1. The Evolution of Plant and Fungal Diversity
Chapter 17
The Evolution of Plant and Fungal Diversity

2. Chapter 17: Big Ideas Plant Evolution and Diversity Alternation of
Figure 17.0_1
Chapter 17: Big Ideas
Plant Evolution
and Diversity
Alternation of
Generations and Plant
Life Cycles
Figure 17.0_1 Chapter 17: Big Ideas
Diversity of Fungi 2

3. ALTERNATION OF GENERATIONS AND PLANT LIFE CYCLES
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4. 17.3 Haploid and diploid generations alternate in plant life cycles
Plants have an alternation of generations in which the haploid and diploid stages are distinct, multicellular bodies.
The haploid gametophyte produces gametes (eggs or sperm) by mitosis.
Fertilization results in a diploid zygote.
The zygote develops into the diploid sporophyte, which produces haploid spores by meiosis.
Spores grow into gametophytes.
Student Misconceptions and Concerns
Students can easily confuse the animal and plant reproductive cycles. However, the unique feature of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. One possible relevant exercise would be to compare the timing of mitosis and meiosis in plant and animal life cycles.
Teaching Tips
1. The authors describe four key adaptations for life on land in Module The following modules (17.3–17.13) describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize).
2. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals.
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5. Gametophyte plant (n) i s s M i t o t i o M s Sperm i s Spores (n)
Figure 17.3_s5
Gametophyte
plant (n) i s s M i t o t i o M s
Sperm i s
Spores
(n)
Gametes (n)
Egg
Meiosis
Fertilization
Zygote (2n)
Figure 17.3_s5 Alternation of generations (step 5) i s s o i t M
Key
Sporophyte
plant (2n)
Haploid (n)
Diploid (2n) 5

6. 17.4 The life cycle of a moss is dominated by the gametophyte
Gametophytes make up a bed of moss.
Gametes develop in male and female gametangia.
Sperm swim through water to the egg in the female gametangium.
Student Misconceptions and Concerns
Students can easily confuse the animal and plant reproductive cycles. However, the unique feature of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. One possible relevant exercise would be to compare the timing of mitosis and meiosis in plant and animal life cycles.
Teaching Tips
1. The authors describe four key adaptations for life on land in Module The following modules (17.3–17.13) describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize).
2. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals.
© 2012 Pearson Education, Inc. 6

7. 17.4 The life cycle of a moss is dominated by the gametophyte
The zygote
develops within the gametangium into a mature sporophyte,
which remains attached to the gametophyte.
Meiosis occurs in sporangia at the tips of the sporophyte stalks.
Haploid spores are released from the sporangium and develop into gametophyte plants.
Student Misconceptions and Concerns
Students can easily confuse the animal and plant reproductive cycles. However, the unique feature of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. One possible relevant exercise would be to compare the timing of mitosis and meiosis in plant and animal life cycles.
Teaching Tips
1. The authors describe four key adaptations for life on land in Module The following modules (17.3–17.13) describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize).
2. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals.
© 2012 Pearson Education, Inc. 7

8. Gametophytes (n) Male Mitosis and development Sperm (n) Female
Figure 17.4_s5
Gametophytes (n)
Male 5
Mitosis and
development
Sperm (n) 1
Female
gametangium
Spores (n)
Female
Egg (n) 1
Sporangium
Fertilization
Stalk 2
Figure 17.4_s5 Life cycle of a moss (step 5)
Zygote (2n)
Sporophyte (2n)
Meiosis 4
Key
Haploid (n) 3
Mitosis and
development
Diploid (2n) 8

9. DIVERSITY OF FUNGI
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10. 17.14 Fungi absorb food after digesting it outside their bodies
are absorptive heterotrophic eukaryotes,
secrete powerful enzymes to digest their food externally, and
acquire their nutrients by absorption.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. The physical relationship between a fungus and its hyphae is generally analogous to a fire hydrant and the underground water pipes. Only the fire hydrant emerges above the surface of the ground.
2. Ask your students to distinguish between fungi and animals. Both are multicellular heterotrophs lacking cellulose. Students will have to dig a little to discover that fungi have cell walls primarily composed of chitin. You might further challenge them to identify animals that also absorb their nutrients directly from their environments (for example, tapeworms).
© 2012 Pearson Education, Inc. 10

