table of contents – pages iv-v

Unit 1: What is Biology?Unit 2: EcologyUnit 3: The Life of a CellUnit 4: GeneticsUnit 5: Change Through TimeUnit 6: Viruses, Bacteria, Protists, and FungiUnit 7: PlantsUnit 8: InvertebratesUnit 9: VertebratesUnit 10: The Human Body

Unit 1: What is Biology?

Chapter 1: Biology: The Study of LifeUnit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and ConservationUnit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell

Unit 4: Genetics

Chapter 10: Mendel and Meiosis

Chapter 11: DNA and Genes

Chapter 12: Patterns of Heredity and Human Genetics

Chapter 13: Genetic Technology

Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: The Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity

Unit 6: Viruses, Bacteria, Protists, and Fungi

Chapter 18: Viruses and Bacteria

Chapter 19: Protists

Chapter 20: Fungi

Unit 7: Plants

Chapter 21: What Is a Plant?

Chapter 22: The Diversity of Plants

Chapter 23: Plant Structure and Function

Chapter 24: Reproduction in Plants

Unit 8: Invertebrates

Chapter 25: What Is an Animal?

Chapter 26: Sponges, Cnidarians, Flatworms, and

Roundworms

Chapter 27: Mollusks and Segmented Worms

Chapter 28: Arthropods

Chapter 29: Echinoderms and Invertebrate

Chordates

Unit 9: Vertebrates Chapter 30: Fishes and Amphibians

Chapter 31: Reptiles and Birds

Chapter 32: Mammals

Chapter 33: Animal Behavior

Unit 10: The Human Body

Chapter 34: Protection, Support, and Locomotion

Chapter 35: The Digestive and Endocrine Systems

Chapter 36: The Nervous System

Chapter 37: Respiration, Circulation, and Excretion

Chapter 38: Reproduction and Development

Chapter 39: Immunity from Disease

Plants

What Is a Plant?

The Diversity of Plants

Plant Structure and Function

Reproduction in Plants

Chapter 21 What Is a Plant?

21.1: Adapting to Life on Land

21.1: Section Check

21.2: Survey of the Plant Kingdom

21.2: Section Check

Chapter 21 Summary

Chapter 21 Assessment

What You’ll Learn

You will identify and evaluate the structural adaptations of plants to their land environments.

You will survey and identify the major divisions of plants.

• Compare and contrast characteristics of algae and plants.

Section Objectives:

• Identify and evaluate structural adaptations of plants to their land environments.

• Describe the alternation of generations in land plants.

• A plant is a multicellular eukaryote.

• Plant cells have thick cell walls made of cellulose.

Origins of PlantsOrigins of Plants

• Most plants can produce their own food in the form of glucose through the process of photosynthesis.

• The stems and leaves of plants have a waxy waterproof coating called a cuticle.

• Scientists hypothesize that all plants probably evolved from filamentous green algae that lived in the ancient oceans.

• Some of the evidence for their relationship can be found in modern members of both groups.

• Green algae and plants have cell walls that contain cellulose.

• Both groups have the same types of chlorophyll used in photosynthesis and store food in the form of starch.

• The first evidence of plants in the fossil record began to appear over 440 million years ago.

• These early plants were simple in structure and did not have leaves.

• They were probably instrumental in turning bare rock into rich soil.

• All organisms need water to survive.

• For most land plants, the only available supply of water and minerals is in the soil, and only the portion of the plant that penetrates the soil can absorb these nutrients.

Adaptations in PlantsAdaptations in Plants

• Land plants evolved structural and physiological adaptations that help protect the gametes from drying out.

• In some plants, the sperm are released near the egg so they only have to travel a short distance.

• Other plants have protective structures to ensure the survival of the gametes.

• Land plants must also withstand the forces of wind and weather and be able to grow against the force of gravity.

• Most fruits, leaves, and stems are covered with a protective, waxy layer called the cuticle.

Preventing water lossPreventing water loss

• The waxy cuticle creates a barrier that helps prevent the water in the plant’s tissues from evaporating into the atmosphere.

Preventing water lossPreventing water loss

• Waxes and oils are lipids, which are biomolecules that do not dissolve in water.

• Each plant species has unique leaves or leaflike structures.

