Chapter 29 Homework

In the life cycle of bryophytes, gametophytes are the dominant stage and are generally larger than sporophytes. The sporophytes of mosses are made up of a foot, a seta, and a sporangium. The foot is embedded in the gametophyte and absorbs nutrients from it. The seta, or stalk, transports the nutrients to the sporangium, which produces spores. Rhizoids, which resemble the roots of vascular plants, anchor the gametophytes to a substrate. Rhizoids are not vascular structures.

chloroplasts. Both algae and seed plants have cells with chloroplasts.

gymnosperms. The branching pattern of the phylogenetic tree in the activity indicates that angiosperms are most closely related to gymnosperms.

gymnosperms. Both gymnosperms and dinosaurs were dominant during the Mesozoic.

charophycean. Charophyceans are the green algae most closely related to plants.

475. Plants evolved from green algae about 475 million years ago.

Ferns. Ferns are seedless vascular plants.

bryophytes. Bryophytes, such as mosses, are the extant plants that are most similar to the first plants to bear gametangia.

charophytes. These green algae and plants share many homologous features.

the development of sporopollenin to prevent the desiccation of zygotes. Without sporopollenin, plant reproduction on land would have been much more difficult. This was one of the first problems that had to be solved in order for plants to take advantage of the habitats available on land.

produces spores. The diploid generation of the plant life cycle always produces spores.

in conjunction with fungi that helped provide them with nutrients from the soil.

green algae.

had non-vascular green plants similar to liverworts forming green mats on rock.

waxy cuticle to decrease evaporation from leaves.

spores are unicellular; seeds are not.

allows it to be nourished by the parent plant.

sporopollenin

2, 3, and 4.

E

antheridia. Moss antheridia, found on the tops of male gametophytes, produce sperm.

Moisture. Moss sperm swim to archegonia.

mitosis ... mitosis. In both, gametes are produced by haploid gametophytes.

The process of meiosis produces haploid cells. The products of meiosis contain one complete set of chromosomes.

Egg, Spores, Gametophyte. Spores, which are haploid, grow by mitosis to become haploid gametophytes. The gametophyte produces eggs by mitosis; eggs are also haploid.

n mosses, the gametophyte is the dominant stage of the life cycle; in ferns, the sporophyte is the dominant stage of the life cycle. In both mosses and ferns, moisture is required for sperm to reach the egg. The gametophyte is the dominant stage of the life cycle in mosses; the sporophyte develops on the body of a gametophyte, where it lives for a briefer time than the gametophyte's life span. In ferns, the sporophyte is dominant; the gametophyte is tiny and short-lived. Both mosses and ferns have swimming sperm that require moisture to reach an egg.

open to allow gas exchange and close to decrease water loss.

They require water for reproduction.

They can easily lose water to, and absorb water from, the atmosphere.

In both groups, sperm swim from antheridia to archegonia.

stomata.

lack true leaves and roots. The bryophytes generally lack true leaves and roots, which all other plants have.

lignified vascular tissue. The polymer lignin strengthens the xylem and phloem, giving the plant more support and allowing it to grow taller.

the presence of chloroplasts.

haploid spores

The chloroplasts of plants and green algae all have both chlorophyll a and b. Of the three choices, this statement does provide the best support for the hypothesis that plants evolved from green algae. In addition to green algae and plants, euglenids and a few dinoflagellates have chlorophyll a and b. The very best evidence for the hypothesis is the derived traits shared by charophytes (a taxon of green algae) and plants.

Plant gametophytes are haploid multicellular bodies. Plant gametophytes vary in size, but they are haploid and multicellular in all plant life cycles. Look for plant gametophytes in the basic sexual life cycle of plants and in the life cycles of nonvascular and seedless vascular plants.

Sporophytes are diploid, whereas gametophytes are haploid. Look at the basic sexual life cycle of plants and the life cycles of nonvascular and seedless vascular plants.