11. 17.14 Fungi absorb food after digesting it outside their bodies
Most fungi consist of a mass of threadlike hyphae making up a mycelium.
Hyphal cells
are separated by cross-walls with pores large enough for ribosomes, mitochondria, and nuclei to cross,
are sometimes multinucleate without cross-walls, and
have a huge surface area to secrete digestive enzymes and absorb food.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. The physical relationship between a fungus and its hyphae is generally analogous to a fire hydrant and the underground water pipes. Only the fire hydrant emerges above the surface of the ground.
2. Ask your students to distinguish between fungi and animals. Both are multicellular heterotrophs lacking cellulose. Students will have to dig a little to discover that fungi have cell walls primarily composed of chitin. You might further challenge them to identify animals that also absorb their nutrients directly from their environments (for example, tapeworms).
© 2012 Pearson Education, Inc. 11

12. Figure 17.14A
Figure 17.14A Mycelium on fallen conifer needles 12

13. structures (tips of hyphae)
Figure 17.14B
Reproductive
structure
Hyphae
Spore-producing
structures (tips of hyphae)
Figure 17.14B Fungal reproductive and feeding structures
Mycelium 13

14. 17.14 Fungi absorb food after digesting it outside their bodies
Fungal hyphae
are surrounded by a cell wall made of chitin instead of cellulose.
Some fungi
are parasites and
obtain their nutrients at the expense of living plants or animals.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. The physical relationship between a fungus and its hyphae is generally analogous to a fire hydrant and the underground water pipes. Only the fire hydrant emerges above the surface of the ground.
2. Ask your students to distinguish between fungi and animals. Both are multicellular heterotrophs lacking cellulose. Students will have to dig a little to discover that fungi have cell walls primarily composed of chitin. You might further challenge them to identify animals that also absorb their nutrients directly from their environments (for example, tapeworms).
© 2012 Pearson Education, Inc. 14

15. 17.14 Fungi absorb food after digesting it outside their bodies
Mycorrhizae (plural)
represent a symbiotic relationship between fungi and plant root cells and
are present in nearly all vascular plants.
Mycorrhizal fungi absorb phosphorus and other essential materials from the soil and make them available to the plant.
Sugars produced by the plant through photosynthesis nourish the mycorrhizal fungi.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. The physical relationship between a fungus and its hyphae is generally analogous to a fire hydrant and the underground water pipes. Only the fire hydrant emerges above the surface of the ground.
2. Ask your students to distinguish between fungi and animals. Both are multicellular heterotrophs lacking cellulose. Students will have to dig a little to discover that fungi have cell walls primarily composed of chitin. You might further challenge them to identify animals that also absorb their nutrients directly from their environments (for example, tapeworms).
© 2012 Pearson Education, Inc. 15

16. 17.15 Fungi produce spores in both asexual and sexual life cycles
Fungi produce huge numbers of asexual spores, each of which can germinate to form a new fungus.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The heterokaryotic stage is like the merger of two kingdoms in which both kings continue to rule.
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17. 17.15 Fungi produce spores in both asexual and sexual life cycles
In many fungi, sexual fusion of haploid hyphae leads to a heterokaryotic stage, in which cells contain two genetically distinct haploid nuclei.
Hours or centuries may pass before parental nuclei fuse to form a short-lived diploid phase.
Zygotes undergo meiosis to produce haploid spores.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The heterokaryotic stage is like the merger of two kingdoms in which both kings continue to rule.
© 2012 Pearson Education, Inc. 17

18. 17.15 Fungi produce spores in both asexual and sexual life cycles
In asexual reproduction, spore-producing structures arise from haploid mycelia that have undergone neither a heterokaryotic stage or meiosis.
Many fungi that reproduce sexually can also produce spores asexually.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The heterokaryotic stage is like the merger of two kingdoms in which both kings continue to rule.
© 2012 Pearson Education, Inc. 18

