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CEB Textbook Chapter 16, pages 316-327; 333-335

Mastering Biology; Chapter 16

TOPIC 21 PLANTS Learning outcomes: After studying this topic, you should be able to:

Name the main components of a plant and describe their

basic functions.

Describe the fundamental differences between the four

major groups of plants.

Give an example of a bryophyte, a fern, a gymnosperm

and an angiosperm.

Describe the main characteristics of ferns and explain how

they reproduce.

Outline the three main adaptations found in gymnosperms

that are not found in ferns.

Name the main parts of a flower and describe the

angiosperm life cycle.

Figure 16.UN01

Bacteria

Archaea

Eukarya

Protists

Plants

Fungi

Animals

COLONIZING LAND

A plant is

a multicellular

eukaryote and

a photoautotroph,

making organic

molecules by

photosynthesis.

Figure 16.1

Reproductive structures

contain spores and gametes

Leaf performs photosynthesis

Cuticle reduces water loss; stomata regulate

gas exchange

Shoot supports plant

Surrounding water supports the alga

Roots anchor plant; absorb water and minerals from the soil (aided by fungi)

Whole alga performs photo-

synthesis; absorbs water,

CO2, and minerals from the

water

Alga

Plant

Figure 16.UN07 Leaves are the main photosynthetic organs

Gametangia protect gametes from dehydration; female gametangia also protect developing embryos

Stomata regulate gas exchange between plant and atmosphere

Cuticle reduces water loss

Lignin hardens cell walls

Shoot supports plant; may perform photosynthesis

Vascular tissues transport water, minerals, and sugars; provide support

Roots anchor plant; mycorrhizae (root-fungus associations) help absorb water and minerals from the soil

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STRUCTURAL ADAPATATIONS

Leaves – main site of photosynthesis

Stomata – pores in leaf for gas exchange

Vascular Tissue – series of vessels throughout plant (xylem transports water, phloem transports sugar)

Cuticle – Waxy layer coating leaf

Figure 16.3

Phloem

Xylem

Oak leaf

Vascular tissue

ORIGIN OF PLANTS FROM GREEN ALGAE

The algal ancestors of plants

carpeted moist fringes of lakes or coastal salt

marshes and

first evolved over 500 million years ago.

LM

PLANT DIVERSITY

The history of the plant

kingdom is a story of

adaptation to diverse

terrestrial habitats.

The fossil record

chronicles four major

periods of plant

evolution, which are

also evident in the

diversity of modern

plants.

PLANT EVOLUTION – FOUR MAIN GROUPS Bryophytes (475 mya)

- includes mosses, liverworts,

hornworts

- Nonvascular (no vessels), no lignin,

no seeds, no true roots or leaves

Ferns (425 mya)

- Has vascular tissue (xylem) hardened

with lignin (similar to calcium), no

seeds

Gymnosperms (360 mya) –

Conifers

- First type of plant to have seeds

Angiosperms (140 mya) –

Flowering plants

- Has flowers which bear seeds within

Figure 16.6

Ancestral green algae

Origin of first terrestrial adaptations

Origin of vascular tissue

Origin of seeds

600 500 400 300 200 100 0

Origin of flowers

Millions of years ago

Angio- sperms

Gymno- sperms

Ferns

Bryophytes

Charophytes

Land

plan

ts Vascu

lar With

se

ed

s

See

d-

less

No

n-

vascular

1

2

3

4

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Figure 16.7

PLANT DIVERSITY

Bryophytes (nonvascular

plants)

Ferns (seedless

vascular plants)

Gymnosperms (naked-seed

plants)

Angiosperms (flowering

plants)

Figure 16.UN08

Origin of gametangia

(protect gametes

and embryos)

Origin of vascular

tissue (conducts water and nutrients)

Origin of seeds (protect

embryos from dessication and other hazards)

Origin of flowers (bear ovules

within protective chambers called

ovaries)

FIGURE 16.8

Peat Moss Bog in Scotland BRYOPHYTES Mosses – Need water to

reproduce because sperm have to swim to reach eggs within the female gametangium

Lack vascular tissue

Has two main forms

- Gametophyte (produces gametes)

- Sporophyte (produces spores)

- The moss will alternate between these two forms in its life cycle (alternation of generations)

Figure 16.9

Spore capsule

Sporophytes

Gametophytes

© 2013 Pearson Education, Inc.

