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biology > 4.2 plant reproduction > Flashcards

4.2 plant reproduction Flashcards

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1
Q

what are the 4 whorls of a flower?

A

calyx
corolla
androecium (stamen)
gynoecium (pistil)

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2
Q

label a flower

A

refer to sheet

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3
Q

what does protandry mean?
what does protogyny mean?

A

stamen ripens first
stigma ripens first

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4
Q

what parts are involved in the pistil? (3)

A

stigma
style
ovary

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5
Q

what is the function of the sepals?

A

pollen grains are produced inside 4 pollen sacs by meiosis

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6
Q

what type of plants have sepals? what type don’t?

A

dicotyledons do
monocotyledons don’t

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7
Q

what is the function of the corolla?

A

contains vascular tissue which transport mineral ions and water to the developing pollen grains

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8
Q

what is the function of the nectary?

A

in insect pollinated plants they are colourful and have scent to attract insects

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9
Q

what is the function of the petals?

A

found at the base of the flower and releases scented nectar to attract pollinators such as insects

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10
Q

what is the function of the stamen?

A

made inside the ovary and contains an egg cell formed by meiosis

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11
Q

what is the function of the anther?

A

the thickened part if the stem from which the flower grows

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12
Q

what is the function of the filament?

A

a ring of colourful petals inside the sepal

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13
Q

what is the function of the carpel?

A

protect the flower when in bud

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14
Q

what is pollination?

A

the transfer of pollen grains from the anther to the stigma

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15
Q

what are the 4 types of pollination?

A

self and cross
wind and insect

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16
Q

what is self pollination?

A

pollen falls from there anther to stigma of the same flower

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17
Q

what is cross pollination?

A

pollen is transferred from anthers of one flower to the stigmas of a different flower of the same species

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18
Q

what are the advantages of self pollination? (3)

A
  • not dependent on pollinating agents
  • if a given genotype is well suited for an environment, self pollination helps to keep this trait stable in the species
  • number of flowers are small of widely spaced
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19
Q

what are the disadvantages of self pollination? (3)

A
  • lack of variation so no adaptations to the changing environment/pathogens
  • can lead to inbreeding depression or the reduced health of the species
  • genetic defects in self pollinating plants cannot be elimainted
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20
Q

what are the advantages of cross pollination? (3)

A
  • increases the variation in the progeny after genetic recombination
  • increases adaptability to the offspring to environmental changes
  • gives plants protection against pathogens
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21
Q

what are the disadvantages of cross pollination? (3)

A
  • requires a pollinating agent - insect, bird or wind
  • require plant to produce structures to attract pollinators
  • not suitable where numbers of flowers are small or widely spaced
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22
Q

how do plants reduce self pollination? (4)

A
  • the stamen and stigma ripen at different times of the year
  • the anthers are below the stigmas so the pollen cannot fall on it
  • separate male and female flowers on the same plant/separate male and female flowers
  • chemical self incompatibility
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23
Q

what is chemical self incompatibility?

A

pollen cannot germinate on the stigma of the flower which produced it

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24
Q

what are the characteristics of wind pollinated flowers? (6)

A
  • petals usually absent or small, green and inconspicuous
  • no scent or nectar
  • produces larger pollen grains to be carried by the wind
  • anthers hanging outside the flower so the pollen can catch the wind
  • large feathery stigmas hanging outside the flower
  • lots of smooth light pollen that can be easily blown (large SA)
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25
Q

give some examples of wind pollinated flowers

A

wheat
rice
corn
barley

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26
Q

what are the characteristics of insect pollinated flowers? (6)

A
  • colourful petals sometimes with nectar guides
  • scent or nectar
  • produced smaller pollen grains
  • anthers within the flower
    stigma within the flower
  • small quantities of sticky, sculptured pollen produced
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27
Q

give some examples of insect pollinated flowers

A

rose
sunflower
orchids
lilies

28
Q

what is the 3 step process in order to get to a pollen grain?

A

microspore mother cell divides by meiosis
formed a tetrad of 4 haploid cells
this divides by mitosis to form a pollen grain

29
Q

what are the 2 layers to the cell wall of a pollen grain and describe them?

A

exile - thick outer wall made of long lasting tough waterproof substance
intine - thinner and more porous inner wall

30
Q

what is the exile adapted to do?

A

help the pollen be transported from the anther to the stigma - the pits in the surface enable gaseous exchange

31
Q

what are the names of the 2 nuclei?
what does each do?

A

generative - divides again by mitosis to produce 2 identical male gametes
tube - controls growth of the pollen tube following pollination - guides it down the style into the micropyle

32
Q

what is the layer of cells surrounding the anther called?
what do they do?
what are the characteristics of it?

