Transcript Plant Reproduction

Plant Reproduction
Asexual Reproduction
• Asexual reproduction is natural “cloning.”
Parts of the plant, such as leaves or
stems, produce roots and become an
independent plant.
Sexual Reproduction
• Sexual reproduction requires fusion of
male cells in the pollen grain with female
cells in the ovule.
Plant Life Cycle
Alternation of Generations
• Plants have a double life cycle with two
distinct forms:
• Sporophyte: diploid, produce haploid
spores by meiosis.
• Gametophyte: haploid, produce
gametes by mitosis.
Non-flowering plants
• Mosses, ferns, and related plants have
motile, swimming sperm.
• What kind of environmental conditions
would be required for reproduction in
these plants?
Moss Life Cycle
Fern Life Cycle
• Moss life cycle:
• http://www.youtube.com/watch?v=o1z0
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• Fern life cycle:
• http://www.youtube.com/watch?v=FhkY0duNjg
Conifers
• Conifers (also non-flowering plants) have
reduced gametophytes.
• Male gametophyte is contained in a dry
pollen grain.
• Female gametophyte is a few cells
inside of the structures that become
the seed.
Conifer life cycle
Conifer pollination
• Conifers are wind-pollinated plants.
• Chance allows some pollen to land on the
scales of female cones.
• Pollen germinates, grows a pollen tube
into the egg to allow sperm to fertilize the
egg.
• Life Cycle:
http://www.youtube.com/watch?v=WPfRV8NWkk4
Plant Reproduction Song
• http://www.youtube.com/watch?v=35vPjd
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Flowers
Flower Parts
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
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
Fertilization
{ After pollen lands on the stigma, a pollen
tube grows down through the style to
ovary
{ Generative cell creates the two sperm
nuclei
{ Double fertilization occurs:
{ one sperm fertilizes the egg
{
one sperm the two polar nuclei
together
Angiosperm Life Cycle
Gametogenesis: Male
Gametogenesis: Female
Double Fertilization
Result of Double Fertilization
{ The sperm nucleus and egg nucleus join
to form a 2n (diploid) embryo
{ The other sperm nucleus and the two
polar nuclei join to form a 3n (triploid)
endosperm. The endosperm is the food
supply for the embryo.
{ First link
Flower to Fruit
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 Mechanisms
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