Why are plants important?

  

Hello, all you have to do read the passage (which is very short) and then answer the following questions from “Check my understanding” and “Chapter review questions” ONLY. Ignore the sketches.Try to keep the answers short 2-3 sentences but well answered please, thank you!
The Green Machine
Understanding the Nonvascular Plants
20
Every life form on the surface of this planet is here because a plant was able to gather
sunlight and store it, and something else was able to eat that plant and take that
sunlight energy in to power its body.
Thom Hartmann (1951-present)
wise man once declared, We need the plants much more than they need
OBJECTIVES
Aw. This sentendre las only accurate bar also meaningfuh. Have you
At the completion of this chapter,
the student will be able to:
1. Discuss the importance
of plants.
2. Describe the origin of plants.
3. Compare and contrast
nonvascular and vascular
plants.
4. Describe the process of
alternation of generations.
5. State the characteristics of
a nonvascular plant.
6. Describe the characteristics
of and give examples of
hepatophytes, anthocerophytes,
and bryophytes.
7. Compare and contrast thallus
and leafy liverworts.
8. Discuss the biology of and
label the anatomy of
Marchantia, Anthoceros,
Polytrichum, and Sphagnum.
9. Compare and contrast water
absorption in Sphagnum and
various other specimens.
ever stopped to thank a plant? Think about it! Plants provide oxygen, food,
shelter, shade, erosion control, and commercial products for human uses, such
as timber, medicine, and even the paper you are looking at right now. In addi-
tion, many species of plants are aesthetically pleasing. As Ralph Waldo Emer-
son said, The Earth laughs with flowers. Rememberthe next time you are
sitting under a majestic treesay thank you!
Plants are a diverse group of eukaryotic, multicellular, photosynthetic
autotrophs that inhabit myriad environments from lush tropical rainforests to
scorching deserts. Figure 20.1 is a cladogram of the plants. Biologists have
identified approximately 300,000 species of plants and estimate 400,000
species may exist. Plants vary in size from the smallest flowering plant, Wolffia
angusta (a duckweed), measuring less than 1 mm in diameter, to the giant
Sequoia sempervirens, which measures nearly 120 m tall. The oldest plant in
the world is thought to be the King Holly (Lomatia tasmanica), a shrub that
lives in Tasmania. This remarkable plant is estimated to be more than 43,000
years old!
Paleobotanists believe plants evolved during the Paleozoic era from
freshwater green algae known as charophytes, approximately 450 million
years ago. To make the transition from the aquatic environment, ancestral
plants had to evolve mechanisms that prevent desiccation, anchor the plant
body, transport water and nutrients, and ensure propagation of the species.
The absence or presence of specialized conducting tissue known as
vascular tissue is a common way to distinguish plants. Nonvascular plants
lack specialized conducting tissues to transport water and nutrients throughout
the plant’s body. In addition, these plants lack true roots, stems, and leaves.
299
Liverworts
Hepatophyta
Mosses
Bryophyta
Ancestral
green alga
Nonvascular
plants
Hornworts
Anthocerophyta
Club mosses
Quillworts
Lycophyta
Spike mosses
Seedless
vascular
plants
Whisk ferns
Psilotophyta
Horsetails
Sphenophyta
Ferns
Pterophyta
Cycads
Cycadophyta
Ginkgo
Ginkgophyta
Seed plants,
cone-bearing
(gymnosperms)
Conifers
Pinophyta
Flowering
plants
Magnoliophyta
Seed plants,
flowering
(angiosperms)
FIGURE 20.1 Phylogenetic relationships and classification of Plantae.
Exploring Biology in the Laboratory
300
Examples of nonvascular plants are liverworts, hornworts, and true mosses. Presently, about 25,000 species of nonvascular
plants have been identified. Most living plants are considered vascular plants because they possess an extensive conducting
system composed of specialized tissues.
Vascular plants can be divided into the seedless vascular plants and the seed plants. The seedless vascular plants
include the club mosses and the ferns. The seed plants are the largest group of vascular plants and include gymnosperms
(such as ginkgos, cycads, and conifers) and angiosperms (flowering plants, such as zinnias and roses).
The life cycle of plants is characterized by an alternation of generations (Fig. 20.2). In this process, two distinct
generations give rise to each other. The haploid (n) gametophyte generation is characterized by the production of male
and female gametes through mitosis. The male and female gametes fuse during fertilization, forming a diploid sporophyte.
The sporophyte generation is diploid (2n). It produces haploid spores that undergo mitosis to form a gametophyte. In
nonvascular plants the gametophyte generation is dominant, but in seedless vascular plants and seed plants, the sporo-
phyte generation dominates. A fern, a pine tree, and a tulip are all examples of sporophytes.
In the history of plants on earth, the nonvascular plants played an important role in establishing the transition from
water to land and dominance of the gametophyte generation. The nonvascular plants are generally small and herbaceous
