Unit B Lesson B13 Selective Breeding and GMOs
Completion requirements
Lesson B13: Selective Breeding and GMOs
Video Lesson
Humans can change the characteristics of plants through selective breeding and through genetic modification. Watch the following video to learn more about selective breeding and genetic modification.
Lesson B13: Selective Breeding and GMOs
Heirloom and Hybrid Seeds
When you look at a package of seeds, you might see the words “hybrid” or “heirloom”. Heirloom refers to something inherited or passed along through several generations – such as great-great-grandma’s special hair clip. Heirloom seeds have been around for many years. People save heirloom seeds from plants that naturally grow well. Plants from heirloom seeds are pollinated by wind or insects, without human help. They have been saved from healthy plants and used year after year to reproduce the same type of plants.
When you look at a package of seeds, you might see the words “hybrid” or “heirloom”. Heirloom refers to something inherited or passed along through several generations – such as great-great-grandma’s special hair clip. Heirloom seeds have been around for many years. People save heirloom seeds from plants that naturally grow well. Plants from heirloom seeds are pollinated by wind or insects, without human help. They have been saved from healthy plants and used year after year to reproduce the same type of plants.
Hybrid seeds come from two plants that deliberately have been cross-pollinated by humans. Hybrid seeds have been chosen because they have the best traits of both parent plants. For example, a tomato plant with strong stems might be cross-pollinated with
a tomato plant that has weak stems but makes lots of fruit. The seeds grow from a tomato plant with strong stems and lots of fruit are saved for the next crop.
However, seeds produced by hybrids are unpredictable. They will not make the exact type of plant as the parent hybrid plant. This means that hybrid plant seeds cannot be saved and used year after year to make the exact type of plant. Every year, hybrid seeds produced by two plants deliberately cross-pollinated to have specific traits must be selected.
However, seeds produced by hybrids are unpredictable. They will not make the exact type of plant as the parent hybrid plant. This means that hybrid plant seeds cannot be saved and used year after year to make the exact type of plant. Every year, hybrid seeds produced by two plants deliberately cross-pollinated to have specific traits must be selected.
Reading and Materials for This Lesson
Science in Action 7
Materials:
Science in Action 7
Reading: Pages 156–159, 168
Materials:
No other materials are required for this lesson.
Figure B.4.13.1 – Early Girl tomatoes are a type of hybrid plant.
Figure B.4.13.2 – Heirloom beefsteak tomatoes are large.
Watch More
Heirloom and Hybrid Tomatoes
Watch this video to learn more about the difference between heirloom and hybrid seeds.
Watch this video to learn more about the difference between heirloom and hybrid seeds.
Domesticated Plants
Ten thousand years ago, humans started growing food on farms rather than only gathering wild plants. Since then, people have bred wild plants selectively to obtain specific plant features. Changing wild plants through selective breeding is called domestication.
Corn was selectively bred by ancient Mayan people in Mexico. Originally, corn came from a wild grass plant called teosinte. Most teosinte plants had seed heads that were only three centimetres long and had only a few seeds (kernels).
Mayan farmers noticed that a few teosinte plants had longer heads with more kernels. They selectively bred these plants together. Over many years, selective breeding of teosinte developed into the large corn cobs that we eat and use today.
Ten thousand years ago, humans started growing food on farms rather than only gathering wild plants. Since then, people have bred wild plants selectively to obtain specific plant features. Changing wild plants through selective breeding is called domestication.
Corn was selectively bred by ancient Mayan people in Mexico. Originally, corn came from a wild grass plant called teosinte. Most teosinte plants had seed heads that were only three centimetres long and had only a few seeds (kernels).
Mayan farmers noticed that a few teosinte plants had longer heads with more kernels. They selectively bred these plants together. Over many years, selective breeding of teosinte developed into the large corn cobs that we eat and use today.
Figure B.4.13.3 – Maize plants were selectively bred so they produced many cobs with many kernels.
The banana is another example of a domesticated plant. Wild bananas are short and are full of hard seeds -- not very useful or tasty! The bananas we eat now have been selectively bred to have no seeds and to be larger. (You’ll recall that new banana
plants are grown from suckers -- new plants that grow up from the roots of their parent plants.)