Carrying out photosynthesisCarrying out photosynthesis

• The leaf, is a plant organ that grows from a stem and usually is where photosynthesis occurs.

• In most plants, a root is a plant organ that absorbs water and minerals usually from the soil.

Putting down rootsPutting down roots

• Plants can take in water and nutrients from the soil with their roots.

• Some roots, such as those of radishes or sweet potatoes, accumulate starch and function as organs of storage.

Putting down rootsPutting down roots

• Roots anchor a plant usually in the ground.

• Water moves from the roots of a tree to its leaves, and the sugars produced in the leaves move to the roots through the stem.

• A stem is a plant organ that provides support for growth.

Transporting materialsTransporting materials

• Stems also can serve as organs for food storage.

• It contains tissues for transporting food, water, and other materials from one part of the plant to another.

• In green stems, some cells contain chlorophyll and can carry out photosynthesis.

Phloem Xylem

Cambium

Xylem transports water and dissolved substances other than sugar throughout the plant.

Phloem transports dissolved sugar throughout the plant.

Cambium produces xylem and phloem as the plant grows.

• Mosses and several other small, less familiar plants called hornwarts and liverworts are usually classified as nonvascular plants.

• The bodies of nonvascular plants are usually no more than a few cells thick, and water and nutrients travel from one cell to another by the process of osmosis and diffusion.

• Nonvascular plants do not have vascular tissues.

• Vascular plants can live farther away from water than nonvascular plants.

• Also, because vascular tissues include thickened cells called fibers that help support growth, vascular plants can grow much larger than nonvascular plants.

Reproductive strategiesReproductive strategies

Embryo

Seed Coat

Food Supply

• Adaptations in some land plants include the evolution of seeds.

Embryo

Seed Coat

Food Supply

• A seed is a plant organ that contains an embryo, along with a food supply, and is covered by a protective coat.

Embryo

Seed Coat

Food Supply

• A seed protects the embryo from drying out and also can aid in its dispersal.

• Land plants reproduce by either spores or seeds.

• In non-seed plants, which include mosses and ferns, the sperm require a film of water on the gametophyte plant to reach the egg.

• In seed plants, which include all conifers and flowering plants, sperm reach the egg without using a film of water.

• This difference is one reason why non-seed plants require wetter habitats than most seed plants.

Gametophyte (n)

Sporophyte (2n)

Spores (n)

Meiosis

Male gamete (n)Female

gamete (n)

Fertilization

Mitosis and cell division

• The lives of all plants include two stages, or alternating generations.

Alternation of generations

Gametophyte (n)

Sporophyte (2n)

Spores (n)

Meiosis

gamete (n)

Fertilization

• The gametophyte generation of a plant results in the development of gametes.

• All cells of the gametophyte, including the gametes, are haploid (n).

Gametophyte (n)

Sporophyte (2n)

Spores (n)

Meiosis

gamete (n)

Fertilization

• The sporophyte generation begins with fertilization. All cells of the sporophyte are diploid (2n) and are produced by mitosis and cell division.

Gametophyte (n)

Sporophyte (2n)

Spores (n)

Meiosis

gamete (n)

Fertilization

• The spores are produced in the sporophyte plant body by meiosis, and are therefore haploid (n).

• In non-seed vascular plants such as ferns, spores have hard outer coverings.

Alternation of generationsAlternation of generations

• These plants produce male and female gametes.

• Spores are released directly into the environment where they can grow into haploid gametophyte plants.

• Following fertilization, the sporophyte plant develops and grows on the gametophyte plant.

• In seed plants, such as conifers and flowering plants, spores develop inside the sporophyte and become the gametophytes.

• Male and female gametes are produced by these gametophytes.

• The gameotophytes consist of only a few cells.

• After fertilization, a new sporophyte develops within a seed. The seed eventually is released and the new sporophyte plant grows.

Question 1

Most plants produce their own food in the form of _______. (TX Obj 2; 4B, 8C, 10ATX Obj 3; 13A)

D. chlorophyll C. glucose B. proteins A. cellulose

The answer is C.

Question 2

Which of the following did NOT precede land plants? (TX Obj 2; 8C)

D. jellyfish

C. amphibians

B. sponges

A. corals

The answer is C.

