Transcript What makes a Plant a Plant?

Chapter 3: Plant Growth
and Reproduction
5th grade Science
Teacher Imarlys Cajigas
http://www.softschools.com/science/
plants/flower_anatomy.jsp
Big Idea: Plants have a variety of structures to help them
carry out life processes.
Lesson 2: How do plants
reproduce?
Vocabulary
 Spore- a single reproductive cell that can grow into a
new plant.
 Gymnosperm- a plant that produces naked seed.
 Angiosperm- a flowering plant that has seeds protected
by fruits.
 Germinate- to sprout.
Plant Characteristics
Plants reproduce by spores or seeds.
there are two stages in a plants life:
Sporophyte (produces spores)
Gametophyte (produces
gametes)
What is a Sporophyte?
A plant in the
spore
producing
stage of life.
Spores can
grow directly
into an adult
plant
What is a Gametophyte?
The stage in a
plant’s life where it
produces male and
female sex cells.
Needs a moist
environment for the
sperm to swim and
fertilize the eggs.
More on Gametophytes
Male and
female sex
cells must
join in order
to grow into a
new plant.
This is called
Fertilization.
Fertilization
 Gametes join to form a
zygote.
 A fertilize egg grows into a
sporophyte,
 Sporophyte grow from the
gametophyte and live on its
own.
 Spores are produced in
clusters called sori that toss
spores several meters from
the ground.
How are Plants Classified?
Vascular Plants
Have tissues that deliver
needed materials throughout a
plant - called vascular tissues.
Can be almost any size.
Are divided into
gymnosperms and
angiosperms
How are Plants Classified?
 Gymnosperms -- non-flowering plants that
produces naked seeds.
 Angiosperms -- flowering plants that produces
seeds protected by a fruit.
Gymnosperms Reproduction
 Male pine cones produces pollen
that contains sperm.
 Females cones are larger and
grow high on trees. Ovules
contains the eggs and grow on
the scales of female cones.
 Mature male cones release
millions of pollen grains that are
blown by the wind.
 Some pollen fertilize the eggs and
a seed develops.
 When the seeds are mature the
cone scales separate and the
seeds travel on the wind.
 If the seed lands in a suitable
habitat a new plant begins to
grow. And the life cycle begins.
The Parts of a Flower
Most flowers
parts:
sepals,
petals,
stamens,
stigma.
The parts of a flower
Petals attract
insects.
Stamens make
pollen.
Stamen (male)
Anther: pollen
grains grow in the
anther.
 When the grains are fully
grown, the anther splits open.
 Petals – attracts insects for
pollination.
Sepals protect the bud until it opens.
Pistil (female)
Stigma
collects pollen
Carpel (ovary)
after
fertilization it develops into a
fruit.
Ovules (eggs)
into a seed.
develop
Pollination
Flowering plants
use the wind,
insects, bats, birds
and mammals to
transfer pollen
from the male
(stamen) part of
the flower to the
female (stigma)
part of the flower.
Pollination
A flower is
pollinated when a
pollen grain lands
on its stigma.
Each ovary grows
into a fruit which
contains the seeds.
Fertilization
 Pollen grains germinate
on the stigma, growing
down the style to
reach an ovule.
 Fertilized ovules
develop into seeds.
 The ovary enlarges to
form the flesh of the
fruit and to protect
the seed.
Wind pollination
 Some flowers, such as
grasses, do not have
brightly coloured
petals and nectar to
attract insects.
 They do have stamens
and carpels.
 These flowers are
pollinated by the wind.
Seed dispersal
Seeds are dispersed in
many different ways:
 Wind
 Explosion
 Water
 Animals
 Birds
 Scatter
How birds and animals help seed
dispersal?
Some seeds are
hidden in the
ground as a winter
store.
Some fruits have
hooks on them and
cling to fur or
clothes.
How birds and animals help seed
dispersal?
Birds and animals
eat the fruits and
excrete the seeds
away from the
parent plant.
Seed Germination
 Seeds are adapted to germinate when
conditions are right for growth of the
embryo.
 A thick seed coat protects the embryo
until it germinates.
 Sometimes seeds stay in the ground for
several years before they grow; the
timing will depend on the needs of the
plant.
 When the time is right, a seed absorbs
water and expands. This breaks the
seed coat, and the embryo begins to
grow.
 First, the root emerges from the seed and begins
to anchor and take up nutrients.
 Then a shoot pushes up. The leaves of an embryo
cannot make food, the nutrients come from a
structure called cotyledon, until the plant grow
and makes its own food.
 When the first leaves emerge from the ground,
they turn green as chlorophyll for photosynthesis
is produced.
 Rapid growth begins and the embryo becomes a
plant seedling.
Lesson Review
 What is a gametophyte?
 What happens during the sporophyte stage?
 Male reproductive cells are called ____________.
 Female reproductive cells are called_________.
 Where do seeds of conifers develop?
 How are angiosperm seeds and gymnosperm seeds
different?
 Which part of the flower eventually develops into a fruit?
 Why are a flower’s petal so important in reproduction?
 Where does the embryo obtains its food?
 How do the leaves of an embryo differ from the leaves of
a mature plant?
Practice
 Answer workbook p. 19-20
 Make a diagram of the flower, identify each part and
write its function.
 Make a diagram of a moss life cycle and a fern life cycle.
 Compare and contrast mosses and ferns.