Sexual Reproduction In Flowering Plants Flashcards Preview

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Flashcards in Sexual Reproduction In Flowering Plants Deck (53)
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1
Q

asexual reproduction

A

a type of reproduction where there is no fusion of gametes as only one parent is involved, and offspring produced are identical to the parent

2
Q

sexual reproduction

A

a type of reproduction which gives rise to variation as it involves the fusion of male and female gametes, one from each parent

3
Q

pollination

A

transfer of pollen from the anther to the stigma of a flower of the same species

4
Q

self-pollination

A

transfer of pollen from the anther to the stigma of a flower on the same plant

5
Q

cross-pollination

A

transfer of pollen from the anther to the stigma of a flower on a different plant of the same species

6
Q

fertilisation

A

the fusion of the male (n) and female (n) gametes to produce a zygote (2n)

7
Q

radicle

A

grows into the root

8
Q

plumule

A

grows into the shoot

9
Q

cotyledon

A

embryonic seed leaf

10
Q

monocotyledon

A

contains one embryonic seed leaf

11
Q

dicotyledon

A

contains two embryonic seed leaves

12
Q

fruit

A

a developed seed leaf

13
Q

dispersal

A

transfer (spreading out) of seeds away from parent plant

14
Q

dormancy

A

a resting period when seeds undergo no growth and have reduced cell activity or metabolism

15
Q

germination

A

the re-growth of the embryo after a period of dormancy, if the environmental conditions are suitable

16
Q

location of male gamete formation

A

pollen grain

17
Q

pollen grain development (Male)

A

microspore mother cell (2n) divides by meiosis in the pollen sac in the anther
tetrad of pollen is produced
pollen grains separate and the nucleus in each divides by mitosis
generative nucleus and tube nucleus formed, both haploid

18
Q

tube nucleus

A

forms pollen tube

19
Q

generative nucleus

A

divides by mitosis to produce two male gametes

20
Q

location of female gamete formation

A

embryo sac

21
Q

embryo sac formation (female)

A

megaspore mother cell (2n) divides by meiosis in the ovule
four haploid cells produced
three die off and one becomes the embryo sac
embryo sac divides by mitosis 3 times to produce eight haploid nuclei: two are polar nuclei one is egg cell

22
Q

pollination methods

A

wind or animals/insects

23
Q

wind pollination

A
eg sycamore tree, oak tree
adaptations: 
no nector
stigmas large, feathery
anthers large, outside petal
24
Q

animal/insect pollination

A
eg bees, dandelions, buttercups
adaptations:
petals brightly coloured, scented with nectaries
small amounts of sticky pollen
pollen larger
25
Q

events leading to fertilisation

A

chemotropism; release of chemicals from the ovary which stimulates the pollen tube to develop from the tube nucleus in the pollen grain
pollen tube develops down the style to the ovule through the micropyle
generative nucleus moves down the pollen tube behind the tube nucleus
generative nucleus divides by mitosis twice; forms the male gametes
two male gametes enter the embryo sac through the micropyle

26
Q

location of fertilisation

A

embryo sac

27
Q

Double fertilisation

A

one male gamete fuses with the two polar nuclei to form the triploid endosperm nucleus
one male gamete fuses with the egg nucleus to form the diploid zygote

28
Q

seed formation

A

integuments(ovule walls) - seed coat (testa)
ovule- seed
ovary-fruit
zygote 2n- embryo 2n (after dividing by mitosis) containing plumule, radicle, cotyledon
Endosperm nucleus 3n- endosperm( food store;fats,oils proteins)
cotyledon absorbs endosperm

29
Q

classification of seeds

A
non endospermic (monocot)
endospermic (dicot)
30
Q

non endospermic seed

A

all of endosperm is absorbed
cotyledon is food store
eg peanut, broad bean

31
Q

endospermic seed

A

retains some endosperm
endosperm is food store
eg maize,corn

32
Q

walls of fruit

A

pericarp

33
Q

seedless fruit

A

egg hasnt been fertilised

34
Q

fruit formation

A

stimulated by auxins produced by the seeds

  1. Genetically - either naturally or by special breeding porgrammes eg bananas, pineapples
  2. Growth regulators- eg gibberllins produce seedless grapes
35
Q

commercial regulator

A

ethene (inhibitor) breaks down chlorophyll

36
Q

advantages of seed and fruit dispersal

A

minimises competition
avoids overcrowding
increases chance of survival

37
Q

methods of fruit and seed dispersal

A

animal, wind, water, self

38
Q

animal dispersal

A

hooked, sticky (to attach to coat), juicy, tasty (to allow digestion)
eg raspberries, stick-weed

39
Q

water

A

air spaces, light, buoyant

eg coconut

40
Q

wind

A

light, winged

eg sycamore

41
Q

self

A

in a pod that bursts to release seeds

eg peas

42
Q

advantages of dormancy

A

plant avoids harsh winter conditions
gives the embryo time to develop
provides time for dispersal

43
Q

how dormancy is brought about

A

growth inhibitors on outer part of seed
testa is impermeable to oxygen,water
testa is too tough for embryo to emerge

44
Q

application of dormancy in agriculture

A

optimum storage conditions can be provided, allows maximum growth
grower can choose when to sow seeds

45
Q

artificial/commercial procedures used to break dormancy

A

physical damage - slightly damaging seed coat with a knife (scarifying)
pre-chilling- storing seeds in cold temp
light availability- exposing seeds to light/dark

46
Q

factors necessary for germination

A

water- medium for metabolic reactions eg digestion, transport
oxygen- aerobic respiration
warmth- allows maximum enzyme activity, optimum for metabolic reactions

47
Q

main events in germination

A

digestion of stored food in endosperm/cotyledon to provide soluble nutrients
respiration to produce ATP to carry out cell division

48
Q

germination of a typical seed eg broad bean

A

water absorbed through micropyle - activates enzymes
food store broken down- brought to growing embryo
respiration occurs in embryo- ATP produced
radicle bursts and grows downward, plumule later develops in shoot above ground and photosynthesis in leaves begins
cotyledons below ground, remain as food store

49
Q

cotyledons above ground

A

sunflower

50
Q

cotyledons below ground`

A

broad bean

51
Q

changes in dry mass in seeds during germination

A

endosperm or cotyledon mass decreases as embryo uses glucose stored here for respiration
embryo mass increases as glucose produced in photosynthesis
dry mass of total seed decreases due to respiration; loss of carbon dioxide causes loss in mass

52
Q

dry mass

A

the mass of a tissue with its water content removed

53
Q

why is dry mass recorded

A

water content varies from seed to seed