Question 3

Which of the following did early plants NOT possess? (TX Obj 2; 4B, 8C, 10ATX Obj 3; 13A)

D. leaves C. vascular systems B. chlorophyll A. stems

The answer is D.

Question 4

Why are most plant roots not covered in a cuticle? (TX Obj 2; 4B, 8C, 10ATX Obj 3; 13A)

Answer

The waxy cuticle would prevent the plant’s roots from absorbing water and nutrients.

Question 5

Which of the following is NOT a function of most plant roots? (TX Obj 2; 4B, 8C, 10ATX Obj 3; 13A)

D. anchoring the plant C. store starch B. conducting photosynthesis A. absorbing water and nutrients

The answer is B.

• Describe the phylogenic relationships among divisions of plants.

Section Objectives:

• Identify the plant kingdom divisions.

Phylogeny of PlantsPhylogeny of Plants

• Many geological and climate changes have taken place since the first plants became adapted to life on land.

• Hundreds of thousands of plant species evolved, and countless numbers of these became extinct as conditions continually changed.

• These processes of evolution and extinction continue to be affected by local and global changes.

• As plant species evolved in this changing landscape, they retained many of their old characteristics and also developed new ones.

• These processes of evolution and extinction continue today.

• The highlights of plant evolution include origins of plants from green algae, the production of a waxy cuticle, the development of vascular tissue and roots, and the production of seeds.

• The production of seeds can be used as a basis to separate the divisions into two groups—non-seed plants and seed plants.

Non-seed PlantsNon-seed Plants• Non-seed plants include vascular or

nonvascular organisms.

HepaticophytaHepaticophyta• Hepaticophytes (heh PAH tih koh fites) include

small plants commonly called liverworts.

HepaticophytaHepaticophyta

• Liverworts are nonvascular plants that grow only in moist environments. Water and nutrients move throughout a liverwort by osmosis and diffusion.

• Studies comparing the biochemistry of different plant divisions suggest that liverworts may be the ancestors of all plants.

HepaticophytaHepaticophyta

• There are two kinds of liverworts: thallose liverworts and leafy liverworts.

• Thallose liverworts have a broad body that looks like a lobed leaf.

• Leafy liverworts are creeping plants with three rows of thin leaves attached to a stem.

AnthocerophytaAnthocerophyta

• Anthocerophytes (an THOH ser oh fites) are also small thallose plants.

• The sporophytes of these plants, which resemble the horns of an animal, give the plants their common name—hornworts.

• These nonvascular plants grow in damp, shady habitats and rely on osmosis and diffusion to transport nutrients.

• Bryophytes (BRI uh fites), the mosses, are nonvascular plants that rely on osmosis and diffusion to transport materials.

BryophytaBryophyta

• However, some mosses have elongated cells that conduct water and sugars.

• Moss plants are usually less than 5 cm tall and have leaflike structures that are usually only one to two cells thick. Their spores are formed in capsules.

PsilophytaPsilophyta

• Psilophytes, known as whisk ferns, consist of thin, green stems.

PsilophytaPsilophyta

• The psilophytes are unique vascular plants because they have neither roots nor leaves.

• Small scales that are flat, rigid, overlapping structures cover each stem.

• The two known genera of psilophytes are tropical or subtropical.

• Only one genus is found in the southern United States.

LycophytaLycophyta

• Lycophytes (LI koh fites), the club mosses, are vascular plants adapted primarily to moist environments.

LycophytaLycophyta

• Lycophytes have stems, roots, and leaves.

• Their leaves, although very small, contain vascular tissue.

• Ancestors grew as tall as 30 m and formed a large part of the vegetation of Paleozoic forests.

LycophytaLycophyta

• The plants of these ancient forests have become part of the coal that is now used by people for fuel.

ArthrophytaArthrophyta

• Arthrophytes (AR throh fites), the horsetails, are vascular plants.

ArthrophytaArthrophyta

• They have hollow, jointed stems surrounded by whorls of scalelike leaves.

• The cells covering the stems of some arthrophytes contain large deposits of silica.

• About 15 species of arthrophytes exist today.

PterophytaPterophyta• Pterophytes

(TER oh fites), ferns, are the most well-known and diverse group of non-seed vascular plants.