Some fruits can be cross-pollinated to make new types of fruit. For example, grapefruits were developed by cross-pollinating oranges and a large Asian fruit called a pummelo (also spelled pomelo or pumelo). Interestingly, the grapefruit was known in the past as the shaddock or shattuck, but its common name today refers to the way the fruit grows, often similar to clusters of grapes.
Some fruits can be cross-pollinated to make new types of fruit. For example, grapefruits were developed by cross-pollinating oranges and a large Asian fruit called a pummelo (also spelled pomelo or pumelo). Interestingly, the grapefruit was known in the past as the shaddock or shattuck, but its common name today refers to the way the fruit grows, often similar to clusters of grapes.
Figure B.4.13.4 – Corn was developed by selectively breeding teosinte grass.
Figure B.4.13.5 – This pummelo fruit has been selectively bred with an orange to produce grapefruit.
Figure B.4.13.6 – Grapefruit is a selectively bred fruit.
Watch More
Wild banana
Wild banana plants contain large seeds. Selective breeding and reproducing by suckers allows the bananas that we eat to be seedless.
Wild banana plants contain large seeds. Selective breeding and reproducing by suckers allows the bananas that we eat to be seedless.
Cruciferous Vegetables
Cruciferous vegetables are a group of 27 vegetables including cabbage, broccoli, and cauliflower. The name cruciferous refers to the crosswise arrangement of the four petals of the flowers. Many cruciferous vegetables were produced through selective breeding.
The wild mustard plant is a species called Brassica oleracea that produces large leaves and yellow flowers. Cabbage, broccoli, cauliflower, kale, and Brussels sprouts are members of the same species as the wild mustard plant. How can all these vegetables be the same species when they look so different?
Over many years, humans selectively bred wild mustard plants with specific characteristics to develop all these vegetables. Cauliflower and broccoli were produced by selectively breeding wild mustard plants with large flower buds. Kale was the result of selective breeding wild mustard plants with large leaves. Selective breeding plants with large leaf buds at the ends of the stems produced cabbage.
Cruciferous vegetables are a group of 27 vegetables including cabbage, broccoli, and cauliflower. The name cruciferous refers to the crosswise arrangement of the four petals of the flowers. Many cruciferous vegetables were produced through selective breeding.
The wild mustard plant is a species called Brassica oleracea that produces large leaves and yellow flowers. Cabbage, broccoli, cauliflower, kale, and Brussels sprouts are members of the same species as the wild mustard plant. How can all these vegetables be the same species when they look so different?
Over many years, humans selectively bred wild mustard plants with specific characteristics to develop all these vegetables. Cauliflower and broccoli were produced by selectively breeding wild mustard plants with large flower buds. Kale was the result of selective breeding wild mustard plants with large leaves. Selective breeding plants with large leaf buds at the ends of the stems produced cabbage.
Figure B.4.13.7 – Many varieties of vegetables originate from the wild mustard plant.
Figure B.4.13.8– Brussels sprouts, cauliflower, and cabbage are the same species as the wild mustard plant.
Figure B.4.13.9 – Cauliflower.
Figure B.4.13.10 – Cabbage.
Connections
Connections: Technology
>> Genetically Modified Organisms
In the last 30 years, scientists have learned how to produce plants quickly with specific abilities. The instructions inside plant cells that tell plants to have a specific appearance or features are called genes. The term DNA refers to these instructions. Scientists can change small sections of plant genes in seeds. Changing the genes of a plant produces a genetically modified organism, or GMO.
GMO seeds have special characteristics that improve the plant or increase the yield of crops. For example, some GMO crops are developed to produce extra vitamins for malnourished people. Other GMO crops are developed so plants grow better during droughts. Some are developed with resistance to weed sprays (herbicides), the fields of which then can be sprayed to kill all plants other than the GMO plants.
