Flowering plants have evolved various reproductive structures and processes to facilitate reproduction. Flowers produce male pollen and female ovules that are necessary for fertilization. Key flower parts include sepals, petals, stamens, and carpels. Pollination involves the transfer of pollen grains between flower stamens to carpels. This leads to fertilization within the ovule and formation of seeds. Seeds contain embryos and food reserves to allow for dispersal and germination into new plants under suitable conditions of water, oxygen, and temperature. Seed dispersal mechanisms include wind, animals, water, and mechanical forces. Germination begins with water uptake and radicle emergence from the seed.

1. REPRODUCTION
IN FLOWERING PLANTS

2. Flowers are the
organs
responsible for
reproduction.

3. Four flower parts
sepal
petal
stamen
carpel

4. Parts of an insect pollinated flower
Male
structure Female
structure

5. Function of sepals:
Protect flower when still a
bud; sepal
May remain, but no function
once flower opens

6. Function of petals:
To attract insects

7. Some flowers, like this pansy,
have differently colored lines
to:
 guide pollinators to the
center of the flower
 provide a landing platform
for them.

8. Female sex organ: Carpel
Function of carpel:
holds female sex
cells (egg cell)
Ovule
Embryo sac
Egg cell

9. Many ovules may be
present inside one ovary
Each ovule becomes a
seed after fertilisation.

10. Stigma: Many pollen grains
sticky to trap may germinate on
pollen grains the stigma.

11. A pollen tube
grows down
the style to
reach the
micropyle
Micropyle
Two male
sex cells

12. One male gamete fertilises one egg cell

13. Male reproductive organ: stamen
Function of:
 anther: forms pollen grains
 filament: hold anther
 pollen grain: contains the male
gamete

14. TS of anther
Pollen
grains

15. Mark with an
‘X’ two places
where meiosis
occurs.
X
[Meiosis occurs
to produce
pollen grains &
egg cells]

16. Some trees e.g. carob, have male flowers and female
flowers on SEPARATE trees
Fruit only on
female trees
Male carob Female carob
flowers flowers

17. Question: MAY, 2001
Diagram Y shows a flower picked
from a holly bush. Some holly
bushes are male and others are
female.
a) Was the flower shown in the diagram
picked from a male or a female holly
bush? Give one reason for your
answer. (2)
Male. Only stamens are present.

18. b) How can a male holly bush be
distinguished from a female one, when
these bushes are not in flower but in
fruit? (1)
Male bushes do
not have fruit.

19. Question: MAY, 2002
Some people grow Holly bushes in their
gardens simply for the beauty of their
fruit. Some Holly bushes are male and
others are female. If you decide to grow
Holly bushes, what must you do to make
sure that you will have holly fruit in your
garden? (2)
Grow a male and a female holly bush in
the same garden.

20. Nectaries
Function of nectaries: produce nectar at the base of
ovary; in insect or bird-pollinated flowers
petal
sepal
haired nectary at the
inner base of each petal

21. Pollination
is the transfer of pollen grains from the
anther to the stigma

22. CROSS-POLLINATION:
the transfer of pollen grains from
the anthers of one flower to the
stigma of another flower of the
same species
SELF-POLLINATION:
the transfer of pollen grains from an
anther to the stigma in the same
flower

23. INSECT & WIND POLLINATED
FLOWERS

24. How can pollen be transported?
By wind: By insects:
Wind pollination Insect pollination

25. Insect pollination

26. proboscis

27. Characteristics of Insect- Pollinated flowers
 Large coloured petals
attract insects

28. Characteristics of Insect Pollinated flowers
 Scented
These flowers smell
like rotten meat
Carrion beetles are attracted
to the rotten smell.

