Ch 30 Bio

cotyledon

A seed leaf of an angiosperm embryo. Some species have one cotyledon, others two.

Angiosperms are different from all other plants because only they have _____

flowers -Angiosperms are recognized on the basis of being flowering plants.

generative cell

in a pollen grain, the cell that divides mitotically and forms two sperm cells

threats to plant diversity

- The loss of forests reduces the absorption of atmospheric carbon dioxide (CO2) that occurs during photosynthesis, potentially contributing to global warming. Also, as forests disappear, so do large numbers of plant species. - Destruction of habitat is causing extinction of many plant species - Loss of plant habitat is often accompanied by loss of the animal species that plants support - At the current rate of habitat loss, 50% of Earths species will become extinct within the next few centuries

gymnosperm

-"Naked seeds", such as pine cones and other conifers. -thrive in dry climates b/c they have the key terrestrial adaptations found in all seed plants like seeds and pollen. Some were well suited for arid climates b/c they had thick cuticles and relatively small surface areas of their needle-shaped leaves -served as the food supply for giant herbivorous dinosaurs and were involved in many other interactions with animals, including being pollinated by insects more than 100 million years ago—the earliest evidence of insect pollination in any plant group -4 phyla: Cycadophyta, Ginkgophyta, Gnetophyta, and Coniferophyta

Bristlecone pine

-Pinus longaeva -in White Mountains of California; includes some of the oldest living organisms, reaching ages of more than 4600 years -Methuselah may be the world's oldest tree

Douglas Fir

-Pseudotsuga menziesii -evergreen tree that provides more timber than any other species in North America -used for house framing, plywood, pulpwood for paper, railroad ties, boxes, and crates

Sequoia

-Sequoiadendron giganteum -huge and weighs about 2500 tons -one of the largest living organisms and also among the most ancient -the coast redwoods (Sequoia sempervirens) grow to more than 110 m tall and only found in northern California and southern Oregon

fruit

-A mature ovary of a flower that protects dormant seeds and aids in their dispersal -As seeds develop from ovules after fertilization, the ovary wall thickens and the ovary matures into a fruit -A pea pod is an example of a fruit, with seeds (mature ovules, the peas) encased in the ripened ovary (the pod) -can be fleshy or dry: Tomatoes, plums, and grapes are examples of fleshy fruits, in which the wall (pericarp) of the ovary becomes soft during ripening. Dry fruits include beans, nuts, and grains. Some dry fruits split open at maturity to release seeds -The dry, wind-dispersed fruits of grasses, harvested while on the plant, are major staple foods for humans. The cereal grains of maize, rice, wheat, and other grasses are each actually a fruit with a dry outer covering (the former wall of the ovary) that adheres to the seed coat of the seed within

double fertilization

-A mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the female gametohpyte/embryo sac to form the zygote and endosperm. -once the pollen tube penetrates the micropyle, it discharges two sperm cells into the embryo sac, and one sperm fertilizes the egg/produces a zygote while the other one fuses with the two nuclei in the central cell of the female gametophyte/produce a triploid cell -double fertilization that produces a zygote and triploid is unique to angiosperms

eudicot

-A member of a clade that contains the vast majority of flowering plants that have two embryonic seed leaves, or cotyledons -veins usually netlike -vascular tissue usually arranged in a ring -taproot (main root) is usually present -has a pollen grain with three openings -has floral organs usually in multiples of four or five -more than 2/3 of angiosperm species are eudicots; largest group is the legume family, which includes peas and beans; also includes the rose family, including many plants with ornamental flowers and some species with edible fruits like strawberry plants, apple and pear trees -most of the familiar flowering trees are eudicots like oak, walnut, willow, maple, and birch

basal angiosperm

-A member of one of three clades of early-diverging lineages of flowering plants. Examples are Amborella, water lilies, and star anise and its relatives. -3 branches: Amborella trichopoda, clade that includes water lilies, and a clade consisting of the star anise and its relatives