However, GMO crops are also very controversial. Certain GMO crops are developed so that they do not die when weed killer is sprayed on them. Some people have concerns about farmers using weed killers on edible crops, which might affect human health in ways not yet discovered. People are also concerned that using GMO crops results in less variety in crops, causing heirloom plant varieties to become extinct. Others are concerned about using genes from one species in another, such as insect or animal genes in plants.
>> Genetically Modified Organisms
In the last 30 years, scientists have learned how to produce plants quickly with specific abilities. The instructions inside plant cells that tell plants to have a specific appearance or features are called genes. The term DNA refers to these instructions. Scientists can change small sections of plant genes in seeds. Changing the genes of a plant produces a genetically modified organism, or GMO.
GMO seeds have special characteristics that improve the plant or increase the yield of crops. For example, some GMO crops are developed to produce extra vitamins for malnourished people. Other GMO crops are developed so plants grow better during droughts. Some are developed with resistance to weed sprays (herbicides), the fields of which then can be sprayed to kill all plants other than the GMO plants.
However, GMO crops are also very controversial. Certain GMO crops are developed so that they do not die when weed killer is sprayed on them. Some people have concerns about farmers using weed killers on edible crops, which might affect human health in ways not yet discovered. People are also concerned that using GMO crops results in less variety in crops, causing heirloom plant varieties to become extinct. Others are concerned about using genes from one species in another, such as insect or animal genes in plants.
Watch More
GMO Seeds
Watch this video to learn more about GMOs.
Watch this video to learn more about GMOs.
Watch this video to learn more about how GMOs are developed by changing the genes of plant seeds.
This video explains the scientific process of developing GMO seeds.
Lesson Activity
GMO Controversy
In this activity, you will learn more about the controversy with GMOs. You will collect information on both sides of the issue. This lesson activity will help you with your Section 4 Assessment.
Download:
DOWNLOAD this document. It provides a chart for you to record your observations as you watch the documentary.
Instructions:
In this activity, you will learn more about the controversy with GMOs. You will collect information on both sides of the issue. This lesson activity will help you with your Section 4 Assessment.
Download:
DOWNLOAD this document. It provides a chart for you to record your observations as you watch the documentary.
Instructions:
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Construct a table with two columns. You can do this on a sheet of paper, type it, or use the downloaded file from above.
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Title the columns “Examples of GMO Advantages” and “Examples of GMO Disadvantages”.
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Watch the half-hour documentary Next Meal: Engineering Food, found below. As you watch the documentary, listen for examples of advantages to GMO crops and examples of disadvantages to GMO crops. Pause the video anytime and summarize the
examples in the correct column of your table.
- Save your table. It will be useful for your Section 4 Assessment.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to
guide your learning.
Unit B Lesson 13 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
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REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Self-Check Time!
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Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
The original tomato plant was a hybrid plant. Hybrids are developed by cross-pollinating two specific plants to produce seeds. However, the seeds of hybrid plants do not always produce plants identical to the original parent plant, which is
why the new tomato plants do not look the same as the parent plant.
One of several examples of selectively bred plants can be used.
- Corn was selectively bred from teosinte grass to form large juicy kernels.
- Various types of cruciferous vegetables were selectively bred from the wild mustard plant. For example, broccoli and cauliflower were developed by selectively breeding wild mustard plants with large flowers.
- Several plans were selectively bred to have no seeds: bananas, watermelons, grapes, oranges.
- Other common examples are large and consistent strawberries, large sunflowers, various tomatoes, and colourful carrots.
Genes are the instructions inside plant cells that tell plants to have a specific appearance or features.
CGMO crops have several advantages such as the following:
- GMO plants can be developed to be resistant to pests such as insects or to weed sprays (herbicides) used to kill weeds.
- GMO plants can be developed to produce specific vitamins and nutrients that humans require.
- GMO plants can increase crop yields.
The use of GMO crops results in several concerns, such as the following:
- Some GMO plants do not die from weed killer, but the weed killer used on food crops might be harmful to human health.
- After continued exposure to some weed killers (herbicides), some weeds are developing resistance to herbicides such as Roundup. If weed killers become ineffective, crop yields could decrease.
- When scientists produce GMO seeds, they might disrupt other genes accidentally and cause plants to start to make unwanted chemicals.