19. Key Haploid (n) Heterokaryotic stage Heterokaryotic (n  n)
Figure 17.15
Key
Haploid (n)
Heterokaryotic
stage
Heterokaryotic (n  n)
(unfused nuclei) 1
Fusion of nuclei
Diploid (2n)
Fusion of cytoplasm 2
Zygote
(2n)
Spore-producing
structures
Sexual
reproduction
Meiosis
Spores
(n)
Asexual
reproduction
Mycelium
Spore-producing
structures
Figure Generalized life cycle of a fungus 4
Germination
Germination 3
Spores (n) 19

20. 17.15 Fungi produce spores in both asexual and sexual life cycles
Molds are any rapidly growing fungus that reproduces asexually by producing spores.
Yeasts are single-celled fungi that reproduce asexually by cell division or budding.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The heterokaryotic stage is like the merger of two kingdoms in which both kings continue to rule.
© 2012 Pearson Education, Inc. 20

21. 17.16 Fungi are classified into five groups
There are over 100,000 described fungi species.
Suspected but as yet undescribed species may number as many as 1.5 million.
Sexual reproductive structures are often used to classify fungi.
Fungi and animals may have diverged
from a flagellated unikont ancestor
more than 1 billion years ago.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 21

22. 17.16 Fungi are classified into five groups
Chytrids are the
only fungi with flagellated spores and
earliest lineage of fungi.
Chytrid fungi are
common in lakes, ponds, and soil and
linked to the widespread decline of amphibian species.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 22

23. Chytrids Zygomycetes (zygote fungi) Glomeromycetes (arbuscular
Figure 17.16A
Chytrids
Zygomycetes
(zygote fungi)
Glomeromycetes
(arbuscular
mycorrhizal fungi)
Ascomycetes
(sac fungi)
Figure 17.16A A proposed phylogenetic tree of fungi
Basidiomycetes
(club fungi) 23

24. 17.16 Fungi are classified into five groups
Zygomycetes, or zygote fungi
are characterized by their protective zygosporangium, where zygotes produce haploid spores by meiosis.
This diverse group includes fast-growing molds that attack
bread
peaches,
strawberries,
sweet potatoes, and
some animals.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 24

25. Figure 17.16B
Figure 17.16B Zygomycete: Rhizopus stolonifer, black bread mold 25

26. 17.16 Fungi are classified into five groups
Glomeromycetes
form a distinct type of mycorrhizae, in which hyphae that invade plant roots branch into treelike structures known as arbuscules.
About 90% of all plants have symbiotic partnerships with glomeromycetes.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 26

27. Figure 17.16C
Figure 17.16C Glomeromycete: an arbuscule in a root cell 27

28. 17.16 Fungi are classified into five groups
Ascomycetes, or sac fungi
form saclike structures called asci, which produce spores in sexual reproduction,
live in marine, freshwater, and terrestrial habitats, and
range in size from unicellular years to elaborate morels and cup fungi.
Some ascomycetes live with green algae or cyanobacteria in symbiotic associations called lichens.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 28

29. Ascomycetes Edible morels Cup fungus Figure 17.16D
Figure 17.16D Ascomycetes
Edible morels
Cup fungus 29

30. 17.16 Fungi are classified into five groups
Basidiomycetes, or club fungi,
include common mushrooms, puffballs, and shelf fungi and
are named for their club-shaped, spore-producing structure called a basidium.
These fungi include
important forest decomposers and
particularly destructive plant parasites called rusts and smuts.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
As the authors note, chytrid fungi are suspected in the worldwide decline of many amphibian species. The following resources are entry points into the extensive information available about that significant threat to amphibian biodiversity.
The Australian government maintains a chytrid fact sheet at
The Centers for Disease Control describe the origin of the chytrid fungus at
is a website devoted to updates on amphibian disease.
© 2012 Pearson Education, Inc. 30

