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sexual reproduction in flowering plants Flashcards

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1
Q

what is main plant body of flower?

A

sporophyte

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2
Q

what is shoot?

A

stem+leaves

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3
Q

flower is a modification of what?

A

modified shoot

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4
Q

thalamus is the modification of what?

A

modified stem

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5
Q

flowers are considered as what by biologists?

A

morphological and embryological marvels

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6
Q

what are the values of flowers in everyday life?

A

CARSO
cultural, aesthetic, religious, social and ornamental

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7
Q

what steps take place before initiation of flowering?

A

hormonal and structural changes<shoot apical meristem<reproductive/floral meristem<inflorescence axis<floral primordia<floral buds<flower

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8
Q

what are the two types of flowers with examples?

A
  1. UNISEXUAL- (cccm)
  2. BISEXUAL- china rose, sweet potato
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9
Q

types of plants with example

A
  1. MONOECIOUS- BOTH FLOWERS SAME PLANTS. (cccm)
  2. DIOCIOUS- both flowers different plants. papaya, date palm
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10
Q

what are the features of filament?

A

long
slender
sterile
anther is attached to distal end of filament

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11
Q

what is epipetalous with example?

A

if stamen is attached to petal
solanaceae(brinjal)

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12
Q

what is epiphyllous with example?

A

if stamen is attached to perianth(tepal)
lily

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13
Q

what are the features of anther?

A

swollen, terminal
tetragonal (4sides)
bi-lobed
each lobe has 2 chambers called THECA-> dithecous
tetrasporangiate(4microsporangium)

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14
Q

what does each microsporangia develop into?

A

pollen sac

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15
Q

what is sporogenous tissue?

A

it is a compactly arranged mass of homogenous cells which occupies centre of each microsporangium.

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16
Q

each cell of sporogenous tissue is a potential?

A

MMC(microspore mother cell) / PMC(pollen mother cell)

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17
Q

what is dehiscence of anther?

A

bursting of anther

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18
Q

what are the anther wall layers?

A
  1. epidermis
  2. endothecium
  3. middle layers
  4. tapetum
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19
Q

features of epidermis?

A

outermost layer
uniseriate(1layer)
protection

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20
Q

features of endothecium?

A

protection in young anther

dehiscence of anther in mature anther

uniseriate(1 layer)

radially elongated cells

alpha-cellulosic fibrous thickenings present on inner tangential and radial walls[HYGROSCOPIC-ability to absorb water]

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21
Q

what is stomium?

A

the portion of endothecium where alpha-cellulosic thickenings are absent.
dehiscence of anther takes place from stomium

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22
Q

features of middle layers?

A

2-3
parenchymatous= store food
cells are EPHEMERAL(short lived)

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23
Q

features of tapetum?

A

innermost
surrounds sporogenous tissue
dense cytoplasm
multinucleated(due to nuclear division)
parenchymatous
polyploidy
polyteny(DNA replication is not followed by chromosomal splitting)

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24
Q

what are the functions of tapetum?

