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