Download Reproduction of Seed Plants

Reproduction of Seed Plants
Pg. 609
Alternation of Generation
• All plants have a life cycle in which a diploid sporophyte
generation alternates with a haploid gametophyte
generation.
• Gametophyte plants produce male and female gametes
– sperm and eggs.
• When the gametes join, they form a zygote that begins
the next sporophyte generation.
• Seed-bearing plants are diploid.
• The gametophytes of seed plants are actually hidden
deep within tissues of the sporophyte plant.
– In gymnosperms they are found in cones.
– In angiosperms they are found inside flowers.
Life Cycle of Gymnosperms
• Reproduction in Gymnosperms takes
place in cones which are produced in the
mature sporophyte plant.
• Pollen cones are male cones.
• Seed cones are female cones and contain
ovules.
Life Cycle Continued…
• 1. The mature sporophyte produces male
and female cones.
• 2. Male cones produce pollen and female
cones produce ovules.
• 3. If an egg is fertilized by the sperm, it
becomes a zygote that is nourished by the
female cone.
• 4. In time, the zygote develops into a new
sporophyte plant.
Gymnosperm Life Cycle
Structure of Flowers
• Flowers are reproductive
organs that are
composed of four kinds of
specialized leaves:
• 1. Sepals – the
outermost circle of
floral parts. Enclose the
bud before it opens, and
protect the flower while it
is developing.
• 2. Petals – brightly
colored; attract pollinators
to the flower.
Structures cont.
• 3. Stamen – male parts
that consist of an anther
and filament.
– Filament – long thin stalk
that supports the anther.
– Anther – Produces pollen
grains.
• 4. Carpels –produce
female gametophytes.
– Ovary – contains one or
more ovules.
– Style – stalk that holds the
stigma.
– Stigma – where pollen
grain stick.
Life Cycle of Angiosperms
• Reproduction in angiosperms takes place within the flower.
• Following pollination and fertilization, the seeds develop inside
protective structures.
• 1. The cycle begins when the mature sporophyte produces flowers.
– Each flower contains anthers and an ovary.
• 2. Gametophytes develop to form pollen and ovules.
• 3. Pollen is transferred from pollen to stigma by a process called
pollination.
• 4. After pollination occurs a pollen tube forms that grows into the
style.
– An endosperm forms – food rich tissue that nourishes the seedling as it
grows.
• 5. Because two fertilizations take place, this is known as Double
Fertilization.
Angiosperm Life Cycle
Review Question…
• 1. What are the reproductive structures of
gymnosperms?
• 2. Describe the flower and how it is involved in
reproduction.
• 3. Are angiosperms typically wind pollinated or animal
pollinated? How does this process take place?
• 4. What is an endosperm? Where does it form in a
flowering plant?
• 5. Many flowers have bright patterns of coloration that
directly surround the reproductive structures. How might
this type of coloration be advantageous to the plant?