31. Basidiomycetes Mushrooms A puffball Shelf fungi Figure 17.16E
Figure 17.16E Basidiomycetes (club fungi)
Shelf fungi 31

32. 17.17 Fungal groups differ in their life cycles and reproductive structures
The life cycle of a black bread mold is typical of zygomycetes.
Hyphae reproduce asexually by producing spores in sporangia at the tips of upright hyphae.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The mechanism of natural selection depends in part on the overproduction of offspring. As noted in Module 17.17, a single mushroom can release as many as one billion spores. In addition to facilitating reproduction, such overproduction also increases the likelihood of dispersal.
© 2012 Pearson Education, Inc. 32

33. 17.17 Fungal groups differ in their life cycles and reproductive structures
When food is depleted, the fungus reproduces sexually.
Mycelia of different mating types join and produce a zygosporangium, a cell containing multiple nuclei from two parents.
The zygosporangium develops into a thick-walled structure that can tolerate dry, harsh conditions.
When conditions are favorable, the parental nuclei fuse to form diploid zygotes, which undergo meiosis producing haploid spores.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The mechanism of natural selection depends in part on the overproduction of offspring. As noted in Module 17.17, a single mushroom can release as many as one billion spores. In addition to facilitating reproduction, such overproduction also increases the likelihood of dispersal.
© 2012 Pearson Education, Inc. 33

34. Zygosporangium (n  n) Cells fuse Fusion of nuclei Meiosis Key
Figure 17.17A
Zygosporangium (n  n)
Cells
fuse
Hyphae of
different
mating types 2 3 1
Fusion of
nuclei 4
Young zygosporangium
(heterokaryotic)
Meiosis
Sporangium
(on stalk arising
from the
zygosporangium)
Spores
(n)
Figure 17.17A Sexual reproduction of a zygote fungus
Key
Haploid (n)
Heterokaryotic (n  n)
Diploid (2n) 34

35. 17.17 Fungal groups differ in their life cycles and reproductive structures
The life cycle of a mushroom is typical of basidiomycetes.
The heterokaryotic stage
begins when mycelia of two different mating types fuse,
forming a heterokaryotic mycelium,
which grows and produces the mushroom.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The mechanism of natural selection depends in part on the overproduction of offspring. As noted in Module 17.17, a single mushroom can release as many as one billion spores. In addition to facilitating reproduction, such overproduction also increases the likelihood of dispersal.
© 2012 Pearson Education, Inc. 35

36. 17.17 Fungal groups differ in their life cycles and reproductive structures
In the club-shaped cells called basidia, which line the gills of the mushroom, the haploid nuclei fuse, forming diploid nuclei.
Each diploid nucleus produces haploid spores by meiosis.
A mushroom can release as many as a billion spores.
If spores land on moist matter that can serve as food, they germinate and grown into haploid mycelia.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
The mechanism of natural selection depends in part on the overproduction of offspring. As noted in Module 17.17, a single mushroom can release as many as one billion spores. In addition to facilitating reproduction, such overproduction also increases the likelihood of dispersal.
© 2012 Pearson Education, Inc. 36

37. Fusion of nuclei Diploid nuclei Meiosis Basidia
Figure 17.17B_s5 3
Fusion of
nuclei
Diploid nuclei
Meiosis
Mushroom
Haploid
nuclei
Basidia 4
Spore
(n) 5
Hyphae of two
different mating types 2
Haploid
mycelia
Figure 17.17B_s5 Life cycle of a mushroom (step 5)
Heterokaryotic
mycelium
Key 1
Haploid (n)
Heterokaryotic (n  n)
Diploid (2n) 37

