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Section_ⅠWarming Up & Reading — Prereading 1．What are the advantages and disadvantages of cloning?2．Not only animals but also plants can be cloned. Do you know the difference between them?Please read the following passage to get the answer.A new study of plants that are reproduced by cloning has shown why cloned plants are not identical.Scientists have known for some time that cloned organisms are not always identical: their observable characteristics and traits can vary, and this variation can be passed on to the next generation. This is despite the fact that they are derived (获得) from genetically identical founder cells.Now, a team from Oxford University, the UK, and King Abdullah University of Science and Technology, Saudi Arabia, believe they have found out why this is the case in plants: the genomes (染色体) of regenerate plants carry relatively high frequencies of new DNA sequence mutations (变异) that were not present in the genome of the donor plant.The team reported their findings in this week’s Current Biology.“Where these new mutations actually come from is still a mystery，” said Professor Harberd. “They may arise during the regeneration process itself or during the cell divisions in the donor plant that gave rise to the root cells from which the regenerate plants are created. We are planning further research to find out which of these two processes is responsible for these mutations. What we can sayis that nature has safely been employing what you might call a ’cloning’process in plants for millions of years, and that there must be good evolutionary reasons why these mutations are introduced.”The new results suggest that variation in clones of plants may have different underlying causes from those of variation in clones of animals — where it is believed that the effect of environmental factors on how animal genes are expressed is more important and no similar high frequencies of mutations have been observed.Professor Harberd said, “While our results highlight that cloned plants and animals are very different, they may give us insights into how bacterial and cancer cells replicate themselves, and how mutations arise during these processes which, ultimately, have an impact on human health.”Warming Up1．How much do are natural clone and manmade clone?Clone_is_a_way_of_making_an_exact_copy_of_another_animal_or_plant.Natural_clone_is_one_that_occurs_from_the_“parent”_in_a_natural_form_of_ cloning_without_human_help.Manmade_clone_is_one_produced_through_human_intervention_(介入)．2．Look at these pictures and tell which ones are natural clones and which ones are manmade clones.Natural_clones：AF；Manmade_clones：BCDE3．See another kind of clone. The two women soldiers look very alike. Can you explain why?They_are_called_twins._They_were_born_almost_at_the_same_time_by_the_same_ motherFast Reading1．The text is mainly about the procedure of animal cloning and the life of Dolly the sheep，as well as the reasons why cloning is still controversial.2．Read the text and then find the main idea of each paragraph.(1)Paragraph 1 (D) A．The effect of Dolly.(2)Paragraph 2 (B) B．The major uses ofcloning.(3)Paragraph 3 (E) C．People’s reaction tocloning.(4)Paragraph 4 (A) D．The definition (定义)of cloning.(5)Paragraph 5 (C) E．The problem of Dolly.Careful Reading(1)Which of the following statements about cloning is NOT true according to the text?A．Cloning is something that has been developed quite recently.B．Twins that look exactly the same are originally from the same egg.C．Cloning is used by gardeners to make more money.D．Animal cloning is much more difficult than plant cloning.(2)The cloning of Dolly the sheep succeeded because ________.A．it’s easier to clone a sheep than other animalsB．the scientists were determined and worked hard with patienceC．the scientists were rewarded and got lots of moneyD．many other attempts to clone mammals failed(3)The sheep that donated the somatic cell most probably lived ________ years.A．3 B．6C．9 D．12(4)Which of the following is NOT an advantage of cloning?A．Cloning can be used for medical purposes.B．Large quantities of food can be produced by cloning.C．Cloning can help keep animals from becoming extinct.D．Famous persons who have passed away can be cloned.(5)We can infer from the last three paragraphs that________.A．the normal development of Dolly had no effect on the cloning of other species B．Dolly’s serious disease and final death disturbed the whole worldC．Dolly successfully cloned a new lamb with the help of cloning scientists D．there were arguments about animal cloning and concerns about the future of cloning答案：(1)～(5) ABDDDSummaryCloning is a way of 1.making (make) an exact copy of another animal or plant.2.It has two major uses. One is3.that gardeners use it to produce commercial quantities of plants. The4.other is that it is valuable for research on new species and for medical research on animals.5.However,_the process of cloning is difficult to undertake.Many attempts to clone mammals failed. The first successful clone, Dolly the sheep, made the whole 6.scientific (science) world follow its process, though it had 7.more problems than the normal sheep. On the other hand, Dolly’s 8.appearance (appear) raised a storm of objections and had a great impact 9.on the media and public imagination. Different people have different opinions on it. However, scientists still wonder whether cloning will help 10.or harm us and where it is leading us.Discussionit.(1)I_am_in_favor_of_cloning,_because_medical_cloning_can_help_humans_cure_serious_illnesses_that_ruin_one’s_quality_of_life.(2)I_am_against_cloning,_because_some_people_may_want_to_clone_themselves_to_l ive_forever,_so_it_will_lead_to_some_social_problems.。
