Chapter 27 : Plants without seeds: From water to land

Hornworts

Sporophytes look like horns Gametophytes are flat plates Sporangium grow up, base of cell is the newest, in contrast to trees

What are the characteristics and life cycle of liverworts, mosses, hornworts, and ferns (seedless plants)

-Live where water is abundant -Lack vascular systems Hard to efficiently transport water and minerals, Minerals move by diffusion, Restricts growth -Lack leaves, stems and roots Have analogous structures dominating generation is gametophyte, and the second is sporophyte No marine man vascular LAND plants

Gametophytes have _________(female, egg) or ___________(male, sperm): produce __________

1. Archegonia 2. Antheridia 3. Gametes

dichotomous

A branching pattern in which the shoot divides at the apex producing two equivalent branches that subsequently never overlap.

Alternation of Generations in Land Plants

A multicellular diploid sporophyte generation that produces spores by meiosis alternates with a multicellular haploid gametophyte generation that produces gametes by mitosis. 1.gametophyte produces haploid gametes by mitosis 2.Gametes fuse to form a zygote 3.zygote develops into a diploid sporophytes 4. Sporophyte produces haploid spores. By meiosis 5.spores germinate and divide to form the haploid gametophyte

microphyll

A small leaf with a single vein, found in club mosses and their relatives.

tracheid

A type of tracheary element found in the xylem of nearly all vascular plants, characterized by tapering ends and walls that are pitted but not perforated. (Contrast with vessel element.)

Which of the following statements about plant divisions is false? Lycophytes and pterophytes are seedless vascular plants. All vascular plants produce seeds. All nonvascular embryophytes are bryophytes. Seed plants include angiosperms and gymnosperms.

All vascular plants produce seeds.

Explain what is meant by "alternation of generations" Why do we not use this phrase for humans?

Alternation of generations is a life cycle in which a multicellular diploid sporophyte generation produces spores by meiosis, alternating with a multicellular haploid ga-metophyte generation that produces gametes by mitosis. Humans (and other animals) do not have alternating sexual and asexual multicellular stages. They undergo meiosis to produce sex cells and use mitosis for growth and maintenance, not for reproduction.

rhizome

An underground stem (as opposed to a root) that runs horizontally beneath the ground.

spore

Any asexual reproductive cell capable of developing into an adult organism without gametic fusion. In plants, haploid spores develop into gametophytes, diploid spores into sporophytes.

rhizoids

Hairlike extensions of cells in mosses, liverworts, and a fewvascular plants that serve the same function as roots and root hairs in vascular plants. The term is also applied to branched, rootlike extensions of some fungi and algae.

Explain the concept of heterospory. How does heterospory provide selective advantages over homospory?

Heterospory refers to the presence of two distinct types of spores, one that develops into a female gametophyte and the other into a male gametophyte. One advantage of heterospory is that it promotes outcrossing among individuals. The fact that heterospory has evolved multiple times from homospory provides evidence that the heterosporous condition is advantageous.

Fern

Homosporous = produces 1 type of spore Vascular system is present in sporophyte (absent in gametophyte)

megagametophyte

In heterosporous plants, the female gametophyte; produces eggs.

microgametophyte

In heterosporous plants, the male gametophyte; produces sperm.

gametophyte

In plants and photosynthetic protists with alternation of generations, the multicellular haploid phase that produces the gametes.

sporophyte

In plants and protists with alternation of generations, the diploid phase that produces the spores. (Contrast with gametophyte.)

xylem

In vascular plants, the tissue that conducts water and minerals; xylem consists, in various plants, of tracheids, vessel elements, fibers, and other highly specialized cells.

phloem

In vascular plants, the vascular tissue that transports sugars and other solutes from sources to sinks.

What Domain and Kingdom are plants found ?

Kingdom: Plantae Domain: Eukariots

What restricted colonization to land and what changes enable colonization?

Loss of water : cuticle and stomata Water transport : Xylem and phloem (vascular tissue) Support against gravity : Xylem and phloem Disperse gametes : wind, seed, fruit

What is the process that produces gametes?

