Bộ sách Scott Foresman reading street grade 5 advance gồm các quyển sau: 5.1.1 This Is the Way We Go to School 5.1.2 Forecasting the Weather (Earth Science) 5.1.3 Harvesting Medicine on the Hill 5.1.4 African American Athletes (Social Studies) 5.1.5 The Land of Opportunity (Social Studies) 5.2.1 When the Disaster Is Over (Social Studies) 5.2.2 A Safe Heaven (Social Studies) 5.2.3 Making Friends in Mali 5.2.4 Saving Endangered Species (Life Science) 5.2.5 The National Guard Modern Minutemen (Social Studies) 5.3.1 The Patent Process (Social Studies) 5.3.2 The Inspiration of Art (Social Studies) 5.3.3 Whats New with Dinosaur Fossils (Life Science) 5.3.4 Music Gets the Blues (Social Studies) 5.3.5 Hollywood Special Effects (Social Studies) 5.4.1 Cheaper, Faster, Better Recent Technological Innovations (Social Studies) 5.4.2 Feel, Think, Move (Life Science) 5.4.3 A Home for Humans in Outer Space Is It Possible? (Space and Technology) 5.4.4 Nathaniel Comes to Town 5.4.5 What Makes Great Athletes? (Social Studies) 5.5.1 The Sandwich Brigade 5.5.2 Inventions from Space Travel (Space and Technology) 5.5.3 Astronauts and Cosmonauts (Space and Technology) 5.5.4 The Shaping of the Continents (Earth Science) 5.5.5 Journey to Statehood (Social Studies) 5.6.1 Oceans of Resources (Social Studies) 5.6.2 MixedUp Vegetables (Life Science) 5.6.3 From Salt to Silk Precious Goods (Social Studies) 5.6.4 Flying into the 21st Century 5.6.5 Unexpected Music (Social Studies)
Trang 1Suggested levels for Guided Reading, DRA, ™
Lexile, ® and Reading Recovery ™ are provided
in the Pearson Scott Foresman Leveling Guide.
ISBN 0-328-13582-8
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Vegetables
Genre Comprehension
Skills and Strategy Text Features
Expository
nonfi ction
• Main Idea and Details
• Compare and Contrast
• Text Structure
• Captions
• Chart
• Graph
• Glossary
Scott Foresman Reading Street 5.6.2
by Laura Johnson
Life Science
Suggested levels for Guided Reading, DRA, ™
Lexile, ® and Reading Recovery ™ are provided
in the Pearson Scott Foresman Leveling Guide.
ISBN 0-328-13582-8
ì<(sk$m)=bdfica< +^-Ä-U-Ä-U
Mixe
Vegetables
Genre Comprehension
Skills and Strategy Text Features
Expository
nonfi ction
• Main Idea and Details
• Compare and Contrast
• Text Structure
• Captions
• Chart
• Graph
• Glossary
Scott Foresman Reading Street 5.6.2
by Laura Johnson
Life Science
Trang 2Reader Response
1 What is the main idea of the section on pages 16 and
17 titled Pro or Con? Use a graphic organizer like this one to note details and help you write a main idea sentence
2 How do the section headings help you understand
and organize the information presented in this book?
Choose one section and outline the information covered in it
3 How many different words in this book come from
the word gene? List them Then define them Use a
dictionary, if necessary
4 Do you think genetic alteration of food is a good
idea? Explain your answer
Main Idea:
Detail:
Detail: Detail:
Editorial Offices: Glenview, Illinois • Parsippany, New Jersey • New York, New York Sales Offices: Needham, Massachusetts • Duluth, Georgia • Glenview, Illinois
Coppell, Texas • Ontario, California • Mesa, Arizona
Mixe
Mixed- d-Up Up Vegetables
by Laura Johnson
13582_001-024_FSD 1 12/8/05 8:59:54 AM
Trang 3Every effort has been made to secure permission and provide appropriate credit for
photographic material The publisher deeply regrets any omission and pledges to
correct errors called to its attention in subsequent editions.
Unless otherwise acknowledged, all photographs are the property of Scott Foresman,
a division of Pearson Education.
Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R),
Background (Bkgd)
Opener ©Mark E Gibson/Corbis; 1 ©Ed Young/Corbis; 3 ©Mark E Gibson/Corbis;
5 ©Pierre Vauthey/Corbis; 7 (B) ©Niall Benvie/Corbis; 8 ©Ed Young/Corbis;
10 ©Anthony Bannister; Gallo Images/Corbis; 11 ©Bill Ross/Corbis; 13 ©Spencer Jones/
PictureArts/Corbis; 15 ©Doug Wilson/Corbis; 17 © Michael and Patricia Fogden/Corbis
ISBN: 0-328-13582-8
Copyright © Pearson Education, Inc
All Rights Reserved Printed in the United States of America This publication is
protected by Copyright, and permission should be obtained from the publisher
prior to any prohibited reproduction, storage in a retrieval system, or transmission
in any form by any means, electronic, mechanical, photocopying, recording, or
likewise For information regarding permission(s), write to: Permissions Department,
Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.