micropyle

-A pore in the integuments of an ovule -The pollen grain absorbs water and germinates after it adheres to the stigma of a carpel. The tube cell produces a pollen tube that grows down within the style of the carpel. After reaching the ovary, the pollen tube penetrates through the micropyle

ovule

-A structure that develops within the ovary of a seed plant and contains the female gametophyte -made up of the megasporangium, megaspore, and integument(s) -inside each, a female gametophyte develops from a megaspore and produces 1 or more eggs

dicot

-A term traditionally used to refer to flowering plants that have two embryonic seed leaves, or cotyledons. -recent molecular evidence shows that dicots don't form a clade; species once classified as dicots are now classified into eudicots, magnoliids, and several lineages of basal angiosperms -these species are paraphyletic

microsporocyte

-Diploid reproductive cell in the stamen of a plant; undergoes meiosis to produce four haploid microspores -microspore mother cell -microsporocytes are inside microsporangia, they divide by meiosis and produce microspores

heterospory

-Ferns and other close relatives of seed plants are homosporous --> seed plants had homosporous ancestors -produce megasporangia and microsporangia -megasporangia on modified leaves called megasporophylls produce megaspores that give rise to female gametophytes -microsporangia on modified leaves called microsporophylls produce microspores that give rise to male gametophytes -Each megasporangium has one megaspore; each microsporangium has many microspores

Phylum Ginkgophyta

-Ginkgo biloba (aka maiden hair tree) is the only surviving species in the phylum -these plants have flagellated sperm -has deciduous, fanlike leaves that turn gold in autumn -popular in cities b/c it tolerates air pollution well -fleshy seeds smell rancid as they decay, so landscapers only plant pollen producing trees

flower

-In an angiosperm, a short stem with four sets of modified leaves, bearing structures that function in sexual reproduction -four sets of modified leaves: sepals (starting at the base of the flower), petals (interior to the sepals), stamens and carpels (two types of fertile floral organs that produce spores; both are sporophylls) -sepals and petals are sterile floral organs, meaning that they do not produce sperm or eggs.

cross pollination

-In angiosperms, the transfer of pollen from an anther of a flower on one plant to the stigma of a flower on another plant of the same species -after its release from the anther, the pollen is carried to the sticky stigma at the tip of a carpel -some flowers self-pollinate, but most cross pollinate -cross pollination enhances genetic variation -In some species, stamens and carpels of a single flower may mature at different times, or they may be so arranged that self-pollination is unlikely.

pollen grain

-In seed plants, a structure consisting of the male gametophyte enclosed within a pollen wall -male gametophyte is in the pollen grain, not equivalent to the pollen grain -Sporopollenin in the pollen wall protects the pollen grain as it is transported by wind or by hitchhiking on an animal

Common Juniper

-Juniperus communis -its "berries" are actually ovule-producing cones with fleshy sporophylls (leaves that bear sporangia)

Phylum Coniferophyta

-Largest of the gymnosperm phyla. Most conifers are evergreens and can carry out photosynthesis year round; when spring comes, they already have fully developed leaves that take advantage of warmer, sunnier days -600 species of conifers; most species have woody cones and a few have fleshy cones; some have needle-like leaves (pines) while others have scale-like leaves (redwoods); some in northern forests and others in Southern Hemisphere -some like the dawn redwood, tamarack, and larch are deciduous and lose leaves every autumn -douglas fir, common juniper, European larch, Wollemi pine, Sequoia, Bristlecone pine