A
  1. nourishment to developing pollen grains
  2. secretion of sporopollenin
  3. production of ubisch bodies[pro-ubisch bodies(microbodies) + sporopollenin]
  4. production of pollen kit(oily sticky, yellow coloured to attract insects)
  5. synthesis of compatible proteins
  6. synthesis of callase enzyme
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25
what is microsporogenesis?
it is the formation of microspores from microspore mother cells(MMC) or pollen mother cell(PMC) MMC/PMC(2n)--->microspores(n)
26
write steps of microsporogenesis?
(meiosis) MMC/PMC < MICROSPORE TETRAD [isobilateral in monocots and tetrahedral in dicots] < (by callase enzyme from tapetum) MICROSPRES(n) < (develops into) POLLEN GRAIN
27
what is the male gametophyte?
POLLEN GRAIN because it carries male gamete i.e. pollen
28
which family has only one functional microspore?
cyperaceae
29
pollen grain: shape dimensions parts
spherical 25-50 micrometer wall(exine and intine) and cytoplasm
30
exine v/s intine?
EXINE: outer thick, rigid discontinuous made up of sporopollenin INTINE: inner thin continuous made up of cellulose and pectin
31
features of sporopollenin?
1. it is the most resistance organic substance 2. it can withstand strong alkali and acids 3. no enzyme that degrades sporopollenin has yet been discovered 4. it helps in fossilization 5. fascinating array of designs and patterns which is of taxonomical significance 6. it is hard so, provides protection to pollen grains in hazardous environment
32
what is germ pore? types? pollen tube?
it is the places where sporopollenin is absent MONOCOPLATE(1)[monocots], BICOLPATE(2)[dicots], TRICOLPATE(3)[dicots] intine protrudes from germ pore forming a germinating pollen tube
33
which plants cause pollen allergy?
especially ANEMOPHILOUS(pollinated by wind)
34
effects of pollen allergy?
1. bronchial afflictions 2. allergy 3. respiratory disorders like; asthma, bronchitis
35
examples of pollen allergy causing plants?
1. PARTHENIUM(carrot/congress grass)- came to India as a contaminant in imported wheat 2. AMARANTHUS 3. CHENOPODIUM
36
what are pollen products?
pollen grains are rich in nutrients, used by athletes and racing horses in the form of TABLETS, SYRUPS
37
what is pollen viability?
period for which pollen grain retains the ability to germinate on the stigma. highly variable
38
what does pollen viability depend on?
prevailing temperature and humidity
39
examples of pollen viability?
wheat, rice: 30 minutes leguminoseae, solanaceae, rosaceae: upto several months
40
what are pollen banks?
pollen grains are stored in -196 degree celsius in LIQUID NITROGEN[k/a cryopreservation] later used in crop breeding programmes
41
write the steps in microgametogenesis?
[EX-SITU] pollen grain < (mitosis) ASSYMETRICAL SPINDLE FORMATION < (karyokinesis) NEGETATIVE NUCLEUS AND GENERATIVE NUCLEUS < (cytokinesis) VEGETATIVE CELL AND GENERATIVE CELL < [IN-SITU] GENERATIVE CELL < (mitosis) 2 MALE GAMETES
42
what is the 3-celled stage?
when the generative cell divides mitotically to form 2 male gametes
43
features of vegetative cell/tube cell?
1. larger cell 2. stores reserve food 3. irregularly shaped nucleus
44
features of generative cell?
1. smaller cell 2. spindle shaped nucleus 3. dense cytoplasm 4. floats in the cytoplasm of vegetative cell
45
pollen grains are shed at the 2-celled stage in how many angiosperms?
more than 60% of angiosperms
46
shedding of pollen at 3-celled stage?
in less than 40% of angiosperms generative cell divides mitotically to form 2 male gametes before the shedding of pollen grains
47
male microsporophyll?
stamen
48
male gametophyte?
pollen grain
49
male microsporangia?
pollen sac
50
male gamete?
pollen
51
division of carpels/pistil on the basis of no.
1. MONOCAPELLARY(1) 2. MULTICARPELLARY(more than 1) (i) APOCARPOUS(free) (ii) SYNCARPOUS(fused)
52
examples of apocarpous and syncarpous?
APOCARPOUS: lotus, rose, michelia SYNCARPOUS: papaver, mustard, tomato, hibiscus
53
what are the parts of each pistil with definition?
1. STIGMA: landing platform for pollen grain 2. STYLE: the elongated slender portion beneath the stigma, through which the pollen tube runs 3. OVARY: is the basal bulged portion of the carpel
54
what is inside ovary?
1. ovarian cavity (LOCULE) (chamber) 2. placenta 3. megasporangia(OVULES) arising from the placenta
