Transcript Plants - Warren County Schools

Plants
 Multicellular eukaryotes
 Cell walls made of cellulose
 Develop from multicellular embryos
 Carry out photosynthesis using Chlorophyll a & b
 Most are autotrophs
 Some are parasites
Plant Life Cycle
 2 phases that
alternate:
 Dipoloid
 Haploid
 Known as
alternation of
generations
 Mitosis & meiosis alternate to produce 2 types of
reproductive cells
 Gametes
 Haploid phase is called a gametophyte
 Spores
 Diploid phase called sporophyte
Survival
 In order to survive, plants need:
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sunlight
water and minerals
gas exchange
transport of water and nutrients throughout the
plant body
Evolution of Plants
 The first plants evolved from an organism similar to
the multicellular green algae living today
 The oldest known plant fossils, about 450 million
years old, are similar to today’s mosses
Division of the Plant
Kingdom
 Plants are divided into four groups based on these
features:
 water-conducting tissues
 seeds
 flowers
 Evolutionary Relationships Among Plants
Flowering plants
Cone-bearing plants
Mosses and
their relatives
Ferns and
their
relatives
Flowers; Seeds
enclosed in fruit
Seeds
Water-conducting (vascular)
tissue
Green algae
ancestor
 Seed plants are divided into two groups:
 Gymnosperms bear seeds directly on the surfaces of
cones.
 Angiosperms, or flowering plants, bear seeds within a
layer of tissue that protects the seed
 Adaptations that allow seed plants to reproduce
without water include:
 flowers or cones
 the transfer of sperm by pollination
 the protection of embryos in seeds
 The male gametophyte is contained in a tiny
structure called a pollen grain
 This transfer of pollen is called pollination.
Seeds
 A seed is an embryo of a plant that is encased in a
protective covering and surrounded by a food
supply.
 An embryo is an organism in its early stage of
development.
 The seed coat surrounds and protects the embryo
and keeps contents of the seed from drying out.
Angiosperms
 The majority of living plant species are flowering plants,
or angiosperms
 Flowers are an evolutionary advantage because they
attract animals, which then transport pollen from flower
to flower.
 Flowers contain ovaries, which surround and
protect the seeds.
 After pollination, the ovary develops into a fruit.
 A fruit is a wall of tissue that surrounds a seed. A
fruit protects the seed and aids in its dispersal.
 There are two classes within the angiosperms—
monocots and dicots
 Monocots and dicots are named for the number
of seed leaves, or cotyledons, in the plant
embryo. Monocots have one seed leaf, and
dicots have two.
 A cotyledon is the first leaf or the first pair of
leaves produced by the embryo of a seed plant
Life Cycles
 There are three categories of plant life spans:
annual, biennial, and perennial.
 Annuals are plants that complete a life cycle in one
growing season.
 Biennials complete their life cycle in two years. In
the first year, they germinate and grow roots, short
stems, and sometimes leaves. In the second year,
they grow new stems and leaves, produce flowers
and seeds, and die.
 Perennials live for more than two years.
Plant Structure
 The three principal organs of seed plants are roots,
stems, and leaves.
 These organs perform functions such as the
transport of nutrients, protection, and coordination
of plant activities.
 Roots:
 absorb water and dissolved nutrients.
 anchor plants in the ground.
 protect the plant from harmful soil bacteria and fungi.
 Stems provide:
 a support system for the plant body.
 a transport system that carries nutrients.
 a defense system that protects the plant against
predators and disease
 Leaves:
 are a plant’s main photosynthetic systems.
 increase the amount of sunlight plants absorb.
 Adjustable pores conserve water and let oxygen and
carbon dioxide enter and exit the leaf.
 Plants consist of three main tissue systems:
 dermal tissue
 vascular tissue
 ground tissue
Vascular Tissue
 Conduct water and nutrients throughout the plant
 The first vascular plants contained tracheids which
are cells specialized to conduct water.
 Tracheids make up xylem, a transport subsystem
that carries water from the roots to every part of a
plant.
 Phloem transports solutions of nutrients and
carbohydrates produced by photosynthesis
 Both xylem and phloem can move fluids through
the plant body, even against the force of gravity
 Xylem moves water
 Phloem moves food
Roots
 The two main types of roots are:
 taproots, which are found mainly in dicots
 carrots
 fibrous roots, which are found mainly in monocots
 grasses
 The most important nutrients plants need include:
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nitrogen
phosphorus
potassium
magnesium
calcium
 Root pressure forces water through the vascular
cylinder and into the xylem
 Root pressure is the starting point for movement of
water through the vascular system of the entire
plant.
Stems
 Stems have three important functions:
 they produce leaves, branches and flowers
 they hold leaves up to the sunlight
 they transport substances between roots and leaves
Leaves
 The structure of a leaf is optimized for absorbing
light and carrying out photosynthesis
Leaf Structure
 .
Blade
Simple leaf
Petiole
Bud
Stem
Copyright Pearson Prentice Hall
Leaflet
Compound leaf
 Stomata are porelike openings in the underside of
the leaf that allow carbon dioxide and oxygen to
diffuse into and out of the leaf.
 Guard cells are specialized cells that control the
opening and closing of stomata by responding to
changes in water pressure.
 Transpiration is the loss of water through its leaves
 Plants keep their stomata open just enough to allow
photosynthesis to take place but not so much that
they lose an excessive amount of water
Reproduction
 Reproduction in gymnosperms takes place in cones,
which are produced by a mature sporophyte plant.
 Gymnosperms produce two types of cones: pollen
cones and seed cones
Meiosis
Fertilization
Flowers
 Flowers are reproductive organs that are composed of
four kinds of specialized leaves: sepals, petals, stamens,
and carpels.
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 Sepals enclose the bud before it opens and protect the flower
while it is developing.
Sepal
 Petals are often brightly colored and are found just inside the
sepals.
 Petals attract insects and other pollinators to the flower.
Petal

 The male parts of a flower consist of an anther and a filament,
which together make up the stamen.
Anther
Filament
Stamen
 An anther is an oval sac where meiosis takes place,
producing pollen grains.
Anther
 The filament is a long, thin stalk that supports an
anther.
Filament
 The innermost floral parts are carpels, also called
pistils, which produce the female gametophytes.
Stigma
Style
Ovary
Carpel
 Each carpel has a broad base forming an ovary.
 The ovary contains one or more ovules where
female gametophytes are produced.
Ovary
Ovule
 The narrow stalk of the carpel is the style.
Style
 At the top of the style is the stigma—a sticky
portion where pollen grains frequently land.
Stigma
 Parts of a Typical Flower
Stamen
Stigma
Anther
Filament
Style
Ovary
Ovary
Petal
Sepal
Ovule
Carpel
 Reproduction in angiosperms takes place within the
flower. Following pollination and fertilization, the
seeds develop inside protective structures
 Seeds are dispersed by animals, wind, and water.
 Seeds dispersed by animals are typically contained
in fleshy, nutritious fruits.
 Environmental factors such as temperature and
moisture can cause a seed to end dormancy and
germinate
Seed
Germination
in
Monocots
Dicots
have
have
1 Cotyledon
2 Cotyledons
that
that
Remains with
the seed
Emerge
above ground
Remain
below ground