(nonwoody). Although most of these plants are found in moist environments, some species can survive in arid environ-
ments. Three distinct phyla of nonvascular plants have been established:
1. Phylum Hepatophyta, the liverworts
2. Phylum Anthocerophyta, the hornworts
3. Phylum Bryophyta, the true mosses
sporophyte (2n)
>
zygote (2n)
mitosis
sporangium (2n)
diploid (2n)
Fertilization
Meiosis
haploid (n)
(n)
(n)
spore (n)
gametes
mitosis
mitosis
gametophyte (n)
FIGURE 20.2 Model of alternation of generations.
* The term bryophyte is often used to describe all of the nonvascular plants, even though it is the proper taxonomic name for the phylum in
which the true mosses are classified.
20.1
Phylum Hepatophyta
hylum Hepatophyta includes approximately 8,000 species of small inconspicuous nonvascular plants commonly known
because the flattened, liver-shaped body of these plants resembled the liver, they could be used in treating liver ailments. The
vast majority of liverworts are terrestrial, living in moist environments, but several aquatic species have been described.
Liverwort leaves can be distinguished from moss leaves in several easy ways: (1) liverwort leaves lack a thick midrib present
in moss leaves, (2) liverwort leaves have both small and larger leaves whereas moss leaves are of equal size and arranged in
spirals, and (3) liverwort leaves are flattened into a single plane instead of radiating out in different directions. Many liver-
worts develop symbiotic relationships with fungi (phylum Glomeromycota) called mycorrhizae. The fungi enter through the
rhizoids (rootlike structures, described below) of the liverwort. Two distinct types of liverworts have been described:
1. The complex thalloid liverworts, which possess flat leaflike lobed bodies (thalli), are most commonly found living
along creek banks or on moist soil. Examples of complex thalloid liverworts include Riccia and Marchantia.
2. The majority of liverworts, known as the leafy liverworts, at first glance resemble mosses. The leafy liverworts are
more commonly found living on the bark of trees in tropical and subtropical environments. Examples of leafy
liverworts include Frullania, Clasmatocolea, and Jungermannia.
Marchantia is an example of a thalloid liverwort. The body, or thallus, is approximately 30 cells thick in the center,
and the edges may be as thin as 10 cells. Marchantia thalli branch out from the center in a flattened pattern. The top
surface
of the small plant is characterized by a diamond-shaped pattern of segments that correspond to chambers below the surface.
Each segment of Marchantia features a small pore leading to the interior of the plant. On the lower surface, hairlike struc-
tures called rhizoids can be found. The rhizoids
extend into the soil and anchor the thallus.
Marchantia is capable of both asexual
and sexual reproduction. Asexually, small cup-
Antheridiophore
shaped structures called gemma cups (or splash
Antheridium
cups) appear on the upper surface of the thallus
and contain tiny pieces of tissue, or gemmae
(Fig. 20.3). In turn, the gemmae detach (perhaps
Male gametophyte
with receptacles
through the action of raindrops), establish a new
location, and grow into a new plant. Sexually,
Longitudinal section
like all plants, the life cycle of Marchantia has
through male receptacle
showing antheridia
a sporophyte and a gametophyte generation. Sporophyte
Meiospores
Sperm
In the nonvascular plants, the gametophyte
Archegoniophore
generation is larger (Fig. 20.4).
Female gametophyte
Longitudinal section
with receptacles
through female
receptack
A
showing
archegonia
Seta (stalk)
SDF
Meiosis
B
Foot
Archegonium
Capsule
-Meiospores
Elaters Young embryo
Archegonium
ature sporophyte
Zygote
Fertilization
Sperm
Rhizoids
Gemmae cupules
20 Figure 20.3 Leafy liverwort, Marchantia sp.:
A rhizoids, and B gemmae cupules.
Figure 20.4 Life cycle of the thalloid liverwort, Marchantia sp.
Exploring Biology in the Laboratory
302
During the gametophyte generation (n), male and female sex cells are produced on separate umbrella-shaped structures
called gametophores that rise above the plant. The top portion of the male gametophore, the antheridiophore, is composed
of antheridia containing numerous sperm cells. The female archegoniophore possesses archegonia containing a single egg
each. Raindrops or splashing water carry sperm to the waiting egg.
After fertilization, the zygote eventually develops into a sporophyte (2n). The maturing sporophyte is anchored to
the archegoniophore by a knob-like foot. A thin seta, or stalk, connects the foot to the main body, called the capsule.
Sporocytes within the capsule undergo meiotic division and produce haploid spores, or meiospores. Initially, the immature
sporophyte is protected by a structure called the calyptra. The spores possess structures called elaters that aid their dispersal
into new environments. The spores germinate, forming a new gametophyte.
Approximately 80% of liverworts are considered leafy. These small plants are more common in tropical regions
of the world. Their overlapping leaflike structures contain prominent oil bodies and many lobes and folds. The sex cells
are produced in archegonia or antheridia in the axial region of the leaflike structures. After a spore germinates, a thin