2 3 4 5 6 7 8 9 10 V0G1 14 13 12 11 10 09 08 07 06 05
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What Are Genetically Altered Vegetables?
What happens when you cross a cold-water fish with a tomato? You get a tomato that can swim Actually, it is no joke that you get a new tomato that can grow in very cold weather You see, most tomatoes grow best in warm weather
Arctic flounders are fish that live in very cold water
Scientists took a gene from an arctic flounder and
put it into a tomato That way they could test to see
if tomatoes could grow in cold weather
This is a strange example of a test done by
scientists to try to create a genetically altered
vegetable Genetically altered means that a change has been made to a plant or animal’s genetic
makeup Many vegetables, such as the cold-weather tomatoes, are still in the testing stages
Many genetically altered vegetables, such as corn, tomatoes, broccoli, and carrots, are sold in stores
All living things have genes Genes tell what living things will look like Your genes determine your hair color, eye color, and your height Genes in plants determine their color, size, and flavor Every cell has genes
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Trang 4A researcher grafts two plants together.
4
Why Mess with Nature?
Many people believe that altering food can be
beneficial in solving the world’s food shortage They
say that these foods can be grown in cold or dry
weather This allows farmers to grow much more
food
Other people believe that altering food is a
mistake They feel that these new foods should be
better tested for safety They worry about possible
harm to people and the Earth
As you read, you will learn how farmers and
scientists have genetically altered vegetables You
will learn how plants can be changed and what
changes are being made today You will also learn
the reasons for such changes
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Is Changing Plants a New Idea?
Farmers have been changing plants to make them better for years using two methods: selective breeding and grafting In selective breeding, a farmer chooses specific plants that have good features, such as good taste or being able to live with very little water The farmer can then breed two plants together to make a new plant that has both
of those good traits Selective breeding can only be done with plants that are closely related, such as two types of corn It often takes several years for changes
to happen
Grafting is attaching a piece of one plant to another so that the two pieces can grow together into one plant For example, an apple tree might hold up in very cold weather, but have weak branches The roots and trunk of that tree could be attached to an apple tree with strong branches The result would be a strong apple tree that can survive
in the cold
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Trang 5Why Alter Food Genetically?
Today, the most common way of genetically
altering food is called genetic engineering Scientists
change or add genetic material to the plant’s cells
The food produced from genetically altered plants
is called genetically modified food The diagram
on page 8 describes how certain plants have been
improved through genetic modification
About thirty years ago, scientists learned how
to inject genes from one life form into a totally
different one This is called genetic engineering It is
an improvement on selective breeding and grafting
because through those methods, only traits that
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Pests are a big problem for farmers.
already exist in plants can be bred into new ones
For example, a potato cannot be bred to fight off leaf-eating pests, because no potato plants have that trait Through genetic engineering, however, scientists can take genes from plants that have chemicals that protect them from insects and put them into potato plants The result is a new potato plant that can make chemicals that will protect it from insects
These newly created plants are called transgenic
organisms Transgenic organisms contain genes that
have been artificially added
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Trang 6Crop Improvement
Broccoli Ripens slower, stays green longer
Cabbage Resists attacks by caterpillars that eat its leaves
Celery Stays crisp longer
Cucumbers Resist disease and fungus
Potatoes Resist leaf-eating pests, such as caterpillars and beetles
Eggplants Have fewer seeds
Soybeans Have greater nutritional value; more protein
Artichokes Resist viruses and bacteria that cause disease
Tomatoes Ripen more slowly; resist rot and frost; have improved taste
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More than forty kinds of genetically altered crops are sold today The chart on page 8 shows some examples
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Trang 7Genetically altered vegetables can fight off insects that harm or kill crops.
What Good Are Genetically Altered Vegetables?
Genetically altered vegetables are scientific
marvels They can grow in less space and can grow
faster As a result, three crops of genetically altered
lettuce can grow in the same amount of time it took
to grow two crops of regular lettuce This can help
feed the growing world population
Genetically altered vegetables can also be
modified to grow in different climates Crops that
grow in warm places can be altered to grow in cooler
places Likewise, plants that grow in cool places can
be altered for warmer climates Vegetables can also
be changed to live without water, for a time
Many farmers use pesticides to kill insects Plants
can be altered to resist pests A pest called the corn
borer kills huge crops of corn Scientists knew about
a bacteria in soil called Bt Bt has a gene that makes
a poison that kills insects They put this Bt gene into
corn plants The result was corn that makes its own
poison to fight off the corn borer This lowers the
need for pesticides that pollute air and water
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11
Many fruits and vegetables have been genetically modified to make them look and taste better One
of the best examples of this is the Flavr Savr tomato
To create the Flavr Savr tomato, scientists changed a tomato gene to make a new feature They didn’t add any genes to the tomato
Tomatoes that ripen on the vine taste best, but ripe tomatoes are soft Ripe tomatoes bruise and tear when they are picked and shipped to stores As a result, tomatoes are picked and packed when they are firm and green, not red and ripe Then they are ripened with a special kind of gas This alters their taste
Scientists changed the gene that makes tomatoes ripen Flavr Savr tomatoes ripen on the vine, but they
do not get soft They have that ripe flavor, but they don’t bruise as easily Flavr Savr tomatoes were the first kind of genetically altered food to be sold in stores
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Trang 8As the graph shows, there is a lot of genetically modified corn and soy
You might be surprised to learn that soy is in many things you eat.
