Transcript CHAPTER 30 - Doral Academy Preparatory

Plant Life Cycles
CHAPTER 30
Flowering Plant Reproduction
Angiosperms (flowering plants)
• Plants that protect their seeds within the body
of a fruit.
• Make up ¾’s of all plants, including:
– Trees, shrubs, herbs,
grasses, water plants…
Male Reproductive Structure
The stamen consists of
two parts: Anther and
Filament
The anther is where
meiosis occurs to
produce haploid pollen
The filament is a stalk
that supports the
anther
Female Reproductive Structure
The pistil consists of
the stigma, style and
ovary
The sticky stigma
receives the pollen
from the anther
The pollen grows a
tube down through the
style
Meiosis occurs in the
ovary to produce
haploid ovules
Reproductive Structures
• Petals: colourful
structures that attract
pollinators.
• Sepals: surround and
protect the flower bud.
Pollination
Wind, insects or other
animals transfer pollen
from the anther of one
flower to the stigma of
another
Flowers vary
depending on
pollination mechanism
Pollination Vectors
Wind Pollination: Dull, scentless
flowers with reduced petals
Bees/Butterfly Pollination: Bright
color, nectaries, scent.
They sip nectar, get pollen on coats,
transfer pollen from flower to flower
Bird Pollination: Nectaries, bright
colors, tube-like flowers
Moth Pollination: White petals,
open at night
Fly Pollination:Rank odor, flesh
colored petals
How Do Flowers Make Seeds
and Fruits?
Ovary – the
bottom part of
the pistil in
which seeds
form
Ovule - the inner
part of an
ovary that
contains an egg
embryo – tiny part
of a seed that
can grow into a
new plant
How Fertilization Occurs
• When a pollen grain reaches a pistil, it
grows a thin tube to the ovary. Sperm from
the pollen grain combines with an egg, and
a seed forms.
What is the Life Cycle of a
Flowering Plant
• Dormant Seed
– Takes in water and the
seed coat gets soft. If the
seed has enough oxygen
and the right temperature,
it will begin to germinate.
dormant – the
resting stage of a
seed
• Geminating Seed
– First a root pushes through the
seed coat and grows downward.
– The top part of the root grows
upward and becomes the stem.
The stem carries the seed coat
and the seed leaves with it. The
seed coat falls off. The seed
leaves provide food for the plant.
Two small leaves begin to grow
from between the seed leaves.
• Seedling
– When the stored food within the original seed
leaves is used up, they dry up and drop off.
More leaves grow from buds on the stem as the
plant grows taller. The new leaves can trap
energy from sunlight and make sugar. Plants
use the energy in the
sugar
to grow.
Seed and Fruit Development
{ After fertilization,
the petals and
sepals fall off
flower
{ Ovary “ripens”
into a fruit
{ The ovule
develops into a
seed
Seed Dispersal MechanismsAllow plants to colonize new areas and avoid
shade of parent plant
Wind Dispersal - Flight mechanisms,
like parachutes, wings, etc.
Ex. Dandelion, maples, birch
Animal Dispersal - Fleshy fruits which
animals eat, drop undigested seeds in
feces or burrs which stick to
animals’ coats
Gravity Dispersal Heavy nuts fall to
ground and roll
ex. acorns
Water Dispersal - Plants
near water create floating
fruits
ex. coconuts
Plant Responses
CHAPTER 31
• How plants move and communicate
Plant Hormones
Plant Hormones
• Plant hormones can be divided into two
classes:
– Growth promoters: Auxins, Gibberellins,
Cytokinins
– Growth inhibitors: Ethylene gas, Abscisic acid
Growth promoters
• Hormones can promote plant growth in
two ways:
– Stimulating cell division in meristems to
produce new cells.
– Stimulating elongation in cells.
Auxin activity
Auxins stimulate genes in cells associated with plant growth.
Auxin roles
• Auxins carry out multiple roles having to
do with plant growth including:
–
–
–
–
Tropisms
Apical dominance
Growth of adventitious roots
Fruit growth
Tropisms
• Tropisms are the growth of a plant toward
or away from a stimulus, including:
– Phototropism: in response to light
– Gravitropism: in response to gravity
– Thigmotropism: in response to touch
Nastic Movements
Nastic
movement in
the sensitive
plant (Mimosa
pudica)
Hinge control in Venus Fly Trap - Nastic movement
Plant Communication
• Plants communicate chemically.
• Injured plants send out chemical signals
that may
– signal other plants to prepare for an attack.
– attract other insects that eat the insects that are
attacking the plant.