Transcript Reproduction of Seed Plants

Reproduction of Seed
Plants
Dragonfly – Ch. 24
Adv Bio – Ch. 38
I. Reproduction with Cones and Flowers
A. Alternation of Generations
1. all plants have a life cycle in which a
diploid sporophyte generation
alternates with a haploid gametophyte
generation
2. gametophyte plants produce both
male and female gametes (ie – egg &
sperm)
3. when the gametes join, they form a
zygote that begins the next sporophyte
generation
Evolution of the Gametophyte and the
Sporophyte
Gametophyte (N)
Sporophyte (2N)
Bryophytes
Ferns
Seed plants
B. Life Cycle of Gymnosperms
1. reproduction takes place in cones
2. cones are produced by mature
sporophyte plants
3. Pollen Cones and Seed Cones
a. Pollen cones
1) male cones
2) smaller
b. Seed cones
1) female
c. Ovules
1) located near the
base of each scale
2) where egg cells
develop
4. Pollination
a. Gymnosperm life cycle takes 2 years
b. Pollen grains blown by the wind
5. Fertilization and Development
a. Pollen tube
1) grows when a pollen grain lands
near an ovule
2) contains 2 haploid sperm – only 1
is needed
b. Fertilization occurs and produces a
diploid zygote
C. Structure of Flowers
1. reproductive organs
2. contains 4 kinds of specialized
leaves
a. Sepals
1) outermost circle of
floral parts
2) enclose the bud
before it opens
b. Petals
1) often brightly colored
2) attract insects and other
pollinators
c. Stamens - male
1) anther
a) meiosis – produces haploid male
gametophytes – pollen grains
2) filament
a) long, thin stalk
supports anther
d. Carpels or pistils
1) produce female gametophyte
2) ovary
a) contains 1 or more ovules where
female gametophytes are produced
3) style
a) narrow stalk
4) stigma
a) at the top of style
b) sticky part where
pollen grains land
D. Life Cycle of Angiosperms
1. reproduction takes place in the
flower
2. after pollination and fertilization,
the seeds develop inside protective
structures
E. Fertilization in Angiosperms
1. endosperm
a. Food-rich tissue in the seed that
provides nutrients to the seedling
2. Double fertilization
a. Two distinct fertilizations occur
b. One of the sperm nuclei fuses
with the egg nucleus to
produce a diploid zygote
1) this will grow into the new
plant embryo
c. The other sperm nucleus fuses
with two polar nuclei to form a
triploid (3N) cell which grows
into the endosperm
II. Seed Development and
Germination
A. Seed and Fruit Development
1. as angiosperm seeds mature, the
ovary walls thicken to form a fruit that
encloses the developing seeds
2. fruit
a. Any seed that is enclosed within
its embryo wall
B. Seed Dispersal
1. animals
2. wind
3. water
C. Seed Dormancy
1. period in which the embryo is alive,
but not growing
2. environmental factors such as
temperature and moisture can end
dormancy causing the seed to
germinate
D. Seed Germination
1. the early growth stage of the plant
embryo
2. absorbed water causes the seed to
swell breaking the seed coat
3. embryo uses endosperm for
nourishment
Section 24-2
Seed
Germination
in
Monocots
Dicots
have
have
1 Cotyledon
2 Cotyledons
that
that
Remains with
the seed
Emerge
above ground
Remain
below ground
III. Plant Propagation and
Agriculture
A. Vegetative reproduction
1. the production of new plants from
horizontal stems, plantlets, and
underground roots
B. Plant Propagation
1. the production of offspring through
artificial means
2. cuttings
a. A length of stem that includes
lateral buds is cut from the
parent plant and partially buried
in soil or rooting mixture to take
root
b. sometimes requires rooting
hormones
3. grafting
a. A piece of stem is cut from the
parent plant and attached to another
plant
4. budding
a. A bud from one plant is inserted into
the stem of another plant where it
continues to grow
C. Agriculture
1. most of the world’s population
depends upon wheat, rice, corn, and
soybeans for the bulk of their food
supply
2. Biotechnology and the Future