photosynthetic filament called a protonema (which means early, or first, thread) develops and soon gives rise to a mature
gametophyte.
Procedure 1
Macroanatomy of Marchantia
1 Procure the necessary materials and supplies.
2 Using a dissecting microscope, observe the lower and upper surface of the
thallus. Pay particular attention to the diamond-shaped sections, pores, and
rhizoids. Place your labeled sketches and observations of Marchantia in the
space provided. If your specimen has gemma cups, antheridiophores, or
archegoniophores, draw and label these structures (Fig. 20.5).
Materials
Dissecting microscope
Living specimen of Marchantia
Colored pencils
A
Antheridial
receptacles
Gametophyte
thallus
B
Archegonial
receptacles
Marchantia
FIGURE 20.5 A Marchantia sp. with prominent male antheridial
receptacles, and B showing archegonial receptacles.
Chapter 20 The Green Machine: Understanding the Nonvascular Plants
303
Marchantia
Magnification
Marchantia
Magnification
Marchantia
Magnification
Check Your Understanding
1.1 What is the function of a rhizoid?
1.2 Describe asexual and sexual reproduction in Marchantia.
1.3 Compare and contrast thallus and leafy liverworts.
2
Chapter 20
The Green Machine: Understanding the Nonvascular Plants
305
TABLE 20.1 Water Absorbency Results
ml
Sphagnum
1 Weigh out 5 g portions of Sphagnum, a true sponge, an artificial sponge,
and a paper towel.
2 Add 250 ml of water to four separate beakers. Label the beakers
Sphagnum, true sponge,
artificial
sponge,
and
paper
towel. Add to
the appropriate beakers the 5 g portions of Sphagnum, a true sponge,
an artificial sponge, and a paper towel.
ml
True sponge
ml
Artificial sponge
3 Allow the material to sit in the beaker for two minutes, then remove the
materials from each beaker. Pour the water left over from each beaker
into the 100 ml graduated cylinder, and record your measurement for
each material.
ml
Paper towel
4 Record your observations in Table 20.1, and in the space provided, discuss your findings.
Check Your Understanding
3.1 Describe two ways in which mosses can reproduce.
3.2 Why was Sphagnum successful as a bandage in World War I?
3.3 Where can Polytrichum sp. be found?
0
Exploring Biology in the Laboratory
312
Chapter 20 Review
Name
Date
Section
1 What are 10 reasons you should “thank a plant”?
2 To conquer the land, what sort of adaptations did early land plants have to develop?
3 Compare and contrast nonvascular plants with vascular plants.
4 Describe the process of alternation of generations.
Chapter 20 The Green Machine: Understanding the Nonvascular Plants
313
5 Name several characteristics and give several examples of phylum Hepatophyta.
6 Name several characteristics and give several examples of phylum Anthocerophyta.
7 Name several characteristics and give several examples of phylum Bryophyta.
8 Sketch and label Polytrichum.
Polytrichum
20
314
Exploring Biology in the Laboratory
Marchantia
Magnification
Marchantia
Magnification
Marchantia
Magnification
Check Your Understanding
1.1 What is the function of a rhizoid?
1.2 Describe asexual and sexual reproduction in Marchantia.
1.3 Compare and contrast thallus and leafy liverworts.
2
Chapter 20
The Green Machine: Understanding the Nonvascular Plants
305
Anthoceros
Magnification
Anthoceros
Magnification
Check Your Understanding
2.1 What is the function of rhizoids in hornworts?
2.2 Where can one find hornworts?
Once you have completed this chapter, go to
www.createmortonpub.com/images/ebl2ebeyondthelab/nonvascularplants.pdf
to fill out a handy chart you can use for studying.
0
308
Exploring Biology in the Laboratory
ml
ml
1 Weigh out 5 g portions of Sphagnum, a true sponge, an artificial sponge, TABLE 20.1 Water Absorbency Results
and a paper towel.
Sphagnum
2 Add 250 ml of water to four separate beakers. Label the beakers
Sphagnum, true sponge, artificial
sponge,
and paper
towel. Add to
the appropriate beakers the 5 g portions of Sphagnum, a true sponge,
True sponge
an artificial sponge, and a paper towel.
Artificial sponge
3 Allow the material to sit in the beaker for two minutes, then remove the
materials from each beaker. Pour the water left over from each beaker
ml
into the 100 ml graduated cylinder, and record your measurement for
Paper towel
each material.
4 Record your observations in Table 20.1, and in the space provided, discuss your findings.
ml
Check Your Understanding
3.1 Describe two ways in which mosses can reproduce.
3.2 Why was Sphagnum successful as a bandage in World War I?
3.3 Where can Polytrichum sp. be found?
0
Exploring Biology in the Laboratory
312
Chapter 20 Review
Name
Date
Section
1 What are 10 reasons you should “thank a plant”?
2 To conquer the land, what sort of adaptations did early land plants have to develop?
3 Compare and contrast nonvascular plants with vascular plants.
4 Describe the process of alternation of generations.
Chapter 20 The Green Machine: Understanding the Nonvascular Plants
313
5 Name several characteristics and give several examples of phylum Hepatophyta.
6 Name several characteristics and give several examples of phylum Anthocerophyta.
7 Name several characteristics and give several examples of phylum Bryophyta.
8 Sketch and label Polytrichum.
Polytrichum
20
Exploring Biology in the Laboratory
314