A

tapetum
provides nutrients and regulatory molecules to the developing grains
tough and resistant to chemicals

33
Q

what is the tapetum also resistant to? (2)

A
  • desiccation which is necessary as pollen travels high in the air during pollination
  • penetration from UV light so the DNA is protected from mutations
34
Q

what does the fibrous layer of the anther do?

A

prevent dehiscence

35
Q

what is dehiscence?

A

the pollen is mature and the anthers outer layers dry out which causes tension = the pollen sacs burst exposing the pollen grains into the air

36
Q

in short terms, what is the process of ovule development?

A
  • the megaspore mother cell undergoes meiosis to form 4 haploid megaspore cells
  • 3 of these cells disintegrate and 1 undergoes 3 rounds of mitosis to produce 8 haploid nuclei
  • 2 haploid fuse to form one diploid nucleus called the polar nucleus
37
Q

what is the role of antipodal cells?

A

play a role in embryo nutrition as seeds germinate into seedlings

38
Q

in short terms, describe the process of double fertilisation

A
  • the pollen grain germinates to produce a pollen tube and at the tip if a male tube nucleus
  • as the pollen tube grows the generative nucleus undergoes mitosis to form 2 sperm nuclei
  • the pollen tube enters the embryo sac via the micropyle
  • the tube nucleus disintegrates
  • the tip of the tube opens to release the 2 sperm nuclei
39
Q

what is the role of the tube nucleus?

A

tube - controls the growth of the pollen tube

40
Q

what does the pollen tube grow against and where does it go?

A

against a gradient of chemo attractants from the ovules and digest its way down the style into the micropyle

41
Q

in a summary what is double fertilisation?

A

sperm nucleus + polar nucleus = endosperm nucleus
sperm nucleus + egg cell nucleus = diploid zygote

42
Q

what does seed dispersal reduce?
what does this increase?
what does this allow?

A

reduces competition following germination
increases chance of growth into mature plants
allows the colonisation of new habitats

43
Q

how are the dispersal of seeds done? (5)

A
  • wind
  • animals
  • water
  • bursting
  • humans
44
Q

what do dormant seeds have?

A

a very low metabolic rate

45
Q

why is the testa important in a seeds survival?

A

chemically resistant to allow seeds to survive adverse chemical conditions

46
Q

what do the cotyledons provide to the endosperm? until when?

A

nutrients until germination when the seedling will photosynthesise

47
Q

what develops into a seed?

A

a fertilised ovule

48
Q

how is an embryo formed?

A

within the seed the diploid zygote divides by mitosis to become the embryo

49
Q

what 3 parts for the embryo consist of?

A

plumule - developing shoot
radicle - developing root
1/2 cotyledons - seed leaves

50
Q

label the parts of the seed

A

testa
micropyle
funicle
endosperm tissue
ovary wall

51
Q

what is the testa?

A

the outer integumentary dries out to form a hard waterproof seed coat

52
Q

what is the micropyle?

A

a pore in the seed

53
Q

what is the funicle?
what does it attach to?

A

the funicle of the ovary becomes the funicle of the seed
ti attaches to the haul and once the funicle detaches the scar of the hilum is still visible

54
Q

how is the endosperm tissue formed? why is it important?

A

the triploid endosperm nucleus develops into the endosperm nucleus - it’s an important food store in cereals

55
Q

what does the ovary wall become?

A

the fruit enclosing the seeds

56
Q

define germination

A

the biochemical and physiological process through which a seed becomes a photosynthesising plant

57
Q

what are the requirements for successful germination? (4)
why?

A

suitable temperature - enzymes work best at their optimum
water - to mobilise enzymes
oxygen - for aerobic respiration
light/dark - depends which species

58
Q

give an example of a non endospermic seed

A

broad bean - dicotyledon

59
Q

in short term, describe germination in non endospermic seeds

A
  • imbibing
  • the cotyledons swell
  • the testa splits to allow entry for more O2 for aerobic respiration
  • starch and proteins from the cotyledons are mobilised through hydrolysis into soluble products
60
Q

what is imbibing?

A

when the seed absorbs water through the micropyle

61
Q

give an example of an endospermic seed

A

maize - monocotyledon

62
Q

in short term, describe germination in endospermic seeds

A
  • following imbibition of water, gibberellin is released by the embryo
  • it issues to the aleurone layer which contains proteins
  • switches on genes to synthesise amylase and protease
  • the AA produced in the layer are used in the synthesis of amylase
  • amylase diffuses from layer to endosperm to hydrolyse starch
  • the maltose + glucose produced diffuse into the radically and plumule
  • they’re used in aerobic respiration and growth in the embryo
63
Q

what is gibberellin?

A

a plant growth regulator

64
Q

what does aerobic respiration do?

A

releases energy from sugars and amino acids to synthesise new proteins

65
Q

what happens to the soluble products of digestion?

A

transported to the embryo and carried in the phloem to the apical meristems of the plumule and radicle

biology (5 decks)

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