Mutations (Figure 2) are changes in the genetic makeup of a plant. Mutations occur naturally and sometimes result in the development of new beneficial traits. In 1940, plant breeders learned that they could make mutations happen faster with a process called mutagenesis. Radiation or chemicals are used to change the plant's DNA, the basic molecular system of all organisms' genetic material. The goal is to cause changes in the sequence of the base pairs of DNA, which provide biochemical instructions for the development of plants. Resultant plants may possess new and desirable characteristics through this modification of their genetic material. During this process, plant breeders must grow and evaluate each plant from each seed produced. Show
Figure 2: The effects of genetic mutations in carrots. More than 2,500 plant varieties (including rice, wheat, grapefruit, lettuce and many fruits) have been developed using radiation mutagenesis (FAO/IAEA, 2008). Induced mutation breeding was widely used in the United States during the 1970's, but today few varieties are produced using this technique. As our understanding of genetics developed, so new technologies for plant variety development arose. Examples of these that are used today include genetic marker assisted breeding, where molecular markers associated with specific traits could be used to direct breeding programs, and genetic engineering. Some of the significant steps leading to the current state of the art are explained below. 1. Discovery by Watson and Crick: structure of DNA, 1953: Another milestone in the development of understanding of genetics and how genes function, was the discovery of the structure of DNA (the basis of genes), and how DNA works. Two scientists, James Watson and Francis Crick made this discovery (Pray 2008), considered to be one of the most significant scientific works in biology, largely through synthesis of the work of other scientists. Their work contributed significantly to understanding what genes were. 2. Discovering genes that move (transposons): Transposons are sections of DNA-genes-that move from one location to another on a chromosome. Transposons have been referred to as "jumping genes", genes that are able to move around. Interestingly, transposons may be manipulated to alter the DNA inside living organisms. Barbara McLintock (1950) discovered an interesting effect of transposons. She was able to show how the changes in DNA caused by transposons affected the color of maize kernels. 3. Tissue culture and plant regeneration: Another significant development in technology that was important for plant breeding was the development of micropropagation techniques, known as tissue culture (Thorpe 2007). Tissue culture permits researchers to clone plant material by excising small amounts of tissue from plants of interest, and then inducing growth of the tissue on media, to ultimately form a new plant. This new plant carries the entire genetic information of the donor plant. Exact copies of a desired plant could thus be produced without depending on pollinators, the need for seeds, and this could all be done quickly. 4. Embryo rescue: Often when distantly related plant species are hybridized are crossed, the embryos formed following fertilization will be aborted. The development of embryo rescue technology permitted crop breeders to make crosses among distantly related varieties, and then to save the resulting embryos and then grow them into whole plants through tissue culture. 5. Protoplast fusion: Protoplasts are cells that have lost their cell walls. The cell wall can be removed either by mechanical means, or by the action of enzymes. They are left with only a cell membrane surrounding the cell. Protoplasts can be manipulated in many ways that can be used in plant breeding. This includes producing hybrid cells (by means of cell fusion) and using protoplasts to introduce new genes into plant cells, which can then be grown using tissue culture techniques (Thorpe 2007). 6. Genetic engineering: Building on the above discoveries into the 1980s, advances in the field of molecular biology provided scientists with the potential to purposefully transfer DNA between organisms, whether closely or distantly related. This set the stage for potentially extremely beneficial advancement in crop breeding, but has also been very controversial. Upgrade to remove ads Only ₩37,125/year
DAVIS BACK AT IT AGAIN BEING THE WORST Terms in this set (107)The intent of the Dawes Act of 1887 was to a The perspective expressed in the excerpt most directly supported the national expansion of C d In the last quarter of the nineteenth century, American agriculture was characterized by D e Which of the following constitutes a significant change in the treatment of American Indians during the last half of the nineteenth century? D e The Ghost Dance, a religious
movement that developed in the late nineteenth century, emerged from which of the following? a Which of the following was a result of the Dawes Severalty Act of 1887 ? c From the 1880's to the beginning of the New Deal, the dominant American Indian policy of the United Stated government sought to D e
From the 1880s to the New Deal, the dominant United States government policy toward American Indians was to try to D e Frederick Jackson Turner's theory emphasized the significance of the frontier for all of the following reasons EXCEPT: D d Which of the following developments best explains the reasons for the growth of a new urban culture in the late 1800s? b Which of the following is a difference between White's and Hahn's claims in the excerpts about how American Indian societies changed in the late 1800s? a The claims made by White and Hahn about United States policies toward American Indians in the late nineteenth century are similar in that they both support which of the following arguments? c Which of the following is a similarity between White's and Hahn's overall arguments in the excerpts about interactions between American Indians and the United States in the late 1800s? b All of the following are true of railroad expansion in the late nineteenth century EXCEPT that it c Which of the following developments best explains changes in agricultural production in the United States during the 1880s and 1890s? a According to historian Frederick Jackson Turner, a key factor in the development of American individualism and democracy was D e In the speech, Lease was reacting primarily to the problems faced by which of the following groups? c Lease's views best reflect the influence of which of the following developments in social and political movements in the 1890s? b The fulfillment of advice such
