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bio component 2 > plant reproduction > Flashcards

plant reproduction Flashcards

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Biology 101 flashcards
1
Q

what are the functions of the petals?

A
  • plural: corolla
  • colourful to attract insects
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2
Q

what is the receptacle?

A

where the petals are attached

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3
Q

what is the function of the sepal?

A

protects the flower when it’s in the bud

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4
Q

which parts of a flower are considered ‘male’ and what are the parts collectively called?

A
  • anther and filament
  • the stamen
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5
Q

what is the function of the anther?

A

produces and releases pollen grains

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6
Q

what are the functions of the filaments?

A

carries water and nutrients to anther and positions it where pollen can be picked up

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7
Q

which parts of a flower are considered ‘female’ and what are the parts collectively called?

A
  • stigma, style and ovary
  • the carpel
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8
Q

what is the function of the stigma?

A

selects pollen grains and stimulates growth of pollen tube

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9
Q

what is the function of the style?

A

positions stigma where it can best receive pollen

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10
Q

what is the function of the ovary?

A

retains and protects ovule, becomes fruit after fertilisation

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11
Q

what is the function of the ovule?

A

contains the embryo sac, becomes seed after fertilisation

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12
Q

what are the differences between an insect-pollinated and a wind-pollinated plant?

A
  • i: large & colourful petals, w: small and brown
  • i: makes smaller quantities of spiky pollen, w: larger quantities of lighter
  • i: anthers and stigma inside petals, w: hang outside petals
  • i: small & sticky stigma, w: large & feathery
  • i: pleasant scent, w: none
  • i: nectar present, w: none
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13
Q

describe how male gametes develop

A
  • pollen mother cell in pollen sacs of anthers divide by meiosis
  • this produces a tetrad of 4 haploid, genetically varied cells
  • each cell becomes a pollen grain, with a double-layered cell wall (intine & exine) (protects from UV and drying out)
  • nucleus divides by mitosis to produce 2 genetically identical nuclei (pollen tube nucleus & generative nucleus)
  • when pollen is ripe, is released when pollen sac bursts (dehiscence)
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14
Q

describe the formation of female gametes

A
  • egg mother cell (megospore) nucleus divides by meiosis but cell doesn’t divide
  • this produces 4 nuclei in one cell, 3 of which die
  • this provides variation and means it is now a haploid cell that can be fertilised to make a diploid zygote
  • single nucleus left undergoes 3 rounds of mitosis, producing 8 identical haploid nuclei (3x antipodals, 2x polar nuclei, 1x egg cell with 2x synergids)
  • this structure is called a embryo sac
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15
Q

what is the definition of cross- pollination?

A

when pollen is transferred from the anther of one plant to the stigma of another

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16
Q

what is self-pollination?

A

when pollen falls from anther onto the stigma of the same flower (or another flower on the same plant)

17
Q

what are the advantages and disadvantages of cross-pollination?

A
  • AD: prevents inbreeding, results in more genetic variation, reduces chances of producing harmful allele combinations
18
Q

what are the advantages and disadvantages of self-pollination?

A
  • AD: can preserve good genomes which may be suited to a suitable environment
  • DIS: allows less variation (depends only on crossing over/ independent assortment in meiosis)
19
Q

how do plants ensure cross-pollination?

A
  • stamen and stigma mature at different times (dichogamy)
  • irregular flower structure: anther below stigma so pollen can’t fall onto it
  • chemical self-incompatibility: pollen cannot germinate on the stigma of the flower which produced it
  • plants that are separated into male and female
20
Q

what is the definition of fertilisation?

A

fusion of male and female gametes to produce a diploid zygote

21
Q

describe the stages of double fertilisation

A
  • pollen grains land on stigma and germinate- produces pollen tube
  • pollen tube nucleus controls growth of pollen tube: synthesises enzymes which digest a path for the tube, synthesises the tube as it grows and uses the digested tissue as a nutrient source
  • pollen tube grows through gap in the integuments (micropyle) whcih allows it to enter the embryo sac
  • PTN enters through one of the synergids
  • synergid disintegrates, allowing a path for the other nuclei to enter
  • generative nucleus divides by mitosis to form 2 male gametes
  • one gamete enters egg cell and fuses- zygote, other fuses with 2 polar nuclei- triploid endosperm nucleus
22
Q

define what a dicotyledon is and give an example of one

A
  • a plant with 2 seed leaves/cotyledons, embryo lies between them
  • broad bean: non-endospermic (endosperm (food store) is absorbed into cotyledons)
23
Q

define what a monocotyledon is and give an example of one

A
  • one cotyledon
  • maize: endospermic (endosperm remains as food store)
24
Q

give an example of a survival strategy that plants can undergo

A
  • seeds can become dormant until suitable conditions are present (testa can also acts as chemical & physical protection)
  • when dormant, water content falls below 10%, which metabolic rate
  • allows plant to survive dessication
25
Q

what is germination?

A
  • from seed -> first photosynthesising leaves
  • all food stored in endosperm/cotyledon is used up
  • rapid onset of biochemical activity and growth until plant can carry out photosynthesis
26
Q

describe the stages of germination

A
  • seed imbibes water through micropyle
  • causes tissues to swell
  • food reserves are broken down into soluble molecules using hydrolytic enzymes
  • products transported to embryo and carried in phloem
  • to apical meristems of radicle & plumule, where cell division occurs
  • testa splits
    radicle emerges, plumule emerges
  • elongation pushes shoot above ground
27
Q

what is the effect of gibberellin on germination?

A
  • water uptake initiates germination
  • embryo synthesises gebberellin in response, it diffuses into aleurone layer
  • aleurone layer synthesises amylase in response to gibberellin
  • amylase diffuses out of aleurone layer & hydrolyses starch stored in endosperm cells
  • maltose and glucose produced diffuse back through endosperm to plumule and radicle of embryo
  • where it is respired and used for growth
28
Q

why are methods of dispersal helpful?

A

reduces competition following germination as offspring carried away from parent plant- increases chance of growth into mature plant

29
Q

and FINALLY- list some methods of seed dispersal :)

A
  • wind
  • animal
  • bursting
  • water

bio component 2 (5 decks)

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