Animation: Moss Life Cycle

Right click slide / select “Play”

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Figure 16.10-1

Gametes: sperm

and eggs (n) Gametophyte

(n)

Key Haploid (n)

Diploid (2n)

Figure 16.10-2

Gametes: sperm

and eggs (n)

Zygote (2n)

Gametophyte (n)

Key Haploid (n)

Diploid (2n)

FERTILIZATION

Figure 16.10-3

Spore capsule

Gametes: sperm

and eggs (n)

Zygote (2n)

Gametophyte (n)

Sporophyte (2n)

Key Haploid (n)

Diploid (2n)

FERTILIZATION

FERNS

Seedless

Vascular

12,000 known

species

The sperm of ferns,

like those of mosses,

have flagella and

must swim through a

film of water to

fertilize eggs.

© 2013 Pearson Education, Inc.

Blast Animation: Non-Flowering Plant Life Cycle

Select ”Play”

© 2013 Pearson Education, Inc.

Animation: Fern Life Cycle

Right click slide / select “Play”

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Figure 16.11

Spore capsule

“Fiddlehead” (young leaf

ready to unfurl)

Gametophyte

New sporophyte

Ferns (seedless vascular plants)

GYMNOSPERMS

Adapted to drier colder climates

Cone bearing plants like pine (conifers)

Cover most of northern Eurasia and North America

Usually evergreen

Includes the tallest, largest and oldest organisms on Earth!

Figure 16.13

GYMNOSPERMS - CONIFERS

Three additional adaptations of gymnosperms which allow them to live in a more diverse range of terrestrial habitats

Seeds

Pollen

Further reduction of the gametophyte

Figure 16.14

Key Haploid (n)

Gametophyte (n) Sporophyte

(2n)

Sporophyte (2n)

Gametophyte (n)

Gametophyte (n)

Sporophyte (2n)

Diploid (2n)

Figure 16.14a

Key

Haploid (n)

Diploid (2n)

Gametophyte (n) Sporophyte

(2n)

(a) Sporophyte dependent on gametophyte (e.g., mosses)

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Figure 16.14b

Key

Haploid (n)

Diploid (2n)

Gametophyte (n)

Sporophyte (2n)

(b) Large sporophyte and small, independent gametophyte (e.g., ferns)

Figure 16.14c

Key

Haploid (n)

Diploid (2n)

Gametophyte (n)

Sporophyte (2n)

(c) Reduced gametophyte dependent on sporophyte (seed plants)

– A pine tree or other conifer is actually a sporophyte with tiny gametophytes living in cones.

© 2013 Pearson Education, Inc.

Animation: Pine Life Cycle

Right click slide / select “Play”

Figure 16.15 Scale

Ovule-producing cones

Pollen-producing cones

Ponderosa pine

ADAPTATIONS OF SEED PLANTS

Pollen Grain – much reduced male gametophyte which houses sperm

Seed – Consisting of plant embryo, food supply and protective seed coat

Ovules - where seeds are developed

Seeds can lay dormant for long periods

Female cone, cross section

Figure 16.16-1

(a) Ovule

Haploid (n) Diploid (2n) Cross section

of scale Female cone, cross section

Integument

Spore

Spore case

Egg nucleus

Key

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Figure 16.16-2

(a) Ovule

Haploid (n) Diploid (2n)

(b) Fertilized ovule

Cross section of scale

Female cone, cross section

Integument

Spore

Spore case

Pollen tube

Spore case

Egg nucleus

Female gametophyte

Discharged sperm nucleus Pollen grain

Key

Figure 16.16-3

(a) Ovule

Haploid (n) Diploid (2n)

(b) Fertilized ovule

(c) Seed

Cross section of scale

Female cone, cross section

Integument

Spore

Spore case

Pollen tube

Spore case

Egg nucleus

Female gametophyte

Discharged sperm nucleus

Seed coat

Embryo

Food supply

Pollen grain

Key

ANGIOSPERMS – FLOWERING PLANTS

Angiosperms dominate the modern

landscape,

are represented by about 250,000 species, and

supply nearly all of our food and much of our fiber for textiles.

Their success is largely due to refinements in vascular

tissue that make water transport more efficient and

the evolution of the flower.

