Post on 22-Dec-2015
Sexual Reproduction
in Plants
Slide 1
Flower Structure
Pistil (female Part) Stigma Style Ovary
Stigma
Style
Ovary
Ovule
Stamen (Male Part)AntherFilament
Anther
Filament
Petal
Sepal
Receptacle
Ovary Fruit
Ovule Seed
Slide # 2
1.Pistil:female reproductive structure
a.Stigma: sticky tip; traps pollen
b.Style: slender tube; transports pollen from stigma to ovary
c.Ovary: contains ovules; ovary develops into fruit
d.Ovule: contains egg cell which develops into a seed when fertilized
FilamentAnther
StigmaStyle
Ovary
Pistil
PetalSepalOvule
Stamen
Slide # 3 Structure of a Flower
2.Stamen: male reproductive structure
a.Filament: thin stalk; supports anther
b.Anther: knob-like structure; produces pollen
c.Pollen: contains microscopic cells that become sperm cells
Structure of a FlowerSlide # 4
FilamentAnther
StigmaStyle
Ovary
Pistil
PetalSepalOvule
Stamen
Slide # 5
Perfect & Imperfect Flowers
Perfect Flower ~ has pistil & stamen
Imperfect Flower ~ only one sex
Slide # 6
3.Sepals: encloses & protects flower before it blooms
4.Petals: usually colorful & scented; attracts pollinators
Structure of a FlowerSlide # 7
FilamentAnther
StigmaStyle
Ovary
Pistil
PetalSepalOvule
Stamen
Slide # 8
PollinationThe 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
Slide # 9
Self-Pollination
The transfer of pollen grains from the anther to the stigma of the same plant.
Cross-PollinationThe 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.
Slide # 10
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.
Slide # 11
Fertilization and Embryo Development
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
Slide # 12
Structure of a Seed (embryo)
Cotyledon: Stored food for early development of embryo(seed leaves)
Epicotyl: Develops into leaves and upper stem
Hypocotyl: Develops into roots and in some species lower stem.
Radical: Develops in roots
Slide # 13
Structure of a Seed
Epicotyl
Slide # 14
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)
Slide # 15
Monocots & Dicots
Monocots – seeds with one cotyledon (corn)
Dicots – seeds with two cotyledons (bean, peanut)
Slide # 16
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).
Slide # 17
Plant
Responses
and
Adaptations
Slide # 18
Slide #19Hormone-producing
cells
Target cells
Movement of hormone
Hormone Action on Plants
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:
1. Plant growth & development
2. Plant responses to environment
Cells in one blooming flower signals other
blooms using hormones to open.
Auxin
High Auxin ~ stimulates stem growth ~ inhibits root growth
Low Auxin ~ reverse effect
Gibberellin
• Increases stem growth • Increases fruit and seed development
Plant HormonesSlide # 20
Plant cells will send signals to one another to tell them:
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.
Slide # 21
Leaf Drop
Fruit Ripening
Sprouting Corn Seeds
Cactus Blooming
Tree Budding
Ethylene causes Fruit to Ripen
1.Fruit tissues release a small amount of ethlyene
2. Ethylene is a gaseous hormone
3.Causes fruits to ripen
4.As fruit become ripe, they produce more and more ethlyene, accelerating the ripening process
Slide # 22
Ethylene released by apples and
tomatoes causes fruit to age quickly.
Plant Tropisms
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
Slide # 23
Slide # 24
Geotropism
What type of tropism is shown in these pictures?
Thigmotrophism
Thigmotrophism
Geotropism
Phototropism
Phototropism