European larch

-Larix decidua -deciduous tree with needle-like leaves that turn yellow before they shed in autumn -native to mountains in central Europe -extremely cold-tolerant, able to survive winters at -50 degrees celsius

monocot

-Member of a clade consisting of flowering plants that have one embryonic seed leaf, or cotyledon -veins are usually parallel -vascular tissue is scattered -root system is usually fibrous with no main root -has a pollen grain with one opening -has floral organs usually in multiples of three -about 1/4 of angiosperm species are monocots; largest groups include orchids, grasses, and palms; grasses include maize, wheat, and rice

magnoliid

-Member of the angiosperm clade that is most closely related to the combined eudicot and monocot clades. Extant examples are magnolias, laurels, and black pepper plants -includes both woody and herbaceous species -share some traits with basal angiosperms (typically spiral rather than whorled arrangement of floral organs), but are more closely related to monocots and eudicots

conifer

-Member of the largest gymnosperm phylum. Most conifers are cone-bearing trees, such as pines and firs -most gymnosperms are conifers -heterosporous -the pine tree is the sporophyte, and its sporangia are on scalelike structures packed densely in cones; each pine tree has -two types of sporangia that produce two types of spores: microsporangia that produce microspores, and megasporangia that produce megaspores. In conifers, the two types of spores are produced by separate cones: small pollen cones and large ovulate cones.

carpel

-The ovule-producing reproductive organ of a flower, consisting of the stigma, style, and ovary -a flower can have one or more carpels -carpels are megasporophylls: they produce megaspores that give rise to female gametophytes -the "container" in which seeds are enclosed; a key structure that distinguishes angiosperms from gymnosperms -At the tip of the carpel is a sticky stigma that receives pollen. A style leads from the stigma to a structure at the base of the carpel, the ovary, which contains one or more ovules

stamen

-The pollen-producing reproductive organ of a flower, consisting of an anther and a filament -stamens are microsporophylls: They produce microspores that develop into pollen grains containing male gametophytes -consists of a stalk called the filament and a terminal sac, the anther, where pollen is produced

pollination

-The transfer of pollen to the part of a seed plant containing the ovules, a process required for fertilization. -If a pollen grain germinates (begins growing), it gives rise to a pollen tube that discharges sperm into the female gametophyte within the ovule

Wollemi pine

-Wollemia nobilis -living Wollemi pines discovered in 1994 near Sydney, Australia, and the species contained 40 known trees -now widely propagated

sperm transport in seeded vascular plants

-a pollen grain can be carried by wind or animals, eliminating the dependence on water for sperm transport, which likely contributed to their colonization of dry habitats -sperm of seed plants also do not require motility because they are carried to the eggs by pollen tubes. -The sperm of some gymnosperm species (such as cycads and ginkgos) retain the ancient flagellated condition, but flagella have been lost in the sperm of most gymnosperms and all angiosperms.

Angiosperm characteristics

-all in a single phylum Anthophyta -two key adaptations include flowers and fruits -in many species, insects or other animals transfer pollen from one flower to the sex organs on another flower -some are wind-pollinated, particularly those species that occur in dense populations, such as grasses and tree species in temperate forests -each angiosperm ovule contains a female gametophyte. If fertilized, an ovule develops into a seed -Flowers vary in symmetry and other aspects of shape, as well as size, color, and odor. Much of this diversity results from adaptation to specific pollinators

evolutionary advantage of seeds

-before seeds, the spore was the only protective stage in any plant life cycle -Moss spores may survive even if the environment becomes too cold, too hot, or too dry for the mosses themselves to live; Their tiny size enables the spores to be dispersed in a dormant state to a new area, where they can germinate and give rise to new moss gametophytes if/when conditions are favorable enough -Spores were the main way that mosses, ferns, and other seedless plants spread over Earth for the first 100 million years of plant life on land. -advantages of seeds: Spores are usually single-celled, whereas seeds are multicellular, consisting of an embryo protected by a layer of tissue, the seed coat. A seed can remain dormant for up to years after being released from the parent plant, whereas most spores have shorter lifetimes; seeds have a supply of stored food- some seeds are carried long distances away from the parental sporophyte, and if conditions are good, seeds can emerge from dormancy and germinate with stored food providing critical support for growth

pollen cone

-cone in gymnosperms that produces male gametophytes in the form of pollen grains -their scales are modified leaves (microsporophylls) that bear microsporangia. Within each microsporangium, cells called microsporocytes undergo meiosis, producing haploid microspores. Each microspore develops into a pollen grain containing a male gametophyte

adaptation of fruits and seeds that help disperse the seeds

-dandelions/maples have seeds in fruits that function like parachutes/they disperse by wind -coconuts are adapted to dispersal by water -the seeds of many angiosperms are carried by animals. Some angiosperms have fruits modified as burrs that cling to animal fur (or the clothes of humans) -Others produce edible fruits and seeds are dispersed in animal feces

what is the difference between the double fertilization in gymnosperms vs angiosperms?