29. Characteristics of Insect- Pollinated
flowers
Stamens
enclosed within
flower
Small stigma, sticky to hold pollen
and enclosed within flower

30. Characteristics of Insect- Pollinated flowers
Nectaries
present

31. Characteristics of Insect- Pollinated flowers
 Pollen grains relatively
heavy and large with sticky
or spiny walls
 Pollen is less abundant than
in wind-pollinated flowers

32. Wind
pollination

33. Wild oat close-up

34. Characteristics of Wind Pollinated
flowers
 No scent or nectary
Flowers are small and
lack bright colours

35. Characteristics of Wind Pollinated
flowers
Several plant families are
dominated by wind-
pollinated flowers, including
the grasses.

36. Characteristics of Wind Pollinated
flowers
Wing / air sac
Pollen is smooth, light &
small and sometimes have
wing-like extensions to
aid wind transport
Produce of a large
amount of pollen

37. Characteristics of Wind Pollinated flowers
 Stamens hanging outside
flower to release pollen
 Anthers are large
 Flower hangs down
The anthers as well as
the flower itself hang
down [sugar maple)

38. Stigmas hang outside flower on long
styles
Stigmas are feathery, giving them a
large surface area to trap pollen

39. Question
What type of pollination does this flower
have?
Give THREE ways shown by the flower that
make it adapted for this type of pollination.

40. Answer
Wind pollinated flower

41. GROWTH OF
POLLEN TUBE

42. Pollen tube emerges from one of the pores in
wall of pollen grain
pollen tube
pore in wall of
pollen grain two male
gametes
embryo sac

43. Fertilisation:
• is the process by which the nucleus of
a male sex cell fuses with the nucleus
of a female sex cell to form a single-
celled zygote
Fertilisation occurs
ovule
inside the ………..

44. Stages in fertilisation
2
Tip of pollen tube
bursts. The male
gametes enter the
embryo sac.
1
Two male gametes
in pollen tube.
3
Fertilisation of the
egg nucleus & the
endosperm nucleus

45. Fertilisation of the endosperm
nucleus: forms
ENDOSPERM (often
contains a food store used by
the embryo plant)
Fertilisation of the egg
nucleus: ZYGOTE (forms
the embryo plant)

46. SEED &
FRUIT FORMATION

47. Petals, stamens, stigma & style fall
off after fertilisation
but the ovary
begins its
transformation
into a fruit.

48.  ovary develops into a fruit
 ovule develops into a seed

49. Wall of ovule develops into the seed
coat [testa]

50. Where is food stored?

51. Embryo: Radicle, Plumule + Cotyledons
Epicotyl: base of plumule
Hypocotyl: base of radicle

52. External Broad bean Longitudinal
appearance of with testa section of
broad bean. removed. broad bean.

53. Label the broad bean seed
cotyledons
plumule
radicle

54. Broad bean seed [learn to draw]
Function of micropyle: water
enters before germination
Testa: a thick seed coat which protects the seed
from drying up and attack by microbes

55. Starch in cotyledons
The seed coat has been
When a thin slice of stained
removed from this bean
cotyledon is examined under
seed and several drops of
the microscope, the starch
iodine solution have been
grains are blue in color.
placed on the cotyledon.

56. SEED DISPERSAL

57. Advantages of seed dispersal:
The chance of survival is increased
because:
1. competition between 2. new habitats may
young plants is reduced be colonised

58. Which structure in flowering plants helps
to disperse seeds?
FRUIT

59. Question: MAY, 2006
Following pollination and fertilisation,
angiosperms and gymnosperms produce
seeds. This is considered as a successful
adaptation of these plants.
a) Give TWO advantages of production of
seeds. (4)
1. Seed contains a store of food for the
embryo to use during germination.
2. Seed can remain dormant and so survive
bad conditions.
3. Testa protects embryo.

60. b) Give ONE disadvantage of production
of seeds. (2)
 Seeds are heavy and so difficult to be
dispersed
 May be eaten by animals
 If too deep in soil, they never germinate

61. Four types of seed dispersal:
1. Wind dispersal
2. Animal dispersal
3. Mechanical dispersal
4. Water dispersal

62. 1. Wind dispersal Thistle
– a wing (e.g. sycamore) or
– parachute (e.g. thistle)
Maple seeds: Winged fruit

63. 1. Wind dispersal
– a wing or parachute allow the seed to remain
airborne for a longer time and this increases its
chance to be carried away some distance away
from the parent plant

64. Pomegranate
2. Animal dispersal
 brightly coloured, juicy,
edible fruits (e.g. cherry)
invites an animal to eat it
Cherry
Seeds within berries
are often dispersed in
animal faeces.