55
there can be either 1 or many ovules in an ovary. write examples of both.
ONE OVULE: wheat, paddy, mango MANY OVULES: watermelon, papaya, orchids
56
what are the parts of ovule?
1. integuments(protection) 2. micropyle 3. chalaza 4. nucellus 5. embryo sac 6. funicle 7. hilum
57
what is micropyle?
it is a pore or passage present on the micropylar end(tip of ovule) where integuments are absent
58
what is chalaza?
it is the basal part of ovule which is opposite to micropylar end
59
what is nucellus?
parenchymatous mass of cells enclosed within the integuments abundant reserve food forms body of ovule
60
what is embryo sac(n)?
embryo sac is the female gametophyte located within the nucellus generally single formed from single megaspore
61
what is funicle?
stalk which attaches ovule to the placenta
62
what is hilum?
the point of attachment of ovule and funicle
63
what are the different types of ovules based on the no. of integuments present?
1. unitegmic(1) 2. bitegmic(2) 3. ategmic(0)
64
types of ovules on the basis of the position of micropyle, funicle and chalaza?
1. ORTHOTROPUS 2. ANATROPOUS 3. HEMIANATROPOUS 4. CAMPYLOTROPOUS 5. AMPHITROPOUS 6. CIRCINOTROPOUS
65
what are the features of orthotropous?
m,f,c lie in a straight line primitive, simplest straight ovule e.g- gymnosperms, polygonum
66
what are the features of anatropous?
inverted ovule M lies close to hilum typical ovule present in 82% angiosperm families[MOST COMMON]
67
what is megasporogenesis?
the formation of megaspore(n) from megaspore mother cell(MMC)
68
how is megaspore mother cell formed?
one of the cells of the nucellus towards the micropylar end differentiate and functions as the MMC.
69
features of MMC? further division of MMC?
large cell prominent nucleus dense cytoplasm MMC < (meiosis-1) MEGASPORE DYAD < (meiosis-2)MEGASPORE TETRAD
70
which cell of the megaspore tetrad is the functional megaspore?
the cell towards the chalazal end. the remaining 3 cells degenerate
71
megasporophyll?
pistil/carpel
72
megasporangia?
ovule
73
female gametophyte?
embryo sac
74
female gamete?
egg cell
75
what are the 3 types of embryonic developments?
1. MONOSPORIC: from 1 megaspore(rest degenerate) [most common, in 80% angiosperms] 2. BISPORIC: from 2 megaspores 3. TETRASPORIC: from 4 megaspores
76
steps in monosporic development of embryo sac?
FYNCTIONAL MEGASPORE < (fnmd) 2-NUCLEATED EMBRYO SAC < (fnmd) 4-NUCLEATED EMBRYOSAC < (fnmd) 8-NUCLEATED EMBRYO SAC < (cell wall formation) EMBRYO SAC
77
how many cells and nuclei does a mature embryo sac have?
7-celled, 8 nucleated
78
how many types of cells are there in an embryo sac?
4
79
features of synergids?
-occur in pair towards the micropylar end -vacuole is towards CE -nucleus is towards ME -usually 1 synergids degenerates just with -pollination -they absorb food from nucellus and transport it to the embryo sac - also called helper cells/ co-operative cells
80
what is filiform apparatus?
-the cell wall of synergids have cellular -thickenings called filiform apparatus. -it is fingerlike projections which secrete chemotrophic substances -it guides the pollen tube towards the synergids
81
features of egg cell?
- female gamete -single large cell towards ME - egg cell+ synergids=EGG APPARATUS -there is PLASMODESMATAL CONNECTIOS b/w egg cell and synergids -exhibits cytoplasmic polarity opposite to that of synergids[VACUOLE: ME; NUCLEUS:CE] -ME: cell wall is THICK -CE: cell wall is THIN
82
features of antipodal/vegetative cells?
towards CE degenerate upon fertilisation
83
features of central cell?
largest cell of embryo sac initially, polar nuclei(n+n) is present | fuse just before fertilisation | secondary nucleus(2n)/ definitive nucleus
84
what is pollination? its types?
it is the transfer of pollen grain from anther to stigma. 1. AUTOGAMY 2. GEITONOGAMY 3. XENOGAMY
85
what is autogamy?
transfer of P.G. from anther to stigma of SAME FLOWER [SELF POLLINATION]
86
what is geitonogamy?
transfer of P.G. from anther to stigma of different flower on same plant. [functionally, ecologically: CROSS-POLLINATION][genetically:SELF-POLLINATION]
87
what is xenogamy?
transfer of P.G. from anther to stigma of different flower on different plant [CROSS-POLLINATION]
88
contrivances for self-pollination[in-breeding devices]?