as that in the excerpt most directly contributed to which of the following in the late nineteenth century? b Which of the following most accurately describes a group who acted on ideas such as those in the excerpt? d In the late nineteenth-century United States, farmers sought federal relief from distress caused by D e The chart above supports which of the following
conclusions regarding economic conditions in the United States during the last third of the nineteenth century? c The Dawes Act (1887) did which of the following? a Which of the following pairs of immigrant groups were most prominent in the construction of the first transcontinental railroad? a The Ghost Dance was an American Indian religious movement associated with D e African Americans who fled the violence of the Reconstruction South in 1879 and 1880 to start anew in Kansas were known as a Which of the following developments helps to
explain the rise in exports from the West Coast depicted in the graph? a Which of the following developments helps to explain the change in agriculture depicted in the graph? a Which of the following helps to explain the development of railroad transportation as depicted in the graph? c Which of the following was true of the Dawes Severalty Act of 1887 ? c Which of the following contexts best explains the construction of transcontinental railroads in the late 1800s? C d By the 1870s, which of the following most reflected the continuation of the trend depicted on the maps? c Between 1870 and 1900,
farmers did all of the following in an attempt to better their condition EXCEPT b Which of the following was typical of agreements such as the Fort Laramie Treaty between the United States government and American Indians in the post-Civil War West? c Which of the following contributed to reducing the conflict that article 11 and similar provisions of other treaties were designed to address? C d Article 6 of the treaty most likely reflected which of the following sentiments? b The conflict between the Sioux nation and the United States was primarily driven by differing b All
of the following contributed to the decline of open-range cattle ranching at the end of the nineteenth century EXCEPT b During the closing decades of the nineteenth century, farmers complained about all of the following EXCEPT a Access to natural resources for businesses changed from the mid-1800s to the late 1800s most directly as a result of which of the following factors? C d The "Atlanta Compromise" is the name given to the a At the end of the nineteenth century, the desire of American business to control supplies of raw materials led to c The "temporary unequal distribution of wealth" that Carnegie refers to in the excerpt resulted most directly from the b Which of the following best
explains a connection between the economic development of the West in the mid-1800s and in the late 1800s? c Which of the following arguments about Southern society in the late 1800s could the excerpt's point of view best be used to support? C d Evidence in the excerpt can best be used to support which of the following arguments about the historical situation of South after the Civil War? c The point of view of the excerpt could best be used by a historian to support the claim that the concept of the New South d The excerpt best reflects which of the following economic developments in the late 1800s? C c The practices of big-business leaders in the late 1800s best reflect which of the following actions illustrated by the excerpt? C d The excerpt best reflects which of the following economic developments in the late 1800s? b Which of the following most directly supports Blight's argument in the excerpt? a The People's (Populist) Party emerged most directly in response to which of the following late-nineteenth-century trends? C c In his Atlanta Compromise speech, Booker T. Washington called for which of the following? c
After the Civil War, some businesspeople and newspaper editors—such as the Atlanta Constitution's Henry Grady—promoted the idea of a New South. Which of the following best describes their vision for the southern states? d In
the last half of the nineteenth century, the New South advocates supported b The 1896 Supreme Court decision Plessy v. Ferguson did which of the following? a
In the late nineteenth and early twentieth centuries, which of the following was the principal public opponent of lynching in the South? D d During the late nineteenth and early twentieth centuries, southern state governments used all of the following methods to restrict African American freedoms EXCEPT D e The author of the statement above was b "In all things that are purely social we can be as separate as the fingers, yet one as the hand in all things essential to mutual progress." e The decisions of the Supreme Court in the late nineteenth and early twentieth centuries generally did which of the following? a Which of
the following best explains a connection between the economic productivity of the United States in the mid-1800s and in the late 1800s? a Which of the following was true of the South in the post-Civil War period? c All of the following were objectives of W.E.B. DuBois EXCEPT D e Which of the following labor organizations endorsed the philosophy of "bread and butter" unionism by concentrating on demands for higher wages, shorter hours, and improved work conditions? c Which of the following best accounts for the curve
on the graph above depicting immigration to the United States from Asia, Africa and the Americas between 1882 and 1900? b All of the following account for nativist sentiment against the "new immigrants" of the late nineteenth century EXCEPT that the immigrants e The excerpt best serves as evidence for which of the following developments in the late 1800s? c Which of the following can best be concluded about the late 1800s based on the situation in which the excerpt was produced? b The creation of libraries in the late 1800s as described in the excerpt best reflects which of the following developments? a "Competition is a law of nature . . . and can no more be done away with than gravitation. . . . [I]f we do not like
