Transcript Mr. Martin`s Chapter 31+32 PowerPoint

IX. Reproductive Structures
of Flowering Plants
A. Sporophyte
1. Growth
• Mitotic division of a
fertilized egg
2. Flowers
• Gametophytes
– Sperm
– Eggs
Carpel
X.
A. A New Generation Begins
1. Cells in pollen sacs
undergo meiosis to
form microspores
3. Cells in ovule undergo
meiosis to form
megaspores
2. Mitosis forms male
gametophyte (pollen
grains)
4. Mitosis without
cytoplasmic division
forms female
gametophyte
B. Pollination to Fertilization
1. Pollination
– Pollen grains to stigma
2. Pollen tube grows to and penetrates embryo
sac, releases two sperm
3. Double fertilization
– One sperm fuses with egg nucleus (2n)
– One sperm fuses with nuclei of endosperm
mother cell (3n)
C. How do plants get pollen from one plant to another?
(plants are rooted in the ground)
A. Wind
1. Gymnosperms and some flowering plants (grasses &
many trees)
2. Hit or miss affair (very chancy)
B. Many flowering plants rely on animals for cross-pollination
1. 3 main animal pollinators- insects, birds, and mammals
a. Insect pollinators- beetles, bees, wasps, flies,
butterflies, and moths
b. Bird pollinators- hummingbirds, honey creepers, and
honeyeaters
c. Mammals- bats
2. Many plants have evolved relationships with animals that
are their pollinators (co-evolution)
D. Seed Structure
(a mature ovule)
1. Seed coat
2. Radicle –
embryonic root
3. Plumule –
embryonic leaves
4. Epicotyl and
hypocotyl – shoot
5. Cotyledons (seed
leaves) derived from
endosperm
E. Fruit = a mature ovary which usually
contains a seed
See Table on pg 537
F. Seed Dispersal
1. Wind Dispersal – Maple Tree, Dandelion
- goal is to land far enough away so they do not have to
compete with parent plants
2. Animals
a.
seed adheres to animal w/ hooks, hairs, and sticky
surfaces
b. Seed survives digestion due to thick seed coat
3. Water Dispersal
a. Waxy coat to avoid water penetration (coconut fruit)
b. Sacs of air to help them float
4. Humans – imports and exotic species
5. Explosives - Impatiens
XI. Asexual Reproduction in Plants (See Table pg 540)
XII. Growth and Development Overview (Chp 32: pgs 546-547)
XIII. Plant hormones
A. Definition – an organic compounds produced in
one part of a plant, transported to another part,
where it stimulates a physiological response
B. Five major types
1. Auxins
a. Stimulates cell elongation in the stem and
thereby phototropism of the plant
b. Produces apical dominance by inhibiting
lateral bud growth
c. Transported through parenchyma
2. Cytokinins
a. Produced in roots
b. Stimulate lateral buds
c. Delay plant aging
3. Ethylene (a gas)
a. Triggers ripening in fruits
b. Produced in nodes, fruit, and aging tissue
4. Gibberellins
a. Promote stem elongation
b. Promote seed germination
5. Abscisic acid
a. Closes stomata under water stress
b. Delays germination of seeds in cold (high
levels in seeds)
XIV. Rate and Direction of Growth
A. Gravitropism – growth response to Earth’s
gravity
B. Phototropism – leaves adjust rate and
direction of growth in response to light
C. Thigmotropism – plant shifts direction of
growth when in contact with solid object
XV. Photoperiodism
A. Processes by which plants control their cycles
using periods of lightness and darkness
B. Types of plants affected by photoperiods
1. Long-day plants - plants affected by a
critical period of darkness or less
a. Flower in spring and early summer
b. Clover, black-eyed Susan, spinach (14 hrs.)
2. Short-day plants - plants affected by a critical
period of darkness or more
a. Flower in late summer or fall
b. Chrysanthemum, poinsettia
C. Phytochromes - light-absorbing pigments that
affect a plant’s photoperiod
1. In short-day plants Pfr inhibits flowering. A long night
means more Pr and therefore lower Pfr levels. Result is
flowering
2. In long day plants Pfr induces flowering. A short night
means more Pfr. Result is flowering
XVI. Leaf abscission (leaf drop)
A. Purpose - to prevent plant dehydration due to transpiration
when ground water is locked up in a frozen state
B. Process
1. In the fall woody parts of plant reabsorb
valuable minerals from the leaves
2. Chlorophyll breaks down leaving and
revealing accessory pigments (carotenoids
and xanthophylls)
3. Changes occur in abscission zone, which has
few fibers and is mostly parenchyma
a. Protective layer of cork cells forms
b. Enzymes digest cell walls in the zone
c. With connection weakened some
mechanical force (wind) knocks leaf off tree
Twig
Petiole
Abscission
zone