-double fertilization in gymnosperms (in the Phylum Gnetophyta) gives rise to two embryos rather than one embryo (a zygote that develops into an embryo) and an endosperm (a triploid cell that develops into an endosperm), which is what happens in double fertilization in angiosperms

ovule to seed in a gymnosperm

-fleshy megasporangium is surrounded by an integument -the micropyle (opening through the integument) allows entry of a pollen grain -a megaspore develops into a female gametophyte, which produces an egg -the pollen grain contains a male gametophyte, which develops a pollen tube that discharges sperm and fertilizes the egg -fertilization starts transformation of the ovule into a seed, which consists of a sporophyte embryo, a food supply (female gametophyte turns into this food supply), and a protective seed coat derived from the integument -the megasporangium shrinks/leaves a remnant that surrounds the spore wall; it also dries out and collapses -seed includes 3 generations of plant life cycle: seed coat- diploid tissues from sporophyte, food supply- from female gametophyte tissue, embryo- new sporophyte generation

rise of gymnosperms

-fossils from the Devonian period (380 mil yrs ago) show some plants that have features of today's seed plants, like megaspores and microspores --> Archaeopteris was a heterosporous tree with woody steam but didn't have seeds -earliest evidence of seed plants comes from Elkinsia fossils (360 mil yrs old); early seed plants lived 55 mil yrs before first classified gymnosperm fossils and 200 mil yrs before first classified angiosperm fossils -early gymnosperms lived in moist Carboniferous ecosystems dominated by lycophytes, horsetails, ferns, seedless vascular plants, but in the Permian period (299-252 mil yrs ago), the climate became much drier and gymnosperms largely replaced the other plants; gymnosperms thrived in dry climates and dominated terrestrial ecosystems through much of the Mesozoic era (252-66 mil yrs ago) -Late in the Mesozoic, angiosperms began to replace gymnosperms in some ecosystems.

Amborella trichopoda

-found only on the South Pacific island of New Caledonia -may be the sole survivor of a branch at the base of the angiosperm tree

gametophyte-sporophyte relationship in nonvascular plants/mosses

-gametophyte is dominant -sporophyte is reduced and dependent on gametophyte for nutrition -well known example is the moss life cycle, where the sporophyte grows out of the archegonia by a seta lengthening and a capsule (sporangia; releases spores when mature) developing at the end of it

gametophyte-sporophyte relationship in seed plants/gymnosperms and angiosperms

-gametophyte is highly reduced/microscopic and dependent on sporophyte tissue for nutrition -sporophyte is dominant -example in gymnosperms: microscopic female gametophytes live inside the ovulate cones (sporophyte); microscopic male gametophytes live inside pollen cones -angiosperms: microscopic female gametophyte live inside the middle of the flowers (doesn't give good description in book); male gametophytes live in sections that branch off from the middle of the flower

gametophyte-sporophyte relationship in seedless vascular plants/ferns

-gametophyte is reduced and independent (photosynthetic and free-living) -sporophyte is dominant -example of the fern life cycle in ch 29

reduced gametophytes

-gametophyte reduction continued further in the vascular plant lineage that led to seed plants -gametophytes of seedless vascular plants are visible to the naked eye, but the gametophytes of most seed plants are microscopic -tiny gametophytes can develop from spores retained within the sporangia of the parental sporophyte, which protects the gametophyte from environmental stresses (drought, UV radiation) -the moist reproductive tissues of the sporophyte shield the gametophytes from UV radiation and protect them from drying out, which enables the developing gametophytes to obtain nutrients from the parental sporophyte