38. 17.18 CONNECTION: Parasitic fungi harm plants and animals
Of the 100,000 known species of fungi, about 30% are either parasites or pathogens in or on plants.
About 80% of plant diseases are caused by fungi.
Between 10 and 50% of the world’s fruit harvest is lost each year to fungal attack.
A variety of fungi, including smuts and rusts, infect grain crops.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. Students often mistakenly conceive of evolution as a deliberate and directed process. Like the elm trees described in Module 17.18, American chestnut trees were nearly driven to extinction because they did not possess adaptations that would have helped them survive the blight fungus. If evolution results from need, why then would the chestnuts or elm trees suffer? (For details on the chestnut blight, see the website of the American Phytopathological Society at
2. Module describes a variety of examples of fungal disease, noting that 80% of plant diseases are from fungi. Further, human diseases include athlete’s foot, ringworm, and vaginal yeast infections. If certain fungal infections are particularly problematic in your region, consider emphasizing them in your lecture.
3. Students are unlikely to appreciate the roles that fungi play in natural environments, or in causing human diseases, or the benefits of fungi to human society, including bioremediation and the production of drugs, alcoholic beverages, baked goods, or fuel. To increase student interest, consider starting your lectures on fungi by noting the many effects of fungi on human life. Also, consider outside of class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors.
© 2012 Pearson Education, Inc. 38

39. Figure 17.18A
Order
Figure 17.18A Stately English elms in Australia, unaffected by Dutch elm disease 39

40. Figure 17.18B
Figure 17.18B Corn smut 40

41. Figure 17.18C
Ergots
Figure 17.18C Ergots on rye 41

42. 17.18 CONNECTION: Parasitic fungi harm plants and animals
Only about 50 species of fungi are parasitic on animals.
The general term for a fungal infection is mycosis.
Skin mycoses include
ringworm, named because it appears as circular red areas on the skin,
athlete’s foot, also caused by the ringworm fungus,
vaginal yeast infections, and
deadly lung diseases.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
1. Students often mistakenly conceive of evolution as a deliberate and directed process. Like the elm trees described in Module 17.18, American chestnut trees were nearly driven to extinction because they did not possess adaptations that would have helped them survive the blight fungus. If evolution results from need, why then would the chestnuts or elm trees suffer? (For details on the chestnut blight, see the website of the American Phytopathological Society at
2. Module describes a variety of examples of fungal disease, noting that 80% of plant diseases are from fungi. Further, human diseases include athlete’s foot, ringworm, and vaginal yeast infections. If certain fungal infections are particularly problematic in your region, consider emphasizing them in your lecture.
3. Students are unlikely to appreciate the roles that fungi play in natural environments, or in causing human diseases, or the benefits of fungi to human society, including bioremediation and the production of drugs, alcoholic beverages, baked goods, or fuel. To increase student interest, consider starting your lectures on fungi by noting the many effects of fungi on human life. Also, consider outside of class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors.
© 2012 Pearson Education, Inc. 42

43. 17.19 CONNECTION: Fungi have enormous ecological benefits
supply essential nutrients to plants through symbiotic mycorrhyizae and
are essential decomposers in ecosystems, breaking down decomposing leaves, logs, and feces and dead animals.
Fungi may also be used to digest petroleum products to clean up oil spills, such as the 2010 BP spill in the Gulf of Mexico.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
Students are unlikely to appreciate the roles that fungi play in natural environments, or in causing human diseases, or the benefits of fungi to human society, including bioremediation and the production of drugs, alcoholic beverages, baked goods, or fuel. To increase student interest, consider starting your lectures on fungi by noting the many effects of fungi on human life. Also, consider outside of class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors.
© 2012 Pearson Education, Inc. 43

44. Figure 17.19
Figure A fungal mycelium 44

45. 17.20 CONNECTION: Fungi have many practical uses
Fungi have many practical uses for humans.
We eat mushrooms and cheeses modified by fungi.
Yeasts produce alcohol and cause bread to rise.
Some fungi provide antibiotics that are used to treat bacterial disease.
Fungi figure prominently in molecular biology and in biotechnology. Yeasts, for example, are often used to study molecular genetics of eukaryotes.
Fungi may play a major role in the future production of biofuels from plants.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
Students are unlikely to appreciate the roles that fungi play in natural environments, or in causing human diseases, or the benefits of fungi to human society, including bioremediation and the production of drugs, alcoholic beverages, baked goods, or fuel. To increase student interest, consider starting your lectures on fungi by noting the many effects of fungi on human life. Also, consider outside of class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors.
© 2012 Pearson Education, Inc. 45

