Chapter 13. Diversity of Plants

a sac-like structure at the tip of the stamen in which pollen grains are produced

anther

the whorl of sepals

calyx

describes a plant without woody tissue

herbaceous

having one kind of spore that gives rise to gametophytes that give rise to both male and female gametes

homosporous

cone-like structures that contain the sporangia

strobili

a seedless vascular plant that lost roots and leaves by evolutionary reduction

whisk fern

Why do mosses grow well in the Arctic tundra? They grow better at cold temperatures. They do not require moisture. They do not have true roots and can grow on hard surfaces. There are no herbivores in the tundra.

They do not have true roots and can grow on hard surfaces.

The bryophytes are divided into three divisions: the liverworts or Marchantiophyta, the hornworts or Anthocerotophyta, and the mosses or true Bryophyta.

What are the three classes of bryophytes?

a plant that lacks vascular tissue formed of specialized cells for the transport of water and nutrients

`nonvascular plant

the growing point in a vascular plant at the tip of a shoot or root where cell division occurs

apical meristem

the female reproductive part of a flower consisting of the stigma, style, and ovary

carpel

the collection of petals

corolla

a group of angiosperms whose embryos possess two cotyledons; also known as eudicot

dicot

a group of angiosperms whose embryos possess two cotyledons; also known as dicot

eudicots

Which group are vascular plants? liverworts mosses hornworts ferns

ferns

describes a life cycle in which the haploid stage is the dominant stage

haplontic

Moss is an example of which type of plant? haplontic plant vascular plant diplontic plant seed plant

haplontic plant

At what stage does the diploid zygote form? When the female cone begins to bud from the tree When the sperm nucleus and the egg nucleus fuse When the seeds drop from the tree When the pollen tube begins to grow

hen the sperm nucleus and the egg nucleus fuse

having two kinds of spores that give rise to male and female gametophytes

heterosporous

smaller spore that produces a male gametophyte in a heterosporous plant

microsporocyte

a related group of angiosperms that produce embryos with one cotyledon and pollen with a single ridge

monocot

a group of plants in which a primitive conductive system appears

moss

the chamber that contains and protects the ovule or female megasporangium

ovary

a modified leaf interior to the sepal; colorful petals attract animal pollinator

petal

the vascular tissue responsible for transport of sugars, proteins, and other solutes

phloem

the group of structures that constitute the female reproductive organ; also called the carpel

pistil

What adaptation do seed plants have in addition to the seed that is not found in seedless plants? gametophytes vascular tissue pollen chlorophyll

pollen

a modified leaf that encloses the bud; outermost structure of a flower

sepal

(plural: sporangia) the organ within which spores are produced

sporangium

a leaf modified structurally to bear sporangia

sporophyll

the diploid plant that produces spores

sporophyte

the group of structures that contain the male reproductive organs

stamen

Pollen grains develop in which structure? the anther the stigma the filament the carpel

the anther

the earliest group of seedless vascular plants

club mosses

the ovulate strobilus on gymnosperms that contains ovules

cone

the dominant division of gymnosperms with the most variety of species

conifer

the one (monocot) or two (dicot) primitive leaves present in a seed

cotyledon

a group of non-vascular plants in which stomata appear

hornwort

a seedless vascular plant characterized by a jointed stem

horsetail

the most primitive group of non-vascular plants

liverwort

a plant in which there is a network of cells that conduct water and solutes through the organism

vascular plant

the vascular tissue responsible for long-distance transport of water and nutrients

xylem

uppermost structure of the carpel where pollen is deposited

stigma

the long thin structure that links the stigma to the ovary

style

the union of two gametes in fertilization

syngamy

Which is the most diverse group of seedless vascular plants? the liverworts the horsetails the club mosses the ferns

the ferns

summary

Angiosperms are the dominant form of plant life in most terrestrial ecosystems, comprising about 90 percent of all plant species. Most crop and ornamental plants are angiosperms. Their success results, in part, from two innovative structures: the flower and the fruit. Flowers are derived evolutionarily from modified leaves. The main parts of a flower are the sepals and petals, which protect the reproductive parts: the stamens and the carpels. The stamens produce the male gametes, which are pollen grains. The carpels contain the female gametes, which are the eggs inside ovaries. The walls of the ovary thicken after fertilization, ripening into fruit that can facilitate seed dispersal. Angiosperms' life cycles are dominated by the sporophyte stage. Double fertilization is an event unique to angiosperms. The flowering plants are divided into two main groups—the monocots and eudicots—according to the number of cotyledons in the seedlings. Basal angiosperms belong to a lineage older than monocots and eudicots.

the division to which angiosperms belong

Anthophyta

Monocots Plants in the monocot group have a single cotyledon in the seedling, and also share other anatomical features. Veins run parallel to the length of the leaves, and flower parts are arranged in a three- or six-fold symmetry. The pollen from the first angiosperms was monosulcate (containing a single furrow or pore through the outer layer). This feature is still seen in the modern monocots. True woody tissue is rarely found in monocots, and the vascular tissue of the stem is not arranged in any particular pattern. The root system is mostly adventitious (unusually positioned) with no major taproot. The monocots include familiar plants such as the true lilies (not to be confused with the water lilies), orchids, grasses, and palms. Many important crops, such as rice and other cereals (Figurea), corn, sugar cane, and tropical fruit, including bananas and pineapple, belong to the monocots

Eudicots Eudicots, or true dicots, are characterized by the presence of two cotyledons. Veins form a network in leaves. Flower parts come in four, five, or many whorls. Vascular tissue forms a ring in the stem. (In monocots, vascular tissue is scattered in the stem.) Eudicots can be herbaceous (like dandelions or violets), or produce woody tissues. Most eudicots produce pollen that is trisulcate or triporate, with three furrows or pores. The root system is usually anchored by one main root developed from the embryonic radicle. Eudicots comprise two-thirds of all flowering plants. Many species seem to exhibit characteristics that belong to either group; therefore, the classification of a plant as a monocot or a eudicot is not always clearly evident

How did the development of a vascular system contribute to the increase in size of plants?

