Reading Essentials for Biology Glencoe (794133), страница 15
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Reintroduction programs take members of an endangered species and breed and raise them in protected habitats.When many of the organisms have been raised, they are releasedback into the area where they would naturally live.Ferrets were reintroduced to their habitat this way. Ferrets feedon prairie dogs. At one time, the land where prairie dogs livedwas being reduced by rural land use. This was destroying thehabitat of the prairie dogs. As a result, the ferrets were losingtheir food supply and becoming endangered.
A number of ferretswere captured and a breeding program was begun. Many blackfooted ferrets have been reintroduced to the wild.An organism that is kept by humans is said to be in captivity.Some species exist only in captivity in zoos or other special places.When endangered species are in captivity, scientists try to increasetheir number. Then they try to reintroduce the species into thehabitat where they would live naturally. It is easier to reintroduceplants into the wild than animals.
Some animals raised in captivitymay lose the behaviors needed to survive in the wild.2. What are reintroductionprograms?________________________________________________________________________◗ After You ReadMini Glossarycaptivity: when people keep members of a speciesin zoos or other conservation facilitiesconservation biology: field of biology that studies methods and carrying out ways to protectbiodiversityREADING ESSENTIALShabitat corridors: natural strips of land thatallow the migration of organisms from onewilderness area to anothernatural resources: those things in the environment that are useful or needed for livingorganismsChapter 551NameDateClassSection5.2Conservation of Biodiversity, continuedreintroduction programs: programs that takemembers of an endangered species andbreed and raise them in protected habitats;when many of the organisms have beenraised, they are released back into the areawhere they would naturally livesustainable use: philosophy that promotes letting people use resources in wilderness areasin ways that will benefit them and maintainthe ecosystem1.
Review the terms and their definitions in the Mini Glossary above. Use one of the terms in asentence that supports conservation efforts in your community.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Use the diagram below to help you review this section. In the top two boxes, list one methodused to protect the natural resources.
In the bottom three boxes, explain what the methodslisted attempt to accomplish.Conservation BiologyHabitat CorridorsHabitatsSustainable UseReintroductionProgramsVisit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about conservation of biodiversity.52Chapter 5READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Endangered andThreatened SpeciesNameDateClassSection6.1 Atoms and Their Interactions◗ Before You ReadSC.B.1.4.2 The student understands that there is conservation of mass and energy whenmatter is transformed. SC.F.1.4.1 The student knows that the body processes involve specific biochemical reactions governed by biochemical principles. Also covers SC.G.1.4.2In this section you will learn about the smallest particles that make up everything you can see, feel,or touch. Think about what living and nonliving things have in common.
On the lines below, write asentence explaining your ideas.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.ElementsEverything—whether it is a rock, frog, or flower—is made ofthings called elements.
An element is a substance that cannot bebroken down into simpler chemical substances. Suppose youfound a nugget of pure gold. You could grind it into a billion bitsof powder and every tiny bit would still be gold. You could treatthe gold with every chemical there is, but the gold would neverbreak down into simpler substances. That is because gold isan element.Natural Elements in Living Things Only about 25 of the elements on Earth are needed by living organisms. Four of these elements—carbon, hydrogen, oxygen, and nitrogen—together makeup more than 96 percent of the mass of a human body. Mass isthe measure of matter a body contains.
Other elements areneeded by organisms but only in very small amounts. These elements are called trace elements. Plants get trace elements by taking them in through their roots. Animals get trace elements fromthe foods they eat.Each element has an abbreviation made of one or two letters.The abbreviation is called a symbol. For example, the symbol Cstands for carbon. H stands for hydrogen. O stands for oxygen.N stands for nitrogen. As mentioned above, these elements areimportant to the human body.READING ESSENTIALSIdentifyDefinitions Highlight thedefinition of each word thatappears in bold.1. What is an element?________________________________________________________________________Chapter 653NameDateClassSection6.1Atoms and Their Interactions, continuedAtoms: The Building Blocks of ElementsAll elements are made of atoms. Atoms are small particles thatare the basic building blocks of all matter.2.
What are the two typesof charged particles inan atom?________________________________________________Boron AtomeeEnergylevel 15p5neEnergylevel 2eAll atoms have the same basic structure. The center of the atomis the nucleus (NEW klee us; the plural of nucleus is nuclei). Allnuclei contain positively charged particles called protons, whichgive the nuclei a positive charge. Most nuclei also contain neutrons. These are particles with no charge. The space around thenucleus contains negatively charged particles called electrons.Electrons are held in this space by their attraction to the positivelycharged nucleus. The space in which electrons stay is divided intoenergy levels. The first level can hold only two electrons. Thesecond level can hold no more than eight electrons.
The thirdlevel can hold up to 18 electrons.Each atom has the same number of electrons as ithas protons. The atom as a whole has no charge.The positive charges of the electrons cancel out thenegative charges of the protons. The figure to theleft shows an example of a boron atom. Its nucleusecontains five protons and five neutrons.Each element has distinct characteristics thatresult from the number of protons in the nuclei ofthat element. For instance, the elements iron, gold,Nucleusand oxygen each have a different number of protonsin their atoms’ nuclei.Isotopes of an ElementAtoms of the same element always have the same number ofprotons. Sometimes, though, they can have different numbers ofneutrons. Atoms of the same element that have different numbersof neutrons are called isotopes (I suh tohps). Different isotopesof the same element act differently.
Scientists have developedsome useful ways to use different isotopes in medicine.54Chapter 6READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What is the structure of an atom?NameDateClassSection6.1Atoms and Their Interactions, continuedCompounds and BondingA compound is a substance made of atoms of two or moreelements. These atoms are chemically combined.
Table salt is acompound of the elements sodium and chlorine. If an electricalcurrent is passed through melted salt, the salt breaks down intothese two elements. The element chlorine is a poison. When it iscombined with sodium to form salt, the chlorine is harmless. Theproperties of a compound are different from the properties of theindividual elements that make it up.3. What is a compound?________________________________________________________________________Why do atoms combine?Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Atoms chemically combine with other atoms to form compounds only when the result is more stable than the individualatoms.
An atom becomes more stable when the energy level farthest from the nucleus is filled with the maximum number ofelectrons it can hold. For most atoms, this means when the second level has eight electrons. One way to fill energy levels is toshare electrons with other atoms. This is what hydrogen atomsdo. When two atoms share electrons, the force that holds theatoms together is called a covalent (koh VAY lunt) bond.Atom• smallest particle of an element• contains protons, neutrons, andelectronsElement• made up of atoms• cannot be broken down intosimpler substances• Hydrogen and oxygen areelements.Compound• made up of chemicallycombined elements• can be broken down into itselements• a water molecule is a compound,made up of two hydrogen atomsand one oxygen atom.READING ESSENTIALSHydrogenatomHydrogenatomWaterOxygenatomChapter 655NameDateClassSection6.1Atoms and Their Interactions, continued4.
What is a group of atomsheld together by covalentbonds called?________________________________________________________________________Hydrogen atoms have only one energy level with one electron.To be full, this level would need two electrons. For this reason, ahydrogen atom will share its one electron with another hydrogenatom. This makes both atoms more stable. The two shared electrons move in the space around the nuclei of both atoms. Thepositively charged nuclei attract the negatively charged electronsthat are shared. This attraction holds the two atoms together.When a group of atoms is held together by covalent bonds, thegroup is called a molecule.
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