Science Starter

Life as we know it today could not exist without plants.Plants provide us with many essential items other than food.

1. With your partner, list five items you use

daily that are byproducts of plants.

Section 22-1

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22–1Introduction to PlantsA. What Is a Plant?B. The Plant Life CycleC. What Plants Need to Survive

1. Sunlight2. Water and Minerals3. Gas Exchange4. Movement of Water and Nutrients

D. Early Plants1. Origins in the Water2. The First Plants

E. Overview of the Plant Kingdom

Section 22-1

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What do we already know about plants? • How many cells? • Eukaryote or prokaryote? • How do they get food? • Special structures in cells?

Plants are multicellular eukaryotes that have cell walls, made of cellulose.

They develop from multicellular embryos

Carry out photosynthesis using green pigment called chlorophyll.

They are autotrophs Examples:

“Stationary animals that eat sunlight!”

Differences between plants and animals:

Two generations: • The haploid (N) gametophyte, or gamete-

producing plant • The diploid (2N) sporophyte, or spore-

producing plant Spores are reproductive cells that produce a new

individual by mitosis.

This may differ dramatically from phylum to phylum!

HaploidDiploid MEIOSIS

Spores(N)

Sporophyte Plant (2N)

Gametophyte Plant (N)

FERTILIZATION

Sperm(N)

Eggs(N)

Section 22-1

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Sunlight• To carry out photosynthesis • Typically photosynthetic organs such as

leaves are broad and flat to maximize light absorption.

Water and Minerals• Water also needed for photosynthesis • Minerals can only be taken in through water• Adaptations to limit water loss

Gas Exchange • Oxygen needed to support respiration• Carbon dioxide needed for photosynthesis• The problem: Exchange these gasses without

losing a lot of water Movement of Water and Nutrients

• Absorption happens at roots, but must move throughout entire plant

• Specialized tissues • OR• Diffusion

Read p. 553 first two paragraphs! Origins in the Water:

• The first plants evolved from an organism much like the multicellular green algae living today

The First Plants: • Read paragraph 2 on page 554

Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

Section 22-1

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Divided into FOUR groups, based on three important features: fig. 22-7• 1. water-conduction tissues• 2. seeds• 3. flowers

Cone-bearing plants760 species

Ferns andtheir relatives11,000 species

Mosses andtheir relatives15,600 species

Floweringplants235,000 species

Section 22-1

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22–2Bryophytes A. Groups of Bryophytes

1. Mosses2. Liverworts3. Hornworts

B. Life Cycle of Bryophytes1. Dependence on Water2. Life Cycle of a Moss

C. Human Use of Mosses

Section 22-2

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Byrophytes• AKA nonvascular plants • Do not have vascular tissues (tissue that are

responsible for conducting water and nutrients) Have a life cycle that depend on water

for reproduction. Draw up water by osmosis

• Can only be a few centimeters off the ground

• Example: Mosses

Characteristics: • Must be low growing• Usually found in shaded or moist areas

Include: • Mosses• Liverwarts• Hornwarts

Most common bryophyte Belong to phylum Bryophyta Grow near water Do not have true roots, instead they

have: • Rhizoids: long thin cells that anchor plant

into the ground, helps to absorb water and minerals from surrounding soil

Rhizoid

Capsule

StalkSporophyte

Gametophyte

Stemlikestructure

Leaflikestructure

Section 22-2

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Looks like a flat leaf, attached to the ground (shaped like a liver)

Phylum: hepaticophyta Reproduce asexually by gemmae

• Small multicellular spheres that contain haploid cells.

• These cells are washed off the parent plant, and they then begin a new plant

The gametophyte is the dominane, recognazible stage of the life cycle, and it’s the stage that carries out most of the plant’s photosynthesis

For fertilization to occur, there must be WATER!

Read page #558 Protonema: after a BRYO

reporduces, it germinates and begins a tangles mass of green filimants

Antheridia: part of BRYO where sperm are produced

Archegonia: part of BRYO where the egg is produced

Haploid (N)

Diploid (2N) MEIOSIS

FERTILIZATION

Maturesporophyte

(2N)

Gametophyte(N)

Gametophyte(N)

Youngsporophyte(2N)

Zygote(2N)

Sperm(N)

Sperm(N)

Egg(N)

Spores(N)

Capsule(sporangium)

Protonema(young gametophyte)(N)

Malegametophyte

Femalegametophyte

Antheridia

Archegonia

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22–3Seedless Vascular PlantsA. Evolution of Vascular TissueB. Ferns and Their Relatives

1. Club Mosses2. Horsetails3. Ferns

C. Life Cycle of Ferns

Section 22-3

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Vascular tissues: specialized tissue used to conduct water and nutrients through the body of the plant. • These types of plants can grow taller

Were byrophytes vascular or nonvascular plants?

Two types of Vascular Tissue: • Xylem: conducts water upwards from roots

to every part of thee plant• Phloem: transports nutrient solutions

Both of these can work against the force of gravity.

Vascular plants produce lignin the substance that make cell wall rigid. • Lignin allows vascular plants to grow

upright and reach great heights.

Seedless vascular plants include mosses, horsetails and ferns.

These all have true:• Roots: underground organs that absorb water

and minerals.• Leaves: contain bundles of vascular tissues,

photosynthesis is carried out here. • Veins: composed of xylem and phloem• Stems: supporting structures that connect

roots and leaves. Carry water and nutrients between them.