Phylum Cycadophyta

-have large cones and palmlike leaves (true palm species are angiosperms) -have flagellated sperm, unlike most seed plants and indicating their descent from seedless vascular plants that had motile sperm -thrived during Mesozoic era (age of cycads/age of dinosaurs) -most endangered of plants groups today, threatened by habitat destruction and other human actions

the life cycle of an angiosperm

-in the megasporangium of each ovule, the megasporocyte divides by meiosis, and one of the four megaspores produced survives and give rise to the female gametophyte -in the anther of a stamen, each microsporangium divides by meiosis and produces microspores -a microspore develops into a pollen grain; the generative cell will split and form 2 sperm, and the tube cell will produce the pollen tube -after pollination, two sperm cells are discharged in each ovule -double fertilization occurs; one sperm fertilizes the egg, forming a zygote and the other one fertilizes the central cell, forming the endosperm (food supply) -the zygote develops into an embryo packaged along with food into a seed -when a seed germinates, the embryo develops into a mature sporophyte

angiosperm evolutionary links with animals

-interactions between plants and animals can cause evolutionary change; herbivores reduce a plant's reproductive success by eating its roots, leaves, or seeds, so if an effective defense mechanism originates in a group of plants, that group will be favored by natural selection. Herbivores that overcome this defense will be favored as well -plant-pollinator interactions: On a flower with bilateral symmetry, an insect pollinator can obtain nectar only when approaching from a certain direction, which makes it more likely that pollen is placed on a part of the insect's body that will come into contact with the stigma of a flower of the same species. This reduces gene flow between diverging populations and increased rates of speciation in plants with bilateral symmetry -flower shape can affect the rate at which new species form, perhaps by affecting the behavior of insect pollinators -plant-pollinator interactions may have contributed to the increasing dominance of flowering plants in the Cretaceous period, helping to make angiosperms of central importance in ecological communities.

sepal

A modified leaf in angiosperms that helps enclose and protect a flower bud before it opens.

which foods come from angiosperms?

-maize, rice, wheat, potatoes, cassava, and sweet potatoes—yield 80% of all the calories consumed by humans -flowering plants also provide two popular beverages from tea leaves and coffee beans; cacao gives us cocoa and chocolate; spices come from the flowers (cloves, saffron), fruits and seeds (vanilla, black pepper, mustard), leaves (basil, mint, sage), and even bark (cinnamon) -We also depend on angiosperms to feed livestock: It takes 5-7 kg of grain to produce 1 kg of grain-fed beef -the crops we eat are the products of artificial selection; the number and size of seeds in domesticated plants are greater than those of their wild relatives, as in the case of maize and the grass teosinte; dramatic changes such as increased cob size and loss of the hard coating around teosinte kernels may have been initiated by as few as five mutations.

what are some other uses of seed plants?

-many seed plants are sources of wood, which consists of tough-walled xylem cells and is the primary fuel source for much of the world; is the most widely used construction material -wood pulp from conifers like fir and pine is used to make paper -human depend on seed plants for medicines; scientists have extracted and identified medicinally active compounds from many of these plants and later synthesized them; plants are also a direct source for medicinal compounds

megasporocyte

-megaspore mother cell -diploid, and undergoes meiosis to produce four haploid megaspores -megasporangia produce megasporocytes, which yield megaspores

Phylum Gnetophyta

-plants in 3 genera: Ephedra, Gnetum, Welwitschia -some are tropical while others live in the desert -Welwitschia: one species- Welwitschia mirabilis, which can live for thousands of years and is found only in deserts of southwestern Africa; straplike leaves among the largest known leaves -Ephedra: 40 species in arid regions worldwide; "Mormon tea" ; produce ephedrine, which is used as a decongestant -Gnetum: 35 species of tropical trees, shrubs, and vines native to Africa and Asia; leaves look similar to those of flowering plants and seeds look somewhat like fruits

