheridia is female, antheridia is male

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15
Q

what are the two adult forms all multicellular plants alternate between during their life cycle

A
  • haploid generation that produces gametes (gametophyte generation)
  • diploid generation that produces haploid spores via meiosis (sporophyte). diploid generation is a result of the fusion of gametes and mitosis)
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16
Q

what is the special case of charophycean algae (multicellular form of blue green algae which forms an actual structure resembling a plant that we used to study form)

A

not a true alteration of generations because the only diploid cell is the zygote which immediately undergoes meiosis to produce spores

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17
Q

what undergoes zygotic meiosis

A

fungi, some algae

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18
Q

what undergoes sporic meiosis (or, alternation of generations)

A

many algae, plants,

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19
Q

why does the time spent in a particular state differ between plants?

A

depends on when meiosis takes place

- if there is delayed meiosis, you get sporophyte more often (more time as a zygote)

20
Q

are bryophyptes gametophyte or sporophyte prominent

A

haploid gametophyte prominent (they’re multicellular also)

21
Q

what are three prominent features of bryophyptes

A
  • low-lying and usually in areas with available water (think moss)
  • seedless
  • non-vascular (they have no conducting tissue xylem, phloem)
22
Q

what are the three types of bryophyptes

A
  • Hepatophyta (liverworts)
  • Anthocerophyta (hornworts)
  • Bryophyta (mosses)
23
Q

what is a thalloid

A

thallus - means the form of the plant lacks clear structure, there is no differentiation of tissue forms in the plant

24
Q

describe liverworts (hepatophyta)

A
  • has a thalloid
  • cells and thin walled
  • shape of thallus depends upon availability of moisture/rainwater/dust
25
Q

how do hepatophyta (liverworts) differentiate

A

the thallus gives rise to separately stalked gametophores (gametophores are the haploid generation that produces gametes)

  • sperm = antheridiophore (produces antheridia)
  • egg = archegoniophore (produces archegonium)
26
Q

what is the difference between the gametophyte (n) and sporophyte (2n) hepatophyta (liverworts)

A

gametophytes are usually larger and are free living, whereas sporophytes are usually smaller and are permanently attached to and nutritionally dependent on the gametophyte

27
Q

describe the sex organs (gametophytes) of hepatophyta (liverworts)

A
  • the sex organs are borne on separate plants on gametophores (which form from the thallus)
  • gametophores bearing male are called antheridiophores
  • gametophores bearing female are called archegoniophores
28
Q

what is a rhizoid

A

a filamentous structure on the ventral / underside of the thallus which anchors the plant and helps conduct water

29
Q

what is dioecious / heterothallic

A

when the sex organs are borne on separate plants

30
Q

describe the asexual reproduction of hepatophytes (liverworts)

A
  • progressive death and decay of the thallus
  • adventitious (random) prancing on the ventral (under) side of the thallus
  • gemmae (asexual propagules) are formed inside gemmae cups and are dispersed by abiotic mechanisms such as raindrops
31
Q

describe the sexual reproduction of hepatophytes (liverworts)

A
  • antheridia and archegonia are on separate male/female gametophytes
  • water passes sperm from antheridial head to archegonial head (fertilization!)
  • the archegonium nourishes the zygote (stays on the mother plant) and the zygote divides by mitosis to grow
  • the mature sporophyte divides by meiosis to produce spores which are released and dispersed to grow and form new gametophytes
32
Q

describe anthocerotophyta (hornworts)

A
  • the sporophytes are horn like and grow from a basal meristem surrounded by meristem tissue
  • the gametophyte is ribbon like (the thallus)
  • mucilage-filled cavities develop and are invaded by cyanobacteria which is N2 fixing
  • because of the cyanobacteria the thallus appears blue-green
33
Q

what is a pyrenoid

A
  • produces and stores food
  • within the chloroplast
  • there is only one chloroplast within each cell in the thallus
34
Q

what features do anthocerotophyta share with algae

A
  • most non algal plants have several chloroplasts per cell but anthocerotophyta do not
  • pyrenoids are present in both algae and anthocerotophyta
35
Q

describe the life cycle of anthocerotophyta (hornworts)

A
  • use a wind or breeze based mechanism for dispersal
  • spores are mixed with pseudoelaters to aid in dispersal
  • sporangium (what spores are produced in) matures toward the tip of the sporophyte
  • within each horn (sporophyte) cells differentiate, mature and die to produce a horn like cylinder with a columella in the centre
36
Q

describe moss

A
  • have protonemata
  • have three cell types (phyllids, hydroids, and leptoids)
  • calypatra contains the spores
37
Q

what is protonemata

A

thread like chain of cells that develops from a spore to create a leafy gametophore
- resembles green algae

38
Q

what are phyllids

A

one cell layer thick with a rudimentary stomata

39
Q

what are hydroids

A

water conducting cells

- central to a cross section of the protonemata

40
Q

what are leptoids

A

sugar conducting cells

- central to a cross section of the protonemata

41
Q

what is a moss model for studies that can be cultured in liquid culture

A

Physcomitrella patens

42
Q

briefly explain DT moss

A

DT= desiccation tolerant

  • can lose up to 70% of their moisture and dry, curl up and brown, but stay alive and dormant
  • if water is added it is quickly absorbed and cytoplasmic streaming, photosynthesis and other processes return within minutes (can see greening immediately)
  • more than 200 species known
43
Q

what is an example of DT moss

A

star moss (tortula ruralis)

44
Q

describe the moss life cycle

A
  • operculum lost and calypatra (capsule) opens
  • spores are released from the capsule
  • haploid spore germinates and forms branched protonema
  • from the protonema, the leafy male/female gametophytes form
  • sperm released from antheridium (male) reach archegonium (female) and fusion occurs in the archegonium to form a zygote
  • zygote divides vis mitosis and forms sporophyte
  • vector of archegonium enlarges to form calypatra (capsule)
  • meiosis occurs within capsule to form spores)
45
Q

what does the sporophyte of moss consist of

A

the capsule raised on a seta and a foot

46
Q

what is the relationship between the sporophyte and gametophyte

A

the sporophyte is borne on and dependent on food from the gametophyte

BOT*2100 (8 decks)

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