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Book Chapter |
Imagine paddling in a rowboat from one shore to the opposite shore with no current. The trip takes you 15 minutes. If you return to the river and venture across again, paddling to the opposite shore with the same…
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It Skips a Generation: Traits, Genes, and Crosses (Student Edition)
Book Chapter |
Long before they understood why the strategy worked, farmers knew how to crossbreed plants to obtain more desirable traits. Even today, a farmer who knows nothing about genetics can tell you that when a blue type of…
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It Skips a Generation: Traits, Genes, and Crosses (Teacher Edition)
Book Chapter |
Many of the early discoveries in genetics occured in plants. Plants have a few special characteristics that make them ideal for studying genetics. From one known cross, many genetically similar "siblings" are produced.…
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Bitterness and Non-Bitterness in Cucumbers: A Story of Mutation (Teacher Edition)
Book Chapter |
In this chapter, students explore the history of the bitter gene in cucumbers, which was found in a genebank and traded internationally between cucumber breeders. The students then explore transcription, translation,…
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Survival Strategies (Teacher Edition)
Book Chapter |
This chapter focuses on ecological principles of plant defenses and insect adaptations to these defenses. Insects either are generalists, often deterred by plant chemical defense compounds, or they are specialists that…
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Domestication: Evolving Toward Home (Teacher Edition)
Book Chapter |
This chapter explores the concept of domestication and the changes that occur in plants as they transition from wild to cultivated. Domestication is a form of evolution driven by artificial selection rather than natural…
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The Risks of Improvement: Genetic Uniformity and an Epidemic (Teacher Edition)
Book Chapter |
This chapter explores the role of genetic diversity in crops. Using hybrid corn as an example, it discusses selection—the genetic narrowing that accompanies gains in traits like yield and disease resistance—and the…
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Genetic Engineering (Teacher Edition)
Book Chapter |
This chapter focuses on genetically engineered foods. Bt corn has bacterial genes that encode a protein toxic to many insects. Therefore the corn plant makes its own pesticide. This chapter explores the DNA basis for…
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Sweet Genes in Corn (Teacher Edition)
Book Chapter |
This chapter begins with consideration of sugars made by the plant during photosynthesis and the movement of those sugars within the plant by diffusion along concentration gradients and by other processes. By exploring…
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Centers of Diversity (Teacher Edition)
Book Chapter |
This chapter discusses genetic diversity of food plants in the context of the geographic regions from which they originate. The center of origin is the site where the plant was domesticated. The center of diversity is…
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Quantitative Traits (Teacher Edition)
Book Chapter |
This chapter begins with single-gene Mendelian traits and compares them to quantitative traits where many genes are involved in determining phenotype. Quantitative trait loci (QTL) studies use molecular markers to…
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Bitterness and Non-Bitterness in Cucumbers: A Story of Mutation (Student Edition)
Book Chapter |
The bitterness of cucumbers is caused by a protein called cucurbitacin. The protein is found in the stems and leaves of many cucumber plants and this is why some people remove the skin and seeds before eating them. The…
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Survival Strategies (Student Edition)
Book Chapter |
Plants are part of complex ecosystems. They must defend themselves from predators. They also must compete with other plants for light, soil, nutrients, and water. Over time, plants have evolved many strategies for…
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Domestication: Evolving Toward Home (Student Edition)
Book Chapter |
Domestication is literally the process of bringing an organism—animal or plant—into the home. It's easy to see the evolution from wild wolf to docile dog as domestication. A domesticated plant is one that is dependent…
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The Risks of Improvement: Genetic Uniformity and an Epidemic (Student Edition)
Book Chapter |
In 1970, an epidemic swept through corn crops in the United States. The farmers alleged that the seed companies had behaved irresponsibility in releasing corn varieties that all had the same gene for T-cytoplasm, and…
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