Chapter 30
Plant Diversity II: The Evolution of Seed Plants
Teaching Objectives
Key Terrestrial Adaptations Were Crucial to the Success of Seed Plants
1. Name five terrestrial adaptations that contributed to the success of seed plants.
2. Compare the size and independence of the gametophytes of bryophytes with those of seed plants.
3. Describe the ovule of a seed plant.
4. Contrast the male gametophytes of bryophytes with those of seed plants.
5. Explain why pollen grains were an important adaptation for successful reproduction on land.
6. Explain how a seed can be said to include contributions from three distinct generations.
7. Compare spores with seeds as dispersal stages in plant life cycles.
Gymnosperms
8. Explain how climatic changes with the formation of the supercontinent Pangaea favored the spread of gymnosperms.
9. List and distinguish among the four phyla of gymnosperms.
10. Describe the life history of a pine. Indicate which structures are part of the gametophyte generation and which are part of the sporophyte generation.
Angiosperms (Flowering Plants)
11. Identify the following floral structures and describe a function for each:
a. sepal f. anther
b. petal g. stigma
c. stamen h. style
d. carpel i. ovary
e. filament j. ovule
12. Define fruit. Explain how fruits may be adapted to disperse seeds.
13. Explain why a cereal grain is a fruit rather than a seed.
14. Diagram the generalized life cycle of an angiosperm. Indicate which structures are part of the gametophyte generation and which are part of the sporophyte generation.
15. Describe the role of the generative cell and the tube cell within the angiosperm pollen grain.
16. Explain the process and function of double fertilization.
17. Explain the significance of Archaefructus.
18. Explain the significance of Amborella.
19. Distinguish between monocots and eudicots.
20. Explain how animals may have influenced the evolution of terrestrial plants and vice versa.
Plants and Human Welfare
21. Name the six angiosperms that are most important in the diet of the human species.
22. Describe the current threat to plant diversity caused by human population growth.
Student Misconceptions
1. Many students have great difficulty understanding the life cycles of seed plants in the context of alternation of gametophyte and sporophyte generations. There are a number of common problems that students may have with these life cycles:
a. Some students may not recognize that meiosis in plants is not a sexual process. Such students think of the meiotic production of megaspores and microspores in seed plants as a step in the production of gametes and do not realize that it represents the asexual production of a new generation of gametophytes.
b. Students may not recognize that the reduced gametophytes of seed plants are not equivalent to the gonads of animals, but rather represent a haploid generation that alternates with the larger sporophyte generation.
c. Students may think of the embryonic sporophyte within the seed as the offspring of the sporophyte, and not recognize that it is actually the “grandchild” of that plant and the offspring of the reduced gametophyte generation.
It is important to discuss alternation of generations in plants in simplified, generalized terms before considering the life cycles of specific plant taxa. In presenting this material, you may wish to contrast plant life cycles to the more familiar life cycles of animals, in order to confront and discuss some of the unacknowledged misconceptions that students may have.
2. Students may think of a seed as equivalent to an amniotic egg. Point out that although seeds and eggs both contain embryos, a seed includes contributions from three generations of plants. In addition to an embryonic sporophyte, a seed has a seed coat derived from the integuments of the “grandparent” sporophyte and a food supply derived from the tissues of the “parent” gametophyte.
Chapter Guide to Teaching Resources
Overview: Feeding the world
Concept 30.1The reduced gametophytes of seed plants are protected in ovules and pollen grains
Transparencies
Figure 30.2 Gametophyte/sporophyte relationships
Figure 30.3 From ovule to seed
Concept 30.2Gymnosperms bear “naked” seeds, typically on cones
Transparencies
Figure 30.5 A progymnosperm
Figure 30.6 The life cycle of a pine (layer 1)
Figure 30.6 The life cycle of a pine (layer 2)
Figure 30.6 The life cycle of a pine (layer 3)
Student Media Resource
Activity: Pine life cycle
Concept 30.3The reproductive adaptations of angiosperms include flowers and fruits
Transparencies
Figure 30.7 The structure of an idealized flower
Figure 30.10 The life cycle of an angiosperm (layer 1)
Figure 30.10 The life cycle of an angiosperm (layer 2)
Figure 30.10 The life cycle of an angiosperm (layer 3)
Figure 30.11 A primitive flowering plant?
Figure 30.12 Angiosperm diversity: Basal angiosperms, hypothetical tree of flowering plants, magnoliids
Figure 30.12 Angiosperm diversity: Monocots and eudicots
Instructor and Student Media Resources
Activity: Angiosperm life cycle
Investigation: How are trees identified by their leaves?
Video: Flower blooming time lapse
Video: Time lapse of flowering plant life cycle
Video: Bee pollinating
Video: Bat pollinating agave plant
Concept 30.4Human welfare depends greatly on seed plants
Transparency
Table 30.1 A sampling of medicines derived from seed plants
For additional resources such as digital images and lecture outlines, go to the Campbell Media Manager or the Instructor Resources section of www.campbellbiology.com.
Key Terms
anther
basal angiosperm
carpel
conifer
cotyledon
cross-pollination
dicot
double fertilization
embryo sac
endosperm
eudicot
filament
flower
fruit
integument
magnoliid
micropyle
monocot
ovary
ovule
pericarp
petal
pollen grain
pollination
progymnosperm
receptacle
seed
sepal
stamen
stigma
style
Word Roots
co- 5 with, together (coevolution: the mutual influence on the evolution of two different species interacting with each other and reciprocally influencing each other’s adaptations)
endo- 5 inner (endosperm: a nutrient-rich tissue formed by the union of a sperm cell with two polar nuclei during double fertilization, which provides nourishment to the developing embryo in angiosperm seeds)
peri- 5 around; -carp 5 fruit (pericarp: the thickened wall of a fruit)
pro- 5 before; gymno- 5 naked; -sperm 5 seed (progymnosperm: an extinct group of plants that is probably ancestral to gymnosperms and angiosperms)Instructor’s Guide for Campbell/Reece Biology, Seventh EditionChapter 30Plant Diversity II: The Evolution of Seed PlantsInstructor’s Guide for Campbell/Reece Biology, Seventh EditionChapter 30Plant Diversity II: The Evolution of Seed Plants