More than 11,000 species of ferns Evolved over 350 million years ago. Page #562 diagram of a fern

• The large leaves = Fronds• Rhizomes: creeping under ground stems

Ferns and other vascular plants have a life cycle in which the diploid sporophyte is the dominant life stage.

Haploid gametophyte (N)

Diploid sporophyte (2N)

MEIOSIS

FERTILIZATION

Maturesporophyte(2N)

Gametophyte(N)

Frond

Sperm

Egg

Spores(N)

Antheridium

Archegonium

Developingsporophyte(2N)

Sporophyteembryo(2N)

Maturegametophyte(N)

Younggametophyte(N)

Sporangium(2N)

Section 22-3

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22–4 Seed PlantsA.Reproduction Free From Water

1. Cones and Flowers2. Pollen3. Seeds

B.Evolution of Seed PlantsC.Gymnosperms—Cone Bearers

1. Gnetophytes2. Cycads3. Ginkgoes4. Conifers5. Ecology of Conifers

Section 22-4

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Seed Plants are divided into two groups: • Gymnosperms: bear their seed directly on

the surfaces of cones Examples: Conifers (pine and spruce trees)

• Angiosperms: (AKA flowering plants) bear their seeds within a layer of tissue that protects the seed. Examples: grasses, flowering trees, shrubs,

wildflower

Still have alternating life cycle b/t gamete and sporophyte stages.

Seed plants DON’T need water to reproduce! • This means seed plants can live about anywhere

Adaptations that allow seed plants to reproduce without water include: flowers or cones, the transfer of sperm by pollination and the protection of embryos in seeds.

Seed plants do not require water for fertilization.

Adaptations that allow this include: • Flowers or cones• Transfer of sperm by pollination • Protection of embryos in seeds

Cones: seed-bearing structures of gymnosperms

Flowers: seed-bearing structure of angiosperms.

The entire male gametophyte is contained in a tiny structure called pollen grain. • This PG is carried to the female

gametophyte by wind, insects, birds, etc. This transfer of pollen from the male

to the felmale gametophyte is pollination

Seed: embryo of a plant, encased in a protective covering and surrounded by a food supply.

After fertilization the zygote contained with in the seed grows into a tiny plante called the embryo.

Seed coat

Embryo

Storedfood supply

Seed

Wing

A

B

Section 22-4

The embryo the early developmental stage of the sporophyte

The seed coast surrounds and protects the embryo and keeps it from drying out!

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Read Evolution of Seed plants p. 566 Gymnosperms

• Reproduce with seeds that are exposed • Means “naked seed” • Conifers are most common in our area

Pine, spruce, cedars, redwoods, etc. • Ginkgoes – read p. 567

Comparing Features of Seed PlantsComparing Features of Seed Plants

Feature

Seeds

Reproduction

Examples

Feature

Seeds

Reproduction

Examples

Section 22-4

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Gymnosperms Angiosperms

Comparing Features of Seed PlantsComparing Features of Seed Plants

Feature

Seeds

Reproduction

Examples

Feature

Seeds

Reproduction

Examples

Section 22-4

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Gymnosperms Angiosperms

Bear their seeds on cones

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Conifers, cycads, ginkgoes, gnetophytes

Bear their seeds within flowers

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Grasses, flowering trees and shrubs, wildflowers, cultivated flowers

22–5Angiosperms—Flowering PlantsA. Flowers and FruitsB. Diversity of Angiosperms

1. Monocots and Dicots2. Woody and Herbaceous Plants3. Annuals, Biennials, and Perennials

Section 22-5

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Flowering plants originated on land and quickly came to dominate life

Angiosperms have reproductive organs known as flowers. • Evolutionary advantage – transport of pollen • More efficient than wind pollination of

GSperm Asperms contain ovaries, witch

surronund and protect the seed• Asperm actually means “enclosed seed”

Figure 22-24 page 569 Fruit: a thick wall of tissue

surrounding the enclosed seed. • Animals spread the seed by eating fruit and

“depositing” seed at another location• Another evolutionary advantage!

Classification by 3 groups These groups can overlap

1.Monocots and dicots2.Woody and herbaceous3.Life cycle

Monocotyledonae Dicotyledonae Figure 22-25 page 570

Monocots Dicots

Seeds

Leaves

Flowers

Stems

Roots

Single cotyledon

Parallel veins

Floral parts often in multiples of 3

Vascularbundlesscattered throughout stem

Fibrous roots

Two cotyledons

Branched veins

Floral parts often in multiplesof 4 or 5

Vascularbundlesarranged ina ring

Taproot

Section 22-5

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Based on stem characteristics Woody plants: thick cell walls that

support plant. • Trees & shrubs

Herbaceous plants: must be smooth and nonwoody. • Dandelions, petunias, sunflowers,

geraniums

3 groups based on length of time Read page 572 Annuals: plants that complete life

cycle in one year• EX: marigolds, petunias, zinnias

Biennial: Year one grow and generate roots. Year two produce flowers and seeds, then die• Parsley, celery and foxglove

Perennial: Live for many years.

are categorized as

that completetheir life cycle in

that completetheir life cycle in

that completetheir life cycle in

Section 22-5

Plants

Annuals Perennials

2 years

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are categorized as

that completetheir life cycle in

that completetheir life cycle in

that completetheir life cycle in

Section 22-5

Plants

Annuals Biennials Perennials

1 growingseason 2 years

More than2 years

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