survival of the fittest, we have only one possible alternative, survival of the unfittest. The former is the law of civilization, the latter is the law of anti-civilization." c "Every contract, combination in form of trust orotherwise, or conspiracy, in
restraint of trade orcommerce in any territory of the United States . . .is hereby declared illegal." c These sentiments are most characteristic
of c Americans advocating the ideas expressed in the passage above would be most accurately described as d Settlement house work as described by Muncy had the most in common with women's activism during which of the following earlier periods? C d Women working in settlement houses such as Hull House initially sought to help b Which of the following was a difference between the immigration from 1865 to 1895 depicted in the graph and immigration in the 1840s and 1850s? b Which of the following was a response to both immigration in the 1850s and the immigration depicted in the graph? c Which of the following was a long-term development that contributed to the change in Chinese immigration depicted in the graph between 1875 and 1885 ? a Which of the
following most directly contributed to the overall trend depicted in the graph? b The majority of immigrants who arrived in the United States between 1821 and 1880 settled in the d The quotation above is an example of c The union membership card pictured above is designed to accomplish which of the following? c Which of the following describes a difference between Washington's and Pillow's arguments in the excerpts? Pillow advocates against labor strikes by southern agricultural workers, while Washington advocates that African American agricultural workers should strike until immigration is halted. d Which of the following describes a similarity between Washington's and Pillow's arguments in the excerpts? c Based on their claims in the excerpts, Washington and Pillow would most likely have taken different positions on which of the following social questions in the 1800s? b The cartoon above is a commentary on late-nineteenth-century a Which of the following policies would Carnegie most likely have supported? C d Which of the following groups would most likely agree with the quote above? C d Which of the following pieces of historical evidence would best modify the claim in the last paragraph of the excerpt? C d Which of the following pieces of historical evidence would support the overall argument in the excerpt? C d Which of the following pieces of historical evidence would best modify the overall argument of the excerpt? b Which of the following historical contexts contributed most directly to the diplomatic development represented in the excerpt? a The discussion of economic neutrality featured in the excerpt is best situated within which of the following historical contexts? C d The foreign policy ideas in the excerpt are best explained by which of the following nineteenth-century developments? B c Which of the following arguments about society during the Gilded Age could Gladden's purpose in the excerpt best be used to support? d The point of view expressed in the excerpt could best be used to support which of the following historical arguments about the late 1800s? b Which of the following arguments about the United States economy during the Gilded Age could the historical situation of the excerpt best be used to support? B c The cartoonist most likely supported B d The People's (Populist) Party emerged most directly in response to which of the following late-nineteenth-century trends? B c The cartoon suggests that the disparate groups that favored the People's (Populist) Party typically shared which of the following? b Which of the following groups would be most likely to support
the Populist Party? a The excerpts above appeared in the platform of which of the following political parties? c Activists formed the Populist Party most directly in response to the a Which of the following best describes the overarching goals of the Populist Party in the late nineteenth century? C d People who agreed with the argument made in the speech would most likely have recommended which of the following solutions? C d Which of the following groups included the passage above in
its platform? c Sets found in the same folderAPUSH83 terms amgranier Birdie40 terms CRylee Chapter 26/27105 terms gditmar31 Unit 6 MCQ57 terms JennyM2003 Other sets by this creatorReligion quiz study guide17 terms amcaghon Lamb of God prophecy religion quiz tuesday 10/59 terms amcaghon Gov chapter 312 terms amcaghon Crucible exam32 terms amcaghon Other Quizlet setsw culture exam 1 (chapters 14-18)200 terms lauren_shorter Case Control Studies18 terms Maggie_Keller44 Lab Values 0110 terms Eugenius15TEACHER Physics Midterm Review - CHAPTERS TWO & THREE20 terms cpsa-school1 Which of the following developments helps explain the rise in exports from the west coast depicted in the graph?Which of the following developments helps to explain the rise in exports from the West Coast depicted in the graph? An expansion in the railroad network led to greater access of western farmers to eastern markets.
Which of the following developments best explains changes in agricultural production in the United States during the 1880s and 1890s?Which of the following developments best explains changes in agricultural production in the United States during the 1880s and 1890s? New systems of transportation integrated farming into national markets.
Which of the following was true of the Dawes Act of 1887?Which of the following is true of the Dawes Act of 1887? It provided each Native American with a portion of land and provided a route to U.S. citizenship.
Which of the following arguments about southern society in the late 1800s could the excerpt's point of view best be used to support?Which of the following arguments about Southern society in the late 1800s could the excerpt's point of view best be used to support? Southern African Americans secured new constitutional rights and opportunities.
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