Meiosis

homosporous

Producing a single type of spore that gives rise to a single type of gametophyte, bearing both female and male reproductive organs.

heterosporous

Producing two types of spores, one of which gives rise to a female megaspore and the other to a male microspore

stoma

Small opening in the plant epidermis that permits gas exchange; bounded by a pair of guard cells whose osmotic status regulates the size of the opening.

Describe key adaptations of plants to the terrestrial environment, and describe the distribution of those adaptations among the liverworts, mosses, and hornworts.

Terrestrial adaptations found in all major lineages of land plants (including liverworts, mosses, and hornworts) include the cuticle, which provides a coating of waxy lipids that retards water loss; gametangia (multicellular organs that enclose plant gametes), which prevent gametes from drying out; protected embryos; pigments that provide protection against ultraviolet radiation; thick-walled spores; and a mutually beneficial association with fungi that promotes nutrient uptake from the soil. Stomata, which are small closable openings in leaves and stems that are used to regulate gas exchange, are a terrestrial adaptation that is found in all land plants except liverworts.

Explain the different possible uses of the term "plant."

The broadest use of the term "plant" refers to eukaryotes that descended from the ancestor with the first primary endosymbiosis of chloroplasts: glaucophytes, red algae, the various lineages of green algae, and land plants. Another use of the term refers to green plants (those that contain chlorophyll b, or the green algae and land plants). The most common use of "plant" refers only to land plants

Describe the evolution and distribution of different kinds of leaves and roots among the vascular plants.

The earliest rootlike structures were rhizomes—horizontal portions of stem that bear water-absorbing filaments called rhizoids. Rhizomes are retained in some modern plants, such as liverworts and mosses, and are also found in some vascular plants, such as ferns and lycophytes. Ferns and lycophytes, along with other vascular plants, also have true roots, a specialized organ for extracting water and minerals from the soil. Leaves may have originated twice among the vascular plants. The simple microphylls of lycophytes may have arisen from sterile sporangia. In contrast, the larger and more complex megaphylls, or true leaves, may have arisen from the flattening of a portion of a branching stem system that exhibited overtopping growth.

megaphyll

The generally large leaf of a fern, horsetail, or seed plant, with several to many veins. (Contrast with microphyll

archegonium

The multicellular structure that produces eggs in nonvascular land plants, ferns, and gymnosperms.

antheridium

The multicellular structure that produces the sperm in nonvascular land plants and ferns.

alternation of generations

The sexual phase, called the gametophyte generation, produces gametes, or sex cells, and the asexual phase, or sporophyte generation, produces spores asexually. In terms of chromosomes, the gametophyte is haploid (has a single set of chromosomes), and the sporophyte is diploid (has a double set). No vascular plants gametophyte is the dominate life cycle Vascular plants (Angiosperms and Gymnosperms) the sporophyte is dominate.

Which two names of plant groups are used in this figure only as convenience terms, and do not refer to clades?

The terms "algae" and "nonvascular plants" are both convenience terms, as neither of those groups forms a monophyletic group.

A Life Cycle Dependent on Water

The visible green structure of such plants is the gametophyte, which contains haploid archegonia and antheridia. Water carries sperm from the antheridia into an archegonium, inside which an egg is fertilized and grows into a multicellular, diploid sporangium.

What is the difference between Vascular and non-vascular plants.

Vascular plants are the green plants, which have specialized tissues for transporting food, water and minerals to all parts of the plant. These tissues (xylem and phloem) constitute the vascular system. These type of plants can grow much longer. Non-Vascular plants are short height plants and lack transport system for minerals, food, water and gas. These plants do not produce wood, fruits or flowers.

All nonvascular plants need ____________, for fertilization.

Water

How do the vascular tissues xylem and phloem serve the vascular plants?

Xylem conducts water and minerals from the soil to aerial parts of the plant. Xylem also provides structural support. Phloem conducts the products of photosynthesis from sites of production to sites of storage within the plant.

bryophytes are divided into three phyla:

the liverworts or Hepaticophyta, the hornworts or Anthocerotophyta, and the mosses or true Bryophyta.

embryo

young plant sporophyte, while it is still contained within a protective structure such as an egg, uterus, or seed.