Chapter Questions
Which statement about alternation of generations in land plants is not true?a. The gametophyte and sporophyte differ in appearance.b. Meiosis occurs in sporangia.c. Gametes are always produced by meiosis.d. The zygote is the first cell of the sporophyte generation.e. The gametophyte and sporophyte differ in chromosome number.
Which of the following provide evidence for the close relationship between land plants and stoneworts?a. Phylogenetic analysis of DNA sequencesb. Similar mechanics of mitosis and cytokinesisc. Similarities in chloroplast structured. Similarities of their biochemistrye. All of the above
Liverworts, mosses, and hornwortsa. lack a sporophyte generation.b. grow in dense masses, allowing capillary movement of water.c. possess xylem and phloem.d. possess true leaves.e. possess true roots.
Which statement about ferns is not true?a. The sporophyte is larger than the gametophyte.b. Most are heterosporous.c. The young sporophyte can grow independently of the gametophyte.d. The leaf is a megaphyll.e. The gametophytes produce archegonia and antheridia.
The fernsa. lack a gametophyte generation.b. have a large and prominent gametophyte but a much smaller sporophyte.c. are more closely related to club mosses than to horsetails.d. are monilophytes.e. produce seeds.
Contrast microphylls with megaphylls in terms of structure, evolutionary origin, and occurrence among plants.
Heterospory is thought to have evolved multiple times within plants, suggesting an advantage to the heterosporous condition. Why might heterospory Provide an evolutionary advantage over homospory?
Contrast the life cycles of mosses (see Figure 28.7 ) and ferns (see Figure 28.15 ). How are these life cycles similar, and how do they differ?
Are the morphological characters plotted on the phylogeny in Figure 28.1 consistent with your analysis of DNA sequences from the Working with Data exercise on $p .571 ?$ What characteristics of plants that we have discussed in this chapter appear to have evolved more than once in the history of land plants?
The findings of Osborne and co-workers on the evolution of megaphylls (see Figure 28.17 ) support the idea that large megaphylls became common only after the atmospheric $\mathrm{CO}_{2}$ level had dropped, so that more stomata were favored, allowing evaporation from the stomata to cool larger leaves. How might you extend that work to confirm the involvement of temperature as a factor limiting leaf size?