65. 2. Animal dispersal
 a hooked seed (e.g. goosegrass)
may drop off the animal’s coat far
away from the parent plant
Burdock: Spiny
fruit
Goosegrass:
hooked fruit

66. 2. Animal dispersal
Acorns are carried
by squirrels

67. 3. Mechanical dispersal
• pods of the pea family dry up in the sun
and shrivel
• the sides curl up, flinging out seeds

68. 4. Water dispersal
- the fruit contains air-filled
walls to help it float
Coconut

69. 4. Water dispersal
Coco de mer

70. What is the method of dispersal in each
group?
A: Wind A B C D
B: Animal
C: Water
D: Mechanical

71. Question: MAY, 2006 [II A]
The seeds of the Squirting
Cucumber (Faqqus il-Hmir)
develop in large oval fruits
which when ripe, shoot out their
seed on a slight disturbance.
a) What type of seed dispersal
is this and what is its
importance? (3)

72. Question: MAY, 2006 [II A]
i) Name TWO other methods of seed dispersal
and for each name ONE type of plant that
disperses its seeds using the method you
mentioned. (4)
Animal dispersal: burdock
Wind dispersal: dandelion
Water dispersal: coconut
dandelion

73. Before a seed is dispersed,
water is removed from it. Why?
1. Seed is lighter.
2. Less likely to be attacked by
microbes.
The water content of
a seed is only about
5~15% of its weight.

74. Seed of extinct date palm sprouts after
2,000 years [news published in 2005]
The date tree that was successfully
germinated from a 2000 year old seed found
in Israel.

75. Question: SEP, 2011
Give a biological explanation for each of the
following statements.
If a seed does not experience ideal conditions
for germination immediately, it will not die even
though it does not germinate. (3)
The seed can remain dormant for many
years. Being dry, microbes do not attack
it. It has a food store that can be used for
respiration to keep the embryo alive.

76. SEED GERMINATION

77. Three conditions for seed
germination
1. WATER
2. OXYGEN
3. A SUITABLE TEMPERATURE

78. 1. WATER
 for the seed to swell & burst open
 for the stored food to be made soluble
& move to the growing embryo
2. OXYGEN
 is needed for the embryo to respire
3. A SUITABLE TEMPERATURE
 usually seeds won’t germinate when
the temperature is below 0-5 C or
above 45-50 C

79. What about light?
 most seeds will germinate in the light
or dark
 but some germinate only in the dark
 others require light – one quick flash is
enough
A seedling

80. EXPERIMENT
AIM: To investigate the conditions
required for germination.

81. RESULT:
Germinated No germination

82. CONCLUSION:
Seed germination requires water,
oxygen and a suitable temperature.

83. Question: MAY, 2004
a) List the three conditions necessary for
germination.
b) Design an experiment that demonstrates
that the three conditions listed in (a) are
all necessary for germination. (7)

84. Two types of germination:
Hypogeal:
cotyledons remain
below the ground
cotyledons
Epigeal:
cotyledons are pulled above the
ground & act as the first leaves
Radicle

85. Hypogeal Epigeal
germination e.g. germination e.g.
broad bean sunflower

86. Which structure elongates in:
Hypogeal Epigeal germination
germination [bean]: [sunflower]:
Epicotyl elongates Hypocotyl elongates

87. Germination or seed growth starts by
water entering micropyle & testa.
Result: testa splits & radicle emerges

88. Why does the radicle emerge
first?
• To anchor seed
• To absorb water & mineral ions

89. Hypogeal germination [learn to
draw ]
Epicotyl
elongates

90. Epigeal germination
Cotyledons
above soil.

91. Epigeal germination

92. THE END
Unisexual flowers