FLOWER – ATTRACTS POLLINATORS Sepal – outer layer

Petal – attracts pollinators

Stamen – Male

reproductive structure

consisting of filament and

anther (makes pollen)

Carpel – Female

reproductive structure

consisting of stigma, style,

ovary (contains eggs) and

ovules (develop into eggs)

Figure 16.17 Petal

Carpel Stamen

Sepal Ovule

Anther

Filament

Stigma

Style

Ovary

Figure 16.18

Pansy Bleeding heart California poppy

Water lily

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© 2013 Pearson Education, Inc.

Blast Animation: Flowering Plant Life Cycle

Select “Play”

Figure 16.19a-1

Key

Haploid (n)

Diploid (2n)

Mature sporophyte plant with flowers

1

Figure 16.19a-2

Key

Haploid (n)

Diploid (2n)

Two sperm nuclei

Egg

Embryo sac (female gametophyte)

Ovule

Ovary

Pollen tube growing down style of carpel

Anther at tip of stamen

Germinated pollen grain (male gametophyte) on stigma of carpel

Mature sporophyte plant with flowers

1

2

3

Figure 16.19a-3

Key

Haploid (n)

Diploid (2n)

Two sperm nuclei

Egg

Zygote

Endosperm

Embryo sac (female gametophyte)

Ovule

Ovary

FERTILIZATION

Pollen tube growing down style of carpel

Anther at tip of stamen

Germinated pollen grain (male gametophyte) on stigma of carpel

Mature sporophyte plant with flowers

1

2

3

4

Figure 16.19

Mature sporophyte plant with flowers

Key Haploid (n)

Diploid (2n)

Sporophyte seedling

Germinating seed

Seed (develops from ovule)

Seed

Fruit (develops from ovary)

Embryo (sporophyte)

Two sperm nuclei

Egg Zygote

Endosperm Embryo sac (female gametophyte)

FERTILIZATION Ovule

Ovary (base of carpel)

Pollen tube growing down style of carpel

Anther at tip of stamen

Germinated pollen grain (male gametophyte) on stigma of carpel

1

2

3

4

6

5

© 2013 Pearson Education, Inc.

Animation: Plant Fertilization

Right click slide / select “Play”

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FLOWERS, FRUIT AND THE ANGIOSPERM

Although both have seeds

- Angiosperm seeds are protected by an ovary

- Gymnosperm seeds are naked

Fruit

- Is a ripened ovary

- Helps protect seed

- Increases seed dispersal

- Major source of food for all animals

Figure 16.19b-1

Key

Haploid (n)

Diploid (2n)

5

Embryo (sporophyte)

Figure 16.19b-2

Key

Haploid (n)

Diploid (2n)

6

5

Seed

Embryo (sporophyte)

Fruit (develops from ovary)

Seed (develops from ovule)

Figure 16.19b-3

Key

Haploid (n)

Diploid (2n)

6

5

Seed

Sporophyte seedling

Germinating seed

Embryo (sporophyte)

Fruit (develops from ovary)

Seed (develops from ovule)

© 2013 Pearson Education, Inc.

Animation: Fruit Development

Right click slide / select “Play”

Figure 16.20

Wind dispersal

Animal transportation

Animal ingestion

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ANGIOSPERMS AND AGRICULTURE Gymnosperms supply

most of our lumber and

paper.

Angiosperms

provide nearly all our food

and

supply fiber, medications,

perfumes, and decoration.

The exploding human population is extinguishing plant species

at an unprecedented rate and

destroying 50 million acres, an area the size of the state of Washington, every year!

Figure 16.21

Table 16.1

Homework • Unit Assessment Topic 21

• Mastering Biology Plant Assignment

• Fill in Key Terms table and Main adaptations of

Gymnosperms in Study Notes

• Learn parts of the Flower from handout and

draw your own sketch

Videos Crash Course Plant Reproduction

http://www.youtube.com/watch?v=ExaQ8shhkw8

Lesson Plants

http://www.youtube.com/watch?v=X4L3r_XJW0I

DOCUMENTARIES ON PLANTS

Intelligence of Plants

http://www.youtube.com/watch?v=NeX6ST7rexs

Secret World of Plants

http://www.youtube.com/watch?v=8QSWP56J8DA

Private Life of Plants Clips

http://www.youtube.com/watch?v=igkjcuw_n_U&list=PLCC07E66503F99BB5