Soybeans
Corn
Cotton
90
80
70
60
50
40
30
20
10
0
1996 1997 1998 1999 2000 2001 2001 2003
Year
U.S use of genetically engineered crops
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Some genetically modified foods, such as these soybeans, taste better, look better, and are more nutritious
13
Vegetables Really Are Good for You!
Some vegetables may be new to you Soybeans have been genetically modified to become more nutritious Soybeans are a good source of protein, which our bodies need to grow and heal Scientists have created genetically altered soybeans with even more protein
Tomatoes contain lycopene, which helps fight cancer, blindness, and heart disease Genetically modified tomatoes have been created that have twice as much lycopene as unaltered tomatoes
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Trang 9Potatoes and spinach are two
of the foods that scientists are
trying to modify to contain
medicine or vaccines.
14
Scientists are attempting to genetically alter foods
to carry vaccines and medicine Vaccines prevent
diseases In 1998, scientists began to genetically
alter potatoes that contain a vaccine that prevents
a disease that causes severe stomachaches Testing is
also being done with transgenic spinach Researchers
are trying to grow spinach with a vaccine for rabies
Neither of these altered foods is ready for humans to
eat yet
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From looking at them, can you tell if these plants are genetically altered?
We don’t know how many genetically altered vegetables are grown or sent to market at this time
We do know that some of the potatoes, corn, and soybeans grown and sold in the United States come from transgenic crops How do you know if you are buying a transgenic vegetable? You probably will find it hard to find out In this country, there is no law requiring that labels tell whether the foods are genetically modified
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Trang 10Pro or Con?
There is much debate about the genetic alteration
of vegetables Many people believe the process is
helpful
Others believe that genetically modified
vegetables and other foods are a big mistake The
following are some of their reasons:
• Pests can become resistant to genetically altered
poisons Scientists put poison into cotton crops to
protect them from cotton borers But the poison
didn’t kill all the insects The remaining insects were
resistant to the poison and bred more resistent
insects As a result, crops in some areas
were killed by cotton borers that were
resistant to the poison
People are afraid that
this might be a problem
as more pests become
resistant to pesticides
• Transgenic plants are a danger to
wildlife Scientists found that the poison
put into corn to make it pest resistant
killed the caterpillars that become monarch
butterflies The caterpillars eat the milkweed
that often grows near corn crops When pollen
from transgenic corn blows around, it lands on
the milkweed The caterpillars eat the pollen
along with the milkweed In just a few days,
the caterpillars die Many people fear that
more wildlife may be killed in the same way
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17
• Transgenic vegetables have caused allergies and health problems Some transgenic vegetables have
caused health problems Some people who handled transgenic celery got severe skin rashes Doctors found out that the altered celery had a chemical that caused these rashes Crops of these vegetables are no longer grown, but people fear that new transgenic foods will cause other health problems
• Genetically modified foods need more testing
Many people believe that transgenic foods have not been tested enough In this country, the U.S
Department of Agriculture (USDA) makes the testing rules New rules have shortened the foods’ testing time People fear that shortened test times could lead to mistakes
• Genetically altered foods are not needed to feed the world’s growing population Many people
believe that the crops that already exist can feed the world They feel that selective breeding can produce more food more safely They also say that we need
to find better ways to send food to the hungry They say these measures will cut the need for genetically altered foods
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Trang 11Now Try This
Working in a small group, write an information
sheet about genetically modified vegetables
Brainstorm information and opinions to be included
One group member can record the facts and
opinions Then poll classmates about pros and cons
of genetic engineering
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Her e’s H ow to D o It!
1 Begin by writing facts about genetically modified vegetables Do not include opinions in this
section List facts about vegetables that have been genetically modified and why
2 Then list four opinions that support the idea that growing these vegetables is beneficial Write a heading for this section
3 Next, list four opinions that support the idea that growing these vegetables is a mistake Write a heading for this section
4 Share your findings with the class
5 Finally, ask the class to vote if they are for or against genetic modification List the totals on a sheet of paper and share them with the class
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