PterophytaPterophyta

• They have leaves called fronds that vary in length from 1 cm to 500 cm.

• The large size and complexity of fronds is one difference between pterophytes and other groups of seedless vascular plants.

• Although ferns are found nearly everywhere, most grow in the tropics.

Seed PlantsSeed Plants• Seed plants produce seeds, which in a dry

environment are a more effective means of reproduction than spores.

Seed PlantsSeed Plants • A seed consists of an embryonic plant and a food supply covered by a hard protective seed coat.

• All seed plants have vascular tissues.

Embryo

Seed coat

Food supply

CycadophytaCycadophyta

• Cycads (SI kuds) were abundant during the Mesozoic Era. Today, there are about 100 species of cycads.

• They are palmlike trees with scaly trunks and can be short or more than 20 m in height.

• Cycads produce male and female cones on separate trees.

CycadophytaCycadophyta

• Cones are scaly structures that support male or female reproductive structures.

• Seeds are produced in female cones. Male cones produce clouds of pollen.

GnetophytaGnetophyta

• There are three genera of gnetophytes (NEE toh fites) and each has distinct characteristics.

• Gnetum (Nee tum) includes about 30 species of tropical trees and climbing vines.

• There are about 35 Ephedra (eh FEH dra) species that grow as shrubby plants in desert and arid regions.

GnetophytaGnetophyta

• Welwitschia (wel WITCH ee uh) has only one species, which is found in the deserts of southwest Africa.

• Its leaves grow from the base of a short stem that resembles a large, shallow cap.

GinkgophytaGinkgophyta• This division has only one living species,

Ginkgo biloba, a distinctive tree with small, fan-shaped leaves.

GinkgophytaGinkgophyta

• Ginkgoes (GING kohs) have male and female reproductive structures on separate trees.

• The seeds produced on female trees have an unpleasant smell, so ginkgoes planted in city parks are usually male trees.

• Ginkgoes are hardy and resistant to insects and to air pollution.

ConiferophytaConiferophyta

• These are the conifers (KAH nuh furz), cone-bearing trees such as pine, fir, cypress, and redwood.

• Conifers are vascular seed plants that produce seeds in cones.

• Species of conifers can be identified by the characteristics of their cones or leaves that are needlelike or scaly.

ConiferophytaConiferophyta

ConiferophytaConiferophyta• Bristlecone pines,

the oldest known living trees in the world, are members of this plant division.

• Another type of conifer, the Pacific yew, is a source of cancer-fighting drugs.

AnthophytaAnthophyta

• Anthophytes (AN thoh fites), commonly called the flowering plants, are the largest, most diverse group of seed plants living on Earth.

• Unlike conifers, anthophytes produce flowers from which fruits develop.

• There are approximately 250 000 species of anthophytes.

• A fruit usually contains one or more seeds.

• This division has two classes: the monocotyledons (mah nuh kah tul EE dunz) and dicotyledons (di kah tul EE dunz).

Which of the following characteristics do plants NOT share with algae? (TX Obj 2; 4B, 8C, 10ATX Obj 3; 13A)

Question 1

D. eukaryotic C. autotrophic B. multicellular A. bioluminescent

The answer is A.

Which of the following plant products is made of vascular tissue? ((TX Obj 2; 4B, 8C, 10A, TX Obj 3; 13A)

Question 2

D. moss C. wood B. seeds A. nuts

The answer is C.

Plants share alternation of generations with which of the following? (TX Obj 2; 4B, 8C, 10A, TX Obj 3; 13A)

Question 3

D. bacteriaC. algae B. fungi A. viruses

The answer is C.

Which of the following are probably the ancestors of all plants? (TX Obj 2; 8CTX Obj 3; 13A)

Question 4

D. downy mildews C. slime molds B. fungi A. liverworts

The answer is A.

• Plants are multicellular eukaryotes with cells that have cell walls containing cellulose. A waterproof cuticle covers the outer surface of most plants. Most plants undergo photosynthesis, which produces glucose, a form of food.

Adapting to Life on Land

• All plants on Earth probably evolved from filamentous green algae that lived in ancient oceans. The first plants to eventually move from water to land probably were leafless forms.