plant-derived medicines

-scientists traced the willow's medicinal property to the chemical salicin. A synthesized derivative, acetylsalicylic acid, is what we call aspirin -atropine, pupil dilator, is from the Belladonna plant -digitalin, heart medication, is from foxglove -menthol, throat soother, is from eucalyptus tree -quinine, malaria preventative, is from cinchona tree -taxol, ovarian cancer drug, is from pacific yew -tubocurarine, muscle relaxer, is from curare tree -vinblastine, leukemia drug, is from periwinkle

main components of a mature gymnosperm seed

-seed coat (derived from integument) -embryo (new sporophyte) -food supply (female gametophyte tissue) -spore wall (surrounded by megasporangium remnant)

integument

-seed plants are unique in retaining the megasporangia within the sporophyte -layer of sporophyte tissue that contributes to the structure of an ovule of a seed plant; envelops and protects the megasporangium -gymnosperm megasporangia are surrounded by one integument, but angiosperm megasporangia are surrounded by two

what are 5 characteristics unique to seed plants?

-seeds -reduced gametophytes -heterospory -ovules -pollen

what is one hypothesis for the function of double fertilization of angiosperms?

-that double fertilization synchronizes the development of food storage in the seed with the development of the embryo. If a particular flower is not pollinated or sperm cells are not discharged into the embryo sac, fertilization does not occur, and neither endosperm nor embryo forms. So perhaps double fertilization is an adaptation that prevents flowering plants from squandering nutrients on infertile ovules.

angiosperm phylogeny

-the most recent common ancestor of extant gymnosperms and angiosperms lived about 305 mil yrs ago -angiosperms may be more closely related to several extinct lineages of woody seed plants than they are to gymnosperms -the Bennettitales and other similar lineages of extinct woody seed plants did not have carpels or flowers and hence are not classified as angiosperms -Like the Bennettitales, Amborella, water lilies, and star anise lack efficient water-conducting cells that are found in most present-day angiosperms -based on the features of ancestral species and angiosperms like Amborella, researchers have hypothesized that early angiosperms were woody shrubs that had small flowers and relatively simple water-conducting cells

what happens to the zygote and triploid cell after double fertilization in angiosperms?

-the ovule matures into a seed -The zygote develops into a sporophyte embryo with a rudimentary root and one or two seed leaves called cotyledons -The triploid central cell of the female gametophyte develops into endosperm, tissue rich in starch and other food reserves that nourish the developing embryo.

ovulate cone

-their scales are compound structures composed of both modified leaves (megasporophylls bearing megasporangia) and modified stem tissue. Within the each megasporangium, megasporocytes undergo meiosis and produce haploid megaspores inside the ovule. Surviving megaspores develop into female gametophytes, which are retained within the sporangia -it takes nearly 3 years for the male and female gametophytes to be produced and brought together and for mature seeds to form from fertilized ovules. The scales of each ovulate cone then separate, and seeds are dispersed by the wind. A seed that lands in a suitable environment germinates, its embryo emerging as a pine seedling.

fossil angiosperms

-thought to have originated during Cretaceous period 140 mil yrs ago, and by mid-Cretaceous angiosperms were dominate in some terrestrial ecosystems. Cretaceous period ended 66 mil yrs ago with extinction of dinosaurs and further increases in diversity/importance of angiosperms -none of the pollen fossils from the Jurassic period have characteristics of angiosperms, suggesting that angiosperms arose after the Jurassic period -larger flowering plant structures include Archaefructus and Leefructus, both had fossils discovered in China in rocks that are about 125 million years old; early angiosperm fossils indicate that the group arose and began to diversify over a 20- to 30-million-year period -all of the seed plants thought to have been closely related to angiosperms were woody, indicating that the common ancestor was probably woody

practical reasons why we should be concerned about the loss of plant diversity

-we have explored the potential uses of only a tiny fraction of the more than 290,000 known plant species -almost all our food is based on the cultivation of only about two dozen species of seed plants -fewer than 5,000 plant species have been studied as potential sources of medicines -The tropical rain forest may be a medicine chest of healing plants that could be extinct before we even know they exist.

