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