Adapting to Life on Land

• Adaptations for life on land include a cuticle; the development of leaves, roots, stems, and vascular tissues; alternation of generations; and the evolution of the seed.

• The plant kingdom is grouped into major categories called divisions.

Survey of the Plant Kingdom

• Nonvascular plants are in the divisions Anthocerophyta, Hepaticophyta, and Bryophyta. They reproduce mainly by using spores. Nonvascular plants do not produce seeds.

• Non-seed vascular plants are in the divisions Psilophyta, Lycophyta, Arthrophyta, and Pterophyta. These plants have tissues that conduct water and other materials and reproduce mainly by spores.

• Vascular seed plants in the divisions Cycadophyta, Gnetophyta, Ginkgophyta, and Coniferophyta produce seeds on cones. Male cones and female cones can be on separate plants or the same plant.

• The division Anthophyta includes vascular, seed-producing plants that flower. Fruits with seeds develop from flowers. Anthophytes are divided into two groups—monocotyledons and dicotyledons.

Question 1Which of the following divisions does not move water and nutrients by osmosis and diffusion?(TX Obj 2; 4B, 8C, 10A, 10B, TX Obj 3; 13A)

D. Psilophyta C. Bryophyta

B. Anthocerophyta A. Hepaticophyta

The answer is D.

What difference between lycophytes and psilophytes allowed lycophyte ancestors to grow so tall? (TX Obj 2; 4B, 8C, 10A, 10BTX Obj 3; 13A)

Answer Lycophytes possess roots that would have

been able to anchor a tall plant in the ground. Psilophytes do not posses roots, and would not be able to stand very tall without falling over.

Question 2

Scaly structures that support male or female reproductive structures on conifers are called _______. (TX Obj 2; 4B, 8C, 10A, 10BTX Obj 3; 13A)

D. seeds

C. cones

B. fronds

A. spores

The answer is C.

Question 3

Which of the following is the youngest plant division? (TX Obj 2; 8C, 10A, 10BTX Obj 3; 13A)

D. Anthophyta C. Coniferophyta

B. Lycophyta A. Cycadophyta

The answer is D.

Question 4

Which of the following does not produce seeds on cones? (TX Obj 2; 8C, 10A, 10B TX Obj 3; 13A)

D. Coniferophyta C. Pterophyta

B. Gnetophyta A. Cycadophyta

The answer is C.

Question 5

Drugs that fight _____ have been derived from the Madagascar rosy periwinkle and the Pacific yew. (TX Obj 2; 8C, 10A, 10BTX Obj 3; 13A)

D. cancer

C. AIDS

B. Down syndrome

A. sickle-cell disease

The answer is D.

Question 6

Identify the following structure and the parts of the structure, describing how the parts contribute to the structure’s biological success. (TX Obj 2; 8C, 10A, 10BTX Obj 3; 13A)

Question 7

The structure is a seed. Inside the seed is an embryo plant. The embryo is surrounded by a food supply that nourishes it until it can get food from its environment and also by a tough seed coat that protects the embryo from drying out.

Embryo

Food supply

Seed coat

The oldest living plants in the world are members of the division _______.

(TX Obj 2; 8C, 10A, 10B, TX Obj 3; 13A)

D. Ginkgophyta C. Anthophyta

B. Coniferophyta A. Cycadophyta

The answer is B.

Question 8

Nearly ____ of the world’s population relies on medications derived from plants. (TX Obj 2; 8C, 10A, 10B, TX Obj 3; 13A)

D. 20%

C. 80%

B. 50%

A. 10%

The answer is C.

Question 9

Which of these divisions has only one living species? (TX Obj 2; 8C, 10A, 10BTX Obj 3; 13A)

D. Hepaticophyta C. Cycadophyta

B. Ginkgophyta A. Gnetophyta

The answer is B.

Question 10

• PhotoDisc

• Mark Thayer

• Aaron Haupt

• Matt Meadows

• Digital Stock

• Doug Martin

Photo CreditsPhoto Credits

• Geoff Butler

• Randy Witherspoon

• David M. Dennis

• Thomas Russell

• Chris Klaming

• Alton Biggs

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table of contents – pages iv-v

cell chapter

bacteria chapter

protists chapter

fungi chapter

biomes chapter

amphibians chapter

genes chapter

arthropods chapter

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