petal

A modified leaf of a flowering plant; petals are the often colorful parts of a flower that advertise it to insects and other pollinators.

life cycle of a pine

1.) Each pine tree (mature sporophyte) (2n) has both ovulate and pollen cones 2.) microsporocytes produce haploid (n) microspores via meiosis. Microspore develops into a pollen grain (male gametophyte enclosed by the pollen wall) 3.) Ovulate cone has 2 ovules (2n) that each contain a megasporangium (2n) 4.) Pollination occurs when pollen grain reaches ovule through the micropyle. Pollen grain forms pollen tube that digests its way thru the megasporangium 5.) while the pollen tube develops, the megasporocyte undergoes meiosis, producing four haploids cells; one survives as a megaspore 6.) the megaspore develops into a female gametophyte that contains 2-3 archegonia, which will each form an egg 7.) by the time the egg cells mature, the sperm have developed in the pollen tube, which extends from the female gametophyte 8.) fertilization occurs usually more than a year after pollination; all eggs may be fertilized, but usually only one zygote develops into an embryo; the ovule becomes a seed, consisting of an embryo, food supply, and seed coat

endosperm

In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. Provides nourishment to the developing embryo in angiosperm seeds.

ovary

In flowers, the portion of a carpel in which the egg-containing ovules develop.

Gymnosperms were most abundant during the _____

Mesozoic

embryo sac

The female gametophyte of angiosperms, formed from the growth and division of the megaspore into a multicellular structure that typically has eight haploid nuclei.

stigma

The sticky part of a flower's carpel, which receives pollen grains

pistil

a single carpel (a simple pistil) or a group of fused carpels (a compound pistil)

When you look at a pine or maple tree, the plant you see is a _____.

diploid sporophyte -The sporophyte generation is the dominant generation of vascular plants.

In pine, the embryo develops within the __________.

female gametophyte -Large ovulate cones make megaspores that develop into female gametophytes, where one fertilized egg will develop into an embryo.

In gymnosperms, megaspores develop into __________.

female gametophytes -Even though the gametophyte stage of alternation of generations is minimized in gymnosperms and angiosperms, spores still give rise to gametophytes.

ALL seeds plants are...

heterosporous

3 reproductive adaptations that have helped the evolution of seed plants

miniaturization of their gametophytes; the advent of the seed as a resistant, dispersible stage in the life cycle; and the appearance of pollen as an airborne agent that brings gametes together

Unlike most angiosperms, grasses are pollinated by wind. As a consequence, some unnecessary parts of grass flowers have almost disappeared. Which of the following parts would you expect to be most reduced in a grass flower?

petals -petals play a role in attracting pollinators, but plants that are pollinated by wind don't need these brightly colored parts

The adaptation that made possible the colonization of dry land environments by seed plants is most likely the result of the evolution of _____.

pollen -In bryophytes and seedless vascular plants, flagellated sperm must swim through a film of water to reach the egg cells. In seed plants, the use of airborne pollen to bring gametes together is a terrestrial adaptation.

The major difference between angiosperms and gymnosperms comes from the _____.

presence or absence of a protective covering over the ovule -Angiosperms have a protective covering over the ovule. Gymnosperms do not. All the other traits listed are shared by both groups.

Human survival literally depends on the produce of _____.

produce -Angiosperms are the source of our major food crops, including rice, wheat, maize, and barley. They also provide cotton and linen, and medicines such as digitalis and codeine. Rubber, coffee, chocolate, and aromatic oils come from flowering plants. Woods such as oak, cherry, and walnut are derived from angiosperms

tube cell

the cell of a pollen grain that gives rise to the pollen tube

style

the stalk of a flower's carpel, with the ovary at the base and the stigma at the top

filament

the stalk portion of the stamen, the pollen-producing reproductive organ of a flower

anther

the terminal pollen sac of a stamen, where pollen grains containing sperm-producing male gametophytes form