Reproduction
Asexual vs. Sexual
Asexual Reproduction
Involves one parent or parent part
Involves mitosis, not meiosis
Offspring’s DNA is identical to parent
Advantage? Parent and offspring are
both adapted
Disadvantage? No variation
Binary Fission (Mitosis) Amoeba
Planaria Regeneration
Hydra
Hydra Budding
Hydra Sexual Reproduction
Daphnia – “water flea”
Plant Asexual Reproduction
Bulbs – underground stems that grow into
new plants by mitosis
Cuttings – pieces of plant stems, roots,
leaves rooted in soil
Why asexual?
Why identical?
Runners – stems “creep” along the ground
and grow a new identical plant by
mitosis
Sexual Reproduction – Plants
Seed Producing Plants
Cone - bearing
Pine Cones
Female Pine Cone
Flowers
Flower Parts
Flower Parts
Receptacle – top of stem upon which the
flower sits
Sepal – usually green; leaf-like; protects
the flower bud prior to opening
Collectively called the Calyx
Petal - usually brightly colored
Function?
Protect reproductive parts; attract insects
Collectively called the Corolla
Male Flower Parts
Male part of the flower
– Stamen
Consists of:
a. Anther – sac
that produces pollen
b. Filament – stalk
that supports anther
Female Flower Parts
Female part of the flower – pistil
(carpel)
Consists of:
a. Stigma – sticky; at the top;
attracts insects; collects
pollen
b. Style – stalk that supports the
stigma
c. Ovary – swollen structure at
the base; contains
ovules (eggs);
Fertilized eggs become
seeds
Flower Vocabulary
Complete = has
sepals, petals,
stamen and pistil
(Most flowers)
Incomplete =
lacks sepals,
petals or both
Usually “not pretty”
Ex: some
trees, grasses
Perfect = has both pistil
and stamen
(Most flowers)
Imperfect = has only pistil
(pistillate) or
has only stamen
(staminate)
Ex: corn, oak trees
Sometimes are even on
separate plants!
Ex: pussy willow, gingko
trees
Most flowers are perfect
and complete with several
stamen and one pistil
Why?
Scientific name: Ginkgo biloba
Common names: Ginkgo, Maidenhair Tree:
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Pussy Willow Bush
Pollination
Process by which pollen is
transferred from anther to stigma
Self - occurs within the same
flower
Cross – occurs between two
different flowers on two different
plants of the same species
What about two different flowers
on the same plant?
Still Self for is the same
organism/same DNA
Corn Pollination
Wind Vs. Insect Pollination
Only about 10%
of flowering
plants are wind
pollinated
Which ones?
What attracts
insects?
Wind Pollination
Ovule Fertilization
Pollen lands on stigma
Grows a pollen tube down the stigma
to reach the ovary
Inside the tube are two nuclei from the
pollen grain (“sperm nuclei”)
Meanwhile the ovule has already
divided into multiple cells
One sperm nucleus fuses with some
ovule cells to form “food”
Why do seeds need food?
Second sperm nucleus fuses with an
ovule cell to form an embryo
Pollen grain
Ovule Fertilization
Actually a
“double
fertilization”
1. Food usually
called
endosperm
Some seeds
contain a lot of it
Often is starch
Ex: corn
2. Second
fertilization is the
embryo
Fruit Development and Seed
Dispersal
Eventually flower petals, sepals, the pistil and
stamens usually wither and fall off
If ovules have been fertilized, they begin
to grow and the ovary swells
Called – biological Fruit
Roles: protect and disperse the seeds
(scatter far from parent)
Biological Fruits
Seed Dispersal
Bean Seed Embryo
Cotyledon = name of
basic seed part
Contains the embryo and
endosperm food
Embryo Parts
a. epicotyl (plumule) =
set of baby leaves
b. hypocotyl = baby
stem
c. radical = baby root
Called Dicot – has 2
cotyledons
Corn Seed Embryo
Monocotyledon
(Monocot)
Contains only one
cotyledon
Usually lots of
endosperm
Monocots Vs. Dicots
Flowering
plants can be
classified into
two basic
groups
Monocots Vs. Dicots
Dicots – two seed parts (cotyledons),
branched veins in leaves, flower parts
in multiples of 4 or 5
Monocots – one seed part (cotyledon),
straight veins in leaves, flower parts
in multiples of 3
Seed Development