Reading Essentials for Biology Glencoe (794133), страница 58
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Infer What might adrought do to the longterm survival of non-seedvascular plants?________________________________________________2. Where do most horsetailsgrow?________________________________________________READING ESSENTIALSChapter 22247NameDateClassSection22.2Non-Seed Vascular Plants, continuedAdaptations in PterophytaFerns are pterophytes. According to the fossil record, fernsappeared nearly 375 million years ago during the time when clubmosses and horsetails were the main members of Earth’s plantpopulation. Ancient ferns grew tall and treelike and formedforests. Over time, ferns evolved into many species. They adaptedto different environments.
Today there are more ferns than clubmosses or horsetails.Ferns range in size from a few meters tall to only a few centimeters in diameter. Some ferns are able to live in dry areas.They become dormant, or inactive, when water is limited, thengrow and reproduce when water is available again.FrondsRootRhizomeAs with most vascular plants, the sporophyte generationof ferns has roots, stems, and leaves. When you see a plantyou know as a fern, you are seeing the sporophyte generation.
In most ferns, the main stem is underground. Thethick, underground stem is called a rhizome. The rhizome contains many starch-filled cells for food storage.Leaves of the fern are called fronds. Fronds grow upwardfrom the rhizome. Ferns are the first of the vascular plantsto have evolved leaves with branching veins of vasculartissue. The branched veins in ferns transport water andfood to and from all the cells in the plant.If you turn the frond of a fern over, you may find tinycircles of brown or rust-colored dust. These are clustersof spore-producing sporangia. Each cluster forms a sorus(plural, sori).Origins of Non-Seed Vascular Plants3. Analyze Why are nonseed vascular plantssmaller and less widespread that their prehistoric ancestors?________________________________________________248Chapter 22The earliest evidence of non-seed vascular plants comes fromthe Devonian period around 375 million years ago.
During theCarboniferous Period, large, tree-sized lycophytes, arthrophytes,and pterophytes were abundant in warm, moist forests. Thenabout 280 million years ago, Earth’s climate became cooler anddrier. Many species of non-seed vascular plants died out. Todaynon-seed vascular plants are much smaller and less widespreadthan their prehistoric ancestors.
The evolution of vascular tissuehelped these plants to live on land and to have larger body sizes incomparison to the nonvascular plants.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What is the structure of ferns?NameDateClassSection22.2Non-Seed Vascular Plants, continued◗ After You ReadMini Glossaryprothallus (proh THA lus): fern gametophyterhizome: thick, underground stem of a fern andother vascular plants; often functions as anorgan for food storagesorus: clusters of sporangia usually found on theunderside of fern frondsstrobilus (stroh BIH lus): compact cluster ofspore-bearing leaves produced by somenon-seed vascular plants1.
Read the terms and definitions in the Mini Glossary above. Write a sentence using at leasttwo of the terms.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Fill in the missing information in the table.Non-seed Vascular PlantsName of dominant generationCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Name of reproductive cell that growsinto gametophyteName of thick underground rootFirst plant to have leaves with vascular tissue3.
Explain why most non-seed vascular plants live in moist habitats.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about non-seed vascular plants.READING ESSENTIALSChapter 22249NameDateClassSection22.3 Seed PlantsSC.F.1.4.2 The student knows that body structures are uniquely designed and adapted for their function.◗ Before You ReadSeed plants are an important part of our economy.
Farmers produce corn, wheat, and oats. Apples,oranges, olives, and figs grow in orchards. In some states there are fields of strawberries, or acresplanted with grapes. Look on your kitchen shelves. See how many products originate from seeds.List those products here.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnIdentify MainIdeas Highlight every sentence in this section that hasthe word seed in it. Say thesentence aloud after youhighlight it.A seed plant is a vascular plant that produces seeds. The seedis actually a small sporophyte plant inside a protective coat.The seed may be surrounded by fruit or carried on the scales ofa cone.In seed plants, the sporophyte generation is dominant.However, alternation of generations still occurs.
The sporophyteproduces spores. The spores develop into male and female gametophytes. In seed plants, the male gametophyte is inside a structure called the pollen grain. The pollen grain contains spermcells, nutrients, and a protective outer coating. The female gametophyte, which produces the egg cell, is inside a sporophyte structure called an ovule. The ovule forms the seed after fertilization.Where does thesporophyte come from?OvaryOvules250Chapter 22The union of the sperm andegg is called fertilization.
Fertilization forms the sporophyte zygote.In most seed plants this does notrequire a continuous film of water.Remember, in nonvascular andnon-seed vascular plants the spermhave to swim to the egg on a continuous film of water.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What is a seed plant?NameDateClassSection22.3Seed Plants, continuedSince seed plants do not need this film of water for fertilization, they can grow and reproduce in a wide variety of habitats,even those with limited water.After fertilization, the zygote develops into an embryo. Anembryo is an early stage of development in an organism.An embryo is the young diploid sporophyte of a plant. Embryosof seed plants include one or more cotyledons.
Cotyledons(kah tuh LEE dunz) usually store or absorb food for the developing embryo. In conifers, or cone-bearing trees, and manyflowering plants, cotyledons are the leaflike structures on theplant’s stem when the plant comes through the soil.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What are the advantages of seeds?A seed is an embryo and its food supply inside a tough, protective coat. Seed plants have important advantages over non-seedplants. The seed contains food for the young plant until the leavesdevelop enough to carry out photosynthesis. In conifers and someflowering plants, the food supply is stored in the cotyledons. Theembryo is protected during harsh conditions by the tough seedcoat.
Some seeds have adaptations that help them move awayfrom the parent plants. The feathery tufts on dandelion seeds ormilkweed seeds are two examples of such seed adaptations. Whenthe seeds are spread out, away from the parent plants, the youngplants do not have to compete with the parent plants for sunlight,water, living space, and soil nutrients.SeedIs there diversity in seed plants?Seed plants are divided into two groups: those whose seeds areprotected by fruit, and those whose seeds are not protected byfruit. Botanists, or biologists who study plants, call plants whoseseeds are not protected by fruit, gymnosperms.
The term gymnosperm means “naked seed.” An example of seeds not protectedby fruits are the seeds released by pinecones. The gymnospermplant divisions are Cycadophyta, Ginkgophyta, Gnetophyta,and Coniferophyta.Plants that produce seeds protected by fruit are called angiosperms. A fruit includes the ripened ovary of a flower. The fruitprovides protection for seeds and helps in seed dispersal. TheAnthophyta division contains all fruit producing plants.READING ESSENTIALS1. What do you call plantsthat produce seeds protected by fruit?________________________________________________________________________Chapter 22251NameDateClassSection22.3Seed Plants, continuedAdaptations in Cycadophyta2.
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