Introduction: Plants are an essential part of life on Earth as they provide oxygen, food, shelter, shade, commercial products, and aesthetic pleasure. The diversity of plants ranges from the smallest duckweed to the tallest Sequoia. Biologists estimate that approximately 400,000 plant species exist. In this chapter, we will explore the origin of plants, their importance, and the differences between nonvascular and vascular plants.

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Description: The chapter introduces the importance of plants and their origin, followed by a cladogram of the different plant species. The first objective of the chapter is to discuss the importance of plants, and the second objective is to describe the origin of plants. The chapter outlines the differences between nonvascular and vascular plants and describes the process of alternation of generations. Additionally, the chapter gives an overview of nonvascular plants and their characteristics. The different types of nonvascular plants, including hepatophytes, anthocerophytes, and bryophytes, are described, along with their characteristics. Furthermore, the biology of and anatomy of Marchantia, Anthoceros, Polytrichum, and Sphagnum are discussed. Finally, the chapter explores the differences in water absorption in Sphagnum and other specimens.

Objectives:
1. To understand the importance of plants and their role in sustaining life on earth.
2. To comprehend the origin of plants and how they evolved to survive in various environments.
3. To differentiate between nonvascular and vascular plants and understand their unique characteristics.
4. To explain the process of alternation of generations in plants.
5. To recognize the characteristics of nonvascular plants.
6. To describe the characteristics of hepatophytes, anthocerophytes, and bryophytes, and provide examples of each.
7. To compare and contrast thallus and leafy liverworts.
8. To describe the biology and label the anatomy of Marchantia, Anthoceros, Polytrichum, and Sphagnum.
9. To compare and contrast water absorption in Sphagnum and other specimens.

Learning Outcomes:
1. Students will appreciate the significance of plants in maintaining the ecological balance.
2. Students will know the evolutionary history of plants and the challenges they face in adapting to different environments.
3. Students will recognize the diversity of plants and understand how nonvascular plants differ from vascular plants.
4. Students will understand the alternation of generations in plants and how it contributes to their reproductive cycle.
5. Students will identify the unique characteristics of nonvascular plants, such as the absence of specialized conducting tissues.
6. Students will be able to distinguish between hepatophytes, anthocerophytes, and bryophytes and their peculiarities.
7. Students will compare and contrast thallus and leafy liverworts and understand their structural differences.
8. Students will comprehend the basic biology and anatomy of Marchantia, Anthoceros, Polytrichum, and Sphagnum.
9. Students will be able to describe the water absorption process in Sphagnum and other specimens and compare their mechanisms.

Solution 1: Importance of Nonvascular Plants

Nonvascular plants play a critical role in the ecosystem as they were the first plants to colonize land. They help in soil formation, carbon cycling, and water regulation. Additionally, they also provide a habitat and a food source for many animals.

Solution 2: The Characteristics of Nonvascular Plants

Nonvascular plants are primitive plants that lack specialized conducting tissue and true roots, stems, and leaves. They reproduce asexually and have a simple body structure. Some examples of nonvascular plants include mosses, liverworts, and hornworts.

Suggested Resources/Books:
– “Botany for Gardeners” by Brian Capon
– “Plant Biology” by Alison Smith and George Coupland
– “How Plants Work: The Science Behind the Amazing Things Plants Do” by Linda Chalker-Scott

Similar Asked Questions:
1. What is the importance of plants?
2. How did plants evolve?
3. What is the difference between nonvascular and vascular plants?
4. What is alternation of generations in plants?
5. Can you describe the characteristics of nonvascular plants?

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