Sexual Reproduction in

1
Slide 1

• Sexual Reproduction in
• Plants

2
Flower Structure
Slide 2
Stigma
Ovary ? Fruit
Anther
Style
Ovule ? Seed
Filament
Ovule
Petal
Sepal

• Pistil (female Part)
• Stigma
• Style
• Ovary

• Stamen (Male Part)
• Anther
• Filament

Receptacle
Ovary
3
Structure of a Flower
Slide 3

• 1.Pistilfemale reproductive structure
• Stigma sticky tip traps pollen
• Style slender tube transports pollen from
  stigma to ovary
• Ovary contains ovules ovary develops into fruit
  
• Ovule contains egg cell which develops into a
  seed when fertilized

4
Structure of a Flower
Slide 4

• Stamen male reproductive structure
• Filament thin stalk supports anther
• Anther knob-like structure produces pollen
• Pollen contains microscopic cells that become
  sperm cells

5
Slide 5
6
Perfect Imperfect Flowers
Slide 6
Perfect Flower has pistil stamen
Imperfect Flower only one sex
Which is male? Female?
7
 Structure of a Flower
Slide 7

• Sepals encloses protects flower before it
  blooms
• Petals usually colorful scented attracts
  pollinators

8
Slide 8
What are the functions of each part?
9
Pollination
Slide 9

• The transfer of pollen grains from the anther to
  the stigma.
• Pollination may be aided by wind, insects, and
  birds. In some instances, the colored petals act
  as a visual attractant for insects.
• If pollination occurred in a dry environment, the
  pollen would not dehydrate (dry up) due to a
  thick wall that surrounds it.
• Two types of pollination
• 1. Self-Pollination
• 2. Cross-Pollination

10
Self-Pollination
Slide 10

• The transfer of pollen grains from the anther to
  the stigma of the same plant.

Cross-Pollination
The transfer of pollen grains from the anther of
a flower on one plant to the stigma of a flower
on a different plant. Allows for variations due
to the combination of two different plants.
11
Slide 11

• Following pollination, the pollen grain
  germinates to the stigma and forms a pollen tube.
• Pollen tube is an adaptation for internal
  fertilization.
• 2 Haploid sperm cells travel down the pollen tube
  and only one fertilizes the egg in the ovule.

12
Fertilization and Embryo Development
Slide 12

• The union of a sperm cell and an egg cell results
  in the formation of a zygote
• The zygote undergoes development resulting in the
  formation of an embryo (ripened ovule)
• The ripened ovule (embryo) develops into the seed
• The ripened ovary develops into the fruit

13
Structure of a Seed (embryo)
Slide 13
Hypocotyl Develops into roots and in some
species lower stem.
Radical Develops in roots
Epicotyl Develops into leaves and upper stem
Cotyledon Stored food for early development of
embryo (seed leaves)
14
Structure of a Seed
Slide 14
Epicotyl
15
Slide 15

• Seed coat
• forms from outer layer of ovule
• protects embryo

Endosperm food storage tissue (the other sperm
creates this triploid (3n) structure when it
fertilizes 2 polar bodies from oogenesis)
16
Monocots Dicots
Slide 16
Monocots seeds with one cotyledon
(corn) Dicots seeds with two cotyledons (bean,
peanut)
17
Slide 17
Germination and Growth
Fruits are specialized structures which aid in
seed dispersal. Seeds develop inside the fruit.
If the temperature and moisture levels are
sufficient, the dispersed seeds will germinate
(activate and grow).
Growth in most plants occurs in the
meristems. The organs of a plant are developed in
the meristems. Apical Meristems are found in the
tips of roots and stems and cause the plant to
grow in height. Lateral Meristems are between
the xylem and phloem and cause the plant to grow
in diameter (get wider).
18
Slide 18

• Plant
• Responses
• and
• Adaptations

19
Hormone Action on Plants
Hormone-producing cells
Slide 19

• A. Plant cells can produce hormones (chemical
  messengers that travel throughout the plant
  causing other cells called target cells to
  respond)
• B. In plants, hormones control
• Plant growth development
• Plant responses to environment

Movement of hormone
Target cells
Cells in one blooming flower signals other
blooms using hormones to open.
20
Auxin
Plant Hormones
Slide 20
High Auxin stimulates stem growth
inhibits root growth Low Auxin reverse effect
Gibberellin

• Increases stem growth
• Increases fruit and seed development

21
Plant cells will send signals to one another to
tell them
Slide 21

1. When trees to drop their leaves.
2. When to start new growth.
3. When to cause fruit to ripen.
4. When to cause flowers to bloom.
5. When to cause seeds to sprout.

Leaf Drop
Cactus Blooming
Fruit Ripening
Tree Budding
Sprouting Corn Seeds
22
Ethylene causes Fruit to Ripen
Slide 22

• Fruit tissues release a small amount of ethlyene
• Ethylene is a gaseous hormone
• Causes fruits to ripen
• As fruit become ripe, they produce more and more
  ethlyene, accelerating the ripening process

Ethylene released by apples and tomatoes causes
fruit to age quickly.
What type of feedback?
23
Plant Tropisms
Slide 23

• Tropism the way a plant grows in response to
  stimuli in the environment caused by an unequal
  distribution of auxin.
• Phototropism growth response to light
• -Plants bend towards light
• Geotrophism growth response to gravity
• -plant roots grow down with gravity, shoots
  (stems) grow up against gravity and out of the
  soil.
• Thigmotropism growth response to touch
• -vines grow up around trees, venus flytrap
  closes when leaves are touched

24
Slide 24
What type of tropism is shown in these pictures?
Phototropism
Geotropism
Thigmotrophism
Thigmotrophism
Geotropism
Phototropism