1. BISEXUALITY/MONOCLINY 2. HOMOGAMY (synchrony in maturation) 3. CLEISTOGAMY(flowers that do not open ensure 100% self-pollination) 4. BUD POLLINATION(pollination before opening of flower) e.g. wheat, rice, pea
89
what are the two types of flowers? produced by?
produced by: viola, oxalis, commelina 1. CLEISTOGAMOUS: closed flowers 2. CHASMOGAMOUS: open flowers
90
types of agents for pollination?
1. ABIOTIC[wind, water]- used by small proportion 2.BIOTIC[animals]-used by majority of plants
91
arrange the agents of pollination from most common to most rare.
animals>wind>water
92
why are P.G. produced in large no. as compared to the no. of ovules present?
because this is a chance phenomenon and non-directional. there is great chance of loss of P.G.
93
characteristics of P.G. of anemophily?
for easy dispersal by wind currents: light small non-stick
94
characteristics of stigma and stamen in anemophilous plants?
STIGMA: long, sticky, feathery[to trap P.G.] STAMEN: well exposed[easy dispersal]
95
no of ovules in each ovary of anemophilous flowers? inflorescence?
1 yes
96
examples of anemophilous plants.
grasses maize wheat sugarcane bamboo rice gymnosperms
97
features of hydrophily?
-quite rare -limited to approx. 30 genera[mostly MONOCOTS]
98
examples of freshwater and marine water plants.
FRESHWATER: vallisneria, hydrilla MARINE: zostera(sea grass)
99
characteristics of P.G. of hydrophilous plants?
light unwettable(mucilagenous covering)
100
characteristics of stigma of hydrophilous plants?
long unwettable(mucilagenous covering) sticky
101
what are the two types of hydrophily with examples?
1.HYPOHYDROPHILY: pollination inside the water surface. e.g.- hydrilla, ceratophyllum, zostera 2.EPIHYDROPHILY: pollination on the surface of water. e.g.-vallisneria
102
features of female flower of vallisneria?
long, coiled stalk stalk uncoils and elongates at maturity
103
describe pollination in vallisneria.
DIOECIOUS female stalk uncoils and reaches surface of water after breakage, P.G. reach water surface reaches stigma by water currents pollinates
104
features of P.G. in zostera
long ribbon-like
105
describe pollination in zostera
MONOECIOUS female flower remains submerged in water P.G. are carried to stigma by water currents pollination
106
how do most aquatic plants pollinate?
come to surface by wind/insects
107
what are the examples of aquatic plants pollinated by insects?
water hyacinth water lily
108
pollination by biotic agents is also called?
zoophily
109
what is the most common insect which acts as pollinating agent?
bee
110
what are different types of zoophily?
1.ENTOMOPHILY(insects) bee, moth, wasps, flies, beetles 2.ORTHINOPHILY(birds: sun birds, humming birds) 3.CHIROPTEROPHILY(BATS) 4. OPHIOPHILY(snakes)santalum 5. MALACOPHILY(snails) 6. MYRMECOPHILY(ants, termites)
111
characteristics of flowers and P.G. for entomophily?
FLOWER: large(if small, then clustered in inflorescence) colourful rich in nectar odour- good(fragrant) OR bad (foul, pollinated by flies and/or beetles) POLLEN GRAINS: sticky
112
what are the large animals which help in pollination?
1. LEMUR(primate) in ravenela plant 2. TREE-DWELLING ARBOREAL RODENTS 3. REPTILES LIKE GECKO LIZARD AND GARDEN LIZARDS
113
what are the pollen rewards for the insects?
1. pollen 2. nectar 3. safe place to lay eggs
114
explain with example the relationship of fig and fig wasp.
fig is pollinated by wasp wasp, in suitable conditon, lays eggsin safe place in the flower(in ovary) the developing seeds are fed on by the larva
115
explain the relationship of yucca and pronuba moth.
moth lays eggs in locule of ovary larva comes out when seeds start developing larva feeds on seeds yucca gets pollinated THE LIFE CYCLES OF YUCCA AND PRONUBA MOTHS ARE NOT COMPLETE WITHOUT EACH OTHER(CAN'T LIVE WITHOUT EACH OTHER)
116
what are pollen and nectar robbers with example?
consume pollen/nectar without bringing about pollination e.g.- QUEEN OF BOMBUS AFFINIS steals nectar from AQUILEGIA SPURS
117
describe the relationship between bee and orchid(ophrys- mediterranean orchid)
one of the petal modifies itself and looks like female bumblebee male tries pseudocopulation with the flower flower gets pollinated
118
examples of insect pollinated flowers?
calotropis yucca ficus salvia aristolochia centaurea
119

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