It became possible to transport water and nutrients through the plant and not be limited by rates of diffusion. Vascularization allowed the development of leaves, which increased efficiency of photosynthesis and provided more energy for plant growth

Land plants evolved traits that made it possible to colonize land and survive out of water. Adaptations to life on land include vascular tissues, roots, leaves, waxy cuticles, and a tough outer layer that protects the spores. Land plants include nonvascular plants and vascular plants. Vascular plants, which include seedless plants and plants with seeds, have apical meristems, and embryos with nutritional stores. All land plants share the following characteristics: alternation of generations, with the haploid plant called a gametophyte and the diploid plant called a sporophyte; formation of haploid spores in a sporangium; and formation of gametes in a gametangium.

Plants are a large and varied group of organisms. There are close to 300,000 species of catalogued plants.1 Of these, about 260,000 are plants that produce seeds. Mosses, ferns, conifers, and flowering plants are all members of the plant kingdom. The plant kingdom contains mostly photosynthetic organisms; a few parasitic forms have lost the ability to photosynthesize. The process of photosynthesis uses chlorophyll, which is located in organelles called chloroplasts. Plants possess cell walls containing cellulose. Most plants reproduce sexually, but they also have diverse methods of asexual reproduction. Plants exhibit indeterminate growth, meaning they do not have a final body form, but continue to grow body mass until they die.

summary: Seedless nonvascular plants are small. The dominant stage of the life cycle is the gametophyte. Without a vascular system and roots, they absorb water and nutrients through all of their exposed surfaces. There are three main groups: the liverworts, the hornworts, and the mosses. They are collectively known as bryophytes. Vascular systems consist of xylem tissue, which transports water and minerals, and phloem tissue, which transports sugars and proteins. With the vascular system, there appeared leaves—large photosynthetic organs—and roots to absorb water from the ground. The seedless vascular plants include club mosses, which are the most primitive; whisk ferns, which lost leaves and roots by reductive evolution; horsetails, and ferns.

The first plants to colonize land were most likely closely related to modern-day mosses (bryophytes) and are thought to have appeared about 500 million years ago. They were followed by liverworts (also bryophytes) and primitive vascular plants, the pterophytes, from which modern ferns are derived. The life cycle of bryophytes and pterophytes is characterized by the alternation of generations. The completion of the life cycle requires water, as the male gametes must swim to the female gametes. The male gametophyte releases sperm, which must swim—propelled by their flagella—to reach and fertilize the female gamete or egg. After fertilization, the zygote matures and grows into a sporophyte, which in turn will form sporangia, or "spore vessels," in which mother cells undergo meiosis and produce haploid spores. The release of spores in a suitable environment will lead to germination and a new generation of gametophytes.

What are the four modern-day groups of gymnosperms?`

The four modern-day groups of gymnosperms are Coniferophyta, Cycadophyta, Gingkophyta, and Gnetophyta.`

Which of the following traits characterizes gymnosperms? The plants carry exposed seeds on modified leaves. Reproductive structures are located in a flower. After fertilization, the ovary thickens and forms a fruit. The gametophyte is longest phase of the life cycle.

The plants carry exposed seeds on modified leaves.

What adaptations do plants have that allow them to survive on land?

The sporangium of plants protects the spores from drying out. Apical meristems ensure that a plant is able to grow in the two directions required to acquire water and nutrients: up toward sunlight and down into the soil. The multicellular embryo is an important adaptation that improves survival of the developing plant in dry environments. The development of molecules that gave plants structural strength allowed them to grow higher on land and obtain more sunlight. A waxy cuticle prevents water loss from aerial surfaces.

If a flower lacked a megasporangium, what type of gamete would it not be able to form? If it lacked a microsporangium, what type of gamete would not form?

Without a megasporangium, an egg would not form; without a microsporangium, pollen would not form.

Corn develops from a seedling with a single cotyledon, displays parallel veins on its leaves, and produces monosulcate pollen. It is most likely: a gymnosperm a monocot a eudicot a basal angiosperm

a monocot

a group of plants that probably branched off before the separation of monocots and eudicots

basal angiosperms

a division of gymnosperms that grow in tropical climates and resemble palm trees

cycad

describes a life cycle in which the diploid stage is the dominant stage

diplontic

a seedless vascular plant that produces large fronds; the most advanced group of seedless vascular plants

fern

The event that leads from the haploid stage to the diploid stage in alternation of generations is ________. meiosis mitosis fertilization germinatio

fertilization

the thin stalk that links the anther to the base of the flowe

filament

(plural: gametangia) the structure within which gametes are produc

gametangium

the haploid plant that produces gametes

gametophyte

a division of gymnosperm with one living species, the Gingko biloba, a tree with fan-shaped leaves

gingkophyte

a division of gymnosperms with varied morphological features that produce vessel elements in their woody tissues

gnetophyte

The land plants are probably descendants of which of these groups? green algae red algae brown algae angiosperms

green algae

a seed plant with naked seeds (seeds exposed on modified leaves or in cones)

gymnosperm

the group of structures that constitute the female reproductive organ; also called the pistil

gynoecium

describes a life cycle in which the haploid and diploid stages alternate; also known as an alternation of generations life cycle

haplodiplontic

a megaspore mother cell; larger spore that germinates into a female gametophyte in a heterosporous plant

megasporocyte