46. Figure 17.20A
Figure 17.20A Blue cheese 46

47. Penicillium (mold) Staphylococcus aureus (bacteria) Zone of inhibited
Figure 17.20B
Penicillium
(mold)
Staphylococcus
aureus (bacteria)
Zone of
inhibited
growth
Figure 17.20B A culture of Penicillium and bacteria 47

48. Figure 17.20C
Figure 17.20C White rot fungus 48

49. 17.21 Lichens are symbiotic associations of fungi and photosynthetic organisms
Lichens consist of algae or cyanobacteria within a mass of fungal hyphae.
Many lichen associations are mutualistic.
The fungus receives food from its photosynthetic partner.
The fungal mycelium helps the alga absorb and retain water and minerals.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
Wonderful coverage of lichens can be found at the aptly named
© 2012 Pearson Education, Inc. 49

50. 17.21 Lichens are symbiotic associations of fungi and photosynthetic organisms
Lichens are important pioneers on new land, where they help to form soil.
Lichens are sensitive to air pollution, because they obtain minerals from the air.
Student Misconceptions and Concerns
1. The diverse ecological and medical roles of fungi are often underappreciated by students. Consider quizzing your students on the ecological importance of fungi and the medical and ecological significance of fungi to humans before assigning or lecturing on these topics. Such assessments can generate increased student interest and help you evaluate their background knowledge.
2. Students often view fungi as some type of plant. However, many differences between them exist (for example, fungi are not photosynthetic and have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group.
Teaching Tips
Wonderful coverage of lichens can be found at the aptly named
© 2012 Pearson Education, Inc. 50

51. Figure 17.21A
Figure 17.21A Several of the 200 to 300 species of lichen that live in Antarctica 51

52. Algal cell Fungal hyphae Figure 17.21B
Figure 17.21B The close relationship between fungal and algal partners in a lichen 52

53. Figure 17.21C
Figure 17.21C Reindeer moss, a lichen 53

54. You should now be able to
Describe the key plant adaptations to life on land.
Describe the alternation of generations life cycle. Explain why it appears that this cycle has evolved independently in algae and land plants.
Describe the key events of the moss, fern, and pine life cycles.
Explain how coal was formed; explain why coal, oil, and natural gas are called fossil fuels.
© 2012 Pearson Education, Inc. 54

55. You should now be able to
Describe the parts of a flower and explain their functions.
Describe the stages of the angiosperm life cycle.
Describe angiosperm adaptations that promote seed dispersal.
Explain how flowers are adapted to attract pollinators.
Compare the life cycles and reproductive structures in the fungal groups.
© 2012 Pearson Education, Inc. 55

56. You should now be able to
Describe the positive ecological and practical roles of fungi.
Describe the structure and characteristics of lichens.
© 2012 Pearson Education, Inc. 56

57. Figure 17.UN02
Figure 17.UN02 Reviewing the Concepts, 17.14 57

58. Ancestral green alga (a) (b) (c) (d)
Figure 17.UN03
Ancestral
green alga 1
(a)
(b) 2
(c)
Figure 17.UN03 Connecting the Concepts, question 1 3
(d) 58

59. (a) Pine tree, a gymnosperm (b) Puffball, a club fungus
Figure 17.UN04
(a) Pine tree, a gymnosperm
Figure 17.UN04 Connecting the Concepts, question 2
(b) Puffball,
a club fungus 59

60. (a) Pine tree, a gymnosperm
Figure 17.UN04_1
Figure 17.UN04_1 Connecting the Concepts, question 2: pine tree (part 1)
(a) Pine tree, a gymnosperm 60

61. (b) Puffball, a club fungus Figure 17.UN04_2
Figure 17.UN04_2 Connecting the Concepts, question 2: puffball (part 2)
(b) Puffball,
a club fungus 61