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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: 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 plantsCone-bearing plants
Ferns and their relatives
Mosses and their relatives
Flowers; Seeds enclosed in fruit
Water-conducting (vascular) tissue
Seeds
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: 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
Copyright Pearson Prentice Hall
Leaf Structure
.Blade
Stem
Bud Petiole
Simple leaf
Compound leaf
Leaflet
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.
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.
Filament
AntherStamen
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.
Carpel Style
Stigma
Ovary
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
Ovary
Ovule
Carpel Style
Stigma
Ovary
Filament
AntherStamen
Parts of a Typical Flower
Sepal
Petal
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
that
in
have
that
have
SeedGermination
Remains withthe seed
Emergeabove ground
Remainbelow ground
Monocots Dicots
1 Cotyledon 2 Cotyledons
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